commit a42aab766721c5946fdde075fff28d2e1b29440b
Author: sam <multisniperism@gmail.com>
Date: Sat Feb 24 20:24:22 2024 +1300
first commit
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..36305ee
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+obj/*
+radix.iso
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..05722e6
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,34 @@
+KERNEL=obj/radix.bin
+ISO=radix.iso
+
+CC=gcc
+LD=ld
+CFLAGS=-ffreestanding -fno-stack-protector -fno-stack-check -O3 -Wall -Wextra -Werror -m32 -Isrc
+LDFLAGS=-T linker.ld -m elf_i386
+NASMFLAGS=-f elf32
+
+CFILES=$(shell cd src && find -L * -type f -name '*.c')
+ASMFILES=$(shell cd src && find -L * -type f -name '*.asm')
+OBJ=$(addprefix obj/,$(CFILES:.c=.c.o) $(ASMFILES:.asm=.asm.o))
+
+$(ISO): $(KERNEL) isolinux.cfg
+ cp isolinux.cfg cdroot/isolinux/
+ cp $(KERNEL) cdroot/
+ mkisofs -o $(ISO) -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table cdroot/
+
+$(KERNEL): makedir linker.ld $(OBJ)
+ $(LD) $(LDFLAGS) $(OBJ) -o $@
+
+obj/%.c.o: src/%.c
+ $(CC) $(CFLAGS) -c $< -o $@
+obj/%.asm.o: src/%.asm
+ nasm $(NASMFLAGS) $< -o $@
+
+makedir:
+ mkdir -p obj
+
+run: $(ISO)
+ qemu-system-i386 -boot d -cdrom $(ISO) -m 1G -enable-kvm -cpu host -serial stdio
+
+clean:
+ rm -rf $(OBJ) $(KERNEL)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e69de29
diff --git a/cdroot/isolinux/isolinux.bin b/cdroot/isolinux/isolinux.bin
new file mode 100644
index 0000000..995cd2d
Binary files /dev/null and b/cdroot/isolinux/isolinux.bin differ
diff --git a/cdroot/isolinux/isolinux.cfg b/cdroot/isolinux/isolinux.cfg
new file mode 100644
index 0000000..2a41f17
--- /dev/null
+++ b/cdroot/isolinux/isolinux.cfg
@@ -0,0 +1,4 @@
+DEFAULT radix
+LABEL radix
+ KERNEL mboot.c32
+ APPEND /radix.bin
diff --git a/cdroot/isolinux/ldlinux.c32 b/cdroot/isolinux/ldlinux.c32
new file mode 100644
index 0000000..e43c6cd
Binary files /dev/null and b/cdroot/isolinux/ldlinux.c32 differ
diff --git a/cdroot/isolinux/libcom32.c32 b/cdroot/isolinux/libcom32.c32
new file mode 100644
index 0000000..73d3f8d
Binary files /dev/null and b/cdroot/isolinux/libcom32.c32 differ
diff --git a/cdroot/isolinux/mboot.c32 b/cdroot/isolinux/mboot.c32
new file mode 100644
index 0000000..22ab5cc
Binary files /dev/null and b/cdroot/isolinux/mboot.c32 differ
diff --git a/cdroot/radix.bin b/cdroot/radix.bin
new file mode 100755
index 0000000..92db9d1
Binary files /dev/null and b/cdroot/radix.bin differ
diff --git a/isolinux.cfg b/isolinux.cfg
new file mode 100644
index 0000000..2a41f17
--- /dev/null
+++ b/isolinux.cfg
@@ -0,0 +1,4 @@
+DEFAULT radix
+LABEL radix
+ KERNEL mboot.c32
+ APPEND /radix.bin
diff --git a/linker.ld b/linker.ld
new file mode 100644
index 0000000..0e93f9b
--- /dev/null
+++ b/linker.ld
@@ -0,0 +1,28 @@
+ENTRY(_start)
+
+SECTIONS
+{
+ . = 1M;
+
+ .text BLOCK(4K) : ALIGN(4K)
+ {
+ *(.multiboot)
+ *(.text)
+ }
+
+ .rodata BLOCK(4K) : ALIGN(4K)
+ {
+ *(.rodata)
+ }
+
+ .data BLOCK(4K) : ALIGN(4K)
+ {
+ *(.data)
+ }
+
+ .bss BLOCK(4K) : ALIGN(4K)
+ {
+ *(COMMON)
+ *(.bss)
+ }
+}
diff --git a/src/boot.asm b/src/boot.asm
new file mode 100644
index 0000000..bc45745
--- /dev/null
+++ b/src/boot.asm
@@ -0,0 +1,36 @@
+extern kernel_main
+
+MBALIGN equ 1 << 0
+MEMINFO equ 1 << 1
+VIDINFO equ 1 << 2
+MBFLAGS equ MBALIGN | MEMINFO | VIDINFO
+MAGIC equ 0x1BADB002
+CHECKSUM equ -(MAGIC + MBFLAGS)
+
+section .multiboot
+align 4
+ dd MAGIC
+ dd MBFLAGS
+ dd CHECKSUM
+ dd 0, 0, 0, 0, 0
+ dd 0
+ dd 320, 200, 8
+
+section .bss
+align 16
+stack_bottom:
+resb 16384
+stack_top:
+
+section .text
+global _start:function (_start.end - _start)
+_start:
+ mov esp, stack_top
+ push ebx
+ push eax
+
+ call kernel_main
+ cli
+.hang:
+ jmp .hang
+.end:
diff --git a/src/ctype.c b/src/ctype.c
new file mode 100644
index 0000000..6a3efa7
--- /dev/null
+++ b/src/ctype.c
@@ -0,0 +1,5 @@
+#include <ctype.h>
+
+int isdigit(char c) {
+ return c >= '0' && c <= '9';
+}
diff --git a/src/ctype.h b/src/ctype.h
new file mode 100644
index 0000000..c27dc9e
--- /dev/null
+++ b/src/ctype.h
@@ -0,0 +1,6 @@
+#ifndef __CTYPE_H__
+#define __CTYPE_H__
+
+int isdigit(char arg);
+
+#endif
diff --git a/src/hcf.asm b/src/hcf.asm
new file mode 100644
index 0000000..23c911d
--- /dev/null
+++ b/src/hcf.asm
@@ -0,0 +1,7 @@
+global hcf
+
+hcf:
+ cli
+.loop:
+ hlt
+ jmp .loop
diff --git a/src/hcf.h b/src/hcf.h
new file mode 100644
index 0000000..9ca36eb
--- /dev/null
+++ b/src/hcf.h
@@ -0,0 +1,6 @@
+#ifndef __HCF_H__
+#define __HCF_H__
+
+void hcf();
+
+#endif
diff --git a/src/kernel.c b/src/kernel.c
new file mode 100644
index 0000000..1904027
--- /dev/null
+++ b/src/kernel.c
@@ -0,0 +1,241 @@
+#include <multiboot.h>
+#include <stdio.h>
+#include <hcf.h>
+#include <vga.h>
+
+#include <string.h>
+#include <stddef.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+void putpixel(unsigned char* addr, int pos_x, int pos_y, unsigned char VGA_COLOR)
+{
+ unsigned char* location = addr + 320 * pos_y + pos_x;
+ *location = VGA_COLOR;
+}
+
+static inline void outb(uint16_t port, uint8_t val)
+{
+ __asm__ volatile ( "outb %b0, %w1" : : "a"(val), "Nd"(port) : "memory");
+ /* There's an outb %al, $imm8 encoding, for compile-time constant port numbers that fit in 8b. (N constraint).
+ * Wider immediate constants would be truncated at assemble-time (e.g. "i" constraint).
+ * The outb %al, %dx encoding is the only option for all other cases.
+ * %1 expands to %dx because port is a uint16_t. %w1 could be used if we had the port number a wider C type */
+}
+
+static inline uint8_t inb(uint16_t port)
+{
+ uint8_t ret;
+ __asm__ volatile ( "inb %w1, %b0"
+ : "=a"(ret)
+ : "Nd"(port)
+ : "memory");
+ return ret;
+}
+
+#define PORT 0x3f8 // COM1
+
+static int init_serial() {
+ outb(PORT + 1, 0x00); // Disable all interrupts
+ outb(PORT + 3, 0x80); // Enable DLAB (set baud rate divisor)
+ outb(PORT + 0, 0x03); // Set divisor to 3 (lo byte) 38400 baud
+ outb(PORT + 1, 0x00); // (hi byte)
+ outb(PORT + 3, 0x03); // 8 bits, no parity, one stop bit
+ outb(PORT + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
+ outb(PORT + 4, 0x0B); // IRQs enabled, RTS/DSR set
+ 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)
+
+ // Check if serial is faulty (i.e: not same byte as sent)
+ if(inb(PORT + 0) != 0xAE) {
+ return 1;
+ }
+
+ // If serial is not faulty set it in normal operation mode
+ // (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
+ outb(PORT + 4, 0x0F);
+ return 0;
+}
+
+int is_transmit_empty() {
+ return inb(PORT + 5) & 0x20;
+}
+
+void write_serial(char a) {
+ while (is_transmit_empty() == 0);
+
+ outb(PORT,a);
+}
+
+void serial_puts(const char* s) {
+ do {
+ write_serial(*s);
+ } while(*++s != '\0');
+}
+
+void sprintf(const char* fmt, ...) {
+ va_list args;
+ va_start(args, fmt);
+
+ for(int i = 0; fmt[i] != '\0'; i++)
+ {
+ switch(fmt[i])
+ {
+ case '%':
+ i++;
+
+ char buf[512];
+
+ size_t width = 0;
+ char padding_char = fmt[i];
+ if(isdigit(fmt[i]) || fmt[i] == ' ') {
+ i++;
+ int pos = 0;
+ while(isdigit(fmt[i])) {
+ buf[pos++] = fmt[i++];
+ }
+ buf[pos] = '\0';
+ width = atoi(buf);
+ }
+
+ const char* out = 0;
+
+ if(fmt[i] == 's')
+ out = va_arg(args, const char*);
+ if(fmt[i] == 'd')
+ out = itoa(va_arg(args, int), buf, 10);
+ if(fmt[i] == 'u')
+ out = ultoa(va_arg(args, uint32_t), buf, 10);
+ if(fmt[i] == 'x')
+ out = ultoa(va_arg(args, uint32_t), buf, 16);
+ if(fmt[i] == 'c')
+ write_serial(va_arg(args, int));
+
+ size_t len = strlen(out);
+ if(width > len) {
+ char padding[256];
+ size_t j = 0;
+ for(; j < width - len; j++)
+ padding[j] = padding_char;
+ padding[j] = '\0';
+ serial_puts(padding);
+ }
+
+ serial_puts(out);
+ break;
+ default:
+ write_serial(fmt[i]);
+ break;
+ }
+ }
+
+ va_end(args);
+}
+
+#define CHECK_FLAG(flags,bit) ((flags) & (1 << (bit)))
+
+void kernel_main(uint32_t magic, multiboot_info_t* mbi) {
+ init_vga();
+ init_serial();
+
+ if(magic != MULTIBOOT_BOOTLOADER_MAGIC) {
+ printf("Invalid bootloader magic: %x", magic);
+ hcf();
+ }
+
+ printf("flags: 0x%x\n", mbi->flags);
+
+ uint32_t mem_total = mbi->mem_upper - mbi->mem_lower;
+ printf("mem_lower: %uKB, mem_upper: %uKB, mem_total: %uKB\n", mbi->mem_lower, mbi->mem_upper, mem_total);
+
+ //sprintf("checking for flag");
+//if (CHECK_FLAG (mbi->flags, 12))
+ //{
+ //sprintf("flag present");
+ multiboot_uint32_t color;
+ unsigned i;
+ void *fb = (void *) (unsigned long) mbi->framebuffer_addr;
+
+sprintf("fb_addr: %x, fb_width: %u, fb_height: %u", fb, mbi->framebuffer_width, mbi->framebuffer_height);
+
+ switch (mbi->framebuffer_type)
+ {
+ case MULTIBOOT_FRAMEBUFFER_TYPE_INDEXED:
+ {
+ //sprintf("indexed");
+ unsigned best_distance, distance;
+ struct multiboot_color *palette;
+
+ palette = (struct multiboot_color *) mbi->framebuffer_palette_addr;
+
+ color = 0;
+ best_distance = 4*256*256;
+
+ for (i = 0; i < mbi->framebuffer_palette_num_colors; i++)
+ {
+ distance = (0xff - palette[i].blue) * (0xff - palette[i].blue)
+ + palette[i].red * palette[i].red
+ + palette[i].green * palette[i].green;
+ if (distance < best_distance)
+ {
+ color = i;
+ best_distance = distance;
+ }
+ }
+ }
+ break;
+
+ case MULTIBOOT_FRAMEBUFFER_TYPE_RGB:
+ color = ((1 << mbi->framebuffer_blue_mask_size) - 1)
+ << mbi->framebuffer_blue_field_position;
+ break;
+
+ case MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT:
+ color = '\\' | 0x0100;
+ break;
+
+ default:
+ color = 0xffffffff;
+ break;
+ }
+ for (i = 0; i < mbi->framebuffer_width
+ && i < mbi->framebuffer_height; i++)
+ {
+ switch (mbi->framebuffer_bpp)
+ {
+ case 8:
+ {
+ multiboot_uint8_t *pixel = fb + mbi->framebuffer_pitch * i + i;
+ *pixel = color;
+ }
+ break;
+ case 15:
+ case 16:
+ {
+ multiboot_uint16_t *pixel
+ = fb + mbi->framebuffer_pitch * i + 2 * i;
+ *pixel = color;
+ }
+ break;
+ case 24:
+ {
+ multiboot_uint32_t *pixel
+ = fb + mbi->framebuffer_pitch * i + 3 * i;
+ *pixel = (color & 0xffffff) | (*pixel & 0xff000000);
+ }
+ break;
+
+ case 32:
+ {
+ multiboot_uint32_t *pixel
+ = fb + mbi->framebuffer_pitch * i + 4 * i;
+ *pixel = color;
+ }
+ break;
+ }
+ }
+ //}
+
+ hcf();
+}
diff --git a/src/multiboot.h b/src/multiboot.h
new file mode 100644
index 0000000..1ba51c4
--- /dev/null
+++ b/src/multiboot.h
@@ -0,0 +1,274 @@
+/* multiboot.h - Multiboot header file. */
+/* Copyright (C) 1999,2003,2007,2008,2009,2010 Free Software Foundation, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ANY
+ * DEVELOPER OR DISTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+ * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef MULTIBOOT_HEADER
+#define MULTIBOOT_HEADER 1
+
+/* How many bytes from the start of the file we search for the header. */
+#define MULTIBOOT_SEARCH 8192
+#define MULTIBOOT_HEADER_ALIGN 4
+
+/* The magic field should contain this. */
+#define MULTIBOOT_HEADER_MAGIC 0x1BADB002
+
+/* This should be in %eax. */
+#define MULTIBOOT_BOOTLOADER_MAGIC 0x2BADB002
+
+/* Alignment of multiboot modules. */
+#define MULTIBOOT_MOD_ALIGN 0x00001000
+
+/* Alignment of the multiboot info structure. */
+#define MULTIBOOT_INFO_ALIGN 0x00000004
+
+/* Flags set in the 'flags' member of the multiboot header. */
+
+/* Align all boot modules on i386 page (4KB) boundaries. */
+#define MULTIBOOT_PAGE_ALIGN 0x00000001
+
+/* Must pass memory information to OS. */
+#define MULTIBOOT_MEMORY_INFO 0x00000002
+
+/* Must pass video information to OS. */
+#define MULTIBOOT_VIDEO_MODE 0x00000004
+
+/* This flag indicates the use of the address fields in the header. */
+#define MULTIBOOT_AOUT_KLUDGE 0x00010000
+
+/* Flags to be set in the 'flags' member of the multiboot info structure. */
+
+/* is there basic lower/upper memory information? */
+#define MULTIBOOT_INFO_MEMORY 0x00000001
+/* is there a boot device set? */
+#define MULTIBOOT_INFO_BOOTDEV 0x00000002
+/* is the command-line defined? */
+#define MULTIBOOT_INFO_CMDLINE 0x00000004
+/* are there modules to do something with? */
+#define MULTIBOOT_INFO_MODS 0x00000008
+
+/* These next two are mutually exclusive */
+
+/* is there a symbol table loaded? */
+#define MULTIBOOT_INFO_AOUT_SYMS 0x00000010
+/* is there an ELF section header table? */
+#define MULTIBOOT_INFO_ELF_SHDR 0X00000020
+
+/* is there a full memory map? */
+#define MULTIBOOT_INFO_MEM_MAP 0x00000040
+
+/* Is there drive info? */
+#define MULTIBOOT_INFO_DRIVE_INFO 0x00000080
+
+/* Is there a config table? */
+#define MULTIBOOT_INFO_CONFIG_TABLE 0x00000100
+
+/* Is there a boot loader name? */
+#define MULTIBOOT_INFO_BOOT_LOADER_NAME 0x00000200
+
+/* Is there a APM table? */
+#define MULTIBOOT_INFO_APM_TABLE 0x00000400
+
+/* Is there video information? */
+#define MULTIBOOT_INFO_VBE_INFO 0x00000800
+#define MULTIBOOT_INFO_FRAMEBUFFER_INFO 0x00001000
+
+#ifndef ASM_FILE
+
+typedef unsigned char multiboot_uint8_t;
+typedef unsigned short multiboot_uint16_t;
+typedef unsigned int multiboot_uint32_t;
+typedef unsigned long long multiboot_uint64_t;
+
+struct multiboot_header
+{
+ /* Must be MULTIBOOT_MAGIC - see above. */
+ multiboot_uint32_t magic;
+
+ /* Feature flags. */
+ multiboot_uint32_t flags;
+
+ /* The above fields plus this one must equal 0 mod 2^32. */
+ multiboot_uint32_t checksum;
+
+ /* These are only valid if MULTIBOOT_AOUT_KLUDGE is set. */
+ multiboot_uint32_t header_addr;
+ multiboot_uint32_t load_addr;
+ multiboot_uint32_t load_end_addr;
+ multiboot_uint32_t bss_end_addr;
+ multiboot_uint32_t entry_addr;
+
+ /* These are only valid if MULTIBOOT_VIDEO_MODE is set. */
+ multiboot_uint32_t mode_type;
+ multiboot_uint32_t width;
+ multiboot_uint32_t height;
+ multiboot_uint32_t depth;
+};
+
+/* The symbol table for a.out. */
+struct multiboot_aout_symbol_table
+{
+ multiboot_uint32_t tabsize;
+ multiboot_uint32_t strsize;
+ multiboot_uint32_t addr;
+ multiboot_uint32_t reserved;
+};
+typedef struct multiboot_aout_symbol_table multiboot_aout_symbol_table_t;
+
+/* The section header table for ELF. */
+struct multiboot_elf_section_header_table
+{
+ multiboot_uint32_t num;
+ multiboot_uint32_t size;
+ multiboot_uint32_t addr;
+ multiboot_uint32_t shndx;
+};
+typedef struct multiboot_elf_section_header_table multiboot_elf_section_header_table_t;
+
+struct multiboot_info
+{
+ /* Multiboot info version number */
+ multiboot_uint32_t flags;
+
+ /* Available memory from BIOS */
+ multiboot_uint32_t mem_lower;
+ multiboot_uint32_t mem_upper;
+
+ /* "root" partition */
+ multiboot_uint32_t boot_device;
+
+ /* Kernel command line */
+ multiboot_uint32_t cmdline;
+
+ /* Boot-Module list */
+ multiboot_uint32_t mods_count;
+ multiboot_uint32_t mods_addr;
+
+ union
+ {
+ multiboot_aout_symbol_table_t aout_sym;
+ multiboot_elf_section_header_table_t elf_sec;
+ } u;
+
+ /* Memory Mapping buffer */
+ multiboot_uint32_t mmap_length;
+ multiboot_uint32_t mmap_addr;
+
+ /* Drive Info buffer */
+ multiboot_uint32_t drives_length;
+ multiboot_uint32_t drives_addr;
+
+ /* ROM configuration table */
+ multiboot_uint32_t config_table;
+
+ /* Boot Loader Name */
+ multiboot_uint32_t boot_loader_name;
+
+ /* APM table */
+ multiboot_uint32_t apm_table;
+
+ /* Video */
+ multiboot_uint32_t vbe_control_info;
+ multiboot_uint32_t vbe_mode_info;
+ multiboot_uint16_t vbe_mode;
+ multiboot_uint16_t vbe_interface_seg;
+ multiboot_uint16_t vbe_interface_off;
+ multiboot_uint16_t vbe_interface_len;
+
+ multiboot_uint64_t framebuffer_addr;
+ multiboot_uint32_t framebuffer_pitch;
+ multiboot_uint32_t framebuffer_width;
+ multiboot_uint32_t framebuffer_height;
+ multiboot_uint8_t framebuffer_bpp;
+#define MULTIBOOT_FRAMEBUFFER_TYPE_INDEXED 0
+#define MULTIBOOT_FRAMEBUFFER_TYPE_RGB 1
+#define MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT 2
+ multiboot_uint8_t framebuffer_type;
+ union
+ {
+ struct
+ {
+ multiboot_uint32_t framebuffer_palette_addr;
+ multiboot_uint16_t framebuffer_palette_num_colors;
+ };
+ struct
+ {
+ multiboot_uint8_t framebuffer_red_field_position;
+ multiboot_uint8_t framebuffer_red_mask_size;
+ multiboot_uint8_t framebuffer_green_field_position;
+ multiboot_uint8_t framebuffer_green_mask_size;
+ multiboot_uint8_t framebuffer_blue_field_position;
+ multiboot_uint8_t framebuffer_blue_mask_size;
+ };
+ };
+};
+typedef struct multiboot_info multiboot_info_t;
+
+struct multiboot_color
+{
+ multiboot_uint8_t red;
+ multiboot_uint8_t green;
+ multiboot_uint8_t blue;
+};
+
+struct multiboot_mmap_entry
+{
+ multiboot_uint32_t size;
+ multiboot_uint64_t addr;
+ multiboot_uint64_t len;
+#define MULTIBOOT_MEMORY_AVAILABLE 1
+#define MULTIBOOT_MEMORY_RESERVED 2
+#define MULTIBOOT_MEMORY_ACPI_RECLAIMABLE 3
+#define MULTIBOOT_MEMORY_NVS 4
+#define MULTIBOOT_MEMORY_BADRAM 5
+ multiboot_uint32_t type;
+} __attribute__((packed));
+typedef struct multiboot_mmap_entry multiboot_memory_map_t;
+
+struct multiboot_mod_list
+{
+ /* the memory used goes from bytes 'mod_start' to 'mod_end-1' inclusive */
+ multiboot_uint32_t mod_start;
+ multiboot_uint32_t mod_end;
+
+ /* Module command line */
+ multiboot_uint32_t cmdline;
+
+ /* padding to take it to 16 bytes (must be zero) */
+ multiboot_uint32_t pad;
+};
+typedef struct multiboot_mod_list multiboot_module_t;
+
+/* APM BIOS info. */
+struct multiboot_apm_info
+{
+ multiboot_uint16_t version;
+ multiboot_uint16_t cseg;
+ multiboot_uint32_t offset;
+ multiboot_uint16_t cseg_16;
+ multiboot_uint16_t dseg;
+ multiboot_uint16_t flags;
+ multiboot_uint16_t cseg_len;
+ multiboot_uint16_t cseg_16_len;
+ multiboot_uint16_t dseg_len;
+};
+
+#endif /* ! ASM_FILE */
+
+#endif /* ! MULTIBOOT_HEADER */
diff --git a/src/stdio.c b/src/stdio.c
new file mode 100644
index 0000000..f1c9678
--- /dev/null
+++ b/src/stdio.c
@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <ctype.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <vga.h>
+
+void putc(char ch) {
+ vga_putc(ch);
+}
+
+void puts(const char* str) {
+ do {
+ putc(*str);
+ } while(*++str != '\0');
+}
+
+void printf(const char* fmt, ...) {
+ va_list args;
+ va_start(args, fmt);
+
+ for(int i = 0; fmt[i] != '\0'; i++)
+ {
+ switch(fmt[i])
+ {
+ case '%':
+ i++;
+
+ char buf[512];
+
+ size_t width = 0;
+ char padding_char = fmt[i];
+ if(isdigit(fmt[i]) || fmt[i] == ' ') {
+ i++;
+ int pos = 0;
+ while(isdigit(fmt[i])) {
+ buf[pos++] = fmt[i++];
+ }
+ buf[pos] = '\0';
+ width = atoi(buf);
+ }
+
+ const char* out = 0;
+
+ if(fmt[i] == 's')
+ out = va_arg(args, const char*);
+ if(fmt[i] == 'd')
+ out = itoa(va_arg(args, int), buf, 10);
+ if(fmt[i] == 'u')
+ out = ultoa(va_arg(args, uint32_t), buf, 10);
+ if(fmt[i] == 'x')
+ out = ultoa(va_arg(args, uint32_t), buf, 16);
+ if(fmt[i] == 'c')
+ putc(va_arg(args, int));
+
+ size_t len = strlen(out);
+ if(width > len) {
+ char padding[256];
+ size_t j = 0;
+ for(; j < width - len; j++)
+ padding[j] = padding_char;
+ padding[j] = '\0';
+ puts(padding);
+ }
+
+ puts(out);
+ break;
+ default:
+ putc(fmt[i]);
+ break;
+ }
+ }
+
+ va_end(args);
+}
diff --git a/src/stdio.h b/src/stdio.h
new file mode 100644
index 0000000..35a69fe
--- /dev/null
+++ b/src/stdio.h
@@ -0,0 +1,9 @@
+#ifndef __STDIO_H__
+#define __STDIO_H__
+#include <stdint.h>
+
+void putc(char ch);
+void puts(const char* str);
+void printf(const char* fmt, ...);
+
+#endif
diff --git a/src/stdlib.c b/src/stdlib.c
new file mode 100644
index 0000000..4d12dcf
--- /dev/null
+++ b/src/stdlib.c
@@ -0,0 +1,77 @@
+#include <stdlib.h>
+#include <ctype.h>
+
+const char* itoa(int value, char* str, int base)
+{
+ char* rc;
+ char* ptr;
+ char* low;
+
+ if (base < 2 || base > 36)
+ {
+ *str = '\0';
+ return str;
+ }
+ rc = ptr = str;
+ if (value < 0 && base == 10)
+ {
+ *ptr++ = '-';
+ }
+
+ low = ptr;
+ do
+ {
+ *ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz"[35 + value % base];
+ value /= base;
+ } while (value);
+
+ *ptr-- = '\0';
+ while (low < ptr)
+ {
+ char tmp = *low;
+ *low++ = *ptr;
+ *ptr-- = tmp;
+ }
+ return rc;
+}
+
+const char* ultoa(uint32_t value, char* str, int base)
+{
+ char* rc;
+ char* ptr;
+ char* low;
+
+ if (base < 2 || base > 36)
+ {
+ *str = '\0';
+ return str;
+ }
+ rc = ptr = str;
+
+ low = ptr;
+ do
+ {
+ *ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz"[35 + value % base];
+ value /= base;
+ } while (value);
+
+ *ptr-- = '\0';
+ while (low < ptr)
+ {
+ char tmp = *low;
+ *low++ = *ptr;
+ *ptr-- = tmp;
+ }
+ return rc;
+}
+
+int atoi(const char* str) {
+ int value = 0;
+ while(isdigit(*str)) {
+ value *= 10;
+ value += (*str)-'0';
+ str++;
+ }
+
+ return value;
+}
diff --git a/src/stdlib.h b/src/stdlib.h
new file mode 100644
index 0000000..dc98a47
--- /dev/null
+++ b/src/stdlib.h
@@ -0,0 +1,9 @@
+#ifndef __STDLIB_H__
+#define __STDLIB_H__
+#include <stdint.h>
+
+const char* itoa(int value, char* str, int base);
+const char* ultoa(uint32_t value, char* str, int base);
+int atoi(const char* str);
+
+#endif
diff --git a/src/string.c b/src/string.c
new file mode 100644
index 0000000..8ac0dbe
--- /dev/null
+++ b/src/string.c
@@ -0,0 +1,8 @@
+#include <string.h>
+
+size_t strlen(const char* str) {
+ size_t len = 0;
+ while (str[len])
+ len++;
+ return len;
+}
diff --git a/src/string.h b/src/string.h
new file mode 100644
index 0000000..7a3003c
--- /dev/null
+++ b/src/string.h
@@ -0,0 +1,7 @@
+#ifndef __STRING_H__
+#define __STRING_H__
+#include <stddef.h>
+
+size_t strlen(const char* str);
+
+#endif
diff --git a/src/vga.c b/src/vga.c
new file mode 100644
index 0000000..ce72f9d
--- /dev/null
+++ b/src/vga.c
@@ -0,0 +1,39 @@
+#include <vga.h>
+#include <stdio.h>
+
+struct vga_terminal vga_term = { 0 };
+uint16_t* VGA = (uint16_t*)0xb8000;
+
+void vga_putc(char ch) {
+ if(ch == '\n') {
+ vga_term.x = 0;
+ vga_term.y++;
+ } else {
+ int index = vga_term.y * VGA_WIDTH + vga_term.x;
+
+ VGA[index] = ch | (vga_term.fg | vga_term.bg << 4) << 8;
+
+ vga_term.x++;
+ if(vga_term.x > VGA_WIDTH) {
+ vga_term.x = 0;
+ vga_term.y++;
+ }
+ }
+}
+
+void vga_clear() {
+ vga_term.x = 0;
+ vga_term.y = 0;
+ for(int i = 0; i < VGA_WIDTH * VGA_HEIGHT; i++)
+ putc(' ');
+}
+
+void init_vga(void) {
+ vga_term.fg = 7;
+ vga_term.bg = 0;
+
+ vga_clear();
+
+ vga_term.x = 0;
+ vga_term.y = 0;
+}
diff --git a/src/vga.h b/src/vga.h
new file mode 100644
index 0000000..807033b
--- /dev/null
+++ b/src/vga.h
@@ -0,0 +1,20 @@
+#ifndef __VGA_H__
+#define __VGA_H__
+#include <stdint.h>
+
+#define VGA_WIDTH 80
+#define VGA_HEIGHT 25
+
+struct vga_terminal {
+ uint8_t bg;
+ uint8_t fg;
+ uint8_t x;
+ uint8_t y;
+};
+
+extern struct vga_terminal vga_term;
+
+void init_vga(void);
+void vga_putc(char ch);
+
+#endif