kopia lustrzana https://github.com/Jean-MarcHarvengt/MCUME
448 wiersze
9.6 KiB
C
Executable File
448 wiersze
9.6 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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** mmc5_snd.c
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**
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** Nintendo MMC5 sound emulation
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** $Id: mmc5_snd.c,v 1.2 2001/04/27 14:37:11 neil Exp $
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*/
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#include <string.h>
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#include "noftypes.h"
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#include "mmc5_snd.h"
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#include "nes_apu.h"
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/* TODO: encapsulate apu/mmc5 rectangle */
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#define APU_OVERSAMPLE
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#define APU_VOLUME_DECAY(x) ((x) -= ((x) >> 7))
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/* look up table madness */
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static int32 decay_lut[16];
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static int vbl_lut[32];
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/* various sound constants for sound emulation */
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/* vblank length table used for rectangles, triangle, noise */
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static const uint8 vbl_length[32] =
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{
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5, 127, 10, 1, 19, 2, 40, 3, 80, 4, 30, 5, 7, 6, 13, 7,
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6, 8, 12, 9, 24, 10, 48, 11, 96, 12, 36, 13, 8, 14, 16, 15
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};
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/* ratios of pos/neg pulse for rectangle waves
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** 2/16 = 12.5%, 4/16 = 25%, 8/16 = 50%, 12/16 = 75%
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** (4-bit adder in rectangles, hence the 16)
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*/
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static const int duty_lut[4] =
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{
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2, 4, 8, 12
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};
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#define MMC5_WRA0 0x5000
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#define MMC5_WRA1 0x5001
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#define MMC5_WRA2 0x5002
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#define MMC5_WRA3 0x5003
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#define MMC5_WRB0 0x5004
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#define MMC5_WRB1 0x5005
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#define MMC5_WRB2 0x5006
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#define MMC5_WRB3 0x5007
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#define MMC5_SMASK 0x5015
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typedef struct mmc5rectangle_s
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{
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uint8 regs[4];
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bool enabled;
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float accum;
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int32 freq;
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int32 output_vol;
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bool fixed_envelope;
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bool holdnote;
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uint8 volume;
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int32 env_phase;
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int32 env_delay;
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uint8 env_vol;
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int vbl_length;
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uint8 adder;
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int duty_flip;
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} mmc5rectangle_t;
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typedef struct mmc5dac_s
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{
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int32 output;
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bool enabled;
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} mmc5dac_t;
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static struct
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{
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float incsize;
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uint8 mul[2];
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mmc5rectangle_t rect[2];
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mmc5dac_t dac;
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} mmc5;
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#define MMC5_RECTANGLE_OUTPUT chan->output_vol
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static int32 mmc5_rectangle(mmc5rectangle_t *chan)
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{
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int32 output;
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#ifdef APU_OVERSAMPLE
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int num_times;
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int32 total;
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#endif /* APU_OVERSAMPLE */
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/* reg0: 0-3=volume, 4=envelope, 5=hold, 6-7=duty cycle
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** reg1: 0-2=sweep shifts, 3=sweep inc/dec, 4-6=sweep length, 7=sweep on
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** reg2: 8 bits of freq
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** reg3: 0-2=high freq, 7-4=vbl length counter
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*/
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APU_VOLUME_DECAY(chan->output_vol);
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if (false == chan->enabled || 0 == chan->vbl_length)
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return MMC5_RECTANGLE_OUTPUT;
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/* vbl length counter */
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if (false == chan->holdnote)
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chan->vbl_length--;
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/* envelope decay at a rate of (env_delay + 1) / 240 secs */
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chan->env_phase -= 4; /* 240/60 */
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while (chan->env_phase < 0)
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{
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chan->env_phase += chan->env_delay;
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if (chan->holdnote)
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chan->env_vol = (chan->env_vol + 1) & 0x0F;
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else if (chan->env_vol < 0x0F)
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chan->env_vol++;
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}
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if (chan->freq < 4)
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return MMC5_RECTANGLE_OUTPUT;
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chan->accum -= mmc5.incsize; /* # of cycles per sample */
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if (chan->accum >= 0)
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return MMC5_RECTANGLE_OUTPUT;
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#ifdef APU_OVERSAMPLE
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num_times = total = 0;
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if (chan->fixed_envelope)
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output = chan->volume << 8; /* fixed volume */
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else
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output = (chan->env_vol ^ 0x0F) << 8;
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#endif
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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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#ifdef APU_OVERSAMPLE
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if (chan->adder < chan->duty_flip)
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total += output;
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else
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total -= output;
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num_times++;
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#endif
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}
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#ifdef APU_OVERSAMPLE
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chan->output_vol = total / num_times;
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#else
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if (chan->fixed_envelope)
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output = chan->volume << 8; /* fixed volume */
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else
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output = (chan->env_vol ^ 0x0F) << 8;
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if (0 == chan->adder)
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chan->output_vol = output;
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else if (chan->adder == chan->duty_flip)
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chan->output_vol = -output;
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#endif
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return MMC5_RECTANGLE_OUTPUT;
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}
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static uint8 mmc5_read(uint32 address)
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{
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uint32 retval;
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retval = (uint32) (mmc5.mul[0] * mmc5.mul[1]);
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switch (address)
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{
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case 0x5205:
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return (uint8) retval;
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case 0x5206:
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return (uint8) (retval >> 8);
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default:
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return 0xFF;
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}
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}
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/* mix vrcvi sound channels together */
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static int32 mmc5_process(void)
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{
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int32 accum;
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accum = mmc5_rectangle(&mmc5.rect[0]);
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accum += mmc5_rectangle(&mmc5.rect[1]);
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if (mmc5.dac.enabled)
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accum += mmc5.dac.output;
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return accum;
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}
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/* write to registers */
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static void mmc5_write(uint32 address, uint8 value)
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{
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int chan;
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switch (address)
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{
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/* rectangles */
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case MMC5_WRA0:
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case MMC5_WRB0:
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chan = (address & 4) ? 1 : 0;
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mmc5.rect[chan].regs[0] = value;
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mmc5.rect[chan].volume = value & 0x0F;
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mmc5.rect[chan].env_delay = decay_lut[value & 0x0F];
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mmc5.rect[chan].holdnote = (value & 0x20) ? true : false;
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mmc5.rect[chan].fixed_envelope = (value & 0x10) ? true : false;
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mmc5.rect[chan].duty_flip = duty_lut[value >> 6];
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break;
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case MMC5_WRA1:
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case MMC5_WRB1:
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break;
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case MMC5_WRA2:
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case MMC5_WRB2:
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chan = (address & 4) ? 1 : 0;
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mmc5.rect[chan].regs[2] = value;
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if (mmc5.rect[chan].enabled)
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mmc5.rect[chan].freq = (((mmc5.rect[chan].regs[3] & 7) << 8) + value) + 1;
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break;
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case MMC5_WRA3:
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case MMC5_WRB3:
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chan = (address & 4) ? 1 : 0;
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mmc5.rect[chan].regs[3] = value;
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if (mmc5.rect[chan].enabled)
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{
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mmc5.rect[chan].vbl_length = vbl_lut[value >> 3];
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mmc5.rect[chan].env_vol = 0;
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mmc5.rect[chan].freq = (((value & 7) << 8) + mmc5.rect[chan].regs[2]) + 1;
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mmc5.rect[chan].adder = 0;
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}
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break;
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case MMC5_SMASK:
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if (value & 0x01)
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{
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mmc5.rect[0].enabled = true;
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}
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else
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{
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mmc5.rect[0].enabled = false;
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mmc5.rect[0].vbl_length = 0;
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}
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if (value & 0x02)
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{
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mmc5.rect[1].enabled = true;
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}
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else
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{
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mmc5.rect[1].enabled = false;
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mmc5.rect[1].vbl_length = 0;
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}
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break;
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case 0x5010:
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if (value & 0x01)
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mmc5.dac.enabled = true;
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else
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mmc5.dac.enabled = false;
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break;
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case 0x5011:
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mmc5.dac.output = (value ^ 0x80) << 8;
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break;
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case 0x5205:
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mmc5.mul[0] = value;
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break;
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case 0x5206:
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mmc5.mul[1] = value;
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break;
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case 0x5114:
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case 0x5115:
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/* ???? */
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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 mmc5_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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mmc5.incsize = apu.cycle_rate;
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for (i = 0x5000; i < 0x5008; i++)
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mmc5_write(i, 0);
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mmc5_write(0x5010, 0);
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mmc5_write(0x5011, 0);
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}
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static int mmc5_init(void)
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{
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int i, num_samples;
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apu_t apu;
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apu_getcontext(&apu);
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num_samples = apu.num_samples;
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/* lut used for enveloping and frequency sweeps */
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for (i = 0; i < 16; i++)
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decay_lut[i] = num_samples * (i + 1);
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/* used for note length, based on vblanks and size of audio buffer */
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for (i = 0; i < 32; i++)
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vbl_lut[i] = vbl_length[i] * num_samples;
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return 0;
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}
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static const apu_memread mmc5_memread[] =
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{
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{ 0x5205, 0x5206, mmc5_read },
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{ -1, -1, NULL }
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};
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static const apu_memwrite mmc5_memwrite[] =
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{
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{ 0x5000, 0x5015, mmc5_write },
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{ 0x5114, 0x5115, mmc5_write },
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{ 0x5205, 0x5206, mmc5_write },
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{ -1, -1, NULL }
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};
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const apuext_t mmc5_ext =
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{
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mmc5_init,
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NULL, /* no shutdown */
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mmc5_reset,
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mmc5_process,
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mmc5_memread,
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mmc5_memwrite
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};
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/*
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** $Log: mmc5_snd.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 2000/11/13 00:57:08 matt
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** doesn't look as nasty now
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**
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** Revision 1.1 2000/10/24 12:19:59 matt
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** changed directory structure
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**
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** Revision 1.16 2000/10/17 11:56:42 matt
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** selectable apu base frequency
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**
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** Revision 1.15 2000/10/10 14:04:29 matt
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** make way for bjarne
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**
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** Revision 1.14 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 1.13 2000/10/08 17:50:18 matt
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** appears $5114/$5115 do something
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**
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** Revision 1.12 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 1.11 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 1.10 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 1.9 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 1.8 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 1.7 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 1.6 2000/07/04 04:51:41 matt
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** cleanups
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**
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** Revision 1.5 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 1.4 2000/06/28 22:03:51 matt
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** fixed stupid oversight
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**
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** Revision 1.3 2000/06/20 20:46:58 matt
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** minor cleanups
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**
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** Revision 1.2 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 1.1 2000/06/20 00:06:47 matt
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** initial revision
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**
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*/
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