207 lines
3.6 KiB
NASM
207 lines
3.6 KiB
NASM
%include "vesa.inc"
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SECTION .text
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USE16
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vesa:
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.getcardinfo:
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mov ax, 0x4F00
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mov di, VBECardInfo
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int 0x10
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cmp ax, 0x4F
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je .findmode
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mov eax, 1
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ret
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.resetlist:
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;if needed, reset mins/maxes/stuff
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xor cx, cx
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mov [.minx], cx
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mov [.miny], cx
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mov [.requiredx], cx
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mov [.requiredy], cx
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mov [.requiredmode], cx
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.findmode:
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mov si, [VBECardInfo.videomodeptr]
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mov ax, [VBECardInfo.videomodeptr+2]
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mov fs, ax
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sub si, 2
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mov cx, [.requiredmode]
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test cx, cx
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jnz .getmodeinfo
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.searchmodes:
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add si, 2
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mov cx, [fs:si]
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cmp cx, 0xFFFF
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jne .getmodeinfo
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cmp word [.goodmode], 0
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je .resetlist
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jmp .findmode
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.getmodeinfo:
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push esi
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mov [.currentmode], cx
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mov ax, 0x4F01
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mov di, VBEModeInfo
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int 0x10
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pop esi
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cmp ax, 0x4F
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je .foundmode
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mov eax, 1
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ret
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.foundmode:
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;check minimum values, really not minimums from an OS perspective but ugly for users
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cmp byte [VBEModeInfo.bitsperpixel], 32
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jb .searchmodes
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.testx:
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mov cx, [VBEModeInfo.xresolution]
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cmp word [.requiredx], 0
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je .notrequiredx
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cmp cx, [.requiredx]
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je .testy
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jmp .searchmodes
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.notrequiredx:
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cmp cx, [.minx]
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jb .searchmodes
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.testy:
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mov cx, [VBEModeInfo.yresolution]
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cmp word [.requiredy], 0
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je .notrequiredy
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cmp cx, [.requiredy]
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jne .searchmodes ;as if there weren't enough warnings, USE WITH CAUTION
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cmp word [.requiredx], 0
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jnz .setmode
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jmp .testgood
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.notrequiredy:
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cmp cx, [.miny]
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jb .searchmodes
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.testgood:
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mov cx, [.currentmode]
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mov [.goodmode], cx
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push esi
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; call decshowrm
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; mov al, ':'
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; call charrm
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mov cx, [VBEModeInfo.xresolution]
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call decshowrm
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mov al, 'x'
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call charrm
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mov cx, [VBEModeInfo.yresolution]
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call decshowrm
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mov al, '@'
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call charrm
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xor ch, ch
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mov cl, [VBEModeInfo.bitsperpixel]
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call decshowrm
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mov si, .modeok
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call printrm
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xor ax, ax
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int 0x16
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pop esi
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cmp al, 'y'
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jne .searchmodes
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.setmode:
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mov bx, [.currentmode]
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cmp bx, 0
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je .nomode
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or bx, 0x4000
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mov ax, 0x4F02
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int 0x10
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.nomode:
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cmp ax, 0x4F
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je .returngood
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mov eax, 1
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ret
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.returngood:
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xor eax, eax
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ret
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.minx dw 640
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.miny dw 480
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.required:
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.requiredx dw 0 ;1024 ;USE THESE WITH CAUTION
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.requiredy dw 0 ;768
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.requiredmode dw 0
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.modeok db ": Is this OK?(y/n)",10,13,0
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.goodmode dw 0
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.currentmode dw 0
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;useful functions
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decshowrm:
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mov si, .number
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.clear:
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mov al, "0"
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mov [si], al
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inc si
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cmp si, .numberend
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jb .clear
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dec si
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call convertrm
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mov si, .number
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.lp:
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lodsb
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cmp si, .numberend
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jae .end
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cmp al, "0"
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jbe .lp
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.end:
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dec si
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call printrm
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ret
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.number times 7 db 0
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.numberend db 0
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convertrm:
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dec si
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mov bx, si ;place to convert into must be in si, number to convert must be in cx
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.cnvrt:
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mov si, bx
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sub si, 4
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.ten4: inc si
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cmp cx, 10000
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jb .ten3
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sub cx, 10000
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inc byte [si]
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jmp .cnvrt
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.ten3: inc si
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cmp cx, 1000
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jb .ten2
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sub cx, 1000
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inc byte [si]
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jmp .cnvrt
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.ten2: inc si
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cmp cx, 100
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jb .ten1
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sub cx, 100
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inc byte [si]
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jmp .cnvrt
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.ten1: inc si
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cmp cx, 10
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jb .ten0
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sub cx, 10
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inc byte [si]
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jmp .cnvrt
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.ten0: inc si
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cmp cx, 1
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jb .return
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sub cx, 1
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inc byte [si]
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jmp .cnvrt
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.return:
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ret
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printrm:
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mov al, [si]
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test al, al
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jz .return
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call charrm
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inc si
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jmp printrm
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.return:
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ret
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charrm: ;char must be in al
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mov bx, 7
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mov ah, 0xE
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int 10h
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ret
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