Add fs.h.

Makefile

@@ -19,7 +19,10 @@ debug: image.bin
 		-ex "break _start" \
 		-ex "continue"
 
-image.bin: mbr.bin kernel.bin
+fs.img: kernel.bin tools/mkfs
+	tools/mkfs $@ $<
+
+image.bin: mbr.bin fs.img
 	cat $^ >$@
 
 kernel.bin: kernel.o vga.o string.o drivers/ata.o
@@ -29,7 +32,7 @@ kernel.bin: kernel.o vga.o string.o drivers/ata.o
 	$(CC) -m32 -ffreestanding -c -g $< -o $@
 
 %.o: %.S
-	$(CC) -m32 $^ -c -g -o $@
+	$(AS) --32 -g $^ -o $@
 
 mbr.bin: mbr.o
 	$(LD) -m elf_i386 -Ttext=0x7c00 --oformat=binary $^ -o $@
@@ -38,4 +41,7 @@ mbr.elf: mbr.o
 	$(LD) -m elf_i386 -Ttext=0x7c00 $^ -o $@
 
 clean:
-	rm -f *.bin *.o
+	rm -f *.bin *.o tools/mkfs
+
+tools/%: tools/%.c
+	gcc -Wall -Werror -g $^ -o $@

drivers/ata.c

@@ -22,7 +22,7 @@ ERR: a 1 indicates that an error occured. An error code has been placed in the e
 #define STATUS_DF 0x20
 #define STATUS_ERR 0x01
 
-//This is really specific to out OS now, assuming ATA bus 0 master 
+//This is really specific to our OS now, assuming ATA bus 0 master
 //Source - OsDev wiki
 static void ATA_wait_BSY();
 static void ATA_wait_DRQ();
@@ -30,22 +30,22 @@ void read_sectors_ATA_PIO(uint32_t target_address, uint32_t LBA, uint8_t sector_
 {
 
 	ATA_wait_BSY();
-	port_byte_out(0x1F6,0xE0 | ((LBA >>24) & 0xF));
-	port_byte_out(0x1F2,sector_count);
+	port_byte_out(0x1F6, 0xE0 | ((LBA >>24) & 0xF));
+	port_byte_out(0x1F2, sector_count);
 	port_byte_out(0x1F3, (uint8_t) LBA);
 	port_byte_out(0x1F4, (uint8_t)(LBA >> 8));
 	port_byte_out(0x1F5, (uint8_t)(LBA >> 16));
-	port_byte_out(0x1F7,0x20); //Send the read command
+	port_byte_out(0x1F7, 0x20); //Send the read command
 
 	uint16_t *target = (uint16_t*) target_address;
 
-	for (int j =0;j<sector_count;j++)
+	for (int j = 0; j < sector_count; j++)
 	{
 		ATA_wait_BSY();
 		ATA_wait_DRQ();
-		for(int i=0;i<256;i++)
+		for(int i = 0; i < 256; i++)
 			target[i] = port_word_in(0x1F0);
-		target+=256;
+		target += 256;
 	}
 }
 
@@ -72,9 +72,9 @@ void write_sectors_ATA_PIO(uint32_t LBA, uint8_t sector_count, uint32_t* bytes)
 
 static void ATA_wait_BSY()   //Wait for bsy to be 0
 {
-	while(port_byte_in(0x1F7)&STATUS_BSY);
+	while (port_byte_in(0x1F7) & STATUS_BSY);
 }
 static void ATA_wait_DRQ()  //Wait fot drq to be 1
 {
-	while(!(port_byte_in(0x1F7)&STATUS_RDY));
+	while(!(port_byte_in(0x1F7) & STATUS_RDY));
 }

drivers/ata.h

@@ -1,2 +1,5 @@
+#pragma once
+#include <stdint.h>
+
 void read_sectors_ATA_PIO(uint32_t target_address, uint32_t LBA, uint8_t sector_count);
 void write_sectors_ATA_PIO(uint32_t LBA, uint8_t sector_count, uint32_t* bytes);

drivers/misc.h

@@ -0,0 +1,8 @@
+#pragma once
+#include "../port.h"
+
+__attribute__((noreturn))
+static inline void qemu_shutdown() {
+	port_word_out(0x604, 0x2000);
+	while(1);
+}

fs/fs.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include <stdint.h>
+
+/* Directory structure:
+
+         32-byte entries
+┌───────────────────────────────┐
+│Reserved                       │
+│char[32]                       │
+├──────┬──────┬────────┬────────┤
+│Offset│Size  │Reserved│Name    │
+│uint32│uint32│uint32  │char[20]│
+├──────┼──────┼────────┼────────┤
+│ ...  │      │        │        │
+
+Offset is in sectors (zero-based),
+size is in bytes, name is 0-terminated.
+
+*/
+
+enum {
+	sector_size = 512,
+};
+
+struct dirent {
+	uint32_t offset_sectors;
+	uint32_t size_bytes;
+	uint32_t reserved;
+	char name[20];
+};
+
+struct dir {
+	char reserved[32];
+	struct dirent entries[15];
+};
+
+struct stat {
+	uint32_t size;
+	uint32_t reserved[3];
+};
+
+/* Find file by name and fill information in buf.
+ * Returns zero on success, nonzero on failure. */
+int stat(const char* name, struct stat *buf);
+
+/* Find file by name and read it into buffer with size bufsize.
+ * At most (bufsize & ~511) bytes will be read.
+ * Return number of bytes read or -1 on failure. */
+int read_file(const char* name, void* buf, uint32_t bufsize);

kernel.c

@@ -1,8 +1,18 @@
+asm(".asciz \"kernel start\"");
+
 #include "vga.h"
+#include "drivers/ata.h"
+#include "drivers/misc.h"
 
 void _start() {
+    char buf[512];
+
     vga_clear_screen();
-    for (int i = 0; i < 24; i++) {
-        vga_print_string("hello world\n");
-    }
+    vga_print_string("YABLOKO\n");
+
+    read_sectors_ATA_PIO((uint32_t)buf, 10, 1);
+    vga_print_string(buf);
+
+    asm("hlt");
+    qemu_shutdown();
 }

mbr.S

@@ -16,7 +16,7 @@ _start:
 .equ ELF32_PHDR_FILESZ_OFFSET, 4*4
 .equ KERNEL_OFFSET, 0x1000
 
-.equ MBR_SECTORS, 1
+.equ MBR_SECTORS, 2
 .equ SECTOR_BASE, 1
 .equ ELFHDR_SECTORS, 8
 

port.h

@@ -13,9 +13,13 @@ static unsigned short port_word_in(unsigned short port) {
 }
 
 static void port_byte_out(unsigned short port, unsigned char data) {
-    __asm__("out %%al, %%dx" : : "a" (data), "d" (port));
+    __asm__("outb %%al, %%dx" : : "a" (data), "d" (port));
+}
+
+static void port_word_out(unsigned short port, unsigned short data) {
+    __asm__("outw %%ax, %%dx" : : "a" (data), "d" (port));
 }
 
 static void port_long_out(unsigned short port, unsigned int data) {
-    __asm__("out %%eax, %%dx" : : "a" (data), "d" (port));
+    __asm__("outl %%eax, %%dx" : : "a" (data), "d" (port));
 }

tools/mkfs.c

@@ -0,0 +1,78 @@
+#include "../fs/fs.h"
+
+#include <stdio.h>
+#include <string.h>
+
+char* basename(char* path) {
+    char* c = strrchr(path, '/');
+    if (c && *c) {
+        return c + 1;
+    }
+    return path;
+}
+
+int main(int argc, char* argv[]) {
+    char sector[sector_size];
+    struct dir dir = {{0}};
+
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s OUT.FS KERNEL.BIN [FILES...]\n", argv[0]);
+        return 1;
+    }
+
+    FILE* image = fopen(argv[1], "wb");
+    if (!image) {
+        perror(argv[1]);
+        return 1;
+    }
+
+    if (fwrite(&dir, sizeof(dir), 1, image) < 1) {
+        perror("fwrite");
+        return 1;
+    }
+    uint32_t sector_offset = 1;
+
+    for (int i = 2; i < argc; ++i) {
+        char* name = argv[i];
+        struct dirent *dirent = &dir.entries[i-2];
+        dirent->offset_sectors = sector_offset;
+        dirent->size_bytes = 0;
+
+        FILE* file = fopen(name, "rb");
+        if (!file) {
+            perror(name);
+            return 1;
+        }
+
+        size_t read_size;
+        while ((read_size = fread(sector, 1, sizeof(sector), file))) {
+            if (fwrite(sector, 1, sizeof(sector), image) != sizeof(sector)) {
+                perror(name);
+                return 1;
+            }
+            sector_offset++;
+            dirent->size_bytes += read_size;
+        }
+
+        if (fclose(file)) {
+            perror(name);
+            return 1;
+        }
+
+        dirent->reserved = 0;
+        strlcpy(dirent->name, basename(name), sizeof(dirent->name));
+    }
+
+    fseek(image, 0, SEEK_SET);
+    if (fwrite(&dir, sizeof(dir), 1, image) < 1) {
+        perror("fwrite");
+        return 1;
+    }
+
+    if (fclose(image)) {
+        perror(argv[0]);
+        return 1;
+    }
+
+    return 0;
+}