81 lines
1.8 KiB
NASM
81 lines
1.8 KiB
NASM
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[bits 32]
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; 32-bit protected print helpers
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; VGA is 80 x 25 characters starting at 0xb8000
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; 1st byte is ASCII code of char to display, 2nd byte is display info
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; Address of particular row/col as: 0xb8000 + 2 * (row * 80 + col)
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; Constants
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i_video_memory equ 0xb8000
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i_white_on_black equ 0x0f
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; Variables
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i_print32_row_start equ 0xb8000
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i_print32_row_current equ 0xb8000
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i_print32_row_end equ 0xb8002 + 160
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print32_raw_simple:
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; prints null-terminated string pointed to by edx
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pusha
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mov edx, i_video_memory ; set edx to start of the row
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print32_raw_simple_loop:
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mov al, [ebx] ; store char at ebx in al
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mov ah, i_white_on_black ; store display info in ah
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cmp al, 0 ; if al is null, then this is the end of the string
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je g_return
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mov [edx], ax ; store char and attributes at current char cell
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add ebx, 1 ; increment ebx to next char in string
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add edx, 2 ; move to next char cell in video memory
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jmp print32_raw_simple_loop
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print32_newline: ; TODO fix this...
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pusha
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mov eax, i_print32_row_start
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mov ebx, i_print32_row_current
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mov ecx, i_print32_row_end
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add eax, 0xa0
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add ebx, 0xa0
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mov ecx, eax
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jmp g_return
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print32_raw:
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; prints null-terminated string pointed to by edx
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pusha
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mov edx, i_print32_row_current ; set edx to start of the row
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jmp print32_raw_loop
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print32_raw_next_line:
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call print32_newline
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print32_raw_loop:
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cmp edx, i_print32_row_end
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je print32_raw_next_line
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mov al, [ebx] ; store char at ebx in al
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mov ah, i_white_on_black ; store display info in ah
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cmp al, 0 ; if al is null, then this is the end of the string
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je g_return
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mov [edx], ax ; store char and attributes at current char cell
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add ebx, 1 ; increment ebx to next char in string
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add edx, 2 ; move to next char cell in video memory
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jmp print32_raw_loop
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print32:
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call print32_raw
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call print32_newline
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ret
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[bits 16]
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