OSDev.org

Code: Select all

void set_plane(unsigned p)
{
	unsigned char pmask;

	p &= 3;
	pmask = 1 << p;
/* set read plane */
	outportb(VGA_GC_INDEX, 4);
	outportb(VGA_GC_DATA, p);
/* set write plane */
	outportb(VGA_SEQ_INDEX, 2);
	outportb(VGA_SEQ_DATA, pmask);
}


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);
}

static void vmemwr(unsigned dst_off, unsigned char *src, unsigned count)
{
	memcpy(dst_off|0xB8000, src, count);
}






 void write_font(unsigned char *buf, unsigned font_height) //buf is pointer to our font.
{
	unsigned char seq2, seq4, gc4, gc5, gc6;
	unsigned i;

/* save registers
set_plane() modifies GC 4 and SEQ 2, so save them as well */
	outportb(VGA_SEQ_INDEX, 2);
	seq2 = inportb(VGA_SEQ_DATA);

	outportb(VGA_SEQ_INDEX, 4);
	seq4 = inportb(VGA_SEQ_DATA);
/* turn off even-odd addressing (set flat addressing)
assume: chain-4 addressing already off */
	outportb(VGA_SEQ_DATA, seq4 | 0x04);

	outportb(VGA_GC_INDEX, 4);
	gc4 = inportb(VGA_GC_DATA);

	outportb(VGA_GC_INDEX, 5);
	gc5 = inportb(VGA_GC_DATA);
/* turn off even-odd addressing */
	outportb(VGA_GC_DATA, gc5 & ~0x10);

	outportb(VGA_GC_INDEX, 6);
	gc6 = inportb(VGA_GC_DATA);
/* turn off even-odd addressing */
	outportb(VGA_GC_DATA, gc6 & ~0x02);
/* write font to plane P4 */
	set_plane(2);
/* write font 0 */
	for(i = 0; i < 256; i++)
	{
		vmemwr(16384u * 0 + i * 32, buf, font_height);
		buf += font_height;
	}
#if 0
/* write font 1 */
	for(i = 0; i < 256; i++)
	{
		vmemwr(16384u * 1 + i * 32, buf, font_height);
		buf += font_height;
	}
#endif
/* restore registers */
	outportb(VGA_SEQ_INDEX, 2);
	outportb(VGA_SEQ_DATA, seq2);
	outportb(VGA_SEQ_INDEX, 4);
	outportb(VGA_SEQ_DATA, seq4);
	outportb(VGA_GC_INDEX, 4);
	outportb(VGA_GC_DATA, gc4);
	outportb(VGA_GC_INDEX, 5);
	outportb(VGA_GC_DATA, gc5);
	outportb(VGA_GC_INDEX, 6);
	outportb(VGA_GC_DATA, gc6);
}