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8bitworkshop/presets/nes/apu.h
2019-04-22 11:39:09 -04:00

91 lines
2.3 KiB
C

#ifndef _APU_H
#define _APU_H
#include <nes.h>
// Functions/macros for direct control
// of APU sound generation
// enable
#define ENABLE_PULSE0 0x1
#define ENABLE_PULSE1 0x2
#define ENABLE_TRIANGLE 0x4
#define ENABLE_NOISE 0x8
#define ENABLE_DMC 0x10
#define APU_ENABLE(enable)\
APU.status = (enable);
// pulse channels
#define DUTY_75 0xc0
#define DUTY_50 0x80
#define DUTY_25 0x40
#define DUTY_12 0x00
#define PULSE_ENVLOOP 0x20
#define PULSE_CONSTVOL 0x10
#define PULSE_VOLENVMASK 0xf
#define PULSE_CH0 0
#define PULSE_CH1 1
#define APU_PULSE_DECAY(channel,period,duty,decay,len)\
APU.pulse[channel].period_low = (period)&0xff;\
APU.pulse[channel].len_period_high = (((period)>>8)&7) | ((len)<<3);\
APU.pulse[channel].control = (duty) | (decay);
#define APU_PULSE_SUSTAIN(channel,period,duty,vol)\
APU.pulse[channel].period_low = (period)&0xff;\
APU.pulse[channel].len_period_high = (((period)>>8)&7);\
APU.pulse[channel].control = (duty) | (vol) | (PULSE_CONSTVOL|PULSE_ENVLOOP);
#define APU_PULSE_SET_DECAY(channel,duty,decay)\
APU.pulse[channel].control = (duty) | (decay);
#define APU_PULSE_SET_VOLUME(channel,duty,vol)\
APU.pulse[channel].control = (duty) | (vol) | (PULSE_CONSTVOL|PULSE_ENVLOOP);
#define APU_PULSE_SWEEP(channel,period,shift,up)\
APU.pulse[channel].ramp = 0x80 | (period<<4) | (up?8:0) | shift;
#define APU_PULSE_SWEEP_DISABLE(channel)\
APU.pulse[channel].ramp = 0;
// triangle channel
#define TRIANGLE_LC_HALT 0x80
#define TRIANGLE_LC_MASK 0x7f
#define APU_TRIANGLE_LENGTH(period,len)\
APU.triangle.counter = 0x7f;\
APU.triangle.period_low = (period)&0xff;\
APU.triangle.len_period_high = (((period)>>8)&7) | ((len)<<3);
#define APU_TRIANGLE_SUSTAIN(period)\
APU.triangle.counter = 0xff;\
APU.triangle.period_low = (period)&0xff;\
APU.triangle.len_period_high = (((period)>>8)&7);
// noise channel
#define NOISE_ENVLOOP 0x20
#define NOISE_CONSTVOL 0x10
#define NOISE_VOLENVMASK 0xf
#define NOISE_PERIOD_BUZZ 0x80
#define APU_NOISE_SUSTAIN(_period,vol)\
APU.noise.control = (vol) | (NOISE_ENVLOOP|NOISE_CONSTVOL);\
APU.noise.period = (_period);
#define APU_NOISE_DECAY(_period,_decay,_len)\
APU.noise.control = (_decay);\
APU.noise.period = (_period);\
APU.noise.len = (_len);
// initialize APU with default state
void apu_init(void);
#endif