Add: brainfuck interpreter; documentation; uptime

README.md

@@ -1,11 +1,19 @@
 # BlankOS
 
-Rewritten monolithic version of Blank OS for the x86 processor architecture. Features a framebuffer, serial port driver, GDT, IDT. The OS relies on an old, legacy version of GRUB as the bootloader (eltorito). This *should* be GRUB 2 compatible. Emulation was tested on Arch Linux 6.9.7-arch1-1. The long-term goal of this OS is to be capable of running user programs and having its own complete kernel C library so that users can write their own C programs and expand the system!
+Rewritten monolithic version of Blank OS for the x86 processor architecture. The OS relies on an old, legacy version of GRUB as the bootloader (eltorito). This *should* be GRUB 2 compatible. Emulation was tested on Bochs and QEMU using Arch Linux 6.9.7-arch1-1, and on real hardware too.
+The long-term goal of this OS is to be capable of running user programs and having its own complete kernel C library so that users can write their own C programs and expand the system!
 
-Next steps for this project will be:
-- User programs
-- Completing the kernel libc
-- Filesystem support
+## Features
+
+- Serial port driver (output & debug)
+- Framebuffer driver (output)
+- PS/2 Keyboard and PIC driver (input)
+- PIT (system clock/timer) driver
+- Working IDT, GDT, ISRs, and IRQs
+- Kernel panicking (exception handling)
+- A kernel-space shell
+- Cool color output!!
+- Some small working kernel-space programs!!
 
 ## Usage
 
@@ -51,9 +59,26 @@ sudo dd bs=4M if=blankos.iso of=/dev/sdX status=progress oflag=sync
 Replace `sdX` with your USB drive name (you can find it by doing `sudo fdisk -l`).
 Tada! You now have a working BlankOS USB stick. Go ahead and try it out!
 
-## Post-install guides
+## Post-install
 
-Two documents are available to help you understand the project better. One is the User's Manual, labelled `USERS.md`, and the other one is the Developer's Manual, labelled `DEVELOPERS.md`. They are full of useful resources around Blank OS.
+Two documents are available to help you understand the project better. One is the User's Manual, labelled `USERS.md`, and the other one is the Developer's Manual, labelled `DEVELOPERS.md`. They are full of useful resources around Blank OS. You'll learn how to use the system and how to contribute to it.
+
+### Next Steps?
+
+Next steps for this project will be:
+
+- User programs
+- Completing the kernel libc
+- Filesystem support
+
+### Resources
+
+- the [OSDev.org](https://wiki.osdev.org/Expanded_Main_Page) wiki and forums
+- the [Nanobyte](https://www.youtube.com/watch?v=9t-SPC7Tczc&list=PLFjM7v6KGMpiH2G-kT781ByCNC_0pKpPN) YouTube channel
+- the [Daedalus Community](https://www.youtube.com/@DaedalusCommunity) YouTube channel
+- a great book named *Operating Systems: From 0 to 1*, by Tu, Do Hoang
+- the Intel [64 and IA-32 Architectures Software Developer Manuals](https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html)
+- [Bran's Kernel Development Tutorial](http://www.osdever.net/bkerndev/index.php)
 
 ### ⚠️ Disclaimer
 

USERS.md

@@ -12,6 +12,41 @@ Once you have launched the OS for the first time, you should first see the welco
 
 To get the list of available commands on the system, type `help`.
 
-## Next what?
+### Commands
 
-Once programs will be added, there will be more info here. For now you can just play around and make the kernel panic. That's it.
+#### `help`
+
+Shows all of the available commands, which are explained here.
+
+#### `panic`
+
+Triggers a kernel panic by trying to divide four by zero.
+
+#### `words`
+
+Prints ten random words using an arbitrary dictionary that you can expand in `src/programs/words.c`.
+
+#### `primes`
+
+Computes prime numbers up to `PRIMES_MAX`, defined in `src/programs/primes.c`.
+
+#### `rainbow`
+
+Asks for text and then outputs it with different vibrant colors.
+
+#### `clear`
+
+Clears the screen by scrolling (screen height) times.
+
+#### `math`
+
+**This program is not working!**
+The lexer and parser should be okay, but I can't figure out the `%f` floating point format specifier in the freestanding printf implementation; it triggers weird exceptions that I don't understand. So no math interpreter for now.
+
+#### `bf`
+
+A brainfuck interpreter with every instruction and default tape size (30k cells).
+
+#### `uptime`
+
+Gets system uptime from the timer in ticks. Ticks are incremented at a rate of 18.222Hz (18.222 ticks per second).

src/drivers/kb.h

@@ -0,0 +1,6 @@
+#ifndef KB_H
+#define KB_H
+
+char keyboard_getchar();
+
+#endif

src/drivers/timer.c

@@ -19,3 +19,8 @@ void delay(int ticks)
 	eticks = global_ticks + ticks;
 	while (global_ticks < eticks);
 }
+
+int uptime()
+{
+	return global_ticks;
+}

src/kernel/shell.c

@@ -21,7 +21,7 @@ void shell_install()
     }
     else if (strcmp(input_buffer, "help") == 0)
     {
-        printf("help\tpanic\twords\tprimes\trainbow\tclear\nmath\n");
+        printf("help\tpanic\twords\tprimes\trainbow\tclear\nmath\tbf\tuptime\n");
     }
     else if (strcmp(input_buffer, "panic") == 0)
     {
@@ -47,6 +47,14 @@ void shell_install()
     {
 	    program_math();
     }
+    else if (strcmp(input_buffer, "bf") == 0)
+    {
+	    program_bf();
+    }
+    else if (strcmp(input_buffer, "uptime") == 0)
+    {
+	    program_uptime();
+    }
     else {
 	printf("Unknown command %s\n", input_buffer);
     }

src/kernel/system.h

@@ -22,6 +22,7 @@ void delay(int ticks);
 void keyboard_install();
 char keyboard_getchar();
 void shell_install();
+int uptime();
 
 extern volatile unsigned long global_ticks;
 

src/programs/bf.c

@@ -0,0 +1,55 @@
+
+#include "../kernel/system.h"
+#include "../libc/stdio.h"
+
+#define BUF_SIZE 256
+
+void brainfuck(char* input)
+{
+	unsigned char tape[30000] = {0};
+	unsigned char* ptr = tape;
+	char current_char;
+	size_t i;
+	size_t loop;
+
+	for (i=0; input[i] != 0; i++)
+	{
+		current_char = input[i];
+		if (current_char == '>') {
+			++ptr;
+		} else if (current_char == '<') {
+			--ptr;
+		} else if (current_char == '+') {
+			++*ptr;
+		} else if (current_char == '-') {
+			--*ptr;
+		} else if (current_char == '.') {
+			putc(*ptr);
+		} else if (current_char == ',') {
+			*ptr = keyboard_getchar();
+		} else if (current_char == '[') {
+			continue;
+		} else if (current_char == ']' && *ptr) {
+			loop = 1;
+			while (loop > 0)
+			{
+				current_char = input[--i];
+				if (current_char == '[') {
+					loop--;
+				} else if (current_char == ']') {
+					loop++;
+				}
+			}
+		}
+	}
+}
+
+void program_bf()
+{
+	char input_buffer[BUF_SIZE];
+	puts("Brainfuck code? ");
+	get_input(input_buffer, BUF_SIZE);
+	brainfuck(input_buffer);
+	//brainfuck(",[.[-],]");
+	puts("\n");
+}

src/programs/misc.c

@@ -1,6 +1,7 @@
 // Miscellaneous small programs
 
 #include "../libc/stdio.h"
+#include "../kernel/system.h"
 
 // Print a rainbow colorful text for testing
 
@@ -29,3 +30,10 @@ void program_clear()
 {	
 	for (int i=0; i<ROWS; i++) scroll(1);
 }
+
+// Get uptime in ticks
+
+void program_uptime()
+{
+	printf("%d ticks\n", uptime());
+}

src/programs/programs.h

@@ -4,8 +4,11 @@
 void program_words();
 void program_primes();
 void program_math();
+void program_bf();
 
 // Misc
 void program_rainbow();
 void program_clear();
+void program_uptime();
+
 #endif