boot_floppy.asm
2.34 KB
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;BLACK 0x0
;BLUE 0x1
;GREEN 0x2
;CYAN 0x3
;RED 0x4
;MAGENTA 0x5
;BROWN 0x6
;GREY 0x7
;DARK_GREY 0x8
;LIGHT_BLUE 0x9
;LIGHT_GREEN 0xA
;LIGHT_CYAN 0xB
;LIGHT_RED 0xC
;LIGHT_MAGENTA 0xD
;LIGHT_BROWN 0xE
;WHITE 0xF
[BITS 16]
[org 0x7C00]
JMP Start
clear_screen:
PUSH ax
MOV al, 03h ; Setting the graphical mode 80x25(text)
MOV ah, 00h ; Code of the function of changing video mode
INT 10h ; Call interruption
MOV cl, 0x06
MOV ah, 0x01
INT 10h
POP ax
RETN
print_string: ; Expects null terminated message in si
PUSH ax
for_print_string_0:
MOV al,[si]
OR al,al
JZ end_for_print_string_0
INC si
CALL print_char
JMP for_print_string_0
end_for_print_string_0:
POP ax
RETN
print_sector:
PUSH ebp
MOV ebp, esp
PUSH ax
PUSH bx
PUSH cx
PUSH dx
MOV al, [8 + ebp] ; num
MOV cl, [6 + ebp] ; offset
MOV ah, 2
XOR ch, ch
XOR dx,dx
INT 0x13
MOV di, 512
XOR ah, ah
IMUL di, ax
XOR si, si
for_print_sector_0:
CMP si, di
JZ end_for_print_sector_0
MOV al,[es:si]
OR al, al
JZ end_print_char_0
CALL print_char
end_print_char_0:
INC si
JMP for_print_sector_0
end_for_print_sector_0:
POP dx
POP cx
POP bx
POP ax
MOV esp, ebp
POP ebp
RETN
print_char:
PUSH ax
PUSH bx
MOV ah,0x0E ; Specifies that we want to write a character to the screen
MOV bl,0x02 ; Specifies output text color. Not required, but useful to know
MOV bh,0x00 ; Page number. Leave this alone.
INT 0x10 ; Signal video interrupt to BIOS
POP bx
POP ax
RETN
execute_sector:
PUSH ebp
MOV ebp, esp
PUSH ax
PUSH bx
PUSH cx
PUSH dx
MOV ax, [10 + ebp] ; base address
MOV es, ax
MOV al, [8 + ebp] ; num
MOV cl, [6 + ebp] ; offset
MOV ah, 2 ; Function read
XOR ch, ch ; cylinder
XOR dx,dx ; Head and drive
INT 0x13
XOR si, si
PUSH es
PUSH bx
RETF
Start:
XOR ax, ax
MOV ds, ax
MOV ax, 0x1000
MOV es, ax
XOR bx, bx
CALL clear_screen
PUSH 2 ; num
PUSH 2 ; offset
CALL print_sector ; (offset, num)
ADD esp, 4
MOV si,str
CALL print_string
PUSH 0x800; Base address, offset is 0
PUSH 1 ; num
PUSH 4 ; offset
XOR bx, bx;
CALL execute_sector
str: db 'THE GAME',0x0A,0x0D,0x00
TIMES 510 - ($ - $$) db 0
DW 0xAA55