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// Squawk Soft-Synthesizer Library for Arduino
//
// Davey Taylor 2013
// d.taylor@arduino.cc
#ifndef _SQUAWK_H_
#define _SQUAWK_H_
#include <stddef.h>
#include <inttypes.h>
#include "Arduino.h"
#define Melody const uint8_t PROGMEM
class SquawkStream {
public:
virtual ~SquawkStream() = 0;
virtual uint8_t read() = 0;
virtual void seek(size_t offset) = 0;
};
inline SquawkStream::~SquawkStream() { }
class SquawkSynth {
protected:
// Load and play specified melody
void play(SquawkStream *melody);
public:
SquawkSynth() {};
// Initialize Squawk to generate samples at sample_rate Hz
void begin(uint16_t sample_rate);
// Load and play specified melody
// melody needs to point to PROGMEM data
void play(const uint8_t *melody);
// Resume currently loaded melody (or enable direct osc manipulation by sketch)
void play();
// Pause playback
void pause();
// Stop playback (unloads song)
void stop();
// Tune Squawk to a different frequency - default is 1.0
void tune(float tuning);
// Change the tempo - default is 50
void tempo(uint16_t tempo);
};
extern SquawkSynth Squawk;
// oscillator structure
typedef struct {
uint8_t vol;
uint16_t freq;
uint16_t phase;
} osc_t;
typedef osc_t Oscillator;
// oscillator memory
extern osc_t osc[4];
extern uint8_t pcm;
// channel 0 is pulse wave @ 25% duty
// channel 1 is square wave
// channel 2 is triangle wave
// channel 3 is noise
// For channel 3, freq is used as part of its LFSR and should not be changed.
// LFSR: Linear feedback shift register, a method of producing a
// pseudo-random bit sequence, used to generate nasty noise.
#ifdef __AVR_ATmega32U4__
// Supported configurations for ATmega32U4
#define SQUAWK_PWM_PIN5 OCR3AL
#define SQUAWK_PWM_PIN11 OCR0A
#define SQUAWK_PWM_PIN3 OCR0B
/*
// NOT SUPPORTED YET
#define SQUAWK_PWM_PIN6 OCR4D
#define SQUAWK_PWM_PIN9 OCR4B
#define SQUAWK_PWM_PIN10 OCR4B
*/
#endif
#ifdef __AVR_ATmega168__
// Supported configurations for ATmega168
#define SQUAWK_PWM_PIN6 OCR0A
#define SQUAWK_PWM_PIN5 OCR0B
#define SQUAWK_PWM_PIN11 OCR2A
#define SQUAWK_PWM_PIN3 OCR2B
#endif
#ifdef __AVR_ATmega328P__
// Supported configurations for ATmega328P
#define SQUAWK_PWM_PIN6 OCR0A
#define SQUAWK_PWM_PIN5 OCR0B
#define SQUAWK_PWM_PIN11 OCR2A
#define SQUAWK_PWM_PIN3 OCR2B
#endif
/*
// NOT SUPPORTED YET
#define SQUAWK_SPI SPDR
#define SQUAWK_RLD_PORTB PORTB
#define SQUAWK_RLD_PORTC PORTC
*/
extern void squawk_playroutine() asm("squawk_playroutine");
// SAMPLE GRINDER
// generates samples and updates oscillators
// uses 132 cycles (not counting playroutine)
// ~1/3 CPU @ 44kHz on 16MHz
#define SQUAWK_CONSTRUCT_ISR(TARGET_REGISTER) \
uint16_t cia, cia_count; \
intptr_t squawk_register = (intptr_t)&TARGET_REGISTER; \
ISR(TIMER1_COMPA_vect, ISR_NAKED) { \
asm volatile( \
"push r2 " "\n\t" \
"in r2, __SREG__ " "\n\t" \
"push r18 " "\n\t" \
"push r27 " "\n\t" \
"push r26 " "\n\t" \
"push r0 " "\n\t" \
"push r1 " "\n\t" \
\
"lds r18, osc+2*%[mul]+%[fre] " "\n\t" \
"lds r0, osc+2*%[mul]+%[pha] " "\n\t" \
"add r0, r18 " "\n\t" \
"sts osc+2*%[mul]+%[pha], r0 " "\n\t" \
"lds r18, osc+2*%[mul]+%[fre]+1" "\n\t" \
"lds r1, osc+2*%[mul]+%[pha]+1" "\n\t" \
"adc r1, r18 " "\n\t" \
"sts osc+2*%[mul]+%[pha]+1, r1 " "\n\t" \
\
"mov r27, r1 " "\n\t" \
"sbrc r27, 7 " "\n\t" \
"com r27 " "\n\t" \
"lsl r27 " "\n\t" \
"lds r26, osc+2*%[mul]+%[vol] " "\n\t" \
"subi r27, 128 " "\n\t" \
"muls r27, r26 " "\n\t" \
"lsl r1 " "\n\t" \
"mov r26, r1 " "\n\t" \
\
"lds r18, osc+0*%[mul]+%[fre] " "\n\t" \
"lds r0, osc+0*%[mul]+%[pha] " "\n\t" \
"add r0, r18 " "\n\t" \
"sts osc+0*%[mul]+%[pha], r0 " "\n\t" \
"lds r18, osc+0*%[mul]+%[fre]+1" "\n\t" \
"lds r1, osc+0*%[mul]+%[pha]+1" "\n\t" \
"adc r1, r18 " "\n\t" \
"sts osc+0*%[mul]+%[pha]+1, r1 " "\n\t" \
\
"mov r18, r1 " "\n\t" \
"lsl r18 " "\n\t" \
"and r18, r1 " "\n\t" \
"lds r27, osc+0*%[mul]+%[vol] " "\n\t" \
"sbrc r18, 7 " "\n\t" \
"neg r27 " "\n\t" \
"add r26, r27 " "\n\t" \
\
"lds r18, osc+1*%[mul]+%[fre] " "\n\t" \
"lds r0, osc+1*%[mul]+%[pha] " "\n\t" \
"add r0, r18 " "\n\t" \
"sts osc+1*%[mul]+%[pha], r0 " "\n\t" \
"lds r18, osc+1*%[mul]+%[fre]+1" "\n\t" \
"lds r1, osc+1*%[mul]+%[pha]+1" "\n\t" \
"adc r1, r18 " "\n\t" \
"sts osc+1*%[mul]+%[pha]+1, r1 " "\n\t" \
\
"lds r27, osc+1*%[mul]+%[vol] " "\n\t" \
"sbrc r1, 7 " "\n\t" \
"neg r27 " "\n\t" \
"add r26, r27 " "\n\t" \
\
"ldi r27, 1 " "\n\t" \
"lds r0, osc+3*%[mul]+%[fre] " "\n\t" \
"lds r1, osc+3*%[mul]+%[fre]+1" "\n\t" \
"add r0, r0 " "\n\t" \
"adc r1, r1 " "\n\t" \
"sbrc r1, 7 " "\n\t" \
"eor r0, r27 " "\n\t" \
"sbrc r1, 6 " "\n\t" \
"eor r0, r27 " "\n\t" \
"sts osc+3*%[mul]+%[fre], r0 " "\n\t" \
"sts osc+3*%[mul]+%[fre]+1, r1 " "\n\t" \
\
"lds r27, osc+3*%[mul]+%[vol] " "\n\t" \
"sbrc r1, 7 " "\n\t" \
"neg r27 " "\n\t" \
"add r26, r27 " "\n\t" \
\
"lds r27, pcm " "\n\t" \
"add r26, r27 " "\n\t" \
"sts %[reg], r26 " "\n\t" \
\
"lds r27, cia_count+1 " "\n\t" \
"lds r26, cia_count " "\n\t" \
"sbiw r26, 1 " "\n\t" \
"breq call_playroutine " "\n\t" \
"sts cia_count+1, r27 " "\n\t" \
"sts cia_count, r26 " "\n\t" \
"pop r1 " "\n\t" \
"pop r0 " "\n\t" \
"pop r26 " "\n\t" \
"pop r27 " "\n\t" \
"pop r18 " "\n\t" \
"out __SREG__, r2 " "\n\t" \
"pop r2 " "\n\t" \
"reti " "\n\t" \
"call_playroutine: " "\n\t" \
\
"lds r27, cia+1 " "\n\t" \
"lds r26, cia " "\n\t" \
"sts cia_count+1, r27 " "\n\t" \
"sts cia_count, r26 " "\n\t" \
\
"sei " "\n\t" \
"push r19 " "\n\t" \
"push r20 " "\n\t" \
"push r21 " "\n\t" \
"push r22 " "\n\t" \
"push r23 " "\n\t" \
"push r24 " "\n\t" \
"push r25 " "\n\t" \
"push r30 " "\n\t" \
"push r31 " "\n\t" \
\
"clr r1 " "\n\t" \
"call squawk_playroutine " "\n\t" \
\
"pop r31 " "\n\t" \
"pop r30 " "\n\t" \
"pop r25 " "\n\t" \
"pop r24 " "\n\t" \
"pop r23 " "\n\t" \
"pop r22 " "\n\t" \
"pop r21 " "\n\t" \
"pop r20 " "\n\t" \
"pop r19 " "\n\t" \
\
"pop r1 " "\n\t" \
"pop r0 " "\n\t" \
"pop r26 " "\n\t" \
"pop r27 " "\n\t" \
"pop r18 " "\n\t" \
"out __SREG__, r2 " "\n\t" \
"pop r2 " "\n\t" \
"reti " "\n\t" \
: \
: [reg] "M" _SFR_MEM_ADDR(TARGET_REGISTER), \
[mul] "M" (sizeof(Oscillator)), \
[pha] "M" (offsetof(Oscillator, phase)), \
[fre] "M" (offsetof(Oscillator, freq)), \
[vol] "M" (offsetof(Oscillator, vol)) \
); \
}
#endif
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