diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/boot.s | 22 | ||||
| -rw-r--r-- | src/gdt.c | 49 | ||||
| -rw-r--r-- | src/kernel.c | 6 |
3 files changed, 69 insertions, 8 deletions
@@ -9,7 +9,15 @@ .long MAGIC .long FLAGS .long CHECKSUM - + +.global _start +.global load_gdt + +load_gdt: + movl 4(%esp), %edx + lgdt (%edx) + ret + .section .bss .align 16 stack_bottom: @@ -17,15 +25,19 @@ stack_bottom: stack_top: .section .text -.global _start .type _start, @function _start: + call init_gdt_table + mov 0x10, %ax + mov %ds, %ax + mov %es, %ax + mov %fs, %ax + mov %gs, %ax + mov %ss, %ax mov $stack_top, %esp - + cli call _init call kernel_main - - cli 1: hlt jmp 1b diff --git a/src/gdt.c b/src/gdt.c new file mode 100644 index 0000000..9f87032 --- /dev/null +++ b/src/gdt.c @@ -0,0 +1,49 @@ +#include<stdbool.h> +#include<stddef.h> +#include<stdint.h> + +struct gdt_entry +{ + uint16_t limit; + uint16_t base1; + uint8_t base2; + uint8_t access; + uint8_t limit_flags; + uint8_t base3; +} __attribute__((packed)); + +struct gdt_pointer +{ + uint16_t size; + uint32_t offset; +} __attribute__((packed)); + +// asm function +extern void load_gdt(struct gdt_pointer *gdtp); + +struct gdt_entry gdt[3]; +struct gdt_pointer gdtp; + +void init_gdt_entry(size_t num, uint32_t limit, uint32_t base1, uint32_t base2, uint8_t access, uint8_t limit_flags, uint8_t base3) +{ + gdt[num].limit=limit; + gdt[num].base1=base1; + gdt[num].access=access; + gdt[num].limit_flags=limit_flags; + gdt[num].base3=base3; +} + +void init_gdt_table() +{ + gdtp.size=sizeof(gdt)-1; + gdtp.offset=(uint32_t)&gdt; + + //null + init_gdt_entry(0,0,0,0,0,0,0); + //code + init_gdt_entry(1,0xffff,0x0000,0x00,0b10011010,0b11001111,0x00); + //data + init_gdt_entry(2,0xffff,0x0000,0x00,0b10010010,0b11001111,0x00); + + load_gdt(&gdtp); +} diff --git a/src/kernel.c b/src/kernel.c index 90f34bd..c6d1045 100644 --- a/src/kernel.c +++ b/src/kernel.c @@ -1,6 +1,6 @@ -#include <stdbool.h> -#include <stddef.h> -#include <stdint.h> +#include<stdbool.h> +#include<stddef.h> +#include<stdint.h> #include"vga.h" static const size_t VGA_WIDTH = 80; |