132 lines
2.5 KiB
NASM
132 lines
2.5 KiB
NASM
; =============================================================================
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; Project : Custom BIOS / ROM
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; File : debug.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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%define DEBUG_PORT 0xe9 ; 0x402 ou 0xe9
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debug_puts:
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.next:
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push dx
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mov dx, DEBUG_PORT
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lodsb ; AL = *SI++
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test al, al
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jz .done
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out dx, al
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jmp .next
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.done:
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pop dx
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ret
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debug_putc:
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push dx
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mov dx, DEBUG_PORT
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out dx, al
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pop dx
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ret
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; AL = 0..15 -> print hex digit
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debug_puthex4:
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and al, 0Fh
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cmp al, 9
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jbe .num
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add al, 'A' - 10
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jmp .pout
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.num:
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add al, '0'
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.pout:
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call debug_putc
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ret
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; AL = byte -> print 2 hex digits
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debug_puthex8:
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push ax
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mov ah, al
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shr al, 4
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call debug_puthex4
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mov al, ah
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call debug_puthex4
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pop ax
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ret
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; AX = word -> print 4 hex digits
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debug_puthex16:
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push ax
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mov al, ah
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call debug_puthex8
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pop ax
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call debug_puthex8
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ret
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; --- screen text functions ---
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; AH = page
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; DH = row
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; DL = column
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scr_gotoxy:
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mov ah, 02h
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mov bh, 0 ; page 0
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int 10h
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ret
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scr_putc:
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mov ah, 0x0E
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mov bh, 0x00
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mov bl, 0x0f
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int 10h
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ret
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; AL = 0..15 -> print hex digit
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scr_puthex4:
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and al, 0Fh ; mask 4 bits low
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cmp al, 9 ; is it 0..9 ?
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jbe .num ; yes
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add al, 'A' - 10 ; convert to 'A'..'F'
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jmp .pout
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.num:
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add al, '0' ; convert to '0'..'9'
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.pout:
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mov ah, 0x0e
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mov bh, 0x00
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mov bl, 0x0f
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int 10h
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ret
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; AL = byte -> print 2 hex digits
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scr_puthex8:
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push ax
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push bx
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mov bl, al ; save al
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shr al, 4 ; 4 bits plus significatifs
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call scr_puthex4
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mov al, bl ; restore al
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call scr_puthex4
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pop bx
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pop ax
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ret
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; AX = word -> print 4 hex digits
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scr_puthex16:
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push ax
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mov al, ah
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call scr_puthex8
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pop ax
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call scr_puthex8
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ret
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