Re-add: ATA PIO driver (w/o paging)

README.md

@@ -79,6 +79,7 @@ Two other documents are available to help you understand the project better. One
 - 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)
 - Ralf Brown's Interrupt List
+- the [little book about OS development](https://littleosbook.github.io/) by Erik Helin and Adam Renberg
 
 ### ⚠️ Disclaimer
 
@@ -90,8 +91,9 @@ This is a hobbyist operating system kernel and it comes without any warranty wha
 - [X] Common basic structures (IDT, GDT, ISRs, IRQs)
 - [X] Common drivers (framebuffer, keyboard, serial, timer)
 - [X] Kernel-space utilities (shell, simple programs)
-- [ ] FAT32 filesystem
+- [ ] Filesystem (FAT32 or VFS ramdisk)
-- [ ] Paging/Page Frame Allocation
+- [ ] Changing the default VGA font
+- [X] Paging/Page Frame Allocation
 - [ ] TCP/IP Network stack
 - [ ] Getting to Ring-3 (userspace)
 - [ ] Multitasking (via round robin scheduling)

src/drivers/ata.c

@@ -0,0 +1,77 @@
+#include "../libc/stdint.h" 
+#include "../kernel/io.h"
+#include "../libc/stdio.h"
+
+#define ATA_PRIMARY_IO 		0x1F0
+#define ATA_PRIMARY_CTRL 	0x3F6
+#define ATA_CMD_READ_PIO	0x20
+#define ATA_CMD_WRITE_PIO 	0x30
+#define ATA_IDENTIFY 		0xEC
+
+#define ATA_REG_DATA 		0x00
+#define ATA_REG_ERROR 		0x01
+#define ATA_REG_SECCOUNT0 	0x02
+#define ATA_REG_LBA0 		0x03
+#define ATA_REG_LBA1 		0x04
+#define ATA_REG_LBA2 		0x05
+#define ATA_REG_HDDEVSEL 	0x06
+#define ATA_REG_COMMAND 	0x07
+#define ATA_REG_STATUS 		0x07
+
+#define ATA_SR_BSY 		0x80
+#define ATA_SR_DRDY 		0x40
+#define ATA_SR_DRQ 		0x08
+#define ATA_SR_ERR 		0x01
+
+static inline uint16_t inw(uint16_t port) {
+    uint16_t result;
+    asm volatile("inw %1, %0" : "=a"(result) : "dN"(port));
+    return result;
+}
+
+static inline void outw(uint16_t port, uint16_t data) {
+    asm volatile("outw %1, %0" : : "dN"(port), "a"(data));
+}
+
+void ata_wait_bsy() {
+    while (inb(ATA_PRIMARY_IO + ATA_REG_STATUS) & ATA_SR_BSY);
+}
+
+void ata_wait_drq() {
+    while (!(inb(ATA_PRIMARY_IO + ATA_REG_STATUS) & ATA_SR_DRQ));
+}
+
+void ata_select_drive(uint8_t drive) {
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | (drive << 4));
+}
+
+void ata_read_sector(uint32_t lba, uint8_t* buffer) {
+    ata_wait_bsy();
+    ata_select_drive(0);
+
+    outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)lba);
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
+
+    outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
+
+    ata_wait_bsy();
+    ata_wait_drq();
+
+    for (int i = 0; i < 256; i++) {
+        ((uint16_t*)buffer)[i] = inw(ATA_PRIMARY_IO + ATA_REG_DATA);
+    }
+}
+
+// Works only w/o paging
+void test_read_sector() {
+    uint8_t buffer[512];
+    ata_read_sector(0, buffer);
+
+    for (int i = 0; i < 512; i++) {
+        if (i%25==0) puts("\n");
+	printf("%02x ", buffer[i]);
+    }
+}

src/drivers/ata.h

@@ -0,0 +1,7 @@
+#ifndef ATA_H
+#define ATA_H
+
+void ata_read_sector(uint32_t lba, uint8_t* buffer);
+void test_read_sector();
+
+#endif

src/kernel/kmain.c

@@ -4,6 +4,7 @@
 #include "idt.h"
 #include "system.h"
 #include "paging.h"
+#include "../drivers/ata.h"
 
 char* ascii_title =
 "\n"
@@ -39,6 +40,8 @@ void kmain(unsigned int multiboot_info_address)
   init_paging();
   printf("Hello, paging world!\n");
 
+  //test_read_sector();
+
   uint32_t *ptr = (uint32_t*)0xA0000000;
   uint32_t do_page_fault = *ptr;
 

src/libc/stdio.c

@@ -226,22 +226,39 @@ void printf(const char* fmt, ...)
     int length = PRINTF_LENGTH_START;
     int radix = 10;
     bool sign = false;
+    int width = 0;
+    char pad_char = ' ';
 
     argp++;
     while (*fmt)
     {
-    switch(state) {
+        switch (state)
+        {
         case PRINTF_STATE_START:
             if (*fmt == '%')
             {
                 state = PRINTF_STATE_LENGTH;
+                width = 0;
+                pad_char = ' ';
             }
-        else {
+            else
+            {
                 putc(*fmt);
             }
             break;
+
         case PRINTF_STATE_LENGTH:
-        if (*fmt == 'h')
+            if (*fmt == '0')
+            {
+                pad_char = '0';
+                state = PRINTF_STATE_WIDTH;
+            }
+            else if (*fmt >= '1' && *fmt <= '9')
+            {
+                width = *fmt - '0';
+                state = PRINTF_STATE_WIDTH;
+            }
+            else if (*fmt == 'h')
             {
                 length = PRINTF_LENGTH_SHORT;
                 state = PRINTF_STATE_SHORT;
@@ -251,30 +268,47 @@ void printf(const char* fmt, ...)
                 length = PRINTF_LENGTH_LONG;
                 state = PRINTF_STATE_LONG;
             }
-        else {
+            else
+            {
                 goto PRINTF_STATE_SPEC_;
             }
             break;
+
+        case PRINTF_STATE_WIDTH:
+            if (*fmt >= '0' && *fmt <= '9')
+            {
+                width = width * 10 + (*fmt - '0');
+            }
+            else
+            {
+                goto PRINTF_STATE_SPEC_;
+            }
+            break;
+
         case PRINTF_STATE_SHORT:
             if (*fmt == 'h')
             {
                 length = PRINTF_LENGTH_SHORT_SHORT;
                 state = PRINTF_STATE_SPEC;
             }
-        else {
+            else
+            {
                 goto PRINTF_STATE_SPEC_;
             }
             break;
+
         case PRINTF_STATE_LONG:
             if (*fmt == 'l')
             {
                 length = PRINTF_LENGTH_LONG_LONG;
                 state = PRINTF_STATE_SPEC;
             }
-        else {
+            else
+            {
                 goto PRINTF_STATE_SPEC_;
             }
             break;
+
         case PRINTF_STATE_SPEC:
         PRINTF_STATE_SPEC_:
             switch (*fmt)
@@ -294,33 +328,32 @@ void printf(const char* fmt, ...)
             case 'i':
                 radix = 10;
                 sign = true;
-            argp = printf_number(argp, length, sign, radix);
+                argp = printf_number(argp, length, sign, radix, width, pad_char);
                 break;
             case 'u':
                 radix = 10;
                 sign = false;
-            argp = printf_number(argp, length, sign, radix);
+                argp = printf_number(argp, length, sign, radix, width, pad_char);
                 break;
             case 'X':
             case 'x':
             case 'p':
                 radix = 16;
                 sign = false;
-            argp = printf_number(argp, length, sign, radix);
+                argp = printf_number(argp, length, sign, radix, width, pad_char);
                 break;
             case 'o':
                 radix = 8;
                 sign = false;
-            argp = printf_number(argp, length, sign, radix);
+                argp = printf_number(argp, length, sign, radix, width, pad_char);
                 break;
             case 'f': {
-            // Handle floating-point numbers
                 double* dargp = (double*)argp;
                 double d = *(double*)dargp;
                 char buffer[64];
-            dtostrf(d, buffer, 6); // Default precision: 6
+                dtostrf(d, buffer, 6);
                 puts(buffer);
-            argp += 2; // Incrementing by 2 to move past the double argument
+                argp += 2;
                 break;
             }
             default:
@@ -330,6 +363,8 @@ void printf(const char* fmt, ...)
             length = PRINTF_LENGTH_START;
             radix = 10;
             sign = false;
+            width = 0;
+            pad_char = ' ';
             break;
         }
         fmt++;
@@ -338,7 +373,7 @@ void printf(const char* fmt, ...)
 
 const char charset[] = "0123456789abcdef";
 
-int* printf_number(int* argp, int length, bool sign, int radix)
+int* printf_number(int* argp, int length, bool sign, int radix, int width, char pad_char)
 {
     char buffer[32];
     unsigned long long number;
@@ -360,7 +395,8 @@ int* printf_number(int* argp, int length, bool sign, int radix)
             }
             number = (unsigned long long)n;
         }
-      else {
+        else
+        {
             number = *(unsigned int*)argp;
         }
         argp++;
@@ -376,7 +412,8 @@ int* printf_number(int* argp, int length, bool sign, int radix)
             }
             number = (unsigned long long)n;
         }
-      else {
+        else
+        {
             number = *(unsigned long int*)argp;
         }
         argp += 2;
@@ -392,14 +429,16 @@ int* printf_number(int* argp, int length, bool sign, int radix)
             }
             number = (unsigned long long)n;
         }
-      else {
+        else
+        {
             number = *(unsigned long long int*)argp;
         }
         argp += 4;
         break;
     }
 
-  do {
+    do
+    {
         uint32_t rem;
         x86_div64_32(number, radix, &number, &rem);
         buffer[pos++] = charset[rem];
@@ -410,6 +449,13 @@ int* printf_number(int* argp, int length, bool sign, int radix)
         buffer[pos++] = '-';
     }
 
+    int padding = width - pos;
+
+    while (padding-- > 0)
+    {
+        putc(pad_char);
+    }
+
     while (--pos >= 0)
     {
         putc(buffer[pos]);

src/libc/stdio.h

@@ -28,6 +28,7 @@ void colorputc(char c, unsigned int color);
 #define PRINTF_STATE_SHORT 		2
 #define PRINTF_STATE_LONG 		3
 #define PRINTF_STATE_SPEC 		4
+#define PRINTF_STATE_WIDTH 		5
 
 #define PRINTF_LENGTH_START 		0
 #define PRINTF_LENGTH_SHORT_SHORT 	1
@@ -36,7 +37,7 @@ void colorputc(char c, unsigned int color);
 #define PRINTF_LENGTH_LONG_LONG 	4
 
 void printf(const char* fmt, ...);
-int* printf_number(int* argp, int length, bool sign, int radix);
+int* printf_number(int* argp, int length, bool sign, int radix, int width, char pad_char);
 int getch();
 void get_input(char *buffer, int size);