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mov ah, 0x00
mov al, 13 ;300x220 mode
int 10h
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#define VGA_AC_INDEX 0x3C0
#define VGA_AC_WRITE 0x3C0
#define VGA_AC_READ 0x3C1
#define VGA_MISC_WRITE 0x3C2
#define VGA_SEQ_INDEX 0x3C4
#define VGA_SEQ_DATA 0x3C5
#define VGA_DAC_READ_INDEX 0x3C7
#define VGA_DAC_WRITE_INDEX 0x3C8
#define VGA_DAC_DATA 0x3C9
#define VGA_MISC_READ 0x3CC
#define VGA_GC_INDEX 0x3CE
#define VGA_GC_DATA 0x3CF
/* COLOR emulation MONO emulation */
#define VGA_CRTC_INDEX 0x3D4 /* 0x3B4 */
#define VGA_CRTC_DATA 0x3D5 /* 0x3B5 */
#define VGA_INSTAT_READ 0x3DA
#define VGA_NUM_SEQ_REGS 5
#define VGA_NUM_CRTC_REGS 25
#define VGA_NUM_GC_REGS 9
#define VGA_NUM_AC_REGS 21
#define VGA_NUM_REGS (1 + VGA_NUM_SEQ_REGS + VGA_NUM_CRTC_REGS + \
VGA_NUM_GC_REGS + VGA_NUM_AC_REGS)
unsigned char g_320x200x256[] =
{
/* MISC */
0x63,
/* SEQ */
0x03, 0x01, 0x0F, 0x00, 0x0E,
/* CRTC */
0x5F, 0x4F, 0x50, 0x82, 0x54, 0x80, 0xBF, 0x1F,
0x00, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x9C, 0x0E, 0x8F, 0x28, 0x40, 0x96, 0xB9, 0xA3,
0xFF,
/* GC */
0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x05, 0x0F,
0xFF,
/* AC */
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x41, 0x00, 0x0F, 0x00, 0x00
};
void write_regs(unsigned char *regs)
{
unsigned i;
/* write MISCELLANEOUS reg */
outportb(VGA_MISC_WRITE, *regs);
regs++;
/* write SEQUENCER regs */
for(i = 0; i < VGA_NUM_SEQ_REGS; i++)
{
outportb(VGA_SEQ_INDEX, i);
outportb(VGA_SEQ_DATA, *regs);
regs++;
}
/* unlock CRTC registers */
outportb(VGA_CRTC_INDEX, 0x03);
outportb(VGA_CRTC_DATA, inportb(VGA_CRTC_DATA) | 0x80);
outportb(VGA_CRTC_INDEX, 0x11);
outportb(VGA_CRTC_DATA, inportb(VGA_CRTC_DATA) & ~0x80);
/* make sure they remain unlocked */
regs[0x03] |= 0x80;
regs[0x11] &= ~0x80;
/* write CRTC regs */
for(i = 0; i < VGA_NUM_CRTC_REGS; i++)
{
outportb(VGA_CRTC_INDEX, i);
outportb(VGA_CRTC_DATA, *regs);
regs++;
}
/* write GRAPHICS CONTROLLER regs */
for(i = 0; i < VGA_NUM_GC_REGS; i++)
{
outportb(VGA_GC_INDEX, i);
outportb(VGA_GC_DATA, *regs);
regs++;
}
/* write ATTRIBUTE CONTROLLER regs */
for(i = 0; i < VGA_NUM_AC_REGS; i++)
{
(void)inportb(VGA_INSTAT_READ);
outportb(VGA_AC_INDEX, i);
outportb(VGA_AC_WRITE, *regs);
regs++;
}
/* lock 16-color palette and unblank display */
(void)inportb(VGA_INSTAT_READ);
outportb(VGA_AC_INDEX, 0x20);
}
void set_vga_300x220(void) {
write_regs(g_320x200x256);
}
Palettes can be nice for certain visual styles. Bit-plane is a pain if you try to tackle it with normal graphics algorithms, but I do remember a web page claiming it can be really powerful if you know how to use it. I think there was something about a barrel shifter.rdos wrote:Nobody should use the 320x200 mode anymore. Bit-plane and palette mapped modes are big no-nos. If you want to use VGA / VBE, make sure you use one that uses RGB components directly. The best alternative is probably to boot with EFI and use the EFI mode linear frame buffer. It's a lot easier than to set up a decent VBE mode.