dosbox-wii/src/hardware/vga_dac.cpp

/*
 *  Copyright (C) 2002  The DOSBox Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "dosbox.h"
#include "inout.h"
#include "render.h"
#include "vga.h"

/*
//TODO PEL Mask Maybe
//TODO Find some way to get palette lookups in groups 
3C6h (R/W):  PEL Mask
bit 0-7  This register is anded with the palette index sent for each dot.
         Should be set to FFh.

3C7h (R):  DAC State Register
bit 0-1  0 indicates the DAC is in Write Mode and 3 indicates Read mode.

3C7h (W):  PEL Address Read Mode
bit 0-7  The PEL data register (0..255) to be read from 3C9h.
Note: After reading the 3 bytes at 3C9h this register will increment,
      pointing to the next data register.

3C8h (R/W):  PEL Address Write Mode
bit 0-7  The PEL data register (0..255) to be written to 3C9h.
Note: After writing the 3 bytes at 3C9h this register will increment, pointing
      to the next data register.

3C9h (R/W):  PEL Data Register
bit 0-5  Color value
Note:  Each read or write of this register will cycle through first the
       registers for Red, Blue and Green, then increment the appropriate
       address register, thus the entire palette can be loaded by writing 0 to
       the PEL Address Write Mode register 3C8h and then writing all 768 bytes
       of the palette to this register.
*/

enum {DAC_READ,DAC_WRITE};


static void write_p3c6(Bit32u port,Bit8u val) {
	if (val!=0xff) LOG_ERROR("VGA:Pel Mask not 0xff");
}


static void write_p3c7(Bit32u port,Bit8u val) {
	vga.dac.index=val;
	vga.dac.pel_index=0;
	vga.dac.state=DAC_READ;
}

static void write_p3c8(Bit32u port,Bit8u val) {
	vga.dac.index=val;
	vga.dac.pel_index=0;
	vga.dac.state=DAC_WRITE;
}

static void write_p3c9(Bit32u port,Bit8u val) {
	switch (vga.dac.pel_index) {
	case 0:
		vga.dac.rgb[vga.dac.index].red=val;
		vga.dac.pel_index=1;
		break;
	case 1:
		vga.dac.rgb[vga.dac.index].green=val;
		vga.dac.pel_index=2;
		break;
	case 2:
		vga.dac.rgb[vga.dac.index].blue=val;
		switch (vga.mode) {
		case GFX_256C:
		case GFX_256U:
				RENDER_SetPal(vga.dac.index,
					vga.dac.rgb[vga.dac.index].red << 2,
					vga.dac.rgb[vga.dac.index].green << 2,
					vga.dac.rgb[vga.dac.index].blue << 2
				);
			break;
		default:
			/* Check for attributes and DAC entry link */
			if (vga.dac.rgb[vga.dac.index].attr_entry>15) return;
			if (vga.attr.palette[vga.dac.rgb[vga.dac.index].attr_entry]==vga.dac.index) {
				RENDER_SetPal(vga.dac.rgb[vga.dac.index].attr_entry,
					vga.dac.rgb[vga.dac.index].red << 2,
					vga.dac.rgb[vga.dac.index].green << 2,
					vga.dac.rgb[vga.dac.index].blue << 2
				);
			}
		}
		vga.dac.index++;
		vga.dac.pel_index=0;
		break;
	default:
		LOG_ERROR("VGA:DAC:Illegal Pel Index");			//If this can actually happen that will be the day
	};
}

static Bit8u read_p3c9(Bit32u port) {
	Bit8u ret;
	switch (vga.dac.pel_index) {
	case 0:
		ret=vga.dac.rgb[vga.dac.index].red;
		vga.dac.pel_index=1;
		break;
	case 1:
		ret=vga.dac.rgb[vga.dac.index].green;
		vga.dac.pel_index=2;
		break;
	case 2:
		ret=vga.dac.rgb[vga.dac.index].blue;
		vga.dac.index++;
		vga.dac.pel_index=0;
		break;
	default:
		LOG_ERROR("VGA:DAC:Illegal Pel Index");			//If this can actually happen that will be the day
	}
	return ret;
}

void VGA_DAC_CombineColor(Bit8u attr,Bit8u pal) {
	/* Check if this is a new color */
	vga.dac.rgb[pal].attr_entry=attr;
	RENDER_SetPal(attr,
		vga.dac.rgb[pal].red << 2,
		vga.dac.rgb[pal].green << 2,
		vga.dac.rgb[pal].blue << 2
		);
}

void VGA_SetupDAC(void) {
	vga.dac.first_changed=256;
	vga.dac.bits=6;
	vga.dac.pel_mask=0xff;
	vga.dac.pel_index=0;
	vga.dac.state=DAC_READ;

	/* Setup the DAC IO port Handlers */
	IO_RegisterWriteHandler(0x3c6,write_p3c6,"PEL Mask");	
	IO_RegisterWriteHandler(0x3c7,write_p3c7,"PEL Read Mode");
	IO_RegisterWriteHandler(0x3c8,write_p3c8,"PEL Write Mode");
	IO_RegisterWriteHandler(0x3c9,write_p3c9,"PEL Data");	
	IO_RegisterReadHandler(0x3c9,read_p3c9,"PEL Data");
};