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VESA Video Modes: Difference between revisions
Added 4f00h, 4f01h function usage example in asm
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(use standered ints) |
(Added 4f00h, 4f01h function usage example in asm) |
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Line 22:
v86_bios(0x10, {ax:0x4f00, es:SEG(vib), di:OFF(vib)}, &out);
if (out.ax!=0x004f) die("Something wrong with VBE get info");
</source>
In assembly(nasm):
<source lang="asm">
struc VesaInfoBlock ; VesaInfoBlock_size = 512 bytes
.Signature resb 4 ; must be 'VESA'
.Version resw 1
.OEMNamePtr resd 1
.Capabilities resd 1
.VideoModesOffset resw 1
.VideoModesSegment resw 1
.CountOf64KBlocks resw 1
.OEMSoftwareRevision resw 1
.OEMVendorNamePtr resd 1
.OEMProductNamePtr resd 1
.OEMProductRevisionPtr resd 1
.Reserved resb 222
.OEMData resb 256
endstruc
Main:
push ds
pop es
mov di, VesaInfoBlockBuffer
call get_vesa_info
jmp $
; in:
; es:di - 512-byte buffer
; out:
; cf - set on error
get_vesa_info:
clc
mov ax, 0x4f00
int 0x10
cmp ax, 0x004f
jne .failed
ret
.failed:
stc
ret
ALIGN(4)
VesaInfoBlockBuffer: istruc VesaInfoBlock
at VesaInfoBlock.Signature, db "VESA"
times 508 db 0
iend
</source>
Line 65 ⟶ 115:
uint8_t reserved1[206];
} __attribute__ ((packed));
</source>
In assembly(nasm):
<source lang="asm">
struc VesaModeInfoBlock ; VesaModeInfoBlock_size = 256 bytes
.ModeAttributes resw 1
.FirstWindowAttributes resb 1
.SecondWindowAttributes resb 1
.WindowGranularity resw 1 ; in KB
.WindowSize resw 1 ; in KB
.FirstWindowSegment resw 1 ; 0 if not supported
.SecondWindowSegment resw 1 ; 0 if not supported
.WindowFunctionPtr resd 1
.BytesPerScanLine resw 1
; Added in Revision 1.2
.Width resw 1 ; in pixels(graphics)/columns(text)
.Height resw 1 ; in pixels(graphics)/columns(text)
.CharWidth resb 1 ; in pixels
.CharHeight resb 1 ; in pixels
.PlanesCount resb 1
.BitsPerPixel resb 1
.BanksCount resb 1
.MemoryModel resb 1 ; http://www.ctyme.com/intr/rb-0274.htm#Table82
.BankSize resb 1 ; in KB
.ImagePagesCount resb 1 ; count - 1
.Reserved1 resb 1 ; equals 0 in Revision 1.0-2.0, 1 in 3.0
.RedMaskSize resb 1
.RedFieldPosition resb 1
.GreenMaskSize resb 1
.GreenFieldPosition resb 1
.BlueMaskSize resb 1
.BlueFieldPosition resb 1
.ReservedMaskSize resb 1
.ReservedMaskPosition resb 1
.DirectColorModeInfo resb 1
; Added in Revision 2.0
.LFBAddress resd 1
.OffscreenMemoryOffset resd 1
.OffscreenMemorySize resw 1 ; in KB
.Reserved2 resb 206 ; available in Revision 3.0, but useless for now
endstruc
Main:
; after getting VesaInfoBlock:
push word [VesaInfoBlockBuffer + VesaInfoBlock.VideoModesSegment]
pop es
mov di, VesaModeInfoBlockBuffer
mov bx, [VesaInfoBlockBuffer + VesaInfoBlock.VideoModesOffset] ; get video modes list address
mov cx, [bx] ; get first video mode number
cmp cx, 0xffff ; vesa modes list empty
je .NoModes
call get_vesa_mode_info
.NoModes:
jmp $
; in:
; cx - VESA mode number
; es:di - 256-byte buffer
; out:
; cf - set on error
get_vesa_mode_info:
clc
mov ax, 0x4f01
int 0x10
cmp ax, 0x004f
jne .failed
ret
.failed:
stc
ret
ALIGN(4)
VesaModeInfoBlockBuffer: istruc VesaModeInfoBlock
times VesaModeInfoBlock_size db 0
iend
</source>
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