kopia lustrzana https://github.com/Jean-MarcHarvengt/MCUME
279 wiersze
6.3 KiB
C
Executable File
279 wiersze
6.3 KiB
C
Executable File
/*
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** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
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**
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**
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** This program is free software; you can redistribute it and/or
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** modify it under the terms of version 2 of the GNU Library General
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** Public License as published by the Free Software Foundation.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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** Library General Public License for more details. To obtain a
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** copy of the GNU Library General Public License, write to the Free
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** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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**
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** Any permitted reproduction of these routines, in whole or in part,
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** must bear this legend.
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**
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**
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** vrcvisnd.c
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**
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** VRCVI sound hardware emulation
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** $Id: vrcvisnd.c,v 1.2 2001/04/27 14:37:11 neil Exp $
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*/
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#include "noftypes.h"
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#include "vrcvisnd.h"
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#include "nes_apu.h"
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typedef struct vrcvirectangle_s
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{
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bool enabled;
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uint8 reg[3];
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float accum;
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uint8 adder;
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int32 freq;
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int32 volume;
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uint8 duty_flip;
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} vrcvirectangle_t;
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typedef struct vrcvisawtooth_s
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{
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bool enabled;
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uint8 reg[3];
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float accum;
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uint8 adder;
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uint8 output_acc;
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int32 freq;
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uint8 volume;
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} vrcvisawtooth_t;
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typedef struct vrcvisnd_s
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{
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vrcvirectangle_t rectangle[2];
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vrcvisawtooth_t saw;
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float incsize;
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} vrcvisnd_t;
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static vrcvisnd_t vrcvi;
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/* VRCVI rectangle wave generation */
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static int32 vrcvi_rectangle(vrcvirectangle_t *chan)
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{
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/* reg0: 0-3=volume, 4-6=duty cycle
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** reg1: 8 bits of freq
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** reg2: 0-3=high freq, 7=enable
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*/
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chan->accum -= vrcvi.incsize; /* # of clocks per wave cycle */
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while (chan->accum < 0)
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{
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chan->accum += chan->freq;
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chan->adder = (chan->adder + 1) & 0x0F;
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}
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/* return if not enabled */
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if (false == chan->enabled)
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return 0;
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if (chan->adder < chan->duty_flip)
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return -(chan->volume);
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else
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return chan->volume;
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}
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/* VRCVI sawtooth wave generation */
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static int32 vrcvi_sawtooth(vrcvisawtooth_t *chan)
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{
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/* reg0: 0-5=phase accumulator bits
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** reg1: 8 bits of freq
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** reg2: 0-3=high freq, 7=enable
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*/
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chan->accum -= vrcvi.incsize; /* # of clocks per wav cycle */
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while (chan->accum < 0)
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{
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chan->accum += chan->freq;
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chan->output_acc += chan->volume;
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chan->adder++;
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if (7 == chan->adder)
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{
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chan->adder = 0;
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chan->output_acc = 0;
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}
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}
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/* return if not enabled */
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if (false == chan->enabled)
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return 0;
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return (chan->output_acc >> 3) << 9;
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}
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/* mix vrcvi sound channels together */
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static int32 vrcvi_process(void)
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{
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int32 output;
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output = vrcvi_rectangle(&vrcvi.rectangle[0]);
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output += vrcvi_rectangle(&vrcvi.rectangle[1]);
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output += vrcvi_sawtooth(&vrcvi.saw);
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return output;
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}
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/* write to registers */
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static void vrcvi_write(uint32 address, uint8 value)
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{
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int chan = (address >> 12) - 9;
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switch (address & 0xB003)
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{
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case 0x9000:
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case 0xA000:
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vrcvi.rectangle[chan].reg[0] = value;
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vrcvi.rectangle[chan].volume = (value & 0x0F) << 8;
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vrcvi.rectangle[chan].duty_flip = (value >> 4) + 1;
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break;
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case 0x9001:
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case 0xA001:
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vrcvi.rectangle[chan].reg[1] = value;
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vrcvi.rectangle[chan].freq = ((vrcvi.rectangle[chan].reg[2] & 0x0F) << 8) + value + 1;
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break;
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case 0x9002:
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case 0xA002:
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vrcvi.rectangle[chan].reg[2] = value;
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vrcvi.rectangle[chan].freq = ((value & 0x0F) << 8) + vrcvi.rectangle[chan].reg[1] + 1;
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vrcvi.rectangle[chan].enabled = (value & 0x80) ? true : false;
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break;
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case 0xB000:
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vrcvi.saw.reg[0] = value;
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vrcvi.saw.volume = value & 0x3F;
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break;
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case 0xB001:
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vrcvi.saw.reg[1] = value;
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vrcvi.saw.freq = (((vrcvi.saw.reg[2] & 0x0F) << 8) + value + 1) << 1;
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break;
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case 0xB002:
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vrcvi.saw.reg[2] = value;
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vrcvi.saw.freq = (((value & 0x0F) << 8) + vrcvi.saw.reg[1] + 1) << 1;
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vrcvi.saw.enabled = (value & 0x80) ? true : false;
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break;
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default:
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break;
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}
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}
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/* reset state of vrcvi sound channels */
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static void vrcvi_reset(void)
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{
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int i;
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apu_t apu;
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/* get the phase period from the apu */
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apu_getcontext(&apu);
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vrcvi.incsize = apu.cycle_rate;
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/* preload regs */
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for (i = 0; i < 3; i++)
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{
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vrcvi_write(0x9000 + i, 0);
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vrcvi_write(0xA000 + i, 0);
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vrcvi_write(0xB000 + i, 0);
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}
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}
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static apu_memwrite vrcvi_memwrite[] =
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{
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{ 0x9000, 0x9002, vrcvi_write }, /* vrc6 */
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{ 0xA000, 0xA002, vrcvi_write },
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{ 0xB000, 0xB002, vrcvi_write },
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{ -1, -1, NULL }
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};
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apuext_t vrcvi_ext =
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{
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NULL, /* no init */
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NULL, /* no shutdown */
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vrcvi_reset,
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vrcvi_process,
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NULL, /* no reads */
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vrcvi_memwrite
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};
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/*
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** $Log: vrcvisnd.c,v $
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** Revision 1.2 2001/04/27 14:37:11 neil
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** wheeee
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**
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** Revision 1.1 2001/04/27 12:54:40 neil
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** blah
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**
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** Revision 1.1.1.1 2001/04/27 07:03:54 neil
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** initial
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**
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** Revision 1.2 2000/11/05 22:21:00 matt
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** help me!
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**
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** Revision 1.1 2000/10/24 12:20:00 matt
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** changed directory structure
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**
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** Revision 1.17 2000/10/10 13:58:18 matt
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** stroustrup squeezing his way in the door
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**
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** Revision 1.16 2000/10/03 11:56:20 matt
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** better support for optional sound ext routines
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**
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** Revision 1.15 2000/09/27 12:26:03 matt
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** changed sound accumulators back to floats
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**
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** Revision 1.14 2000/09/15 13:38:40 matt
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** changes for optimized apu core
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**
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** Revision 1.13 2000/09/15 04:58:07 matt
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** simplifying and optimizing APU core
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**
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** Revision 1.12 2000/07/30 04:32:59 matt
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** no more apu_getcyclerate hack
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**
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** Revision 1.11 2000/07/17 01:52:31 matt
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** made sure last line of all source files is a newline
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**
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** Revision 1.10 2000/07/06 11:42:41 matt
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** forgot to remove FDS register range
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**
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** Revision 1.9 2000/07/04 04:51:41 matt
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** cleanups
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**
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** Revision 1.8 2000/07/03 02:18:53 matt
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** much better external module exporting
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**
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** Revision 1.7 2000/06/20 04:06:16 matt
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** migrated external sound definition to apu module
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**
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** Revision 1.6 2000/06/20 00:08:58 matt
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** changed to driver based API
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**
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** Revision 1.5 2000/06/09 16:49:02 matt
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** removed all floating point from sound generation
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**
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** Revision 1.4 2000/06/09 15:12:28 matt
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** initial revision
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**
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*/
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