/* ** 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 2001/04/27 14:37:11 neil Exp $ */ #include "noftypes.h" #include "vrcvisnd.h" #include "nes_apu.h" typedef struct vrcvirectangle_s { bool enabled; uint8 reg[3]; float accum; uint8 adder; int32 freq; int32 volume; uint8 duty_flip; } vrcvirectangle_t; typedef struct vrcvisawtooth_s { bool enabled; uint8 reg[3]; float accum; uint8 adder; uint8 output_acc; int32 freq; uint8 volume; } vrcvisawtooth_t; typedef struct vrcvisnd_s { vrcvirectangle_t rectangle[2]; vrcvisawtooth_t saw; float incsize; } vrcvisnd_t; static vrcvisnd_t vrcvi; /* 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->accum -= vrcvi.incsize; /* # of clocks per wave cycle */ while (chan->accum < 0) { chan->accum += 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->accum -= vrcvi.incsize; /* # of clocks per wav cycle */ while (chan->accum < 0) { chan->accum += chan->freq; chan->output_acc += chan->volume; chan->adder++; if (7 == chan->adder) { chan->adder = 0; chan->output_acc = 0; } } /* return if not enabled */ if (false == chan->enabled) return 0; 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 = (address >> 12) - 9; switch (address & 0xB003) { case 0x9000: case 0xA000: 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: vrcvi.rectangle[chan].reg[1] = value; vrcvi.rectangle[chan].freq = ((vrcvi.rectangle[chan].reg[2] & 0x0F) << 8) + value + 1; break; case 0x9002: case 0xA002: vrcvi.rectangle[chan].reg[2] = value; vrcvi.rectangle[chan].freq = ((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 = (((vrcvi.saw.reg[2] & 0x0F) << 8) + value + 1) << 1; break; case 0xB002: vrcvi.saw.reg[2] = value; vrcvi.saw.freq = (((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; apu_t apu; /* get the phase period from the apu */ apu_getcontext(&apu); vrcvi.incsize = apu.cycle_rate; /* preload regs */ for (i = 0; i < 3; i++) { vrcvi_write(0x9000 + i, 0); vrcvi_write(0xA000 + i, 0); vrcvi_write(0xB000 + i, 0); } } static apu_memwrite vrcvi_memwrite[] = { { 0x9000, 0x9002, vrcvi_write }, /* vrc6 */ { 0xA000, 0xA002, vrcvi_write }, { 0xB000, 0xB002, vrcvi_write }, { -1, -1, NULL } }; apuext_t vrcvi_ext = { NULL, /* no init */ NULL, /* no shutdown */ vrcvi_reset, vrcvi_process, NULL, /* no reads */ vrcvi_memwrite }; /* ** $Log: vrcvisnd.c,v $ ** Revision 1.2 2001/04/27 14:37:11 neil ** wheeee ** ** Revision 1.1 2001/04/27 12:54:40 neil ** blah ** ** Revision 1.1.1.1 2001/04/27 07:03:54 neil ** initial ** ** Revision 1.2 2000/11/05 22:21:00 matt ** help me! ** ** Revision 1.1 2000/10/24 12:20:00 matt ** changed directory structure ** ** Revision 1.17 2000/10/10 13:58:18 matt ** stroustrup squeezing his way in the door ** ** Revision 1.16 2000/10/03 11:56:20 matt ** better support for optional sound ext routines ** ** Revision 1.15 2000/09/27 12:26:03 matt ** changed sound accumulators back to floats ** ** Revision 1.14 2000/09/15 13:38:40 matt ** changes for optimized apu core ** ** Revision 1.13 2000/09/15 04:58:07 matt ** simplifying and optimizing APU core ** ** Revision 1.12 2000/07/30 04:32:59 matt ** no more apu_getcyclerate hack ** ** Revision 1.11 2000/07/17 01:52:31 matt ** made sure last line of all source files is a newline ** ** Revision 1.10 2000/07/06 11:42:41 matt ** forgot to remove FDS register range ** ** 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 ** */