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Cleaned up the bios call code somewhat

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This commit is contained in:
Thomas Oltmann 2026-02-21 14:36:05 +01:00
parent c1737c30b7
commit 37f53699ff
3 changed files with 24 additions and 27 deletions
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1
.gitignore vendored
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@ -1,4 +1,5 @@
*.o
*.swp
/boot.bin
/boot.elf
/serve

46
src/bios.S
View file

@ -31,8 +31,7 @@ bios_write: push %ebp
PROT32
pop %ebx
mov %ebp, %esp
pop %ebp
leave
ret
.global bios_getmap
@ -68,8 +67,7 @@ _gmdone: add $24, %di
pop %edi
pop %ebx
mov %ebp, %esp
pop %ebp
leave
ret
.global bios_func
@ -80,39 +78,38 @@ bios_func: push %ebp
push %edi
push %esi
mov 8+0(%ebp), %eax
mov 8+4(%ebp), %edi
// The interrupt number is given as an immediate value to INT.
// To support any interrupt number, we use self-modifying code.
mov 8+0(%ebp), %eax
mov %al, _bf_int+1
PROT16
REAL
mov 0(%edi), %eax
mov 4(%edi), %ecx
mov 8(%edi), %edx
mov 12(%edi), %ebx
mov 16(%edi), %ebp
mov 20(%edi), %esi
mov 24(%edi), %edi
mov 8+4(%ebp), %edi
mov 0(%edi), %ax
mov 2(%edi), %cx
mov 4(%edi), %dx
mov 6(%edi), %bx
mov 8(%edi), %bp
mov 10(%edi), %si
mov 12(%edi), %di
// This instruction will get written at runtime
_bf_int: .byte 0xCD, 0 // INT imm8
push $0
pushf
push %edi
push %di
mov 8+4(%ebp), %edi
mov %eax, 0(%edi)
mov %ecx, 4(%edi)
mov %edx, 8(%edi)
mov %ebx, 12(%edi)
mov %ebp, 16(%edi)
mov %esi, 20(%edi)
pop %eax
mov %eax, 24(%edi)
mov %ax, 0(%edi)
mov %cx, 2(%edi)
mov %dx, 4(%edi)
mov %bx, 6(%edi)
mov %bp, 8(%edi)
mov %si, 10(%edi)
pop %ax
mov %ax, 12(%edi)
PROT
PROT32
@ -123,6 +120,5 @@ _bf_int: .byte 0xCD, 0 // INT imm8
pop %edi
pop %ebp
pop %ebx
mov %ebp, %esp
pop %ebp
leave
ret

4
src/main.c
View file

@ -49,7 +49,7 @@ struct vesa_info {
uint8_t reserved[492];
};
extern uint16_t bios_func(uint8_t inum, uint32_t reg[]);
extern uint16_t bios_func(uint8_t inum, uint16_t reg[]);
#define PG_PRESENT 0x001
#define PG_WRITE 0x002
@ -123,7 +123,7 @@ main()
bios_write(buf);
#endif
uint32_t reg[7];
uint16_t reg[7];
reg[0] = (0x0E << 8) + 'J';
reg[1] = 0;
reg[2] = 0;