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gusemu_mixer.c
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gusemu_mixer.c
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/*
* GUSEMU32 - mixing engine (similar to Interwave GF1 compatibility)
*
* Copyright (C) 2000-2007 Tibor "TS" Schütz
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "gusemu.h"
#include "gustate.h"
#define GUSregb(position) (* (gusptr+(position)))
#define GUSregw(position) (*(GUSword *) (gusptr+(position)))
#define GUSregd(position) (*(GUSdword *)(gusptr+(position)))
#define GUSvoice(position) (*(GUSword *)(voiceptr+(position)))
/* samples are always 16bit stereo (4 bytes each, first right then left interleaved) */
void gus_mixvoices(GUSEmuState * state, unsigned int playback_freq, unsigned int numsamples,
GUSsample *bufferpos)
{
/* note that byte registers are stored in the upper half of each voice register! */
GUSbyte *gusptr;
int Voice;
GUSword *voiceptr;
unsigned int count;
for (count = 0; count < numsamples * 2; count++)
*(bufferpos + count) = 0; /* clear */
gusptr = state->gusdatapos;
voiceptr = (GUSword *) gusptr;
if (!(GUSregb(GUS4cReset) & 0x01)) /* reset flag active? */
return;
for (Voice = 0; Voice <= (GUSregb(NumVoices) & 31); Voice++)
{
if (GUSvoice(wVSRControl) & 0x200)
GUSvoice(wVSRControl) |= 0x100; /* voice stop request */
if (GUSvoice(wVSRVolRampControl) & 0x200)
GUSvoice(wVSRVolRampControl) |= 0x100; /* Volume ramp stop request */
if (!(GUSvoice(wVSRControl) & GUSvoice(wVSRVolRampControl) & 0x100)) /* neither voice nor volume calculation active - save some time here ;) */
{
unsigned int sample;
unsigned int LoopStart = (GUSvoice(wVSRLoopStartHi) << 16) | GUSvoice(wVSRLoopStartLo); /* 23.9 format */
unsigned int LoopEnd = (GUSvoice(wVSRLoopEndHi) << 16) | GUSvoice(wVSRLoopEndLo); /* 23.9 format */
unsigned int CurrPos = (GUSvoice(wVSRCurrPosHi) << 16) | GUSvoice(wVSRCurrPosLo); /* 23.9 format */
int VoiceIncrement = ((((unsigned long) GUSvoice(wVSRFreq) * 44100) / playback_freq) * (14 >> 1)) /
((GUSregb(NumVoices) & 31) + 1); /* 6.10 increment/frame to 23.9 increment/sample */
int PanningPos = (GUSvoice(wVSRPanning) >> 8) & 0xf;
unsigned int Volume32 = 32 * GUSvoice(wVSRCurrVol); /* 32 times larger than original gus for maintaining precision while ramping */
unsigned int StartVol32 = (GUSvoice(wVSRVolRampStartVol) & 0xff00) * 32;
unsigned int EndVol32 = (GUSvoice(wVSRVolRampEndVol) & 0xff00) * 32;
int VolumeIncrement32 = (32 * 16 * (GUSvoice(wVSRVolRampRate) & 0x3f00) >> 8) >> ((((GUSvoice(wVSRVolRampRate) & 0xc000) >> 8) >> 6) * 3); /* including 1/8/64/512 volume speed divisor */
VolumeIncrement32 = (((VolumeIncrement32 * 44100 / 2) / playback_freq) * 14) / ((GUSregb(NumVoices) & 31) + 1); /* adjust ramping speed to playback speed */
if (GUSvoice(wVSRControl) & 0x4000)
VoiceIncrement = -VoiceIncrement; /* reverse playback */
if (GUSvoice(wVSRVolRampControl) & 0x4000)
VolumeIncrement32 = -VolumeIncrement32; /* reverse ramping */
for (sample = 0; sample < numsamples; sample++)
{
int sample1, sample2, Volume;
if (GUSvoice(wVSRControl) & 0x400) /* 16bit */
{
int offset = ((CurrPos >> 9) & 0xc0000) + (((CurrPos >> 9) & 0x1ffff) << 1);
GUSchar *adr;
adr = (GUSchar *) state->himemaddr + offset;
sample1 = (*adr & 0xff) + (*(adr + 1) * 256);
sample2 = (*(adr + 2) & 0xff) + (*(adr + 2 + 1) * 256);
}
else /* 8bit */
{
int offset = (CurrPos >> 9) & 0xfffff;
GUSchar *adr;
adr = (GUSchar *) state->himemaddr + offset;
sample1 = (*adr) * 256;
sample2 = (*(adr + 1)) * 256;
}
Volume = ((((Volume32 >> (4 + 5)) & 0xff) + 256) << (Volume32 >> ((4 + 8) + 5))) / 512; /* semi-logarithmic volume, +5 due to additional precision */
sample1 = (((sample1 * Volume) >> 16) * (512 - (CurrPos % 512))) / 512;
sample2 = (((sample2 * Volume) >> 16) * (CurrPos % 512)) / 512;
sample1 += sample2;
if (!(GUSvoice(wVSRVolRampControl) & 0x100))
{
Volume32 += VolumeIncrement32;
if ((GUSvoice(wVSRVolRampControl) & 0x4000) ? (Volume32 <= StartVol32) : (Volume32 >= EndVol32)) /* ramp up boundary cross */
{
if (GUSvoice(wVSRVolRampControl) & 0x2000)
GUSvoice(wVSRVolRampControl) |= 0x8000; /* volramp IRQ enabled? -> IRQ wait flag */
if (GUSvoice(wVSRVolRampControl) & 0x800) /* loop enabled */
{
if (GUSvoice(wVSRVolRampControl) & 0x1000) /* bidir. loop */
{
GUSvoice(wVSRVolRampControl) ^= 0x4000; /* toggle dir */
VolumeIncrement32 = -VolumeIncrement32;
}
else
Volume32 = (GUSvoice(wVSRVolRampControl) & 0x4000) ? EndVol32 : StartVol32; /* unidir. loop ramp */
}
else
{
GUSvoice(wVSRVolRampControl) |= 0x100;
Volume32 =
(GUSvoice(wVSRVolRampControl) & 0x4000) ? StartVol32 : EndVol32;
}
}
}
if ((GUSvoice(wVSRVolRampControl) & 0xa000) == 0xa000) /* volramp IRQ set and enabled? */
{
GUSregd(voicevolrampirq) |= 1 << Voice; /* set irq slot */
}
else
{
GUSregd(voicevolrampirq) &= (~(1 << Voice)); /* clear irq slot */
GUSvoice(wVSRVolRampControl) &= 0x7f00;
}
if (!(GUSvoice(wVSRControl) & 0x100))
{
CurrPos += VoiceIncrement;
if ((GUSvoice(wVSRControl) & 0x4000) ? (CurrPos <= LoopStart) : (CurrPos >= LoopEnd)) /* playback boundary cross */
{
if (GUSvoice(wVSRControl) & 0x2000)
GUSvoice(wVSRControl) |= 0x8000; /* voice IRQ enabled -> IRQ wait flag */
if (GUSvoice(wVSRControl) & 0x800) /* loop enabled */
{
if (GUSvoice(wVSRControl) & 0x1000) /* pingpong loop */
{
GUSvoice(wVSRControl) ^= 0x4000; /* toggle dir */
VoiceIncrement = -VoiceIncrement;
}
else
CurrPos = (GUSvoice(wVSRControl) & 0x4000) ? LoopEnd : LoopStart; /* unidir. loop */
}
else if (!(GUSvoice(wVSRVolRampControl) & 0x400))
GUSvoice(wVSRControl) |= 0x100; /* loop disabled, rollover check */
}
}
if ((GUSvoice(wVSRControl) & 0xa000) == 0xa000) /* wavetable IRQ set and enabled? */
{
GUSregd(voicewavetableirq) |= 1 << Voice; /* set irq slot */
}
else
{
GUSregd(voicewavetableirq) &= (~(1 << Voice)); /* clear irq slot */
GUSvoice(wVSRControl) &= 0x7f00;
}
/* mix samples into buffer */
*(bufferpos + 2 * sample) += (GUSsample) ((sample1 * PanningPos) >> 4); /* right */
*(bufferpos + 2 * sample + 1) += (GUSsample) ((sample1 * (15 - PanningPos)) >> 4); /* left */
}
/* write back voice and volume */
GUSvoice(wVSRCurrVol) = Volume32 / 32;
GUSvoice(wVSRCurrPosHi) = CurrPos >> 16;
GUSvoice(wVSRCurrPosLo) = CurrPos & 0xffff;
}
voiceptr += 16; /* next voice */
}
}
void gus_irqgen(GUSEmuState * state, unsigned int elapsed_time)
/* time given in microseconds */
{
int requestedIRQs = 0;
GUSbyte *gusptr;
gusptr = state->gusdatapos;
if (GUSregb(TimerDataReg2x9) & 1) /* start timer 1 (80us decrement rate) */
{
unsigned int timer1fraction = state->timer1fraction;
int newtimerirqs;
newtimerirqs = (elapsed_time + timer1fraction) / (80 * (256 - GUSregb(GUS46Counter1)));
state->timer1fraction = (elapsed_time + timer1fraction) % (80 * (256 - GUSregb(GUS46Counter1)));
if (newtimerirqs)
{
if (!(GUSregb(TimerDataReg2x9) & 0x40))
GUSregb(TimerStatus2x8) |= 0xc0; /* maskable bits */
if (GUSregb(GUS45TimerCtrl) & 4) /* timer1 irq enable */
{
GUSregb(TimerStatus2x8) |= 4; /* nonmaskable bit */
GUSregb(IRQStatReg2x6) |= 4; /* timer 1 irq pending */
GUSregw(TimerIRQs) += newtimerirqs;
requestedIRQs += newtimerirqs;
}
}
}
if (GUSregb(TimerDataReg2x9) & 2) /* start timer 2 (320us decrement rate) */
{
unsigned int timer2fraction = state->timer2fraction;
int newtimerirqs;
newtimerirqs = (elapsed_time + timer2fraction) / (320 * (256 - GUSregb(GUS47Counter2)));
state->timer2fraction = (elapsed_time + timer2fraction) % (320 * (256 - GUSregb(GUS47Counter2)));
if (newtimerirqs)
{
if (!(GUSregb(TimerDataReg2x9) & 0x20))
GUSregb(TimerStatus2x8) |= 0xa0; /* maskable bits */
if (GUSregb(GUS45TimerCtrl) & 8) /* timer2 irq enable */
{
GUSregb(TimerStatus2x8) |= 2; /* nonmaskable bit */
GUSregb(IRQStatReg2x6) |= 8; /* timer 2 irq pending */
GUSregw(TimerIRQs) += newtimerirqs;
requestedIRQs += newtimerirqs;
}
}
}
if (GUSregb(GUS4cReset) & 0x4) /* synth IRQ enable */
{
if (GUSregd(voicewavetableirq))
GUSregb(IRQStatReg2x6) |= 0x20;
if (GUSregd(voicevolrampirq))
GUSregb(IRQStatReg2x6) |= 0x40;
}
if ((!requestedIRQs) && GUSregb(IRQStatReg2x6))
requestedIRQs++;
if (GUSregb(IRQStatReg2x6))
GUSregw(BusyTimerIRQs) = GUS_irqrequest(state, state->gusirq, requestedIRQs);
}