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/*
** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
**
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of version 2 of the GNU Library General
** Public License as published by the Free Software Foundation.
**
** 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. To obtain a
** copy of the GNU Library General Public License, write to the Free
** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**
** Any permitted reproduction of these routines, in whole or in part,
** must bear this legend.
**
**
** vrcvisnd.c
**
** VRCVI sound hardware emulation
** $Id: vrcvisnd.c,v 1.2 2003/12/05 15:55:01 f1rmb Exp $
*/
#include "types.h"
#include "vrcvisnd.h"
#include "nes_apu.h"
static vrcvisnd_t vrcvi;
static int32 vrcvi_incsize;
/* VRCVI rectangle wave generation */
static int32 vrcvi_rectangle(vrcvirectangle_t *chan)
{
/* reg0: 0-3=volume, 4-6=duty cycle
** reg1: 8 bits of freq
** reg2: 0-3=high freq, 7=enable
*/
chan->phaseacc -= vrcvi_incsize; /* # of clocks per wave cycle */
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
chan->adder = (chan->adder + 1) & 0x0F;
}
/* return if not enabled */
if (FALSE == chan->enabled)
return 0;
if (chan->adder < chan->duty_flip)
return -(chan->volume);
else
return chan->volume;
}
/* VRCVI sawtooth wave generation */
static int32 vrcvi_sawtooth(vrcvisawtooth_t *chan)
{
/* reg0: 0-5=phase accumulator bits
** reg1: 8 bits of freq
** reg2: 0-3=high freq, 7=enable
*/
chan->phaseacc -= vrcvi_incsize; /* # of clocks per wav cycle */
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
chan->output_acc += chan->volume;
if (7 == ++chan->adder)
{
chan->adder = 0;
chan->output_acc = 0;
}
}
/* return if not enabled */
if (FALSE == chan->enabled)
return 0;
else
return (chan->output_acc >> 3) << 9;
}
/* mix vrcvi sound channels together */
static int32 vrcvi_process(void)
{
int32 output;
output = vrcvi_rectangle(&vrcvi.rectangle[0]);
output += vrcvi_rectangle(&vrcvi.rectangle[1]);
output += vrcvi_sawtooth(&vrcvi.saw);
return output;
}
/* write to registers */
static void vrcvi_write(uint32 address, uint8 value)
{
int chan;
switch (address & 0xB003)
{
case 0x9000:
case 0xA000:
chan = (address >> 12) - 9;
vrcvi.rectangle[chan].reg[0] = value;
vrcvi.rectangle[chan].volume = (value & 0x0F) << 8;
vrcvi.rectangle[chan].duty_flip = (value >> 4) + 1;
break;
case 0x9001:
case 0xA001:
chan = (address >> 12) - 9;
vrcvi.rectangle[chan].reg[1] = value;
vrcvi.rectangle[chan].freq = APU_TO_FIXED(((vrcvi.rectangle[chan].reg[2] & 0x0F) << 8) + value + 1);
break;
case 0x9002:
case 0xA002:
chan = (address >> 12) - 9;
vrcvi.rectangle[chan].reg[2] = value;
vrcvi.rectangle[chan].freq = APU_TO_FIXED(((value & 0x0F) << 8) + vrcvi.rectangle[chan].reg[1] + 1);
vrcvi.rectangle[chan].enabled = (value & 0x80) ? TRUE : FALSE;
break;
case 0xB000:
vrcvi.saw.reg[0] = value;
vrcvi.saw.volume = value & 0x3F;
break;
case 0xB001:
vrcvi.saw.reg[1] = value;
vrcvi.saw.freq = APU_TO_FIXED((((vrcvi.saw.reg[2] & 0x0F) << 8) + value + 1) << 1);
break;
case 0xB002:
vrcvi.saw.reg[2] = value;
vrcvi.saw.freq = APU_TO_FIXED((((value & 0x0F) << 8) + vrcvi.saw.reg[1] + 1) << 1);
vrcvi.saw.enabled = (value & 0x80) ? TRUE : FALSE;
break;
default:
break;
}
}
/* reset state of vrcvi sound channels */
static void vrcvi_reset(void)
{
int i;
/* preload regs */
for (i = 0; i < 3; i++)
{
vrcvi_write(0x9000 + i, 0);
vrcvi_write(0xA000 + i, 0);
vrcvi_write(0xB000 + i, 0);
}
/* get the phase period from the apu */
vrcvi_incsize = apu_getcyclerate();
}
static void vrcvi_dummy(void)
{
}
static apu_memwrite vrcvi_memwrite[] =
{
// { 0x4040, 0x4092, ext_write }, /* FDS sound regs */
{ 0x9000, 0x9002, vrcvi_write }, /* vrc6 */
{ 0xA000, 0xA002, vrcvi_write },
{ 0xB000, 0xB002, vrcvi_write },
{ -1, -1, NULL }
};
apuext_t vrcvi_ext =
{
vrcvi_dummy, /* no init */
vrcvi_dummy, /* no shutdown */
vrcvi_reset,
vrcvi_process,
NULL, /* no reads */
vrcvi_memwrite
};
/*
** $Log: vrcvisnd.c,v $
** Revision 1.2 2003/12/05 15:55:01 f1rmb
** cleanup phase II. use xprintf when it's relevant, use xine_xmalloc when it's relevant too. Small other little fix (can't remember). Change few internal function prototype because it xine_t pointer need to be used if some xine's internal sections. NOTE: libdvd{nav,read} is still too noisy, i will take a look to made it quit, without invasive changes. To be continued...
**
** Revision 1.1 2003/01/08 07:04:36 tmmm
** initial import of Nosefart sources
**
** Revision 1.9 2000/07/04 04:51:41 matt
** cleanups
**
** Revision 1.8 2000/07/03 02:18:53 matt
** much better external module exporting
**
** Revision 1.7 2000/06/20 04:06:16 matt
** migrated external sound definition to apu module
**
** Revision 1.6 2000/06/20 00:08:58 matt
** changed to driver based API
**
** Revision 1.5 2000/06/09 16:49:02 matt
** removed all floating point from sound generation
**
** Revision 1.4 2000/06/09 15:12:28 matt
** initial revision
**
*/
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