vision964.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <bio.h>

#include "pci.h"
#include "vga.h"

/*
 * S3 Vision964 GUI Accelerator.
 */
static void
snarf(Vga* vga, Ctlr* ctlr)
{
	s3generic.snarf(vga, ctlr);
	vga->crt[0x22] = vgaxi(Crtx, 0x22);
	vga->crt[0x24] = vgaxi(Crtx, 0x24);
	vga->crt[0x26] = vgaxi(Crtx, 0x26);
}

static void
options(Vga*, Ctlr* ctlr)
{	
	ctlr->flag |= Hlinear|Henhanced|Foptions;
}

static void
init(Vga* vga, Ctlr* ctlr)
{
	Mode *mode;
	ulong x;
	int sid, dbl, bpp, divide;
	char *val;

	if(vga->mode->z > 8)
		error("depth %d not supported\n", vga->mode->z);

	mode = vga->mode;
	if(vga->ramdac && (vga->ramdac->flag & Uclk2)){
		resyncinit(vga, ctlr, Uenhanced, 0);
		vga->crt[0x00] = ((mode->ht/2)>>3)-5;
		vga->crt[0x01] = ((mode->x/2)>>3)-1;
		vga->crt[0x02] = ((mode->shb/2)>>3)-1;
	
		x = (mode->ehb/2)>>3;
		vga->crt[0x03] = 0x80|(x & 0x1F);
		vga->crt[0x04] = (mode->shs/2)>>3;
		vga->crt[0x05] = ((mode->ehs/2)>>3) & 0x1F;
		if(x & 0x20)
			vga->crt[0x05] |= 0x80;
		vga->crt[0x13] = mode->x/8;
	}
	else if(mode->z == 8)
		resyncinit(vga, ctlr, Uenhanced, 0);
	s3generic.init(vga, ctlr);
	/*
	if((ctlr->flag & Uenhanced) == 0)
		vga->crt[0x33] &= ~0x20;
	 */
	vga->crt[0x3B] = (vga->crt[0]+vga->crt[4]+1)/2;
	if(vga->crt[0x3B] & 0x100)
		vga->crt[0x5D] |= 0x40;
	vga->crt[0x55] = 0x00;

	vga->crt[0x40] &= ~0x10;
	vga->crt[0x53] &= ~0x20;
	vga->crt[0x58] &= ~0x48;
	if(dbattr(vga->attr, "sam512") == 0)
		vga->crt[0x58] |= 0x40;		/* set 256 word SAM, always works */
	vga->crt[0x65] = 0x00;
	vga->crt[0x66] &= ~0x07;
	vga->crt[0x6D] = 0x00;
	if(ctlr->flag & Uenhanced){
		if(vga->ramdac && (vga->ramdac->flag & Hsid32))
			sid = 32;
		else
			sid = 64;
		if(vga->ramdac && (vga->ramdac->flag & Uclk2))
			dbl = 2;
		else
			dbl = 1;
		if(mode->z < 4)
			bpp = 4;
		else
			bpp = mode->z;
		divide = sid/(dbl*bpp);
		switch(divide){
		case 2:
			vga->crt[0x66] |= 0x01;
			break;
		case 4:
			vga->crt[0x66] |= 0x02;
			break;
		case 8:
			vga->crt[0x66] |= 0x03;
			break;
		case 16:
			vga->crt[0x66] |= 0x04;
			break;
		case 32:
			vga->crt[0x66] |= 0x05;
			break;
		}

		vga->crt[0x40] |= 0x10;
		vga->crt[0x65] |= 0x02;
		if(vga->ramdac && (vga->ramdac->flag & Hsid32))
			vga->crt[0x66] |= 0x10;

		/*
		 * Some heuristics (what part of aux/vga isn't?)
		 * to prevent some of the right border appearing
		 * on the left edge of the screen.
		 */
		if(dbattr(vga->attr, "vclkphs"))
			vga->crt[0x67] |= 0x01;
		if(val = dbattr(vga->attr, "delaybl"))
			vga->crt[0x6D] |= strtoul(val, 0, 0) & 0x07;
		else if(mode->x > 1024)
			vga->crt[0x6D] |= 0x01;
		else
			vga->crt[0x6D] |= 0x03;

		if(val = dbattr(vga->attr, "delaysc"))
			vga->crt[0x6D] |= (strtoul(val, 0, 0) & 0x07)<<4;
	}
}

static void
load(Vga* vga, Ctlr* ctlr)
{
	ushort advfunc;

	s3generic.load(vga, ctlr);
	vgaxo(Crtx, 0x65, vga->crt[0x65]);
	vgaxo(Crtx, 0x66, vga->crt[0x66]);
	vgaxo(Crtx, 0x6D, vga->crt[0x6D]);

	advfunc = 0x0000;
	if(ctlr->flag & Uenhanced)
		advfunc = 0x0001;
	outportw(0x4AE8, advfunc);
}

static void
dump(Vga* vga, Ctlr* ctlr)
{
	s3generic.dump(vga, ctlr);
	printitem(ctlr->name, "Crt22");
	printreg(vga->crt[0x22]);
	printitem(ctlr->name, "Crt24");
	printreg(vga->crt[0x24]);
	printitem(ctlr->name, "Crt26");
	printreg(vga->crt[0x26]);
}

Ctlr vision964 = {
	"vision964",			/* name */
	snarf,				/* snarf */
	options,			/* options */
	init,				/* init */
	load,				/* load */
	dump,				/* dump */
};