Stack trace all black & void arg fix

Reviewed-on: #12

.gitignore

@@ -11,3 +11,6 @@ iso_root
 symbols.map
 symbols.S
 *.log
+build/
+compile_commands.json
+.cache/

DOOM.txt

@@ -1,24 +0,0 @@
-up to doom:
-
-- Return from pedicel_main() normally (to idle)
-
-** Checkpoint: ring0 process working
-
-- VFS layer (open/read/write/...) with USTar filesystem (for initrd)
-
-** Checkpoint: files not linked to but accessible by the kernel
-
-- Ring3 memory mappings 
-- Ring3 privilege switch
-
-** Checkpoint: welcome to userland
-
-- Syscall interface
-- Implement syscalls needed for doom
-
-** Checkpoint: can run simple programs, ring 3, loaded from filesystem 
-
-- Properly handle the keyboard interrupt (keyboard buffer)
-- Port DOOMgeneric (few functions with Framebuffer/ticks/etc.)
-
-** Achievement: It runs doom!

Makefile

@@ -1,16 +1,21 @@
 SOURCES = src/debug/misc.c src/io/term/flanterm_backends/fb.c src/io/term/flanterm.c src/debug/panic.c src/debug/stacktrace.c src/boot/boot.c src/sched/scheduler.c src/sched/process.c src/mem/heap/kheap.c src/mem/paging/vmm.c src/mem/paging/paging.c src/mem/paging/pmm.c src/string/string.c src/io/kbd/ps2.c src/io/serial/serial.c src/io/term/printf.c src/io/term/term.c src/idt/idt.c src/mem/gdt/gdt.c src/mem/misc/utils.c src/time/timer.c src/kmain.c
 
-PROBLEMATIC_FLAGS=-Wno-unused-parameter -Wno-unused-variable
+CC_FLAGS=-Wall -Wextra -std=gnu99 -nostdlib -ffreestanding -fno-stack-protector -fno-omit-frame-pointer -fno-stack-check -fno-PIC -ffunction-sections -fdata-sections -mcmodel=kernel
+CC_PROBLEMATIC_FLAGS=-Wno-unused-parameter -Wno-unused-variable
+
+.PHONY: build build-iso debug debug2 run clean
 
 build:
-	rm -f *.o
+	mkdir -p build
-	x86_64-elf-gcc -g -c -Isrc $(SOURCES) $(PROBLEMATIC_FLAGS) -Wall -Wextra -std=gnu99 -nostdlib -ffreestanding -fno-stack-protector -fno-omit-frame-pointer -fno-stack-check -fno-PIC -ffunction-sections -fdata-sections -mcmodel=kernel
+	rm -f *.o build/*.o
-	nasm -f elf64 src/idt/idt.S -o idt_stub.o
+	x86_64-elf-gcc -g -c -Isrc $(SOURCES) $(CC_PROBLEMATIC_FLAGS) $(CC_FLAGS)
-	x86_64-elf-ld -o pepperk -T linker.ld *.o
+	mv *.o build/
+	nasm -f elf64 src/idt/idt.S -o build/idt_stub.o
+	x86_64-elf-ld -o pepperk -T linker.ld build/*.o
 	nm -n pepperk | awk '$$2 ~ /[TtDdBbRr]/ {print $$1, $$3}' > symbols.map
 	python3 symbols.py
-	nasm -f elf64 symbols.S -o symbols.o
+	nasm -f elf64 symbols.S -o build/symbols.o
-	x86_64-elf-ld -o pepperk -T linker.ld *.o
+	x86_64-elf-ld -o pepperk -T linker.ld build/*.o
 
 limine/limine:
 	rm -rf limine
@@ -46,4 +51,4 @@ run: build-iso
 	/usr/bin/qemu-system-x86_64 -cdrom pepper.iso -serial stdio
 
 clean:
-	rm -rf *.o symbols.map symbols.S pepperk iso_root pepper.iso limine
+	rm -rf *.o symbols.map symbols.S pepperk iso_root pepper.iso limine build/*.o

README.md

@@ -4,6 +4,12 @@
 
 First install the dependencies: `sudo apt install python3 xorriso make qemu-system`
 
+Also, you have to get an x86_64 toolchain for compilation. The easiest way to do that on most systems is to install it from Homebrew:
+
+```
+brew install x86_64-elf-gcc
+```
+
 Then, to compile the kernel and make an ISO image file: `make build-iso`
 To run it with QEMU, `make run`
 
@@ -13,11 +19,10 @@ The basics that I'm targeting are:
 
 ### Basic utility of what we call a "kernel"
 
-- Fix terminal driver (backspace issues, scrolling) OR add Flanterm or equivalent
 - Implement tasks, and task switching + context switching and spinlock acquire/release
 - Load an executable
 - Filesystem (TAR for read-only initfs, then maybe read-write using FAT12/16/32 or easier fs) w/ VFS layer
-- Getting to userspace (syscalls)
+- Getting to userspace (ring 3 switching, syscall interface)
 - Porting musl libc or equivalent
 
 ### Scalability/maintenance/expansion features
@@ -26,7 +31,6 @@ The basics that I'm targeting are:
 - SOME error handling in functions
 - Unit tests
 - Good error codes (like Linux kernel: ENOMEM, ENOENT, ...)
-- Make the panic function work within itself without dependencies + error message (and still get cpu context?)
 
 ### Optional features
 
@@ -41,8 +45,10 @@ PepperOS wouldn't be possible without the following freely-licensed software:
 
 - the [Limine](https://codeberg.org/Limine/Limine) portable bootloader
 - Marco Paland's freestanding [printf implementation](https://github.com/mpaland)
-- the [ZAP](https://www.zap.org.au/projects/console-fonts-zap/) PSF console fonts
+- Mintuski's [Flanterm](https://codeberg.org/Mintsuki/Flanterm) terminal emulator
 
 ...and without these amazing resources:
 
 - the [OSDev](https://osdev.org) wiki & forums
+- Intel 64 and IA-32 Architectures Software Developer's Manual
+- Documentation for the [GNU Compiler Collection](https://gcc.gnu.org/onlinedocs/gcc/)

docs/STYLE.md

@@ -0,0 +1,93 @@
+# Pepper kernel coding style
+
+This document describes the coding style for the Pepper kernel. It is used as a guideline across all source files.
+
+## Indentation
+
+Indentations should be 4 characters long.
+
+## Line length
+
+Lines should not be more than 100 characters long. Exceptions is made for printing strings.
+
+## Variables
+
+Variables should be declared at most once per line.
+
+## Braces
+
+Non-function statement blocks should have an opening brace last on the line, and a closing brace first. Exception is made for `else`, `else if` statements and the like:
+
+```c
+if (something) {
+    do_something();
+} else if (something_else) {
+    do_something_else();
+}
+```
+
+Having no braces for a single statement structure is fine.
+
+Functions should have their opening brace on a separate line, and the same goes for the closing brace:
+
+```c
+void function()
+{
+    do_something();
+}
+```
+
+## Spaces
+
+Use a space after `if, switch, case, for, do, while` keywords, but not for `sizeof, typeof, alignof, __attribute__` and the like.
+
+For pointers, the asterisk should always be placed adjacent to the type name, like `char* str;`.
+
+## Naming
+
+Functions should be named with whole words, beginning with the corresponding name of the module in the kernel (the parent folder). Words should be spaced with underscores, like so:
+
+```c
+serial_init(void* ptr, char* str, int foo);
+```
+
+Constants should be named in all caps, separated by underscores:
+
+```c
+#define MAX_HEAP_SIZE 0x1000
+```
+
+Global variables need to have descriptive names. Local variables can be kept short (especially for loop counters).
+
+## Typedefs
+
+Structures should not be `typedef`'d. However using `typedef` for an enumeration is fine.
+
+## Functions
+
+Functions should be short, simple, and only do one thing.
+
+Function prototypes should include parameter names and their data types.
+
+## Commenting
+
+Comments should describe what a function does and why, not how it does it. The preferred way of commenting functions is the following:
+
+```c
+/*
+ * function_name - Function brief description
+ * @arg1: Argument 1 description
+ * @arg2: Argument 2 description
+ *
+ * A longer description can be featured here, explaining more
+ * in detail what the function does and why it does it.
+ */
+```
+
+## Kernel messages
+
+When printing kernel messages with the `DEBUG` macro, they should start with a capital letter.
+
+### Resources
+
+Some of the elements here are inspired by the [Linux kernel coding style](https://www.kernel.org/doc/html/v4.10/process/coding-style.html).

src/boot/boot.c

@@ -1,33 +1,34 @@
 /*
  * @author  xamidev <xamidev@riseup.net>
  * @brief   Limine requests for boot
+ * @description
+ * The kernel makes a few requests to the Limine bootloader
+ * in order to get precious information about the system.
+ * We get a framebuffer, a memory map, the address of the
+ * kernel in memory, and the Higher Half Direct Map offset.
  * @license GPL-3.0-only
  */
 
 #include <limine.h>
 
-// Framebuffer request
 __attribute__((used, section(".limine_requests")))
 volatile struct limine_framebuffer_request framebuffer_request = {
 	.id = LIMINE_FRAMEBUFFER_REQUEST,
 	.revision = 0
 };
 
-// Memory map request
 __attribute__((used, section(".limine_requests")))
 volatile struct limine_memmap_request memmap_request = {
 	.id = LIMINE_MEMMAP_REQUEST,
 	.revision = 0
 };
 
-// Higher Half Direct Map
 __attribute__((used, section(".limine_requests")))
 volatile struct limine_hhdm_request hhdm_request = {
 	.id = LIMINE_HHDM_REQUEST,
 	.revision = 0
 };
 
-// Executable Address/Kernel Address (find base phys/virt address of kernel)
 __attribute__((used, section(".limine_requests")))
 volatile struct limine_kernel_address_request kerneladdr_request = {
 	.id = LIMINE_KERNEL_ADDRESS_REQUEST,

src/config.h

@@ -28,6 +28,10 @@
 // 2 MB should be enough (as of now, the whole kernel ELF is around 75kb)
 #define KERNEL_SIZE 0x200000
 #define KERNEL_STACK_SIZE 65536
+#define KERNEL_IDT_ENTRIES 33
+
+/* paging */
+#define PAGING_MAX_PHYS 0x100000000
 
 /* heap */
 #define KHEAP_SIZE (32*1024*1024)
@@ -35,4 +39,7 @@
 /* term */
 #define TERM_HISTORY_MAX_LINES 256
 
+/* time */
+#define TIMER_FREQUENCY 1000
+
 #endif

src/debug/misc.c

@@ -1,20 +1,31 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Miscellaneous debug features
+ * @license GPL-3.0-only
+ */
+
 #include <kernel.h>
 #include "limine.h"
 #include "string/string.h"
 
 extern struct boot_context boot_ctx;
 
-// Display the memmap so we see how the memory is laid out at handoff
+/*
+ * memmap_display - displays a memory map
+ * @response: Limine memory map response
+ *
+ * Displays the memory map we get from Limine
+ * to see different regions, their sizes, and
+ * how the memory is laid out at handoff.
+ */
 void memmap_display(struct limine_memmap_response* response)
 {
 	DEBUG("Got memory map from Limine: revision %u, %u entries", response->revision, response->entry_count);
 
-	for (size_t i=0; i<response->entry_count; i++)
+	for (size_t i=0; i<response->entry_count; i++) {
-	{
 		struct limine_memmap_entry* entry = response->entries[i];
 		char type[32] = {0};
-		switch(entry->type)
+		switch(entry->type) {
-		{
 			case LIMINE_MEMMAP_USABLE:
 				strcpy(type, "USABLE");
 				break;
@@ -43,19 +54,25 @@ void memmap_display(struct limine_memmap_response* response)
 				strcpy(type, "UNKNOWN");
 				break;
 		}
-		DEBUG("entry %02u: [0x%016x | %016u bytes] - %s", i, entry->base, entry->length, type);
+		DEBUG("Entry %02u: [0x%016x | %016u bytes] - %s", i, entry->base, entry->length, type);
 	}
 }
 
-// Display the HHDM
+/*
+ * hhdm_display - displays the HHDM offset
+ * @hhdm: Limine HHDM offset response
+ */
 void hhdm_display(struct limine_hhdm_response* hhdm)
 {
 	DEBUG("Got HHDM revision=%u offset=0x%p", hhdm->revision, hhdm->offset);
 }
 
+/*
+ * boot_mem_display - displays all memory info
+ */
 void boot_mem_display()
 {
 	memmap_display(boot_ctx.mmap);
 	hhdm_display(boot_ctx.hhdm);
-	DEBUG("kernel: phys_base=0x%p virt_base=0x%p", boot_ctx.kaddr->physical_base, boot_ctx.kaddr->virtual_base);
+	DEBUG("Kernel is at phys_base=0x%p virt_base=0x%p", boot_ctx.kaddr->physical_base, boot_ctx.kaddr->virtual_base);
 }

src/debug/panic.c

@@ -1,13 +1,29 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Kernel panic
+ * @license GPL-3.0-only
+ */
+
 #include <stddef.h>
 #include "idt/idt.h"
 #include "io/serial/serial.h"
 #include "kernel.h"
 
+extern struct init_status init;
+
+/*
+ * panic - Kernel panic
+ * @ctx: CPU context (optional)
+ * @str: Error message 
+ *
+ * Ends execution of the kernel in case of an unrecoverable error.
+ * Will display to terminal if it is initialized, otherwise serial only.
+ * Can be called with or without a CPU context.
+ */
 void panic(struct cpu_status_t* ctx, const char* str)
 {
 	CLEAR_INTERRUPTS;
-	if (ctx == NULL)
+	if (ctx == NULL) {
-	{
 		DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m Something went horribly wrong! (no cpu ctx)");
 		fctprintf((void*)&skputc, 0, "\x1b[38;5;231m\x1b[48;5;27m");
 		DIE_DEBUG(str);
@@ -15,13 +31,29 @@ void panic(struct cpu_status_t* ctx, const char* str)
 		skputc('\r');
 		skputc('\n');
 		DEBUG("\x1b[38;5;231m\x1b[48;5;196mend Kernel panic - halting...\x1b[0m");
+
+		if (init.terminal) {
+			printf("\r\n\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[48;5;232m Something went horribly wrong! (no cpu ctx)");
+			printf("\r\n%s\r\n\x1b[38;5;231mend Kernel panic - halting...\x1b[0m", str);
+		}
+
 		hcf();
 	}
-	DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m at rip=%p\r\nSomething went horribly wrong! (%s) vect=0x%.2x errcode=0x%x\n\rrax=%p rbx=%p rcx=%p rdx=%p\n\rrsi=%p rdi=%p  r8=%p  r9=%p\n\rr10=%p r11=%p r12=%p r13=%p\n\rr14=%p r15=%p\n\n\rflags=%p\n\rHalting...",
+	DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m at rip=%p\r\nSomething went horribly wrong! (%s) vect=0x%.2x errcode=0x%x\n\rrax=%p rbx=%p rcx=%p rdx=%p\n\rrsi=%p rdi=%p  r8=%p  r9=%p\n\rr10=%p r11=%p r12=%p r13=%p\n\rr14=%p r15=%p\n\n\rflags=%p\n\rHalting...\x1b[0m",
 		ctx->iret_rip,
 		str,
 		ctx->vector_number, ctx->error_code, ctx->rax, ctx->rbx, ctx->rcx, ctx->rdx, ctx->rsi, ctx->rdi,
 		ctx->r8, ctx->r9, ctx->r10, ctx->r11, ctx->r12, ctx->r13, ctx->r14, ctx->r15, ctx->iret_flags);
+	
+	if (init.terminal) {
+		printf("\r\n\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[48;5;232mat rip=%p\r\nSomething went horribly wrong! (%s) vect=0x%.2x errcode=0x%x\n\rrax=%p rbx=%p rcx=%p rdx=%p\n\rrsi=%p rdi=%p  r8=%p  r9=%p\n\rr10=%p r11=%p r12=%p r13=%p\n\rr14=%p r15=%p\n\n\rflags=%p\n\rHalting...\x1b[0m",
+		ctx->iret_rip,
+		str,
+		ctx->vector_number, ctx->error_code, ctx->rax, ctx->rbx, ctx->rcx, ctx->rdx, ctx->rsi, ctx->rdi,
+		ctx->r8, ctx->r9, ctx->r10, ctx->r11, ctx->r12, ctx->r13, ctx->r14, ctx->r15, ctx->iret_flags);
+	}
+	
 	debug_stack_trace(100);
+	
 	hcf();
 }

src/debug/stacktrace.c

@@ -1,35 +1,57 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Stack trace tools
+ * @license GPL-3.0-only
+ */
+
 #include <stdint.h>
 #include "kernel.h"
 
+extern struct init_status init;
+
+/*
+ * debug_stack_trace - Prints the stack trace
+ * @max_frames: Maximum amount of stack frames to walk
+ *
+ * Walks back the stack and gets all return values (RIP)
+ * and prints them to the DEBUG interface.
+ */
 void debug_stack_trace(unsigned int max_frames)
 {
     DEBUG("*** begin stack trace ***");
+    if (init.terminal) {
+        printf("\r\n\x1b[48;5;232m\x1b[38;5;231m*** begin stack trace ***\r\n");
+    }
     // Thanks GCC :)
     uintptr_t* rbp = (uintptr_t*)__builtin_frame_address(0);
 
-    for (unsigned int frame=0; frame<max_frames && rbp != NULL; frame++)
+    for (unsigned int frame=0; frame<max_frames && rbp != NULL; frame++) {
-    {
         // Return address, 1 word above saved rbp
         uintptr_t rip = rbp[1];
         uintptr_t offset = 0;
         const char* name = debug_find_symbol(rip, &offset);
         DEBUG("[%u] <0x%p> (%s+0x%x)", frame, (void*)rip, name, offset);
 
+        if (init.terminal) {
+            printf("[%u] <0x%p> (%s+0x%x)\r\n", frame, (void*)rip, name, offset);
+        }
+
         uintptr_t* next_rbp = (uintptr_t*)rbp[0];
 
-        // invalid rbp or we're at the end
+        // Invalid rbp or we're at the end
-        if (next_rbp <= rbp || next_rbp == NULL)
+        if (next_rbp <= rbp || next_rbp == NULL) {
-        {
             break;
         }
 
         rbp = next_rbp;
     }
+    if (init.terminal) {
+        printf("*** end stack trace ***\x1b[0m");
+    }
     DEBUG("*** end stack trace ***");
 }
 
-typedef struct
+typedef struct {
-{
     uint64_t addr;
     const char *name;
 } __attribute__((packed)) kernel_symbol_t;
@@ -37,11 +59,19 @@ typedef struct
 __attribute__((weak)) extern kernel_symbol_t symbol_table[];
 __attribute__((weak)) extern uint64_t symbol_count;
 
-// binary search
+/*
+ * debug_find_symbol - Finds the symbol name associated to an address
+ * @rip:    Pointer to executable code
+ * @offset: Out pointer to reference the offset in the found function, if any
+ *
+ * Return:
+ * <symbol name> - symbol name
+ * "???"         - no symbol table found
+ * "unknown"     - symbol table found, but address isn't in the table
+ */
 const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset)
 {
-    if (!symbol_table || symbol_count == 0)
+    if (!symbol_table || symbol_count == 0) {
-    {
         if (offset) *offset = 0;
         return "???";
     }
@@ -49,11 +79,9 @@ const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset)
     int low = 0, high = (int)symbol_count - 1;
     int best = -1;
 
-    while (low <= high)
+    while (low <= high) {
-    {
         int mid = (low + high) / 2;
-        if (symbol_table[mid].addr <= rip)
+        if (symbol_table[mid].addr <= rip) {
-        {
             best = mid;
             low = mid + 1;
         } else {
@@ -61,15 +89,15 @@ const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset)
         }
     }
 
-    if (best != -1)
+    if (best != -1) {
-    {
+        if (offset) {
-        if (offset)
-        {
             *offset = rip - symbol_table[best].addr;
         }
         return symbol_table[best].name;
     }
 
-    if (offset) *offset = 0;
+    if (offset) {
+        *offset = 0;
+    }
     return "unknown";
 }

src/idt/idt.S

@@ -151,12 +151,13 @@ vector_7_handler:
 align 16
 vector_8_handler:
     ; No error code, we only push vector number
-    push qword 1
+    push qword 8
     jmp interrupt_stub
 
 ; Coprocessor Segment Overrun
 align 16
 vector_9_handler:
+    push qword 0
     push qword 9
     jmp interrupt_stub
 

src/idt/idt.c

@@ -22,8 +22,14 @@ struct idtr idt_reg;
 extern char vector_0_handler[];
 
 // Timer ticks
-extern uint64_t ticks;
+extern volatile uint64_t ticks;
 
+/*
+ * idt_set_entry - Sets an Interrupt Descriptor Table entry
+ * @vector:  Vector number in the IDT
+ * @handler: Pointer to the executable Interrupt Service Routine
+ * @dpl:     Desired privilege level
+ */
 void idt_set_entry(uint8_t vector, void* handler, uint8_t dpl)
 {
     uint64_t handler_addr = (uint64_t)handler;
@@ -42,6 +48,10 @@ void idt_set_entry(uint8_t vector, void* handler, uint8_t dpl)
     entry->ist = 0;
 }
 
+/*
+ * idt_load - Loads the Interrupt Descriptor Table
+ * @idt_addr: Address to the IDT
+ */
 void idt_load(void* idt_addr)
 {
     // "limit" = "size" = Size of the IDT - 1 byte = (16*256)-1 = 0xFFF
@@ -50,12 +60,15 @@ void idt_load(void* idt_addr)
     asm volatile("lidt %0" :: "m"(idt_reg));
 }
 
+/*
+ * idt_init - Initializes the Interrupt Descriptor Table
+ *
+ * Sets all IDT entries and their corresponding service routines,
+ * then loads it.
+ */
 void idt_init()
 {
-    // We set 256 entries, but we have only the first few stubs.
+    for (size_t i=0; i<=KERNEL_IDT_ENTRIES; i++) {
-    // Undefined behavior?
-    for (size_t i=0; i<256; i++)
-    {
         // Each vector handler is 16-byte aligned, so <vector_no>*16 = address of that handler
         idt_set_entry(i, vector_0_handler + (i*16), 0);
     }
@@ -63,6 +76,15 @@ void idt_init()
     DEBUG("IDT initialized");
 }
 
+/*
+ * read_cr2 - Reads the CR2 register
+ *
+ * This function is useful because it gets the address
+ * that the CPU tried to access in the case of a #PF.
+ *
+ * Return:
+ * %val - CR2 register value
+ */
 static inline uint64_t read_cr2(void)
 {
     uint64_t val;
@@ -70,6 +92,15 @@ static inline uint64_t read_cr2(void)
     return val;
 }
 
+/*
+ * page_fault_handler - Handler for #PF
+ * @ctx: CPU context
+ *
+ * Shows detail about a #PF, especially what instruction (RIP)
+ * caused it, and what address access (CR2) caused it.
+ * Also displays an interpretation of the thrown error code.
+ * Then halts the system. We could implement demand paging later.
+ */
 static void page_fault_handler(struct cpu_status_t* ctx)
 {
     // It could be used to remap pages etc. to fix the fault, but right now what I'm more
@@ -91,6 +122,13 @@ static void page_fault_handler(struct cpu_status_t* ctx)
     panic(ctx, "page fault");
 }
 
+/*
+ * gp_fault_handler - Handler for #GP
+ * @ctx: CPU context
+ *
+ * Shows detail about a General Protection Fault,
+ * and what may have caused it. Halts the system.
+ */
 static void gp_fault_handler(struct cpu_status_t* ctx)
 {
     DEBUG("\x1b[38;5;231mGeneral Protection Fault at rip=0x%p, err=%u (%s)\x1b[0m",
@@ -99,8 +137,7 @@ static void gp_fault_handler(struct cpu_status_t* ctx)
     (ctx->error_code == 0) ? "NOT_SEGMENT_RELATED" : "SEGMENT_RELATED");
 
     // Segment-related
-    if (ctx->error_code != 0)
+    if (ctx->error_code != 0) {
-    {
         bool is_external = CHECK_BIT(ctx->error_code, 0);
         // is it IDT, GDT, LDT?
         uint8_t table = ctx->error_code & 0x6; // 0b110 (isolate table)
@@ -117,82 +154,89 @@ static void gp_fault_handler(struct cpu_status_t* ctx)
     panic(ctx, "gp fault");
 }
 
+/*
+ * interrupt_dispatch - Interrupt dispatcher
+ * @context: CPU context
+ *
+ * This function is where all interrupt routines go, after they passed
+ * through their corresponding vector handler in the IDT assembly stub.
+ * It catches all exceptions.
+ *
+ * Return:
+ * <context> - CPU context after interrupt
+ */
 struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
 {
-    if (context == NULL)
+    if (context == NULL) {
-    {
         panic(NULL, "Interrupt dispatch recieved NULL context!");
     }
 
-    switch(context->vector_number)
+    switch(context->vector_number) {
-    {
         case 0:
-            DEBUG("Divide Error!");
+            panic(context, "Divide Error");
             break;
         case 1:
-            DEBUG("Debug Exception!");
+            panic(context, "Debug Exception");
             break;
         case 2:
-            DEBUG("NMI Interrupt!");
+            panic(context, "NMI Interrupt");
             break;
         case 3:
-            DEBUG("Breakpoint Interrupt!");
+            panic(context, "Breakpoint Interrupt");
             break;
         case 4:
-            DEBUG("Overflow Trap!");
+            panic(context, "Overflow Trap");
             break;
         case 5:
-            DEBUG("BOUND Range Exceeded!");
+            panic(context, "BOUND Range Exceeded");
             break;
         case 6:
-            DEBUG("Invalid Opcode!");
+            panic(context, "Invalid Opcode");
-            panic(context, "Invalid Opcode!");
             break;
         case 7:
-            DEBUG("Device Not Available!");
+            panic(context, "Device Not Available");
             break;
         case 8:
-            DEBUG("Double Fault!");
+            panic(context, "Double Fault");
             break;
         case 9:
-            DEBUG("Coprocessor Segment Overrun!");
+            panic(context, "Coprocessor Segment Overrun");
             break;
         case 10:
-            DEBUG("Invalid TSS!");
+            panic(context, "Invalid TSS");
             break;
         case 11:
-            DEBUG("Segment Not Present!");
+            panic(context, "Segment Not Present");
             break;
         case 12:
-            DEBUG("Stack-Segment Fault!");
+            panic(context, "Stack-Segment Fault");
             break;
         case 13:
             gp_fault_handler(context);
             break;
         case 14:
-            // Better debugging for page faults...
             page_fault_handler(context);
             break;
         case 15:
-            DEBUG("Intel Reserved Interrupt! (Achievement unlocked: How Did We Get Here?)");
+            panic(context, "Intel Reserved Interrupt (Achievement unlocked: How Did We Get Here?)");
             break;
         case 16:
-            DEBUG("x87 Floating-Point Error!");
+            panic(context, "x87 Floating-Point Error");
             break;
         case 17:
-            DEBUG("Alignment Check Fault!");
+            panic(context, "Alignment Check Fault");
             break;
         case 18:
-            DEBUG("Machine Check!");
+            panic(context, "Machine Check");
             break;
         case 19:
-            DEBUG("SIMD Floating-Point Exception!");
+            panic(context, "SIMD Floating-Point Exception");
             break;
         case 20:
-            DEBUG("Virtualization Exception!");
+            panic(context, "Virtualization Exception");
             break;
         case 21:
-            DEBUG("Control Protection Exception!");
+            panic(context, "Control Protection Exception");
             break;
 
         case 32: // Timer Interrupt
@@ -200,20 +244,19 @@ struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
             // Send an EOI so that we can continue having interrupts
             outb(0x20, 0x20);
 
-            if (ticks % SCHEDULER_QUANTUM == 0)
+            if (ticks % SCHEDULER_QUANTUM == 0) {
-            {
                 return scheduler_schedule(context);
             }
 
             break;
 
-        case 33:
+        case 33: // Keyboard Interrupt
-            DEBUG("Keyboard Interrupt");
             keyboard_handler();
+            outb(0x20, 0x20);
             break;
 
         default:
-            DEBUG("Unexpected interrupt");
+            DEBUG("Unexpected Interrupt");
             break;
     }
 

src/idt/idt.h

@@ -9,10 +9,9 @@
 
 #include <stdint.h>
 
-void idt_init();
+void idt_init(void);
 
-struct interrupt_descriptor
+struct interrupt_descriptor {
-{
     uint16_t address_low;
     uint16_t selector;
     uint8_t ist;
@@ -22,8 +21,7 @@ struct interrupt_descriptor
     uint32_t reserved;
 } __attribute__((packed));
 
-struct idtr 
+struct idtr {
-{
     uint16_t limit;
     uint64_t base;
 } __attribute__((packed));
@@ -31,8 +29,7 @@ struct idtr
 // All general-purpose registers (except rsp) as stored on the stack,
 // plus the values we pushed (vector number, error code) and the iret frame
 // In reverse order because the stack grows downwards.
-struct cpu_status_t
+struct cpu_status_t {
-{
     uint64_t r15;
     uint64_t r14;
     uint64_t r13;
@@ -42,7 +39,6 @@ struct cpu_status_t
     uint64_t r9;
     uint64_t r8;
     uint64_t rbp;
-    //uint64_t rsp;
     uint64_t rdi;
     uint64_t rsi;
     uint64_t rdx;

src/io/kbd/ps2.c

@@ -17,6 +17,8 @@ uint8_t key_status = 0b00000000;
 unsigned char* keymap;
 unsigned char* keymap_shifted;
 
+extern struct init_status init;
+
 unsigned char kbdus[128] =
 {
     0,  27, '1', '2', '3', '4', '5', '6', '7', '8',	/* 9 */
@@ -154,16 +156,22 @@ unsigned char kbdfr_shifted[128] =
     0
 };
 
+/*
+ * keyboard_handler - Keyboard event handler
+ *
+ * Is called from the interrupt dispatcher.
+ * When a key is pressed or released, we get a scancode, and
+ * it is then translated to an ASCII character.
+ * Left Shift, Ctrl, and Alt keys are also taken into consideration. 
+ */
 void keyboard_handler()
 {
     unsigned char scancode = inb(0x60);
 
     // Key release (bit 7 set)
-    if (scancode & 0x80)
+    if (scancode & 0x80) {
-    {
         unsigned char code = scancode & 0x7F;
-        switch (code)
+        switch (code) {
-        {
             // Clear the corresponding bit if corresponding key is released
             case LEFT_SHIFT_PRESSED:
             case RIGHT_SHIFT_PRESSED:
@@ -176,16 +184,10 @@ void keyboard_handler()
                 key_status &= ~ALT_PRESSED_BIT;
                 break;
         }
-
-        // Send EOI
-        outb(0x20, 0x20);
         return;
-    }
+    } else {
-    else
-    {
         // Key press
-        switch (scancode)
+        switch (scancode) {
-        {
             // Set bits for corresponding special key press
             case LEFT_SHIFT_PRESSED:
             case RIGHT_SHIFT_PRESSED:
@@ -200,29 +202,36 @@ void keyboard_handler()
 
             default:
             {
+                // Avoiding buffer overflow from extended keys lol
+                if (scancode < 128) {
                     // Should we get a SHIFTED char or a regular one?
                     unsigned char c = (key_status & SHIFT_PRESSED_BIT) ? keymap_shifted[scancode] : keymap[scancode];
 
-                if (c)
+                    if (c) {
-                {
+                        if (c == '\n') {
+                            _putchar('\r');
+                        }
                         // Should probably have a keyboard buffer here... instead of this
                         _putchar(c);
                     }
                 }
             }
         }
-
+    }
-    // End of Interrupt (to master PIC)
-    outb(0x20, 0x20);
 }
 
+/*
+ * keyboard_init - Keyboard initialization
+ * @layout: Desired layout
+ *
+ * Prepares the PS/2 keyboard to recieve input.
+ */
 void keyboard_init(unsigned char layout)
 {
     // Here we might go and select PS/2, USB, or other... (once we implement multiple keyboard protocols)
 
     // Keyboard layout selection
-    switch (layout)
+    switch (layout) {
-    {
         case US:
             keymap = kbdus;
             keymap_shifted = kbdus_shifted;
@@ -233,14 +242,20 @@ void keyboard_init(unsigned char layout)
             break;
         
         default:
-            skputs("Unsupported layout.");
+            panic(NULL, "Unsupported keyboard layout");
             return;
     }
 
+    // Flush keyboard buffer
+    while (inb(0x64) & 1) {
+        inb(0x60);
+    }
+
     // Unmask IRQ1
     uint8_t mask = inb(0x21);
     mask &= ~(1 << 1);
     outb(0x21, mask);
 
     DEBUG("PS/2 Keyboard initialized");
+    init.keyboard = true;
 }

src/io/kbd/ps2.h

@@ -7,21 +7,19 @@
 #ifndef PS2_H
 #define PS2_H
 
-void keyboard_handler();
+void keyboard_handler(void);
 
 #define SHIFT_PRESSED_BIT 0b00000001
 #define ALT_PRESSED_BIT   0b00000010
 #define CTRL_PRESSED_BIT  0b00000100
 
-enum SpecialKeys
+enum SpecialKeys {
-{
     SHIFT = 255,
     ALT = 254,
     CTRL = 253
 };
 
-enum SpecialScancodes
+enum SpecialScancodes {
-{
     LEFT_SHIFT_PRESSED = 0x2A,
     LEFT_SHIFT_RELEASED = 0xAA,
     RIGHT_SHIFT_PRESSED = 0x36,
@@ -32,8 +30,7 @@ enum SpecialScancodes
     ALT_RELEASED = 0xB8  
 };
 
-enum KeyboardLayout
+enum KeyboardLayout {
-{
     US,
     FR  
 };

src/io/serial/serial.c

@@ -7,11 +7,27 @@
 #include <kernel.h>
 #include "serial.h"
 
+extern struct init_status init;
+
+/*
+ * outb - Writes a byte to a CPU port
+ * @port: CPU port to write to
+ * @data: Byte to write
+ *
+ * Writes a single byte to the serial interface.
+ */
 void outb(int port, unsigned char data)
 {
     __asm__ __volatile__("outb %%al, %%dx" :: "a" (data),"d" (port));
 }
 
+/*
+ * inb - Gets a byte in through a CPU port
+ * @port: The CPU port to get a byte from
+ *
+ * Return:
+ * <data> - byte got from port
+ */
 unsigned char inb(int port)
 {
     unsigned char data = 0;
@@ -19,9 +35,13 @@ unsigned char inb(int port)
     return data;
 }
 
-// COM1
+/*
-#define PORT 0x3F8
+ * serial_init - Initializes serial interface
-
+ * 
+ * Return:
+ * %-EIO - Input/output error
+ * %0    - Success
+ */
 int serial_init()
 {
     outb(PORT + 1, 0x00);      // Disable all interrupts
@@ -34,8 +54,7 @@ int serial_init()
     outb(PORT + 4, 0x1E);    // Set in loopback mode, test the serial chip
     outb(PORT + 0, 0xAE);    // Test serial chip (send byte 0xAE and check if serial returns same byte)
 
-    if (inb(PORT) != 0xAE)
+    if (inb(PORT) != 0xAE) {
-    {
         return -EIO;
     }
 
@@ -43,27 +62,44 @@ int serial_init()
     outb(PORT + 4, 0x0F);
 
     DEBUG("*** Welcome to PepperOS! ***");
+    init.serial = true;
     return 0;
 }
 
+/*
+ * is_transmit_empty - Check if the serial transmit register is empty
+ *
+ * Return: Non-zero if the transmit register is empty and a new
+ * byte can be written to the serial port, 0 otherwise.
+ */
 static int is_transmit_empty()
 {
     return inb(PORT + 5) & 0x20;
 }
 
-// Serial kernel putchar
+/*
+ * skputc - Serial kernel putchar
+ * @c: character to write
+ *
+ * Writes a single character to the serial interface.
+ */
 void skputc(char c)
 {
+    // TODO: Spinlock here (serial access)
     while (!is_transmit_empty()); // wait for free spot
     outb(PORT, c);
 }
 
-// Serial kernel putstring
+/*
+ * skputs - Serial kernel puts
+ * @str: Message to write
+ *
+ * Writes a non-formatted string to serial output.
+ */
 void skputs(const char* str)
 {
     unsigned int i=0;
-    while (str[i])
+    while (str[i]) {
-    {
         skputc(str[i]);
         i++;
     }

src/io/serial/serial.h

@@ -7,10 +7,13 @@
 #ifndef SERIAL_H
 #define SERIAL_H
 
+// COM1
+#define PORT 0x3F8
+
 void outb(int port, unsigned char data);
 unsigned char inb(int port);
 
-int serial_init();
+int serial_init(void);
 void skputs(const char* str);
 void skputc(char c);
 

src/io/term/term.c

@@ -16,23 +16,80 @@ because this shitty implementation will be replaced one day by Flanterm
 #include "term.h"
 #include "config.h"
 #include "flanterm.h"
+#include "flanterm_backends/fb.h"
+#include "mem/heap/kheap.h"
+#include "limine.h"
 
 extern struct flanterm_context* ft_ctx;
+extern struct init_status init;
 
-// Overhead that could be avoided, right? (for printf)
+/*
+ * _putchar - Writes a character to terminal
+ * @character: character to write
+ */
 void _putchar(char character)
 {
+	// TODO: Spinlock here (terminal access)
 	flanterm_write(ft_ctx, &character, 1);
 }
 
-// Debug-printing
+/*
+ * kputs - Kernel puts
+ * @str: String to write
+ *
+ * Writes a non-formatted string to terminal
+ */
 void kputs(const char* str)
 {
 	size_t i=0;
-	while (str[i] != 0)
+	while (str[i] != 0) {
-	{
 		_putchar(str[i]);
 		i++;
 	}
 	_putchar('\r');
 }
+
+extern struct flanterm_context* ft_ctx;
+extern struct boot_context boot_ctx;
+
+/*
+ * flanterm_free_wrapper - free() wrapper for Flanterm 
+ * @ptr:  pointer to free
+ * @size: amount of bytes to free
+ *
+ * This function exists solely because the Flanterm initialization
+ * function only accepts a free() function with a size parameter,
+ * and the default one doesn't have it.
+ */
+void flanterm_free_wrapper(void* ptr, size_t size)
+{
+	(void)size;
+	kfree(ptr);
+}
+
+/*
+ * term_init - Video output/terminal initialization
+ *
+ * Uses Flanterm and the framebuffer given by Limine.
+ */
+void term_init()
+{
+	uint32_t bgColor = 0x252525;
+	ft_ctx = flanterm_fb_init(
+        kmalloc,
+        flanterm_free_wrapper,
+        boot_ctx.fb->address, boot_ctx.fb->width, boot_ctx.fb->height, boot_ctx.fb->pitch,
+        boot_ctx.fb->red_mask_size, boot_ctx.fb->red_mask_shift,
+        boot_ctx.fb->green_mask_size, boot_ctx.fb->green_mask_shift,
+        boot_ctx.fb->blue_mask_size, boot_ctx.fb->blue_mask_shift,
+        NULL,
+        NULL, NULL,
+        &bgColor, NULL,
+        NULL, NULL,
+        NULL, 0, 0, 1,
+        0, 0,
+        0,
+        0
+    );
+	init.terminal = true;
+}

src/io/term/term.h

@@ -9,5 +9,6 @@
 
 void kputs(const char* str);
 void _putchar(char character);
+void term_init(void);
 
 #endif

src/kernel.h

@@ -7,8 +7,7 @@
 #ifndef KERNEL_H
 #define KERNEL_H
 
-enum ErrorCodes
+enum ErrorCodes {
-{
 	ENOMEM,
 	EIO
 };
@@ -19,9 +18,11 @@ enum ErrorCodes
 #include "io/serial/serial.h"
 #include "io/term/printf.h"
 #include "idt/idt.h"
+#include <stdbool.h>
 
-#define DEBUG(log, ...) fctprintf((void*)&skputc, 0, "debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__)
+extern volatile uint64_t ticks;
 
+#define DEBUG(log, ...) fctprintf((void*)&skputc, 0, "[%8u] debug: <%s>: " log "\r\n", ticks, __func__, ##__VA_ARGS__)
 
 /* #define DEBUG(log, ...) \
 	printf("debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__); \
@@ -35,21 +36,29 @@ enum ErrorCodes
 // printf("debug: [%s]: " log "\n", __FILE__, ##__VA_ARGS__);
 
 void panic(struct cpu_status_t* ctx, const char* str);
-void hcf();
+void hcf(void);
-void idle();
+void idle(void);
 
+/* debug */
 void debug_stack_trace(unsigned int max_frames);
 const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset);
-void boot_mem_display();
+void boot_mem_display(void);
 
 #define assert(check) do { if(!(check)) hcf(); } while(0)
 
-struct boot_context
+struct boot_context {
-{
 	struct limine_framebuffer* fb;
 	struct limine_memmap_response* mmap;
 	struct limine_hhdm_response* hhdm;
 	struct limine_kernel_address_response* kaddr;
 };
 
+// Are these modules initialized yet?
+struct init_status {
+	bool terminal;
+	bool serial;
+	bool keyboard;
+	bool timer;
+};
+
 #endif

src/kmain.c

@@ -30,20 +30,30 @@
 __attribute__((used, section(".limine_requests")))
 volatile LIMINE_BASE_REVISION(3);
 
-struct flanterm_context *ft_ctx;
+/*
-
+ * hcf - Halt and catch fire
-// Halt and catch fire (makes machine stall)
+ *
+ * This function is called only in the case of an unrecoverable
+ * error. It halts interrupts, and stops execution. The machine
+ * will stay in an infinite loop state.
+ */
 void hcf()
 {
 	CLEAR_INTERRUPTS; for (;;)asm("hlt");
 }
 
-// Doing nothing (can be interrupted)
+/*
+ * idle - Make the machine idle
+ *
+ * When there is nothing else to do, this function
+ * gets called. It can be interrupted, so it allows
+ * the scheduler, timer, and keyboard to work.
+ */
 void idle() {SET_INTERRUPTS; for(;;)asm("hlt");}
 
-// uint8_t kernel_stack[KERNEL_STACK_SIZE] __attribute__((aligned(16)));
+struct flanterm_context *ft_ctx;
-
 struct boot_context boot_ctx;
+struct init_status init = {0};
 
 extern volatile struct limine_framebuffer_request framebuffer_request;
 extern volatile struct limine_memmap_request memmap_request;
@@ -52,33 +62,38 @@ extern volatile struct limine_kernel_address_request kerneladdr_request;
 
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
+struct process_t* idle_proc;
 
+// Never gets executed although pedicel is scheduled?
 void pedicel_main(void* arg)
 {
-	// FROM THE NEXT LINE ONWARDS, CANNOT WRITE TO FRAMEBUFFER WITHOUT PAGE FAULT!
+	printf("\n\nWelcome to PepperOS! Pedicel speaking.\r\nNothing left to do, let's go idle!");
-	//printf("\n\nWelcome to PepperOS! Pedicel speaking.\nNothing left to do, halting the system!");
 }
 
 void idle_main(void* arg)
 {
-	for(;;)asm("hlt");
+	for (;;) {
-}
+		asm("hlt");
-
+	}
-void flanterm_free_wrapper(void* ptr, size_t size)
-{
-	(void)size;
-	kfree(ptr);
 }
 
 extern uintptr_t kheap_start;
 
-// This is our entry point
+/*
+ * kmain - Kernel entry point
+ *
+ * This is where execution begins at handoff from Limine.
+ * The function fetches all needed information from the
+ * bootloader, initializes all kernel modules and structures,
+ * and then goes in an idle state.
+ */
 void kmain()
 {
 	CLEAR_INTERRUPTS;
 	if (!LIMINE_BASE_REVISION_SUPPORTED) hcf();
 
 	serial_init();
+	timer_init();
 
 	// Populate boot context
  	boot_ctx.fb = framebuffer_request.response ? framebuffer_request.response->framebuffers[0] : NULL;
@@ -87,49 +102,28 @@ void kmain()
 	boot_ctx.kaddr = kerneladdr_request.response ? kerneladdr_request.response : NULL;
 
 	boot_mem_display();
-	pmm_init(boot_ctx.mmap, boot_ctx.hhdm);
+	pmm_init(boot_ctx);
 
 	// Remap kernel , HHDM and framebuffer
-	paging_init(boot_ctx.kaddr, boot_ctx.fb);
+	paging_init(boot_ctx);
 	kheap_init();
 
 	keyboard_init(FR);
 
-	uint32_t bgColor = 0x252525;
+	term_init();
-	ft_ctx = flanterm_fb_init(
-        kmalloc,
-        flanterm_free_wrapper,
-        boot_ctx.fb->address, boot_ctx.fb->width, boot_ctx.fb->height, boot_ctx.fb->pitch,
-        boot_ctx.fb->red_mask_size, boot_ctx.fb->red_mask_shift,
-        boot_ctx.fb->green_mask_size, boot_ctx.fb->green_mask_shift,
-        boot_ctx.fb->blue_mask_size, boot_ctx.fb->blue_mask_shift,
-        NULL,
-        NULL, NULL,
-        &bgColor, NULL, // &bgColor
-        NULL, NULL,
-        NULL, 0, 0, 1,
-        0, 0,
-        0,
-        0
-    );
 
 	gdt_init();
 	idt_init();
 	
-	timer_init();
-	vmm_init();
-	
 	process_init();
-	struct process_t* idle_proc = process_create("idle", (void*)idle_main, 0);
+	idle_proc = process_create("idle", (void*)idle_main, 0);
 	struct process_t* pedicel = process_create("pedicel", (void*)pedicel_main, 0);
 
 	process_display_list(processes_list);
 
 	scheduler_init();
 
-	current_process = idle_proc; 
-    current_process->status = RUNNING;
-
 	kputs(PEPPEROS_SPLASH);
+	
 	idle();
 }

src/mem/gdt/gdt.c

@@ -14,11 +14,20 @@
 uint64_t gdt_entries[NUM_GDT_ENTRIES];
 struct GDTR gdtr;
 
+/*
+ * gdt_load - Loads Global Descriptor Table
+ */
 static void gdt_load()
 {
     asm("lgdt %0" : : "m"(gdtr));
 }
 
+/*
+ * gdt_flush - Flushes the Global Descriptor Table
+ *
+ * This function loads new Segment Selectors to make
+ * the GDT changes take effect
+ */
 static void gdt_flush()
 {
     // Here, 0x8 is the kernel code selector
@@ -42,6 +51,15 @@ static void gdt_flush()
     );
 }
 
+/*
+ * gdt_init - Global Descriptor Table initialization 
+ *
+ * This function loads a new GDT in the CPU.
+ * It contains a null descriptor, kernel code and data
+ * segments, and user code and data segments.
+ * However, we do not use segmentation to manage memory on
+ * 64-bit x86, as it's deprecated. Instead, we use paging. 
+ */
 void gdt_init()
 {
     // Null descriptor (required)

src/mem/gdt/gdt.h

@@ -21,12 +21,11 @@
 #define USER_CODE_SEGMENT 0x18
 #define USER_DATA_SEGMENT 0x20
 
-struct GDTR 
+struct GDTR {
-{
     uint16_t limit;
     uint64_t address;
 } __attribute__((packed));
 
-void gdt_init();
+void gdt_init(void);
 
 #endif

src/mem/heap/kheap.c

@@ -23,6 +23,15 @@ static uintptr_t end;
 // Kernel root table (level 4)
 extern uint64_t *kernel_pml4;
 
+/*
+ * kheap_init - Kernel heap initialization
+ *
+ * This function physically allocates and maps enough pages
+ * of memory for KHEAP_SIZE, which is defined in config.h.
+ *
+ * It then creates one big heap block, which will be the
+ * base for a linked list.
+ */
 void kheap_init()
 {
     kheap_start = ALIGN_UP(kernel_virt_base + KERNEL_SIZE, PAGE_SIZE);
@@ -33,11 +42,9 @@ void kheap_init()
     uintptr_t current_addr = kheap_start;
 
     // Map/alloc enough pages for heap (KHEAP_SIZE)
-    for (size_t i=0; i<heap_pages; i++)
+    for (size_t i=0; i<heap_pages; i++) {
-    {
         uintptr_t phys = pmm_alloc();
-        if (phys == 0)
+        if (phys == 0) {
-        {
             panic(NULL, "Not enough memory available to initialize kernel heap.");
         }
 
@@ -55,6 +62,18 @@ void kheap_init()
     DEBUG("Kernel heap initialized, head=0x%p, size=%u bytes", head, head->size);
 }
 
+/*
+ * kmalloc - Kernel memory allocation
+ * @size: number of bytes to allocate
+ *
+ * Looks for a big enough free block and marks it
+ * as taken. Each block of memory is preceded by
+ * the linked list header.
+ *
+ * Return:
+ * <ptr> - Pointer to at least <size> bytes of usable memory
+ * NULL  - No more memory, or no valid size given
+ */
 void* kmalloc(size_t size)
 {
     // No size, no memory allocated!
@@ -63,15 +82,11 @@ void* kmalloc(size_t size)
 
     struct heap_block_t* curr = head;
 
-    while (curr)
+    while (curr) {
-    {
         // Is block free and big enough for us?
-        if (curr->free && curr->size >= size)
+        if (curr->free && curr->size >= size) {
-        {
             // We split the block if it is big enough
-            if (curr->size >= size + sizeof(struct heap_block_t) + 16)
+            if (curr->size >= size + sizeof(struct heap_block_t) + 16) {
-            {
-                //struct heap_block_t* new_block = (struct heap_block_t*)((uintptr_t)curr + sizeof(struct heap_block_t) + size);
                 struct heap_block_t* split = (struct heap_block_t*)((uintptr_t)curr + sizeof(struct heap_block_t) + size);
                 
                 split->size = curr->size - size - sizeof(struct heap_block_t);
@@ -98,6 +113,14 @@ void* kmalloc(size_t size)
     return NULL;
 }
 
+/*
+ * kfree - Kernel memory freeing
+ * @ptr: pointer to memory region to free
+ *
+ * Marks the memory block beginning at <ptr>
+ * as free. Also merges adjacent free blocks
+ * to lessen fragmentation.
+ */
 void kfree(void* ptr)
 {
     // Nothing to free
@@ -109,10 +132,8 @@ void kfree(void* ptr)
 
     // merge adjacent free blocks (coalescing)
     struct heap_block_t* curr = head;
-    while (curr && curr->next)
+    while (curr && curr->next) {
-    {
+        if (curr->free && curr->next->free) {
-        if (curr->free && curr->next->free)
-        {
             curr->size += sizeof(*curr) + curr->next->size;
             curr->next = curr->next->next;
             continue;
@@ -121,8 +142,17 @@ void kfree(void* ptr)
     }
 }
 
-// Should alloc enough for a stack (at least 64kb) to be used for a process.
+/*
-// Should return a pointer to top of the stack (as stack grows DOWNWARDS)
+ * kalloc_stack - Stack memory allocation
+ *
+ * Allocates a memory region of at least PROCESS_STACK_SIZE,
+ * to be used as a stack for a process. The pointer returned
+ * points to the end of the region, as the stack grows downwards.
+ *
+ * Return:
+ * <ptr> - Pointer to a region after at least PROCESS_STACK_SIZE bytes of usable memory
+ * NULL  - No more memory
+ */
 void* kalloc_stack()
 {
     uint8_t* ptr = kmalloc(PROCESS_STACK_SIZE); // As it's out of kmalloc, stack is already mapped into kernel space

src/mem/heap/kheap.h

@@ -16,18 +16,17 @@
 #include <stddef.h>
 #include <stdint.h>
 
-struct heap_block_t
+struct heap_block_t {
-{
     size_t size;
     bool free; // 1byte
     uint8_t reserved[7]; // (7+1 = 8 bytes)
     struct heap_block_t* next;
 } __attribute__((aligned(16)));
 
-void kheap_init();
+void kheap_init(void);
 void* kmalloc(size_t size);
 void kfree(void* ptr);
-void* kalloc_stack();
+void* kalloc_stack(void);
-void kheap_map_page();
+void kheap_map_page(void);
 
 #endif

src/mem/misc/utils.c

@@ -16,61 +16,104 @@
 // We use the "restrict" keyword on pointers so that the compiler knows it can
 // do more optimization on them (and as it's a much used function, it's good to
 // be able to do that)
+
+/*
+ * memcpy - Copy memory from one place to another
+ * @dest: pointer to the destination region
+ * @src:  pointer to the source region
+ * @n:    amount of bytes to copy
+ *
+ * This function copies n bytes of memory from
+ * src to dest.
+ *
+ * Return:
+ * <dest> - Pointer to destination region
+ */
 void* memcpy(void* restrict dest, const void* restrict src, size_t n)
 {
 	uint8_t* restrict pdest = (uint8_t* restrict)dest;
 	const uint8_t* restrict psrc = (const uint8_t* restrict)src;
 
-	for (size_t i=0; i<n; i++)
+	for (size_t i=0; i<n; i++) {
-	{
 		pdest[i] = psrc[i];
 	}
 
 	return dest;
 }
 
+/*
+ * memset - Sets a memory region to given byte
+ * @s:    pointer to memory region
+ * @c:    byte to be written
+ * @n:    amount of bytes to write
+ *
+ * This function writes n times the byte c
+ * to the memory region pointed to by s.
+ *
+ * Return:
+ * <s> - Pointer to memory region
+ */
 void* memset(void* s, int c, size_t n)
 {
 	uint8_t* p = (uint8_t*)s;
 
-	for (size_t i=0; i<n; i++)
+	for (size_t i=0; i<n; i++) {
-	{
 		p[i] = (uint8_t)c;
 	}
 
 	return s;
 }
 
+/*
+ * memmove - Move memory from one place to another
+ * @dest: pointer to the destination region
+ * @src:  pointer to the source region
+ * @n:    amount of bytes to move
+ *
+ * This function moves n bytes of memory from
+ * src to dest.
+ *
+ * Return:
+ * <dest> - Pointer to destination region
+ */
 void* memmove(void *dest, const void* src, size_t n)
 {
 	uint8_t* pdest = (uint8_t*)dest;
 	const uint8_t* psrc = (uint8_t*)src;
 
-	if (src > dest)
+	if (src > dest) {
-	{
+		for (size_t i=0; i<n; i++) {
-		for (size_t i=0; i<n; i++)
-		{
 			pdest[i] = psrc[i];
 		}
-	} else if (src < dest) 
+	} else if (src < dest) {
-	{
+		for (size_t i=n; i>0; i--) {
-		for (size_t i=n; i>0; i--)
-		{
 			pdest[i-1] = psrc[i-1];
 		}
 	}
 	return dest;	
 }
 
+/*
+ * memcmp - Compare two memory regions
+ * @s1:   pointer to the first region
+ * @s2:   pointer to the second region
+ * @n:    amount of bytes to compare
+ *
+ * This function compares n bytes of memory
+ * bewteen regions pointed to by s1 and s2.
+ *
+ * Return:
+ * %0     - if s1 and s2 are equal 
+ * %-1    - if s1 is smaller than s2
+ * %1     - if s1 is greater than s2
+ */
 int memcmp(const void* s1, const void* s2, size_t n)
 {
 	const uint8_t* p1 = (const uint8_t*)s1;
 	const uint8_t* p2 = (const uint8_t*)s2;
 
-	for (size_t i=0; i<n; i++)
+	for (size_t i=0; i<n; i++) {
-	{
+		if (p1[i] != p2[i]) {
-		if (p1[i] != p2[i])
-		{
 			return p1[i] < p2[i] ? -1 : 1;
 		}
 	}

src/mem/paging/paging.c

@@ -24,23 +24,46 @@ If we use 1GB huge pages: PML4 -> PDPT -> 1gb pages
 4KB (regular size): PML4 -> PDPT -> PD -> PT -> 4kb pages
 */
 
+/*
+ * load_cr3 - Load a new value into the CR3 register
+ * @value: the value to load
+ *
+ * This function is used to load the physical address
+ * of the root page table (PML4), to switch the paging
+ * structures the CPU sees and uses.
+ */
 void load_cr3(uint64_t value) {
     asm volatile ("mov %0, %%cr3" :: "r"(value) : "memory");
 }
 
-// To flush TLB
+/*
+ * invlpg - Invalidates a Translation Lookaside Buffer entry
+ * @addr: page memory address
+ *
+ * This function is used to flush at least the TLB entrie(s)
+ * for the page that contains the <addr> address.
+ */
 static inline void invlpg(void *addr)
 {
     asm volatile("invlpg (%0)" :: "r"(addr) : "memory");
 }
 
-// Allocates a 512-entry 64bit page table/directory/whatever (zeroed)
+/*
+ * alloc_page_table - Page table allocation
+ *
+ * This function allocates enough memory for a 512-entry
+ * 64-bit page table, for any level (PML4/3/2).
+ *
+ * Memory allocated here is zeroed.
+ *
+ * Return:
+ * <virt> - Pointer to allocated page table
+ */
 static uint64_t* alloc_page_table()
 {
     uint64_t* virt = (uint64_t*)PHYS_TO_VIRT(pmm_alloc());
 
-    for (size_t i=0; i<512; i++)
+    for (size_t i=0; i<512; i++) {
-    {
         virt[i] = 0;
     }
     return virt;
@@ -50,10 +73,19 @@ static uint64_t* alloc_page_table()
 __attribute__((aligned(4096)))
 uint64_t *kernel_pml4;
 
-// Map a page, taking virt and phys address. This will go through the paging structures
+/*
-// beginning at the given root table, translate the virtual address in indexes in
+ * paging_map_page - Mapping a memory page
-// page table/directories, and then mapping the correct page table entry with the
+ * @root_table: Address of the PML4
-// given physical address + flags
+ * @virt:       Virtual address
+ * @phys:       Physical address
+ * @flags:      Flags to set on page
+ *
+ * This function maps the physical address <phys> to the virtual
+ * address <virt>, using the paging structures beginning at
+ * <root_table>. <flags> can be set according to the PTE_FLAGS enum.
+ *
+ * If a page table/directory entry is not present yet, it creates it.
+ */
 void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_t flags)
 {
     virt = PAGE_ALIGN_DOWN(virt);
@@ -70,32 +102,26 @@ void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_
     // PML4
     // If the entry at index is not present, allocate enough space for it
     // then populate the entry with correct addr + flags
-    if (!(root_table[pml4_i] & PTE_PRESENT))
+    if (!(root_table[pml4_i] & PTE_PRESENT)) {
-    {
         pdpt = alloc_page_table();
         root_table[pml4_i] = VIRT_TO_PHYS(pdpt) | PTE_PRESENT | PTE_WRITABLE;
-    }
+    } else {
-    else {
         pdpt = (uint64_t *)PHYS_TO_VIRT(root_table[pml4_i] & PTE_ADDR_MASK);
     }
 
     // PDPT: same here
-    if (!(pdpt[pdpt_i] & PTE_PRESENT))
+    if (!(pdpt[pdpt_i] & PTE_PRESENT)) {
-    {
         pd = alloc_page_table();
         pdpt[pdpt_i] = VIRT_TO_PHYS(pd) | PTE_PRESENT | PTE_WRITABLE;
-    } 
+    } else {
-    else {
         pd = (uint64_t *)PHYS_TO_VIRT(pdpt[pdpt_i] & PTE_ADDR_MASK);
     }
 
     // PD: and here
-    if (!(pd[pd_i] & PTE_PRESENT))
+    if (!(pd[pd_i] & PTE_PRESENT)) {
-    {
         pt = alloc_page_table();
         pd[pd_i] = VIRT_TO_PHYS(pt) | PTE_PRESENT | PTE_WRITABLE;
-    }
+    } else {
-    else {
         pt = (uint64_t *)PHYS_TO_VIRT(pd[pd_i] & PTE_ADDR_MASK);
     }
 
@@ -109,9 +135,16 @@ void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_
 uint64_t kernel_phys_base;
 uint64_t kernel_virt_base;
 
-extern struct boot_context boot_ctx;
+/*
-
+ * paging_init - Paging initialization
-void paging_init()
+ * @boot_ctx: Boot context structure
+ *
+ * This function initializes new paging structures, to replace
+ * the ones given by the bootloader.
+ *
+ * It maps the kernel, the HHDM space, and the framebuffer.
+ */
+void paging_init(struct boot_context boot_ctx)
 {
     // We should map the kernel, GDT, IDT, stack, framebuffer.
     // Optionally we could map ACPI tables (we can find them in the Limine memmap)
@@ -129,32 +162,25 @@ void paging_init()
 
     // Find max physical address from limine memmap
     uint64_t max_phys = 0;
-    for (uint64_t i=0; i<boot_ctx.mmap->entry_count; i++)
+    for (uint64_t i=0; i<boot_ctx.mmap->entry_count; i++) {
-    {
         struct limine_memmap_entry* entry = boot_ctx.mmap->entries[i];
-        if (entry->length == 0)
+        if (entry->length == 0) {
-        {
             continue;
         }
         uint64_t top = entry->base + entry->length;
-        if (top > max_phys)
+        if (top > max_phys) {
-        {
             max_phys = top;
         }
-        //DEBUG("max_phys=0x%p", max_phys);
     }
 
     // 4GB
-    if (max_phys > 0x100000000)
+    if (max_phys > PAGING_MAX_PHYS) {
-    {
+        DEBUG("WARNING: max_phys capped to 4GB (%x) (from max_phys=%p)", PAGING_MAX_PHYS, max_phys);
-        DEBUG("WARNING: max_phys capped to 4GB (0x100000000) (from max_phys=%p)", max_phys);
+        max_phys = PAGING_MAX_PHYS;
-        max_phys = 0x100000000;
     }
 
-    // HHDM map up to max_phys or 4GB, whichever is smaller, using given offset
+    // HHDM map up to max_phys or PAGING_MAX_PHYS, whichever is smaller, using given offset
-    for (uint64_t i=0; i<max_phys; i += PAGE_SIZE)
+    for (uint64_t i=0; i<max_phys; i += PAGE_SIZE) {
-    {
-        //paging_kmap_page(i+hhdm_off, i, PTE_WRITABLE);
         paging_map_page(kernel_pml4, i+hhdm_off, i, PTE_WRITABLE | PTE_PRESENT);
         page_count++;
     }
@@ -164,9 +190,7 @@ void paging_init()
     // SOME DAY when we want a safer kernel we should map .text as Read/Exec
     // .rodata as Read and .data as Read/Write
     // For now who gives a shit, let's RWX all kernel
-    for (uint64_t i = 0; i < KERNEL_SIZE; i += PAGE_SIZE)
+    for (uint64_t i = 0; i < KERNEL_SIZE; i += PAGE_SIZE) {
-    {
-        //paging_kmap_page(kernel_virt_base+i, kernel_phys_base+i, PTE_WRITABLE);
         paging_map_page(kernel_pml4, kernel_virt_base+i, kernel_phys_base+i, PTE_WRITABLE);
         page_count++;
     }
@@ -179,23 +203,13 @@ void paging_init()
     uint64_t fb_pages = (fb_size + PAGE_SIZE-1)/PAGE_SIZE;
 
     // Map the framebuffer (with cache-disable & write-through)
-    for (uint64_t i=0; i<fb_pages; i++)
+    for (uint64_t i=0; i<fb_pages; i++) {
-    {
-        //paging_kmap_page(fb_virt+i*PAGE_SIZE, fb_phys+i*PAGE_SIZE, PTE_WRITABLE | PTE_PCD | PTE_PWT);
         paging_map_page(kernel_pml4, fb_virt+i*PAGE_SIZE, fb_phys+i*PAGE_SIZE, PTE_WRITABLE | PTE_PCD | PTE_PWT);
         page_count++;
     }
     DEBUG("Mapped %u pages for framebuffer", page_count);
 
-    // test for flanterm
-    // When 10 pages are mapped, SOMETIMES (1 out of 50 times) it prints everything without problem!
-    // Other times it prints garbage (almost full cursors) and/or panics.
-/*     for (uint64_t i=0; i<10; i++)
-    {
-        paging_map_page(kernel_pml4, 0, kernel_phys_base+KERNEL_SIZE+i*PAGE_SIZE, PTE_WRITABLE);
-    } */
-
     // Finally, we load the physical address of our PML4 (root table) into cr3
     load_cr3(VIRT_TO_PHYS(kernel_pml4));
-    DEBUG("cr3 loaded, we're still alive");
+    DEBUG("Loaded kernel PML4 into CR3");
 }

src/mem/paging/paging.h

@@ -12,8 +12,9 @@
 #include <stdint.h>
 #include <limine.h>
 #include "mem/heap/kheap.h"
+#include <kernel.h>
 
-void paging_init();
+void paging_init(struct boot_context boot_ctx);
 void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_t flags);
 
 // To swap root page tables
@@ -40,12 +41,15 @@ extern uint64_t hhdm_off;
 
 // Page entry special bits
 // Bits set on a parent (directory, table) fall back to their children
-#define PTE_PRESENT     (1ULL << 0)
+enum PTE_FLAGS
-#define PTE_WRITABLE    (1ULL << 1)
+{
-#define PTE_USER        (1ULL << 2)
+    PTE_PRESENT = (1ULL << 0),
-#define PTE_PWT         (1ULL << 3)
+    PTE_WRITABLE = (1ULL << 1),
-#define PTE_PCD         (1ULL << 4)
+    PTE_USER = (1ULL << 2),
-#define PTE_HUGE        (1ULL << 7)
+    PTE_PWT = (1ULL << 3),
-#define PTE_NOEXEC      (1ULL << 63)
+    PTE_PCD = (1ULL << 4),
+    PTE_HUGE = (1ULL << 7),
+    PTE_NOEXEC = (1ULL << 63)
+};
 
 #endif

src/mem/paging/pmm.c

@@ -24,13 +24,16 @@ First we'll have to discover the physical memory layout,
 and for that we can use a Limine request.
 */
 
-/*
-We will look for the biggest usable physical memory region
-and use this for the bitmap. The reserved memory will be ignored.
-*/
-
 struct limine_memmap_entry* biggest_entry;
 
+/*
+ * pmm_find_biggest_usable_region - Finding the biggest free memory region
+ * @memmap: Limine memory map
+ * @hhdm:   Limine HHDM offset
+ *
+ * This function uses the memory map provided by the bootloader
+ * to find the single biggest free memory region we can use.
+ */
 static void pmm_find_biggest_usable_region(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm)
 {
     // Max length of a usable memory region
@@ -38,12 +41,10 @@ static void pmm_find_biggest_usable_region(struct limine_memmap_response* memmap
     uint64_t offset = hhdm->offset;
 
     DEBUG("Usable Memory:");
-    for (size_t i=0; i<memmap->entry_count; i++)
+    for (size_t i=0; i<memmap->entry_count; i++) {
-    {
         struct limine_memmap_entry* entry = memmap->entries[i];
 
-        if (entry->type == LIMINE_MEMMAP_USABLE)
+        if (entry->type == LIMINE_MEMMAP_USABLE) {
-        {
             DEBUG("0x%p-0x%p mapped at 0x%p-0x%p", entry->base, entry->base+entry->length,
                         entry->base+offset, entry->base+entry->length+offset);
             if (entry->length > length_max)
@@ -64,10 +65,17 @@ uint64_t hhdm_off;
 
 static uintptr_t g_freelist = 0;
 
+/*
+ * pmm_alloc - Allocate a physical page
+ *
+ * This function allocates a single physical page (frame)
+ * 
+ * Return:
+ * <addr> - Address for the allocated page
+ */
 uintptr_t pmm_alloc()
 {
-    if (!g_freelist)
+    if (!g_freelist) {
-	{
 		panic(NULL, "PMM is out of memory!");		
 	}
     uintptr_t addr = g_freelist;
@@ -75,12 +83,22 @@ uintptr_t pmm_alloc()
     return addr;
 }
 
+/*
+ * pmm_free - Frees a memory page
+ * @addr: Address to the page
+ */
 void pmm_free(uintptr_t addr)
 {
     *(uintptr_t*) PHYS_TO_VIRT(addr) = g_freelist;
     g_freelist = addr;
 }
 
+/*
+ * pmm_init_freelist - PMM freelist initialization
+ *
+ * This function marks the biggest memory region as
+ * free, so we can use it in pmm_alloc.
+ */
 static void pmm_init_freelist()
 {
     // We simply call pmm_free() on each page that is marked USABLE
@@ -89,20 +107,24 @@ static void pmm_init_freelist()
     uint64_t end = ALIGN_DOWN(biggest_entry->base + biggest_entry->length, PAGE_SIZE);
 
     uint64_t page_count=0;
-    for (uint64_t addr = base; addr < end; addr += PAGE_SIZE)
+    for (uint64_t addr = base; addr < end; addr += PAGE_SIZE) {
-    {
         pmm_free(addr);
-        //DEBUG("page %u lives at phys 0x%p (virt 0x%p)", page_count, addr, PHYS_TO_VIRT(addr));
         page_count++;
     }
     DEBUG("%u frames in freelist, available for use (%u bytes)", page_count, page_count*PAGE_SIZE);
 }
 
-void pmm_init(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm)
+/*
+ * pmm_init - Physical memory manager initialization
+ * @boot_ctx: Boot context structure
+ *
+ * This function prepares the PMM for use.
+ * The PMM works with a freelist.
+ */
+void pmm_init(struct boot_context boot_ctx)
 {
-    hhdm_off = hhdm->offset;
+    hhdm_off = boot_ctx.hhdm->offset;
-    pmm_find_biggest_usable_region(memmap, hhdm);
+    pmm_find_biggest_usable_region(boot_ctx.mmap, boot_ctx.hhdm);
-    //pmm_allocate_bitmap(hhdm); too complicated for my small brain
 
     // Now we have biggest USABLE region,
     // so to populate the free list we just iterate through it

src/mem/paging/pmm.h

@@ -8,9 +8,10 @@
 #define PAGING_PMM_H
 
 #include <limine.h>
+#include <kernel.h>
 
-void pmm_init(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm);
+void pmm_init(struct boot_context boot_ctx);
 void pmm_free(uintptr_t addr);
-uintptr_t pmm_alloc();
+uintptr_t pmm_alloc(void);
 
 #endif

src/mem/paging/vmm.c

@@ -24,6 +24,14 @@ void* vmm_pt_root = 0;
 // Linked list head for virtual memory objects
 struct vm_object* vm_objs = NULL;
 
+/*
+ * Will have to be rewritten and expanded,
+ * to prepare for userspace.
+ * The platform-agnostic flags will be removed
+ * because as long as the kernel is x86 only,
+ * we don't need over complication.
+ * Plus I don't plan to port to other architectures
+*/
 
 uint64_t convert_x86_vm_flags(size_t flags)
 {

src/mem/paging/vmm.h

@@ -16,8 +16,7 @@ Flags here aren't x86 flags, they are platform-agnostic
 kernel-defined flags.
 */
 
-struct vm_object
+struct vm_object {
-{
     uintptr_t base;
     size_t length;
     size_t flags;
@@ -30,6 +29,6 @@ struct vm_object
 #define VM_FLAG_EXEC (1 << 1)
 #define VM_FLAG_USER (1 << 2)
 
-void vmm_init();
+void vmm_init(void);
 
 #endif

src/sched/process.c

@@ -23,19 +23,27 @@ extern uint64_t *kernel_pml4;
 
 size_t next_free_pid = 0;
 
+/*
+ * process_init - Initializes process list
+ */
 void process_init()
 {
     processes_list = NULL;
     current_process = NULL;
 }
 
-// Only for debug
+/*
+ * process_display_list - Debug function to display processes
+ * @processes_list: head of the process linked list
+ *
+ * This function prints the linked list of processes
+ * to the DEBUG output.
+ */
 void process_display_list(struct process_t* processes_list)
 {
     int process_view_id = 0;
     struct process_t* tmp = processes_list;
-    while (tmp != NULL)
+    while (tmp != NULL) {
-    {
         DEBUG("{%d: %p} -> ", process_view_id, tmp);
         tmp = tmp->next;
         process_view_id++;
@@ -43,11 +51,23 @@ void process_display_list(struct process_t* processes_list)
     DEBUG("NULL");
 }
 
+/*
+ * process_create - Create a process
+ * @name:     name of the process
+ * @function: beginning of process executable code
+ * @arg:      (optional) argument provided to process
+ *
+ * This function creates a process, gives it all
+ * necessary context and a stack, and adds the
+ * process to the linked list.
+ *
+ * Return:
+ * <proc> - pointer to created process
+ */
 struct process_t* process_create(char* name, void(*function)(void*), void* arg)
 {
-/*     CLEAR_INTERRUPTS; */
+    CLEAR_INTERRUPTS;
     struct process_t* proc = (struct process_t*)kmalloc(sizeof(struct process_t));
-    
     struct cpu_status_t* ctx = (struct cpu_status_t*)kmalloc(sizeof(struct cpu_status_t));
 
     // No more memory?
@@ -79,38 +99,44 @@ struct process_t* process_create(char* name, void(*function)(void*), void* arg)
 
     process_add(&processes_list, proc);
 
-/*     SET_INTERRUPTS; */
+    SET_INTERRUPTS;
     return proc;
 }
 
+/*
+ * process_add - Add a process to the end of the linked list
+ * @processes_list: pointer to the head of the linked list
+ * @process:        process to add at the end of the linked list
+ */
 void process_add(struct process_t** processes_list, struct process_t* process)
 {
     if (!process) return;
     process->next = NULL;
 
-    if (*processes_list == NULL)
+    if (*processes_list == NULL) {
-    {
         // List is empty
         *processes_list = process;
         return;
     }
 
     struct process_t* tmp = *processes_list;
-    while (tmp->next != NULL)
+    while (tmp->next != NULL) {
-    {
         tmp = tmp->next;
     }
     // We're at last process before NULL
     tmp->next = process;
-    // process->next = NULL;
 }
 
+/*
+ * process_delete - Delete a process from the linked list
+ * @processes_list: pointer to head of linked list
+ * @process:        the process to delete from the list
+ */
 void process_delete(struct process_t** processes_list, struct process_t* process)
 {
     if (!processes_list || !*processes_list || !process) return;
 
-    if (*processes_list == process)
+    if (*processes_list == process) {
-    {
         // process to delete is at head
         *processes_list = process->next;
         process->next = NULL;
@@ -119,13 +145,11 @@ void process_delete(struct process_t** processes_list, struct process_t* process
     }
 
     struct process_t* tmp = *processes_list;
-    while (tmp->next && tmp->next != process)
+    while (tmp->next && tmp->next != process) {
-    {
         tmp = tmp->next;
     }
 
-    if (tmp->next == NULL)
+    if (tmp->next == NULL) {
-    {
         // Didn't find the process
         return;
     }
@@ -136,27 +160,40 @@ void process_delete(struct process_t** processes_list, struct process_t* process
     kfree(process);
 }
 
+/*
+ * process_get_next - Get the next process (unused)
+ * @process: pointer to process
+ *
+ * Return:
+ * <process->next> - process right after the one specified
+ */
 struct process_t* process_get_next(struct process_t* process)
 {
     if (!process) return NULL;
     return process->next;
 }
 
-// Will be used to clean up resources (if any, when we implement it)
+/*
-// Just mark as DEAD then idle. Scheduler will delete process at next timer interrupt % quantum.
+ * process_exit - Exit from a process
+ *
+ * This function is pushed to all process stacks, as a last
+ * return address. Once the process is done executing, it 
+ * ends up here.
+ *
+ * Process is marked as DEAD, and then execution loops.
+ * Next time the scheduler sees the process, it will
+ * automatically delete it from the linked list.
+ */
 void process_exit()
 {
     DEBUG("Exiting from process '%s'", current_process->name);
     CLEAR_INTERRUPTS;
-    if (current_process)
+    if (current_process) {
-    {
         current_process->status = DEAD;
     }
     SET_INTERRUPTS;
     
-    //outb(0x20, 0x20);
+    for (;;) {
-    for (;;)
-    {
         asm("hlt");
     }
 }

src/sched/process.h

@@ -11,15 +11,13 @@
 #include "config.h"
 #include <stdint.h>
 
-typedef enum 
+typedef enum {
-{
     READY,
     RUNNING,
     DEAD
 } status_t;
 
-struct process_t
+struct process_t {
-{
     size_t pid;
     char name[PROCESS_NAME_MAX];
 
@@ -29,12 +27,12 @@ struct process_t
     struct process_t* next;
 };
 
-void process_init();
+void process_init(void);
 struct process_t* process_create(char* name, void(*function)(void*), void* arg);
 void process_add(struct process_t** processes_list, struct process_t* process);
 void process_delete(struct process_t** processes_list, struct process_t* process);
 struct process_t* process_get_next(struct process_t* process);
-void process_exit();
+void process_exit(void);
 
 void process_display_list(struct process_t* processes_list);
 

src/sched/scheduler.c

@@ -12,25 +12,40 @@
 
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
+extern struct process_t* idle_proc;
 
+/*
+ * scheduler_init - Choose the first process
+ */
 void scheduler_init()
 {
-    // Choose first process?
     current_process = processes_list;
 }
 
+/*
+ * scheduler_schedule - Main scheduling routine
+ * @context: CPU context of previous process
+ *
+ * Chooses the next process that we should run.
+ * The routine is executed every SCHEDULER_QUANTUM ticks.
+ *
+ * Return:
+ * <context> - CPU context for next process
+ */
 struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
 {
-    if (context == NULL)
+    if (context == NULL) {
-    {
         panic(NULL, "Scheduler called with NULL context"); 
     }
 
-    if (current_process == NULL)
+    if (current_process == NULL) {
+        // If no more processes, then set IDLE as the current process, that's it.
+        current_process = idle_proc;
+    }
+
+    if (current_process == idle_proc && current_process->next == NULL)
     {
-        // Wtf happened
+        return idle_proc->context;
-        current_process = processes_list;
-        //panic(NULL, "Scheduler called without current process");
     }
 
     current_process->context = context;
@@ -38,30 +53,26 @@ struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context)
 
     for (;;) {
         struct process_t* prev_process = current_process;
-        if (current_process->next != NULL)
+        if (current_process->next != NULL) {
-        {
             current_process = current_process->next;
-        } else
+        } else {
-        {
             current_process = processes_list;
         }
         
-        if (current_process != NULL && current_process->status == DEAD)
+        if (current_process != NULL && current_process->status == DEAD) {
-        {
             process_delete(&prev_process, current_process);
-        } else
+            current_process = NULL;
-        {
+            return idle_proc->context;
+        } else {
             current_process->status = RUNNING;
             break;
         }
     }
 
-
-    // Current_process gets wrong context?? (iret_rip points to other stuff than process function; like putpixel() for example)
     DEBUG("current_process={pid=%u, name='%s', root_page_table[virt]=%p}", current_process->pid, current_process->name, current_process->root_page_table);
 
     load_cr3(VIRT_TO_PHYS((uint64_t)current_process->root_page_table));
-    DEBUG("loaded process pml4 into cr3");
+    DEBUG("Loaded process PML4 into CR3");
 
     return current_process->context;
 }

src/sched/scheduler.h

@@ -8,6 +8,6 @@
 #define SCHEDULER_H
 
 struct cpu_status_t* scheduler_schedule(struct cpu_status_t* context);
-void scheduler_init();
+void scheduler_init(void);
 
 #endif

src/string/string.c

@@ -6,6 +6,16 @@
 
 #include <stddef.h>
 
+/*
+ * strcpy - copy a NULL-terminated string
+ * @dest: destination buffer where the string is copied
+ * @src:  source string to copy from
+ *
+ * Copies the string pointed to by @src (including the terminating
+ * NULL byte) into the buffer pointed to by @dest.
+ *
+ * Return: pointer to the destination string (@dest)
+ */
 char* strcpy(char *dest, const char *src)
 {
     char *temp = dest;
@@ -13,18 +23,48 @@ char* strcpy(char *dest, const char *src)
     return temp;
 }
 
-// https://stackoverflow.com/questions/2488563/strcat-implementation
+/*
-char *strcat(char *dest, const char *src){
+ * strcat - append a NUL-terminated string
+ * @dest: destination buffer containing the initial string
+ * @src:  source string to append
+ *
+ * Appends the string pointed to by @src to the end of the string
+ * pointed to by @dest. The terminating NUL byte in @dest is
+ * overwritten and a new terminating NUL byte is added.
+ *
+ * The destination buffer must be large enough to hold the result.
+ *
+ * Taken from: https://stackoverflow.com/questions/2488563/strcat-implementation
+ *
+ * Return: pointer to the destination string (@dest)
+ */
+char *strcat(char *dest, const char *src)
+{
     size_t i,j;
-    for (i = 0; dest[i] != '\0'; i++)
+    for (i = 0; dest[i] != '\0'; i++);
-        ;
+
     for (j = 0; src[j] != '\0'; j++)
         dest[i+j] = src[j];
+    
     dest[i+j] = '\0';
     return dest;
 }
 
-// https://stackoverflow.com/questions/14159625/implementation-of-strncpy
+/*
+ * strncpy - copy a string with length limit
+ * @dst: destination buffer
+ * @src: source string
+ * @n:   maximum number of bytes to copy
+ *
+ * Copies up to @n bytes from @src to @dst. Copying stops early if a
+ * NULL byte is encountered in @src. If @src is shorter than @n, the
+ * remaining bytes in @dst are left unchanged in this implementation.
+ *
+ * Note: This differs slightly from the standard strncpy behavior,
+ * which pads the remaining bytes with NULL.
+ *
+ * Taken from: https://stackoverflow.com/questions/14159625/implementation-of-strncpy
+ */
 void strncpy(char* dst, const char* src, size_t n)
 {
    size_t i = 0;

src/time/timer.c

@@ -7,6 +7,7 @@
 #include <stdint.h>
 #include "io/serial/serial.h"
 #include <kernel.h>
+#include "config.h"
 
 /*
 For now, the timer module will be using the PIC.
@@ -18,6 +19,15 @@ interested in multi-core functionnality like SMP)
 
 volatile uint64_t ticks = 0;
 
+extern struct init_status init;
+
+/*
+ * pic_remap - Remap the Programmable Interrupt Controller
+ *
+ * By default, interrupts are mapped at the wrong place.
+ * This function remaps interrupt numbers so interrupts
+ * don't conflict with each other. 
+ */
 void pic_remap()
 {
     uint8_t master_mask = inb(0x21);
@@ -45,6 +55,12 @@ void pic_remap()
     outb(0xA1, slave_mask);
 }
 
+/*
+ * pic_enable - Enable the Programmable Interrupt Controller
+ *
+ * This function enables IRQ0 and IRQ1, which correspond to
+ * the timer and keyboard interrupts, respectively.
+ */
 void pic_enable()
 {
     // Enabling IRQ0 (unmasking it) but not the others
@@ -55,12 +71,15 @@ void pic_enable()
 }
 
 /*
-Base frequency = 1.193182 MHz
+ * pit_init - Initialization of the Programmable Interval Timer
-1 tick per ms (divide by 1000) = roughly 1193 Hz
+ *
-*/
+ * The PIT is the simplest timer we can get working on x86.
+ * It has a base frequency of 1.193182 MHz.
+ * A custom frequency can be set using TIMER_FREQUENCY macro.
+ */
 void pit_init()
 {
-    uint32_t frequency = 1000; // 1 kHz
+    uint32_t frequency = TIMER_FREQUENCY;
     uint32_t divisor = 1193182 / frequency;
 
     // Set PIT to mode 3, channel 0
@@ -71,17 +90,25 @@ void pit_init()
     outb(0x40, (divisor >> 8) & 0xFF);
 }
 
-// Wait n ticks
+/*
-// Given that there's a tick every 1ms, wait n milliseconds
+ * timer_wait - Wait for X ticks
+ *
+ * By default, the timer frequency is 1000Hz, meaning
+ * ticks are equal to milliseconds.
+ */
 void timer_wait(uint64_t wait_ticks)
 {
     uint64_t then = ticks + wait_ticks;
-    while (ticks < then)
+    while (ticks < then) {
-    {
         asm("hlt");
     };
 }
 
+/*
+ * timer_init - Initialization of the timer
+ *
+ * This function wakes the PIT.
+ */
 void timer_init()
 {
     // Remapping the PIC, because at startup it conflicts with
@@ -91,4 +118,5 @@ void timer_init()
     pic_enable();
     pit_init();
     DEBUG("PIT initialized");
+    init.timer = true;
 }

src/time/timer.h

@@ -7,7 +7,7 @@
 #ifndef TIMER_H
 #define TIMER_H
 
-void timer_init();
+void timer_init(void);
 void timer_wait(unsigned int wait_ticks);
 
 #endif

test.bin

@@ -1 +0,0 @@
-ｸ<EFBFBD>ｭﾞ<EFBFBD>