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nes_apu.c    1257 lines (1047 with data), 31.1 kB

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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.
**
**
** nes_apu.c
**
** NES APU emulation
** $Id: nes_apu.c,v 1.4 2005/05/07 09:11:39 valtri Exp $
*/
#include <string.h>
#include "types.h"
#include "log.h"
#include "nes_apu.h"
#include "nes6502.h"
#ifdef NSF_PLAYER
#include "nsf.h"
#else
#include "nes.h"
#include "nes_ppu.h"
#include "nes_mmc.h"
#include "nesinput.h"
#endif /* !NSF_PLAYER */
#define APU_OVERSAMPLE
#define APU_VOLUME_DECAY(x) ((x) -= ((x) >> 7))
/* pointer to active APU */
static apu_t *apu;
/* look up table madness */
static int32 decay_lut[16];
static int vbl_lut[32];
static int trilength_lut[128];
/* noise lookups for both modes */
#ifndef REALTIME_NOISE
static int8 noise_long_lut[APU_NOISE_32K];
static int8 noise_short_lut[APU_NOISE_93];
#endif /* !REALTIME_NOISE */
/* $$$ ben : last error */
#define SET_APU_ERROR(APU,X) \
if (APU) (APU)->errstr = "apu: " X; else
#define APU_MIX_ENABLE(BIT) (apu->mix_enable&(1<<(BIT)))
/* vblank length table used for rectangles, triangle, noise */
static const uint8 vbl_length[32] =
{
5, 127,
10, 1,
19, 2,
40, 3,
80, 4,
30, 5,
7, 6,
13, 7,
6, 8,
12, 9,
24, 10,
48, 11,
96, 12,
36, 13,
8, 14,
16, 15
};
/* frequency limit of rectangle channels */
static const int freq_limit[8] =
{
0x3FF, 0x555, 0x666, 0x71C, 0x787, 0x7C1, 0x7E0, 0x7F0
};
/* noise frequency lookup table */
static const int noise_freq[16] =
{
4, 8, 16, 32, 64, 96, 128, 160,
202, 254, 380, 508, 762, 1016, 2034, 4068
};
/* DMC transfer freqs */
const int dmc_clocks[16] =
{
428, 380, 340, 320, 286, 254, 226, 214,
190, 160, 142, 128, 106, 85, 72, 54
};
/* ratios of pos/neg pulse for rectangle waves */
static const int duty_lut[4] = { 2, 4, 8, 12 };
void apu_setcontext(apu_t *src_apu)
{
apu = src_apu;
/* $$$ ben reset eoor string here. */
SET_APU_ERROR(apu,"no error");
}
/*
** Simple queue routines
*/
#define APU_QEMPTY() (apu->q_head == apu->q_tail)
static int apu_enqueue(apudata_t *d)
{
ASSERT(apu);
apu->queue[apu->q_head] = *d;
apu->q_head = (apu->q_head + 1) & APUQUEUE_MASK;
if (APU_QEMPTY()) {
log_printf("apu: queue overflow\n");
SET_APU_ERROR(apu,"queue overflow");
return -1;
}
return 0;
}
static apudata_t *apu_dequeue(void)
{
int loc;
ASSERT(apu);
if (APU_QEMPTY()) {
log_printf("apu: queue empty\n");
SET_APU_ERROR(apu,"queue empty");
/* $$$ ben : should return 0 ??? */
}
loc = apu->q_tail;
apu->q_tail = (apu->q_tail + 1) & APUQUEUE_MASK;
return &apu->queue[loc];
}
int apu_setchan(int chan, boolean enabled)
{
const unsigned int max = 6;
int old;
ASSERT(apu);
if ((unsigned int)chan >= max) {
SET_APU_ERROR(apu,"channel out of range");
return -1;
}
old = (apu->mix_enable>>chan) & 1;
if (enabled != (boolean)-1) {
apu->mix_enable = (apu->mix_enable & ~(1<<chan)) | ((!!enabled)<<chan);
}
return old;
}
/* emulation of the 15-bit shift register the
** NES uses to generate pseudo-random series
** for the white noise channel
*/
#ifdef REALTIME_NOISE
INLINE int8 shift_register15(uint8 xor_tap)
{
static int sreg = 0x4000;
int bit0, tap, bit14;
bit0 = sreg & 1;
tap = (sreg & xor_tap) ? 1 : 0;
bit14 = (bit0 ^ tap);
sreg >>= 1;
sreg |= (bit14 << 14);
return (bit0 ^ 1);
}
#else
static void shift_register15(int8 *buf, int count)
{
static int sreg = 0x4000;
int bit0, bit1, bit6, bit14;
if (count == APU_NOISE_93)
{
while (count--)
{
bit0 = sreg & 1;
bit6 = (sreg & 0x40) >> 6;
bit14 = (bit0 ^ bit6);
sreg >>= 1;
sreg |= (bit14 << 14);
*buf++ = bit0 ^ 1;
}
}
else /* 32K noise */
{
while (count--)
{
bit0 = sreg & 1;
bit1 = (sreg & 2) >> 1;
bit14 = (bit0 ^ bit1);
sreg >>= 1;
sreg |= (bit14 << 14);
*buf++ = bit0 ^ 1;
}
}
}
#endif
/* RECTANGLE WAVE
** ==============
** reg0: 0-3=volume, 4=envelope, 5=hold, 6-7=duty cycle
** reg1: 0-2=sweep shifts, 3=sweep inc/dec, 4-6=sweep length, 7=sweep on
** reg2: 8 bits of freq
** reg3: 0-2=high freq, 7-4=vbl length counter
*/
#define APU_RECTANGLE_OUTPUT chan->output_vol
static int32 apu_rectangle(rectangle_t *chan)
{
int32 output;
#ifdef APU_OVERSAMPLE
int num_times;
int32 total;
#endif
APU_VOLUME_DECAY(chan->output_vol);
if (FALSE == chan->enabled || 0 == chan->vbl_length)
return APU_RECTANGLE_OUTPUT;
/* vbl length counter */
if (FALSE == chan->holdnote)
chan->vbl_length--;
/* envelope decay at a rate of (env_delay + 1) / 240 secs */
chan->env_phase -= 4; /* 240/60 */
while (chan->env_phase < 0)
{
chan->env_phase += chan->env_delay;
if (chan->holdnote)
chan->env_vol = (chan->env_vol + 1) & 0x0F;
else if (chan->env_vol < 0x0F)
chan->env_vol++;
}
if ((FALSE == chan->sweep_inc && chan->freq > chan->freq_limit)
|| chan->freq < APU_TO_FIXED(4))
return APU_RECTANGLE_OUTPUT;
/* frequency sweeping at a rate of (sweep_delay + 1) / 120 secs */
if (chan->sweep_on && chan->sweep_shifts)
{
chan->sweep_phase -= 2; /* 120/60 */
while (chan->sweep_phase < 0)
{
chan->sweep_phase += chan->sweep_delay;
if (chan->sweep_inc) /* ramp up */
chan->freq -= chan->freq >> (chan->sweep_shifts);
else /* ramp down */
chan->freq += chan->freq >> (chan->sweep_shifts);
}
}
chan->phaseacc -= apu->cycle_rate; /* # of cycles per sample */
if (chan->phaseacc >= 0)
return APU_RECTANGLE_OUTPUT;
#ifdef APU_OVERSAMPLE
num_times = total = 0;
if (chan->fixed_envelope)
output = chan->volume << 8; /* fixed volume */
else
output = (chan->env_vol ^ 0x0F) << 8;
#endif
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
chan->adder = (chan->adder + 1) & 0x0F;
#ifdef APU_OVERSAMPLE
if (chan->adder < chan->duty_flip)
total += output;
else
total -= output;
num_times++;
#endif
}
#ifdef APU_OVERSAMPLE
chan->output_vol = total / num_times;
#else
if (chan->fixed_envelope)
output = chan->volume << 8; /* fixed volume */
else
output = (chan->env_vol ^ 0x0F) << 8;
if (0 == chan->adder)
chan->output_vol = output;
else if (chan->adder == chan->duty_flip)
chan->output_vol = -output;
#endif
return APU_RECTANGLE_OUTPUT;
}
/* TRIANGLE WAVE
** =============
** reg0: 7=holdnote, 6-0=linear length counter
** reg2: low 8 bits of frequency
** reg3: 7-3=length counter, 2-0=high 3 bits of frequency
*/
#define APU_TRIANGLE_OUTPUT (chan->output_vol + (chan->output_vol >> 2))
static int32 apu_triangle(triangle_t *chan)
{
APU_VOLUME_DECAY(chan->output_vol);
if (FALSE == chan->enabled || 0 == chan->vbl_length)
return APU_TRIANGLE_OUTPUT;
if (chan->counter_started)
{
if (chan->linear_length > 0)
chan->linear_length--;
if (chan->vbl_length && FALSE == chan->holdnote)
chan->vbl_length--;
}
else if (FALSE == chan->holdnote && chan->write_latency)
{
if (--chan->write_latency == 0)
chan->counter_started = TRUE;
}
/*
if (chan->countmode == COUNTMODE_COUNT)
{
if (chan->linear_length > 0)
chan->linear_length--;
if (chan->vbl_length)
chan->vbl_length--;
}
*/
if (0 == chan->linear_length || chan->freq < APU_TO_FIXED(4)) /* inaudible */
return APU_TRIANGLE_OUTPUT;
chan->phaseacc -= apu->cycle_rate; /* # of cycles per sample */
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
chan->adder = (chan->adder + 1) & 0x1F;
if (chan->adder & 0x10)
chan->output_vol -= (2 << 8);
else
chan->output_vol += (2 << 8);
}
return APU_TRIANGLE_OUTPUT;
}
/* WHITE NOISE CHANNEL
** ===================
** reg0: 0-3=volume, 4=envelope, 5=hold
** reg2: 7=small(93 byte) sample,3-0=freq lookup
** reg3: 7-4=vbl length counter
*/
#define APU_NOISE_OUTPUT ((chan->output_vol + chan->output_vol + chan->output_vol) >> 2)
static int32 apu_noise(noise_t *chan)
{
int32 outvol;
#if defined(APU_OVERSAMPLE) && defined(REALTIME_NOISE)
#else
int32 noise_bit;
#endif
#ifdef APU_OVERSAMPLE
int num_times;
int32 total;
#endif
APU_VOLUME_DECAY(chan->output_vol);
if (FALSE == chan->enabled || 0 == chan->vbl_length)
return APU_NOISE_OUTPUT;
/* vbl length counter */
if (FALSE == chan->holdnote)
chan->vbl_length--;
/* envelope decay at a rate of (env_delay + 1) / 240 secs */
chan->env_phase -= 4; /* 240/60 */
while (chan->env_phase < 0)
{
chan->env_phase += chan->env_delay;
if (chan->holdnote)
chan->env_vol = (chan->env_vol + 1) & 0x0F;
else if (chan->env_vol < 0x0F)
chan->env_vol++;
}
chan->phaseacc -= apu->cycle_rate; /* # of cycles per sample */
if (chan->phaseacc >= 0)
return APU_NOISE_OUTPUT;
#ifdef APU_OVERSAMPLE
num_times = total = 0;
if (chan->fixed_envelope)
outvol = chan->volume << 8; /* fixed volume */
else
outvol = (chan->env_vol ^ 0x0F) << 8;
#endif
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
#ifdef REALTIME_NOISE
#ifdef APU_OVERSAMPLE
if (shift_register15(chan->xor_tap))
total += outvol;
else
total -= outvol;
num_times++;
#else
noise_bit = shift_register15(chan->xor_tap);
#endif
#else
chan->cur_pos++;
if (chan->short_sample)
{
if (APU_NOISE_93 == chan->cur_pos)
chan->cur_pos = 0;
}
else
{
if (APU_NOISE_32K == chan->cur_pos)
chan->cur_pos = 0;
}
#ifdef APU_OVERSAMPLE
if (chan->short_sample)
noise_bit = noise_short_lut[chan->cur_pos];
else
noise_bit = noise_long_lut[chan->cur_pos];
if (noise_bit)
total += outvol;
else
total -= outvol;
num_times++;
#endif
#endif /* REALTIME_NOISE */
}
#ifdef APU_OVERSAMPLE
chan->output_vol = total / num_times;
#else
if (chan->fixed_envelope)
outvol = chan->volume << 8; /* fixed volume */
else
outvol = (chan->env_vol ^ 0x0F) << 8;
#ifndef REALTIME_NOISE
if (chan->short_sample)
noise_bit = noise_short_lut[chan->cur_pos];
else
noise_bit = noise_long_lut[chan->cur_pos];
#endif /* !REALTIME_NOISE */
if (noise_bit)
chan->output_vol = outvol;
else
chan->output_vol = -outvol;
#endif
return APU_NOISE_OUTPUT;
}
INLINE void apu_dmcreload(dmc_t *chan)
{
chan->address = chan->cached_addr;
chan->dma_length = chan->cached_dmalength;
chan->irq_occurred = FALSE;
}
/* DELTA MODULATION CHANNEL
** =========================
** reg0: 7=irq gen, 6=looping, 3-0=pointer to clock table
** reg1: output dc level, 6 bits unsigned
** reg2: 8 bits of 64-byte aligned address offset : $C000 + (value * 64)
** reg3: length, (value * 16) + 1
*/
#define APU_DMC_OUTPUT ((chan->output_vol + chan->output_vol + chan->output_vol) >> 2)
static int32 apu_dmc(dmc_t *chan)
{
int delta_bit;
APU_VOLUME_DECAY(chan->output_vol);
/* only process when channel is alive */
if (chan->dma_length)
{
chan->phaseacc -= apu->cycle_rate; /* # of cycles per sample */
while (chan->phaseacc < 0)
{
chan->phaseacc += chan->freq;
delta_bit = (chan->dma_length & 7) ^ 7;
if (7 == delta_bit)
{
chan->cur_byte = nes6502_getbyte(chan->address);
/* steal a cycle from CPU*/
nes6502_setdma(1);
if (0xFFFF == chan->address)
chan->address = 0x8000;
else
chan->address++;
}
if (--chan->dma_length == 0)
{
/* if loop bit set, we're cool to retrigger sample */
if (chan->looping)
apu_dmcreload(chan);
else
{
/* check to see if we should generate an irq */
if (chan->irq_gen)
{
chan->irq_occurred = TRUE;
nes6502_irq();
}
/* bodge for timestamp queue */
chan->enabled = FALSE;
break;
}
}
/* positive delta */
if (chan->cur_byte & (1 << delta_bit))
{
if (chan->regs[1] < 0x7D)
{
chan->regs[1] += 2;
chan->output_vol += (2 << 8);
}
/*
if (chan->regs[1] < 0x3F)
chan->regs[1]++;
chan->output_vol &= ~(0x7E << 8);
chan->output_vol |= ((chan->regs[1] << 1) << 8);
*/
}
/* negative delta */
else
{
if (chan->regs[1] > 1)
{
chan->regs[1] -= 2;
chan->output_vol -= (2 << 8);
}
/*
if (chan->regs[1] > 0)
chan->regs[1]--;
chan->output_vol &= ~(0x7E << 8);
chan->output_vol |= ((chan->regs[1] << 1) << 8);
*/
}
}
}
return APU_DMC_OUTPUT;
}
static void apu_regwrite(uint32 address, uint8 value)
{
int chan;
ASSERT(apu);
switch (address)
{
/* rectangles */
case APU_WRA0:
case APU_WRB0:
chan = (address & 4) ? 1 : 0;
apu->rectangle[chan].regs[0] = value;
apu->rectangle[chan].volume = value & 0x0F;
apu->rectangle[chan].env_delay = decay_lut[value & 0x0F];
apu->rectangle[chan].holdnote = (value & 0x20) ? TRUE : FALSE;
apu->rectangle[chan].fixed_envelope = (value & 0x10) ? TRUE : FALSE;
apu->rectangle[chan].duty_flip = duty_lut[value >> 6];
break;
case APU_WRA1:
case APU_WRB1:
chan = (address & 4) ? 1 : 0;
apu->rectangle[chan].regs[1] = value;
apu->rectangle[chan].sweep_on = (value & 0x80) ? TRUE : FALSE;
apu->rectangle[chan].sweep_shifts = value & 7;
apu->rectangle[chan].sweep_delay = decay_lut[(value >> 4) & 7];
apu->rectangle[chan].sweep_inc = (value & 0x08) ? TRUE : FALSE;
apu->rectangle[chan].freq_limit = APU_TO_FIXED(freq_limit[value & 7]);
break;
case APU_WRA2:
case APU_WRB2:
chan = (address & 4) ? 1 : 0;
apu->rectangle[chan].regs[2] = value;
// if (apu->rectangle[chan].enabled)
apu->rectangle[chan].freq = APU_TO_FIXED((((apu->rectangle[chan].regs[3] & 7) << 8) + value) + 1);
break;
case APU_WRA3:
case APU_WRB3:
chan = (address & 4) ? 1 : 0;
apu->rectangle[chan].regs[3] = value;
// if (apu->rectangle[chan].enabled)
{
apu->rectangle[chan].vbl_length = vbl_lut[value >> 3];
apu->rectangle[chan].env_vol = 0;
apu->rectangle[chan].freq = APU_TO_FIXED((((value & 7) << 8) + apu->rectangle[chan].regs[2]) + 1);
apu->rectangle[chan].adder = 0;
}
break;
/* triangle */
case APU_WRC0:
/*
if (0 == (apu->triangle.regs[0] & 0x80))
apu->triangle.countmode = COUNTMODE_COUNT;
else
{
if (apu->triangle.countmode == COUNTMODE_LOAD && apu->triangle.vbl_length)
apu->triangle.linear_length = trilength_lut[value & 0x7F];
if (0 == (value & 0x80))
apu->triangle.countmode = COUNTMODE_COUNT;
}
*/
apu->triangle.regs[0] = value;
apu->triangle.holdnote = (value & 0x80) ? TRUE : FALSE;
// if (apu->triangle.enabled)
{
if (FALSE == apu->triangle.counter_started && apu->triangle.vbl_length)
apu->triangle.linear_length = trilength_lut[value & 0x7F];
}
break;
case APU_WRC2:
apu->triangle.regs[1] = value;
// if (apu->triangle.enabled)
apu->triangle.freq = APU_TO_FIXED((((apu->triangle.regs[2] & 7) << 8) + value) + 1);
break;
case APU_WRC3:
apu->triangle.regs[2] = value;
/* this is somewhat of a hack. there appears to be some latency on
** the Real Thing between when trireg0 is written to and when the
** linear length counter actually begins its countdown. we want to
** prevent the case where the program writes to the freq regs first,
** then to reg 0, and the counter accidentally starts running because
** of the sound queue's timestamp processing.
**
** set latency to a couple scanlines -- should be plenty of time for
** the 6502 code to do a couple of table dereferences and load up the
** other triregs
*/
/* 06/13/00 MPC -- seems to work OK */
apu->triangle.write_latency = (int) (2 * NES_SCANLINE_CYCLES / APU_FROM_FIXED(apu->cycle_rate));
/*
apu->triangle.linear_length = trilength_lut[apu->triangle.regs[0] & 0x7F];
if (0 == (apu->triangle.regs[0] & 0x80))
apu->triangle.countmode = COUNTMODE_COUNT;
else
apu->triangle.countmode = COUNTMODE_LOAD;
*/
// if (apu->triangle.enabled)
{
apu->triangle.freq = APU_TO_FIXED((((value & 7) << 8) + apu->triangle.regs[1]) + 1);
apu->triangle.vbl_length = vbl_lut[value >> 3];
apu->triangle.counter_started = FALSE;
apu->triangle.linear_length = trilength_lut[apu->triangle.regs[0] & 0x7F];
}
break;
/* noise */
case APU_WRD0:
apu->noise.regs[0] = value;
apu->noise.env_delay = decay_lut[value & 0x0F];
apu->noise.holdnote = (value & 0x20) ? TRUE : FALSE;
apu->noise.fixed_envelope = (value & 0x10) ? TRUE : FALSE;
apu->noise.volume = value & 0x0F;
break;
case APU_WRD2:
apu->noise.regs[1] = value;
apu->noise.freq = APU_TO_FIXED(noise_freq[value & 0x0F]);
#ifdef REALTIME_NOISE
apu->noise.xor_tap = (value & 0x80) ? 0x40: 0x02;
#else
/* detect transition from long->short sample */
if ((value & 0x80) && FALSE == apu->noise.short_sample)
{
/* recalculate short noise buffer */
shift_register15(noise_short_lut, APU_NOISE_93);
apu->noise.cur_pos = 0;
}
apu->noise.short_sample = (value & 0x80) ? TRUE : FALSE;
#endif
break;
case APU_WRD3:
apu->noise.regs[2] = value;
// if (apu->noise.enabled)
{
apu->noise.vbl_length = vbl_lut[value >> 3];
apu->noise.env_vol = 0; /* reset envelope */
}
break;
/* DMC */
case APU_WRE0:
apu->dmc.regs[0] = value;
apu->dmc.freq = APU_TO_FIXED(dmc_clocks[value & 0x0F]);
apu->dmc.looping = (value & 0x40) ? TRUE : FALSE;
if (value & 0x80)
apu->dmc.irq_gen = TRUE;
else
{
apu->dmc.irq_gen = FALSE;
apu->dmc.irq_occurred = FALSE;
}
break;
case APU_WRE1: /* 7-bit DAC */
/* add the _delta_ between written value and
** current output level of the volume reg
*/
value &= 0x7F; /* bit 7 ignored */
apu->dmc.output_vol += ((value - apu->dmc.regs[1]) << 8);
apu->dmc.regs[1] = value;
/*
apu->dmc.output_vol = (value & 0x7F) << 8;
apu->dmc.regs[1] = (value & 0x7E) >> 1;
*/
break;
case APU_WRE2:
apu->dmc.regs[2] = value;
apu->dmc.cached_addr = 0xC000 + (uint16) (value << 6);
break;
case APU_WRE3:
apu->dmc.regs[3] = value;
apu->dmc.cached_dmalength = ((value << 4) + 1) << 3;
break;
case APU_SMASK:
/* bodge for timestamp queue */
apu->dmc.enabled = (value & 0x10) ? TRUE : FALSE;
apu->enable_reg = value;
for (chan = 0; chan < 2; chan++)
{
if (value & (1 << chan))
apu->rectangle[chan].enabled = TRUE;
else
{
apu->rectangle[chan].enabled = FALSE;
apu->rectangle[chan].vbl_length = 0;
}
}
if (value & 0x04)
apu->triangle.enabled = TRUE;
else
{
apu->triangle.enabled = FALSE;
apu->triangle.vbl_length = 0;
apu->triangle.linear_length = 0;
apu->triangle.counter_started = FALSE;
apu->triangle.write_latency = 0;
}
if (value & 0x08)
apu->noise.enabled = TRUE;
else
{
apu->noise.enabled = FALSE;
apu->noise.vbl_length = 0;
}
if (value & 0x10)
{
if (0 == apu->dmc.dma_length)
apu_dmcreload(&apu->dmc);
}
else
apu->dmc.dma_length = 0;
apu->dmc.irq_occurred = FALSE;
break;
/* unused, but they get hit in some mem-clear loops */
case 0x4009:
case 0x400D:
break;
default:
break;
}
}
/* Read from $4000-$4017 */
uint8 apu_read(uint32 address)
{
uint8 value;
ASSERT(apu);
switch (address)
{
case APU_SMASK:
/* seems that bit 6 denotes vblank -- return 1 for now */
value = 0x40;
/* Return 1 in 0-5 bit pos if a channel is playing */
if (apu->rectangle[0].enabled && apu->rectangle[0].vbl_length)
value |= 0x01;
if (apu->rectangle[1].enabled && apu->rectangle[1].vbl_length)
value |= 0x02;
if (apu->triangle.enabled && apu->triangle.vbl_length)
value |= 0x04;
if (apu->noise.enabled && apu->noise.vbl_length)
value |= 0x08;
//if (apu->dmc.dma_length)
/* bodge for timestamp queue */
if (apu->dmc.enabled)
value |= 0x10;
if (apu->dmc.irq_occurred)
value |= 0x80;
break;
#ifndef NSF_PLAYER
case APU_JOY0:
value = input_get(INP_JOYPAD0);
break;
case APU_JOY1:
value = input_get(INP_ZAPPER | INP_JOYPAD1 /*| INP_ARKANOID*/ /*| INP_POWERPAD*/);
break;
#endif /* !NSF_PLAYER */
default:
value = (address >> 8); /* heavy capacitance on data bus */
break;
}
return value;
}
void apu_write(uint32 address, uint8 value)
{
#ifndef NSF_PLAYER
static uint8 last_write;
#endif /* !NSF_PLAYER */
apudata_t d;
switch (address)
{
case 0x4015:
/* bodge for timestamp queue */
apu->dmc.enabled = (value & 0x10) ? TRUE : FALSE;
case 0x4000: case 0x4001: case 0x4002: case 0x4003:
case 0x4004: case 0x4005: case 0x4006: case 0x4007:
case 0x4008: case 0x4009: case 0x400A: case 0x400B:
case 0x400C: case 0x400D: case 0x400E: case 0x400F:
case 0x4010: case 0x4011: case 0x4012: case 0x4013:
d.timestamp = nes6502_getcycles(FALSE);
d.address = address;
d.value = value;
apu_enqueue(&d);
break;
#ifndef NSF_PLAYER
case APU_OAMDMA:
ppu_oamdma(address, value);
break;
case APU_JOY0:
/* VS system VROM switching */
mmc_vsvrom(value & 4);
/* see if we need to strobe them joypads */
value &= 1;
if ((0 == value) && last_write)
input_strobe();
last_write = value;
break;
case APU_JOY1: /* Some kind of IRQ control business */
break;
#endif /* !NSF_PLAYER */
default:
break;
}
}
void apu_getpcmdata(void **data, int *num_samples, int *sample_bits)
{
ASSERT(apu);
*data = apu->buffer;
*num_samples = apu->num_samples;
*sample_bits = apu->sample_bits;
}
void apu_process(void *buffer, int num_samples)
{
apudata_t *d;
uint32 elapsed_cycles;
static int32 prev_sample = 0;
int32 next_sample, accum;
ASSERT(apu);
/* grab it, keep it local for speed */
elapsed_cycles = (uint32) apu->elapsed_cycles;
/* BLEH */
apu->buffer = buffer;
while (num_samples--)
{
while ((FALSE == APU_QEMPTY()) && (apu->queue[apu->q_tail].timestamp <= elapsed_cycles))
{
d = apu_dequeue();
apu_regwrite(d->address, d->value);
}
elapsed_cycles += APU_FROM_FIXED(apu->cycle_rate);
accum = 0;
if (APU_MIX_ENABLE(0)) accum += apu_rectangle(&apu->rectangle[0]);
if (APU_MIX_ENABLE(1)) accum += apu_rectangle(&apu->rectangle[1]);
if (APU_MIX_ENABLE(2)) accum += apu_triangle(&apu->triangle);
if (APU_MIX_ENABLE(3)) accum += apu_noise(&apu->noise);
if (APU_MIX_ENABLE(4)) accum += apu_dmc(&apu->dmc);
if (apu->ext && APU_MIX_ENABLE(5)) accum += apu->ext->process();
/* do any filtering */
if (APU_FILTER_NONE != apu->filter_type)
{
next_sample = accum;
if (APU_FILTER_LOWPASS == apu->filter_type)
{
accum += prev_sample;
accum >>= 1;
}
else
accum = (accum + accum + accum + prev_sample) >> 2;
prev_sample = next_sample;
}
/* little extra kick for the kids */
accum <<= 1;
/* prevent clipping */
if (accum > 0x7FFF)
accum = 0x7FFF;
else if (accum < -0x8000)
accum = -0x8000;
/* signed 16-bit output, unsigned 8-bit */
if (16 == apu->sample_bits) {
*(int16 *)(buffer) = (int16) accum;
buffer += sizeof(int16);
}
else {
*(uint8 *)(buffer) = (accum >> 8) ^ 0x80;
buffer += sizeof(uint8);
}
}
/* resync cycle counter */
apu->elapsed_cycles = nes6502_getcycles(FALSE);
}
/* set the filter type */
/* $$$ ben :
* Add a get feature (filter_type == -1) and returns old filter type
*/
int apu_setfilter(int filter_type)
{
int old;
ASSERT(apu);
old = apu->filter_type;
if (filter_type != -1) {
apu->filter_type = filter_type;
}
return old;
}
void apu_reset(void)
{
uint32 address;
ASSERT(apu);
apu->elapsed_cycles = 0;
memset(&apu->queue, 0, APUQUEUE_SIZE * sizeof(apudata_t));
apu->q_head = 0;
apu->q_tail = 0;
/* use to avoid bugs =) */
for (address = 0x4000; address <= 0x4013; address++)
apu_regwrite(address, 0);
#ifdef NSF_PLAYER
apu_regwrite(0x400C, 0x10); /* silence noise channel on NSF start */
apu_regwrite(0x4015, 0x0F);
#else
apu_regwrite(0x4015, 0);
#endif /* NSF_PLAYER */
if (apu->ext)
apu->ext->reset();
}
void apu_build_luts(int num_samples)
{
int i;
/* lut used for enveloping and frequency sweeps */
for (i = 0; i < 16; i++)
decay_lut[i] = num_samples * (i + 1);
/* used for note length, based on vblanks and size of audio buffer */
for (i = 0; i < 32; i++)
vbl_lut[i] = vbl_length[i] * num_samples;
/* triangle wave channel's linear length table */
for (i = 0; i < 128; i++)
trilength_lut[i] = (i * num_samples) / 4;
#ifndef REALTIME_NOISE
/* generate noise samples */
shift_register15(noise_long_lut, APU_NOISE_32K);
shift_register15(noise_short_lut, APU_NOISE_93);
#endif /* !REALTIME_NOISE */
}
static void apu_setactive(apu_t *active)
{
ASSERT(active);
apu = active;
}
/* Initializes emulated sound hardware, creates waveforms/voices */
apu_t *apu_create(int sample_rate, int refresh_rate, int sample_bits, boolean stereo)
{
apu_t *temp_apu;
/* int channel; */
temp_apu = malloc(sizeof(apu_t));
if (NULL == temp_apu)
return NULL;
/* $$$ ben : safety net, in case we forgot to init something */
memset(temp_apu,0,sizeof(apu_t));
SET_APU_ERROR(temp_apu,"no error");
temp_apu->sample_rate = sample_rate;
temp_apu->refresh_rate = refresh_rate;
temp_apu->sample_bits = sample_bits;
temp_apu->num_samples = sample_rate / refresh_rate;
/* turn into fixed point! */
temp_apu->cycle_rate = (int32) (APU_BASEFREQ * 65536.0 / (float) sample_rate);
/* build various lookup tables for apu */
apu_build_luts(temp_apu->num_samples);
/* set the update routine */
temp_apu->process = apu_process;
temp_apu->ext = NULL;
apu_setactive(temp_apu);
apu_reset();
temp_apu->mix_enable = 0x3F;
/* for (channel = 0; channel < 6; channel++) */
/* apu_setchan(channel, TRUE); */
apu_setfilter(APU_FILTER_LOWPASS);
return temp_apu;
}
apu_t *apu_getcontext(void)
{
return apu;
}
void apu_destroy(apu_t *src_apu)
{
if (src_apu)
{
if (src_apu->ext)
src_apu->ext->shutdown();
free(src_apu);
}
}
int apu_setext(apu_t *src_apu, apuext_t *ext)
{
ASSERT(src_apu);
/* $$$ ben : seem cleaner like this */
if (src_apu->ext) {
src_apu->ext->shutdown();
}
src_apu->ext = ext;
/* initialize it */
if (src_apu->ext)
src_apu->ext->init();
/* $$$ ben : May be one day extension int () will return error code */
return 0;
}
/* this exists for external mixing routines */
int32 apu_getcyclerate(void)
{
ASSERT(apu);
return apu->cycle_rate;
}
/*
** $Log: nes_apu.c,v $
** Revision 1.4 2005/05/07 09:11:39 valtri
** *BUGFIX*
** gcc4 patches from Dams Nad�� (livna.org) and Keenan Pepper.
**
** Revision 1.3 2004/12/12 06:55:59 athp
** Code cleanups and elimination of some compiler warnings; patch courtesy of AL13N
**
** Revision 1.2 2003/08/25 21:51:43 f1rmb
** Reduce GCC verbosity (various prototype declaration fixes). ffmpeg, wine and fft*post are untouched (fft: for now).
**
** Revision 1.1 2003/01/08 07:04:35 tmmm
** initial import of Nosefart sources
**
** Revision 1.19 2000/07/04 04:53:26 matt
** minor changes, sound amplification
**
** Revision 1.18 2000/07/03 02:18:53 matt
** much better external module exporting
**
** Revision 1.17 2000/06/26 11:01:55 matt
** made triangle a tad quieter
**
** Revision 1.16 2000/06/26 05:10:33 matt
** fixed cycle rate generation accuracy
**
** Revision 1.15 2000/06/26 05:00:37 matt
** cleanups
**
** Revision 1.14 2000/06/23 11:06:24 matt
** more faithful mixing of channels
**
** Revision 1.13 2000/06/23 03:29:27 matt
** cleaned up external sound inteface
**
** Revision 1.12 2000/06/20 00:08:39 matt
** bugfix to rectangle wave
**
** Revision 1.11 2000/06/13 13:48:58 matt
** fixed triangle write latency for fixed point apu cycle rate
**
** Revision 1.10 2000/06/12 01:14:36 matt
** minor change to clipping extents
**
** Revision 1.9 2000/06/09 20:00:56 matt
** fixed noise hiccup in NSF player mode
**
** Revision 1.8 2000/06/09 16:49:02 matt
** removed all floating point from sound generation
**
** Revision 1.7 2000/06/09 15:12:28 matt
** initial revision
**
*/