commit d3e57436f9d5065b330b61be60ff40d15c02aee9 Author: Stuart Longland Date: Sat Apr 1 19:38:19 2017 +1000 Check-in of polyphonic synthesizer diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..3912109 --- /dev/null +++ b/LICENSE @@ -0,0 +1,340 @@ + GNU GENERAL PUBLIC LICENSE + Version 2, June 1991 + + Copyright (C) 1989, 1991 Free Software Foundation, Inc. + 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public +License is intended to guarantee your freedom to share and change free +software--to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. 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Of course, the commands you use may +be called something other than `show w' and `show c'; they could even be +mouse-clicks or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your +school, if any, to sign a "copyright disclaimer" for the program, if +necessary. Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the program + `Gnomovision' (which makes passes at compilers) written by James Hacker. + + , 1 April 1989 + Ty Coon, President of Vice + +This General Public License does not permit incorporating your program into +proprietary programs. If your program is a subroutine library, you may +consider it more useful to permit linking proprietary applications with the +library. If this is what you want to do, use the GNU Library General +Public License instead of this License. diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..da286ce --- /dev/null +++ b/Makefile @@ -0,0 +1,25 @@ +# Compiler definitions +CROSS_COMPILE ?= avr- +CC = $(CROSS_COMPILE)gcc +OBJCOPY = $(CROSS_COMPILE)objcopy +MCU ?= attiny85 +CFLAGS ?= -mmcu=$(MCU) -Os +CPPFLAGS ?= -DF_CPU=8000000 -D_POLY_CFG=\"poly_cfg.h\" +LDFLAGS ?= -mmcu=$(MCU) -Os -Wl,--as-needed + +all: synth.hex + +%.hex: %.elf + $(OBJCOPY) -j .text -j .data -O ihex $< $@ + +synth.elf: main.o poly.o + $(CC) -o $@ $(LDFLAGS) $^ + +poly.o: poly.h +main.o: poly.h + +%.E: %.c + $(CC) $(CFLAGS) $(CPPFLAGS) -o $@ -E $^ + +clean: + -rm -f *.o *.hex *.elf diff --git a/Makefile.pc b/Makefile.pc new file mode 100644 index 0000000..097d0d2 --- /dev/null +++ b/Makefile.pc @@ -0,0 +1,11 @@ +# vim: set filetype=make: +# Makefile for building synthesizer test application on PC +# Requires libao + +LIBS=-lao + +pctest: poly.pc.o pctest.pc.o + $(CC) $(LIBS) $(LDFLAGS) -o $@ $^ + +%.pc.o: %.c + $(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@ diff --git a/README.md b/README.md new file mode 100644 index 0000000..ce8be63 --- /dev/null +++ b/README.md @@ -0,0 +1,78 @@ +Polyphonic Synthesizer +====================== + +This project is intended to be a polyphonic synthesizer for use in +embedded microcontrollers. It features multi-voice synthesis for up to 16 +channels, with channels outputting either a fixed DC offset, sinusoidal +output or whitenoise. + +The phase or amplitude of one channel may be modulated by the output of +another channel, allowing for various effects. + +Configuration +============= + +There are two ways to configure this library: + +Using C preprocessor constants +------------------------------ + +The following C preprocessor definitions should be defined in your project +`Makefile`. + +* `_POLY_NUM_CHANNELS`: The number of polyphonic channels (voices) that + you wish to instantiate. Each channel occupies 16 bytes. +* `_POLY_FREQ`: The output sample rate for the polyphonic synthesizer in + Hz. + +Using linker symbols +-------------------- + +Alternatively, these things can be decided at run-time. Your application +should export the following symbols: + +* `const uint8_t poly_num_channels`: The number of polyphonic channels + currently configured. +* `const uint16_t poly_freq`: The output sample rate for the polyphonic + synthesizer in Hz. +* `const uint16_t poly_freq_max`: The maximum output frequency for the + polyphonic synthesizer. This should be set to `poly_freq/2` (the + nyquist frequency). +* `struct poly_voice_t poly_voice[]`: The array of voice channels. + +You may declare functions using these symbols, or you may use linker +aliasing to expose variables/structures with alternate names. + +Usage +===== + +Global structures +----------------- + +A global counter, `poly_remain`, counts down the number of audio samples +remaining before the next set of events are due to be loaded. When this +variable reaches 0, you should start calling `poly_load` with new data or +call `poly_reset` to stop playback. + +Functions +--------- + +`poly_reset` clears the state of the polyphonic synthesizer, cancelling +any in-progress playback. This should be done as part of your program +initialisation. + +`poly_load` is used to load in the next event. Events are covered below. + +`poly_next` returns the next audio sample, or `0` if there is no more +audio left to be played. + +Events +====== + +The structure of the event system is loosely based on ideas from the MIDI +standard. Essentially, an "event" is a parameter change for a given +channel. + +Each event is represented by a 4-byte data structure, a `struct +poly_evt_t` which has two fields, `flags` and `value`. `poly.h` covers +each of the events. See the comments up the top of that file for detail. diff --git a/fifo.h b/fifo.h new file mode 100644 index 0000000..be92609 --- /dev/null +++ b/fifo.h @@ -0,0 +1,208 @@ +#ifndef _UTIL_FIFO_H +#define _UTIL_FIFO_H + +/*! + * Simple ring FIFO buffer. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program (see COPYING); if not, write to the Free + * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA + * 02110-1301 USA + */ + +#include + +/*! + * Empty event. Indicates that the buffer is now empty and the next read + * will generate an underrun. + */ +#define FIFO_EVT_EMPTY (1 << 0) + +/*! + * Underrun event flag, indicates that the consumer tried to read when the + * buffer was empty. + */ +#define FIFO_EVT_UNDERRUN (1 << 1) + +/*! + * Data arrived event. Indicates that new data has arrived. + */ +#define FIFO_EVT_NEW (1 << 2) + +/*! + * Buffer full event. Indicates that the buffer is now full and the next + * write will generate an overrun. + */ +#define FIFO_EVT_FULL (1 << 3) + +/*! + * Overrun event flag, indicates that the producer tried to write when the + * buffer was full. + */ +#define FIFO_EVT_OVERRUN (1 << 4) + +/*! + * FIFO Buffer interface. + */ +struct fifo_t { + /*! FIFO producer event handler */ + void (*producer_evth)(struct fifo_t* const fifo, uint8_t events); + + /*! FIFO consumer event handler */ + void (*consumer_evth)(struct fifo_t* const fifo, uint8_t events); + + volatile uint8_t* buffer; /*!< Buffer storage location */ + uint8_t total_sz; /*!< Buffer total size */ + volatile uint8_t stored_sz; /*!< Buffer usage size */ + volatile uint8_t read_ptr; /*!< Read pointer location */ + volatile uint8_t write_ptr; /*!< Write pointer location */ + + uint8_t producer_evtm; /*!< Producer event mask */ + uint8_t consumer_evtm; /*!< Consumer event mask */ + + void* producer_data; /*!< Producer data pointer */ + void* consumer_data; /*!< Consumer data pointer */ +}; + +/*! + * Execute one or more FIFO events. + */ +static void fifo_exec(struct fifo_t* const fifo, uint8_t events) { + if (fifo->producer_evth && (fifo->producer_evtm & events)) + fifo->producer_evth(fifo, events); + if (fifo->consumer_evth && (fifo->consumer_evtm & events)) + fifo->consumer_evth(fifo, events); +} + +/*! + * Empty the buffer. + */ +static void fifo_empty(struct fifo_t* const fifo) { + fifo->stored_sz = 0; + fifo->read_ptr = 0; + fifo->write_ptr = 0; +} + +/*! + * Initialise the buffer + */ +static void fifo_init(struct fifo_t* const fifo, + volatile uint8_t* buffer, uint8_t sz) { + fifo_empty(fifo); + fifo->buffer = buffer; + fifo->total_sz = sz; +} + +/*! + * Read a byte from the buffer. Returns the byte read, or -1 if no + * data is available. + */ +static int16_t fifo_read_one(struct fifo_t* const fifo) { + if (!fifo->stored_sz) { + fifo_exec(fifo, FIFO_EVT_UNDERRUN); + return -1; + } + + uint8_t byte = fifo->buffer[fifo->read_ptr]; + fifo->stored_sz--; + fifo->read_ptr = (fifo->read_ptr + 1) % fifo->total_sz; + if (!fifo->stored_sz) + fifo_exec(fifo, FIFO_EVT_EMPTY); + return byte; +} + +/*! + * Read a byte from the buffer without consuming it. + * Returns the byte read, or -1 if no data is available. + */ +static int16_t fifo_peek_one(struct fifo_t* const fifo) { + if (!fifo->stored_sz) + return -1; + + return fifo->buffer[fifo->read_ptr]; +} + +/*! + * Write a byte to the buffer. Returns 1 on success, + * 0 if no space available. + */ +static uint8_t fifo_write_one(struct fifo_t* const fifo, uint8_t byte) { + if (fifo->stored_sz >= fifo->total_sz) { + fifo_exec(fifo, FIFO_EVT_OVERRUN); + return 0; + } + + fifo->buffer[fifo->write_ptr] = byte; + fifo->stored_sz++; + fifo->write_ptr = (fifo->write_ptr + 1) % fifo->total_sz; + + if (fifo->stored_sz) + fifo_exec(fifo, FIFO_EVT_NEW); + + if (fifo->stored_sz == fifo->total_sz) + fifo_exec(fifo, FIFO_EVT_FULL); + return 1; +} + +/*! + * Read bytes from the buffer + */ +static uint8_t fifo_read(struct fifo_t* const fifo, + uint8_t* buffer, uint8_t sz) { + uint8_t count = 0; + int16_t byte = fifo_read_one(fifo); + while(sz && (byte >= 0)) { + *buffer = byte; + sz--; + buffer++; + count++; + byte = fifo_read_one(fifo); + } + return count; +} + +/*! + * Read bytes from the buffer without consuming them. + */ +static uint8_t fifo_peek(struct fifo_t* const fifo, + uint8_t* buffer, uint8_t sz) { + uint8_t count = 0; + uint8_t ptr = fifo->read_ptr; + if (sz > fifo->stored_sz) + sz = fifo->stored_sz; + + while(sz) { + *buffer = fifo->buffer[ptr]; + sz--; + buffer++; + count++; + ptr = (ptr + 1) % fifo->total_sz; + } + return count; +} + +/*! + * Write bytes to the buffer + */ +static uint8_t fifo_write(struct fifo_t* const fifo, + const uint8_t* buffer, uint8_t sz) { + uint8_t count = 0; + while(sz && fifo_write_one(fifo, *buffer)) { + buffer++; + sz--; + count++; + } + return count; +} + +#endif diff --git a/main.c b/main.c new file mode 100644 index 0000000..907ec0b --- /dev/null +++ b/main.c @@ -0,0 +1,106 @@ +/*! + * Polyphonic synthesizer for microcontrollers: Atmel ATTiny85 port. + * (C) 2016 Stuart Longland + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, + * MA 02110-1301 USA + */ + +#include "poly.h" +#include "fifo.h" +#include +#include +#include + +#define SAMPLE_LEN 16 +static volatile uint8_t sample_buffer[SAMPLE_LEN]; +static struct fifo_t sample_fifo; + +int main(void) { + struct poly_evt_t poly_evt; + + /* Turn on all except ADC */ + PRR = (1 << PRADC); + + /* Start up PLL */ + PLLCSR = (1 << PLLE); + while (!(PLLCSR & (1<> 9)); + + } + PORTB ^= (1 << 3); + } + } + return 0; +} + +ISR(TIM0_COMPA_vect) { + uint8_t sample = fifo_read_one(&sample_fifo); + if (sample >= 0) + OCR1B = sample; + else + OCR1B = 128; +} diff --git a/pctest.c b/pctest.c new file mode 100644 index 0000000..7424164 --- /dev/null +++ b/pctest.c @@ -0,0 +1,165 @@ +#include "poly.h" +#include +#include +#include + +const uint16_t poly_freq = 32000; +const uint16_t poly_freq_max = 16000; +const uint8_t poly_num_channels = 8; +struct poly_voice_t poly_voice[8]; + +int main(int argc, char** argv) { + struct poly_evt_t event; + int voice = 0; + int16_t samples[8192]; + uint16_t samples_sz = 0; + ao_device* device; + ao_sample_format format; + ao_initialize(); + poly_reset(); + FILE* out = fopen("out.raw", "wb"); + + { + int driver = ao_default_driver_id(); + memset(&format, 0, sizeof(format)); + format.bits = 16; + format.channels = 1; + format.rate = poly_freq; + format.byte_format = AO_FMT_NATIVE; + device = ao_open_live(driver, &format, NULL); + if (!device) { + fprintf(stderr, "Failed to open audio device\n"); + return 1; + } + } + + argc--; + argv++; + while (argc > 0) { + int res = 0; + if (!strcmp(argv[0], "end")) + break; + if (!strcmp(argv[0], "voice")) { + voice = atoi(argv[1]); + argv++; + argc--; + } else if (!strcmp(argv[0], "mute")) { + int mute = atoi(argv[1]); + event.flags = POLY_EVT_TYPE_MUTE; + event.value = mute; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "en")) { + int en = atoi(argv[1]); + event.flags = POLY_EVT_TYPE_ENABLE; + event.value = en; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "freq")) { + int freq = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_IFREQ; + event.value = freq; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "dfreq")) { + int freq = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_DFREQ; + event.value = freq; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "ascale")) { + int amp = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_ASCALE; + event.value = amp; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "amp")) { + int amp = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_IAMP; + event.value = amp; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "damp")) { + int damp = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_DAMP; + event.value = damp; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "pmod")) { + int pmod = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_PMOD; + event.value = pmod; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "amod")) { + int amod = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_AMOD; + event.value = amod; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "dscale")) { + int dt = atoi(argv[1]); + event.flags = (voice << POLY_CH_BIT) + | POLY_EVT_TYPE_DSCALE; + event.value = dt; + res = poly_load(&event); + argv++; + argc--; + } else if (!strcmp(argv[0], "time")) { + int time = atoi(argv[1]); + argv++; + argc--; + event.flags = POLY_EVT_TYPE_TIME; + event.value = time; + res = poly_load(&event); + } + if (res < 0) { + fprintf(stderr, "Failed: %s\n", + strerror(-res)); + break; + } + argv++; + argc--; + + /* Play out any remaining samples */ + while (poly_remain) { + int16_t* sample_ptr = samples; + uint16_t samples_remain = 8192; + /* Fill the buffer as much as we can */ + while (poly_remain && samples_remain) { + int16_t s = poly_next(); + //printf("%d: %d\n", samples_sz, s); + *sample_ptr = s << 7; + sample_ptr++; + samples_sz++; + samples_remain--; + } + fwrite(samples, samples_sz, 2, out); + ao_play(device, (char*)samples, 2*samples_sz); + samples_sz = 0; + } + } + + poly_reset(); + fclose(out); + + ao_close(device); + ao_shutdown(); + return 0; +} diff --git a/poly.c b/poly.c new file mode 100644 index 0000000..b1b9dad --- /dev/null +++ b/poly.c @@ -0,0 +1,332 @@ +/*! + * Polyphonic synthesizer for microcontrollers. + * (C) 2016 Stuart Longland + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, + * MA 02110-1301 USA + */ + +#include "poly.h" +#include +#include +#include + +#ifdef __AVR_ARCH__ +#include +#endif + +#ifdef _DEBUG +#include +#define _DPRINTF(s, a...) printf(__FILE__ ": %d " s, __LINE__, a) +#else +#define _DPRINTF(s, a...) +#endif + +#ifdef _POLY_NUM_CHANNELS +static struct poly_voice_t poly_voice[_POLY_NUM_CHANNELS]; +#endif + +#define POLY_SINE_SZ 360 +static const uint8_t _poly_sine[POLY_SINE_SZ]; + +/* Master sample clock */ +/*static volatile uint16_t _poly_remain __attribute__((nocommon)) = 0; +extern const volatile uint16_t + __attribute__((alias ("_poly_remain"))) poly_remain;*/ +volatile uint16_t poly_remain; +#define _poly_remain poly_remain + +/* Enabled channels */ +static uint16_t _poly_enable = 0; +/* Muted channels */ +static uint16_t _poly_mute = 0; + +/*! + * Reset the polyphonic synthesizer. + */ +void poly_reset() { + memset(poly_voice, 0, + sizeof(struct poly_voice_t)*poly_num_channels); + _poly_remain = 0; +} + +/*! + * Load a sample event into the polyphonic registers. + * @param event Polyphonic event to load. + */ +int poly_load(const struct poly_evt_t* const event) { + uint16_t type = (event->flags) & POLY_EVT_TYPE_MASK; + switch (type) { + case POLY_EVT_TYPE_TIME: + _poly_remain = event->value; + return 0; + case POLY_EVT_TYPE_END: + poly_reset(); + return 0; + } + + /* Forbid updating of voice states while we are waiting! */ + if (_poly_remain) + return -EINPROGRESS; + + switch (type) { + case POLY_EVT_TYPE_ENABLE: + _poly_enable = event->value; + return 0; + case POLY_EVT_TYPE_MUTE: + _poly_mute = event->value; + return 0; + } + + struct poly_voice_t* const voice = &poly_voice[ + (event->flags >> POLY_CH_BIT) & 0x0f]; + switch (type) { + case POLY_EVT_TYPE_IFREQ: + voice->freq = event->value; + voice->time = 0; + return 0; + case POLY_EVT_TYPE_DFREQ: + voice->dfreq = event->value; + return 0; + case POLY_EVT_TYPE_PMOD: + if (event->value == UINT16_MAX) + voice->pmod = 0; + else + voice->pmod = event->value | 0x80; + return 0; + case POLY_EVT_TYPE_IAMP: + voice->amp = event->value; + return 0; + case POLY_EVT_TYPE_DAMP: + voice->damp = event->value; + return 0; + case POLY_EVT_TYPE_AMOD: + if (event->value == UINT16_MAX) + voice->amod = 0; + else + voice->amod = event->value | 0x80; + return 0; + case POLY_EVT_TYPE_ASCALE: + if (event->value > 31) + return -ERANGE; + voice->ascale = event->value; + return 0; + case POLY_EVT_TYPE_DSCALE: + voice->dscale = event->value; + return 0; + } + + /* If we get here, then it was a bad event */ + return -EINVAL; +} + +/*! + * Emit the sinusoid at the given fixed-point angle in ¼ degrees. + */ +static int16_t poly_sine(uint16_t angle) { + int16_t amp = 1; + angle %= (POLY_SINE_SZ*4); + if (angle >= (POLY_SINE_SZ*2)) { + amp = -1; + angle = (POLY_SINE_SZ*4) - angle - 1; + } + if (angle >= POLY_SINE_SZ) + angle = (POLY_SINE_SZ*2) - angle - 1; + + assert(angle < POLY_SINE_SZ); + return amp * +#ifdef __AVR_ARCH__ + pgm_read_byte(&_poly_sine[angle]) +#else + _poly_sine[angle] +#endif + ; +} + +/*! + * Compute the output of a single voice. + */ +static void poly_compute(struct poly_voice_t* const voice) { + int32_t amp = voice->amp; + int32_t sample = 0; + + /* Amplitude modulation? */ + if (voice->amod) { + _DPRINTF("amplitude mod: %d + amp(%d)\n", + amp, voice->amod & 0x0f); + amp += poly_voice[voice->amod & 0x0f].sample; + } + + _DPRINTF("amplitude %d\n", amp); + if (amp) { + /* Frequency modulation? */ + if (voice->freq) { + if (voice->freq < UINT16_MAX) { + /* + * Time T is N/Fs. + * Angle in ¼° is 1440*F*T + */ + int64_t angle = (4*POLY_SINE_SZ) + * voice->freq + * (int64_t)voice->time; + angle /= poly_freq; + if (voice->pmod) + angle += poly_voice[voice->pmod + & 0x0f].sample; + angle %= (4*POLY_SINE_SZ); + sample = poly_sine(angle); + _DPRINTF("sine %d Hz sample %d " + "(angle %ld) = %d\n", + voice->freq, voice->time, + angle, sample); + } else { + sample = (rand() / (RAND_MAX/512)) - 256; + _DPRINTF("noise %d @ %d\n", sample, amp); + } + sample *= amp; + _DPRINTF("amplitude * sample = %d\n", + sample * amp); + } else { + /* DC */ + _DPRINTF("DC = %d\n", amp); + sample = amp; + } + sample >>= voice->ascale; + _DPRINTF("scale %d = %d\n", voice->ascale, sample); + } else { + /* No signal */ + sample = 0; + } + + if (voice->dscale && (!(voice->time % voice->dscale))) { + /* Delta frequency adjustment */ + if (voice->dfreq) { + int32_t freq = voice->freq; + freq += voice->dfreq; + if (freq < 0) + voice->freq = 0; + else if (freq > poly_freq_max) + voice->freq = poly_freq_max; + else + voice->freq = freq; + } + + /* Delta amplitude adjustment */ + if (voice->damp) { + amp = (int32_t)voice->amp + (int32_t)voice->damp; + if (amp < 0) { + voice->amp = 0; + voice->damp = 0; + } else if (amp > UINT8_MAX) { + voice->amp = UINT8_MAX; + voice->damp = 0; + } else + voice->amp = amp; + } + } + + /* Clipping */ + if (sample > INT16_MAX) + sample = INT16_MAX; + else if (sample < INT16_MIN) + sample = INT16_MIN; + + /* Update sample */ + voice->sample = sample; + + /* Time step update */ + voice->time++; +} + +/*! + * Retrieve the next output sample from the polyphonic synthesizer. + */ +int16_t poly_next() { + /* Do not return samples unless we're in the waiting state. */ + if (!_poly_remain) + return 0; + + /* Compute all the voices, tally up the samples */ + uint8_t vid; + int16_t sample = 0; + uint16_t mask = 1; + for (vid = 0; vid < poly_num_channels; vid++) { + if (_poly_enable & mask) { + _DPRINTF("compute %d\n", vid); + poly_compute(&poly_voice[vid]); + } else { + _DPRINTF("skip compute %d\n", vid); + } + if (!(_poly_mute & mask)) { + sample += poly_voice[vid].sample; + } else { + _DPRINTF("muted %d\n", vid); + } + mask <<= 1; + } + + /* Decrement our global sample counter */ + _poly_remain--; + return sample; +} + +static const uint8_t _poly_sine[POLY_SINE_SZ] +#ifdef __AVR_ARCH__ +PROGMEM +#endif += { + + 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0A, + 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x14, 0x15, + 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1F, 0x20, + 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x2A, 0x2B, + 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x35, 0x36, + 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, + 0x41, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, + 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x53, 0x54, 0x55, 0x56, + 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F, 0x60, + 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, + 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, + 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, + 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, + 0x89, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, + 0x92, 0x93, 0x94, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, + 0x9B, 0x9C, 0x9C, 0x9D, 0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, + 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA8, 0xA9, 0xAA, 0xAB, + 0xAC, 0xAD, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB1, 0xB2, 0xB3, + 0xB4, 0xB5, 0xB5, 0xB6, 0xB7, 0xB8, 0xB8, 0xB9, 0xBA, 0xBB, + 0xBC, 0xBC, 0xBD, 0xBE, 0xBE, 0xBF, 0xC0, 0xC1, 0xC1, 0xC2, + 0xC3, 0xC4, 0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC8, 0xC9, + 0xCA, 0xCA, 0xCB, 0xCC, 0xCC, 0xCD, 0xCE, 0xCE, 0xCF, 0xD0, + 0xD0, 0xD1, 0xD2, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD5, 0xD6, + 0xD7, 0xD7, 0xD8, 0xD8, 0xD9, 0xDA, 0xDA, 0xDB, 0xDB, 0xDC, + 0xDC, 0xDD, 0xDD, 0xDE, 0xDF, 0xDF, 0xE0, 0xE0, 0xE1, 0xE1, + 0xE2, 0xE2, 0xE3, 0xE3, 0xE4, 0xE4, 0xE5, 0xE5, 0xE6, 0xE6, + 0xE7, 0xE7, 0xE8, 0xE8, 0xE8, 0xE9, 0xE9, 0xEA, 0xEA, 0xEB, + 0xEB, 0xEC, 0xEC, 0xEC, 0xED, 0xED, 0xEE, 0xEE, 0xEE, 0xEF, + 0xEF, 0xEF, 0xF0, 0xF0, 0xF1, 0xF1, 0xF1, 0xF2, 0xF2, 0xF2, + 0xF3, 0xF3, 0xF3, 0xF4, 0xF4, 0xF4, 0xF5, 0xF5, 0xF5, 0xF6, + 0xF6, 0xF6, 0xF6, 0xF7, 0xF7, 0xF7, 0xF7, 0xF8, 0xF8, 0xF8, + 0xF8, 0xF9, 0xF9, 0xF9, 0xF9, 0xFA, 0xFA, 0xFA, 0xFA, 0xFA, + 0xFB, 0xFB, 0xFB, 0xFB, 0xFB, 0xFC, 0xFC, 0xFC, 0xFC, 0xFC, + 0xFC, 0xFC, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, 0xFD, + 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, + 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, + +}; + +/* + * vim: set sw=8 ts=8 noet si tw=72 + */ diff --git a/poly.h b/poly.h new file mode 100644 index 0000000..dbc0232 --- /dev/null +++ b/poly.h @@ -0,0 +1,252 @@ +#ifndef _POLY_H +#define _POLY_H + +/*! + * Polyphonic synthesizer for microcontrollers. + * (C) 2016 Stuart Longland + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, + * MA 02110-1301 USA + */ + +#include +#include + +/* + * _POLY_CFG_H is a definition that can be given when compiling poly.c + * and firmware code to define a header file that contains definitions for + * the Polyphonic synthesizer. + */ +#ifdef _POLY_CFG +#include _POLY_CFG +#endif + +/*! + * Polyphonic event. This is a base struct for describing what happens + * within a voice channel. An array of these forms a musical piece or + * sound effect. Each event can take the form of a chnage to a voice's + * parameters, or timing events. + */ +struct poly_evt_t { + uint16_t flags; /*!< Event flags */ + uint16_t value; /*!< New register value */ +}; + +/* Event flags */ + +/*! + * Bits 15-12 represent the event type. + */ +#define POLY_EVT_TYPE_BIT (12) + +/*! + * Bit mask for event type. + */ +#define POLY_EVT_TYPE_MASK (0x0f << POLY_EVT_TYPE_BIT) + +/*! + * END event. This terminates the musical piece and causes a reset of + * the synthesizer state. Event is valid at any time. + */ +#define POLY_EVT_TYPE_END (0x00 << POLY_EVT_TYPE_BIT) + +/*! + * TIME event. This indicates the synthesizer should emit samples with the + * currently defined parameters for the number of samples given in the + * value field. Event is valid at any time. + */ +#define POLY_EVT_TYPE_TIME (0x01 << POLY_EVT_TYPE_BIT) + +/*! + * ENABLE event. This turns on and off computation of the named channels. + */ +#define POLY_EVT_TYPE_ENABLE (0x02 << POLY_EVT_TYPE_BIT) + +/*! + * MUTE event. This turns on and off inclusion of a channel in the output. + */ +#define POLY_EVT_TYPE_MUTE (0x03 << POLY_EVT_TYPE_BIT) + +/*! + * IFREQ change event. This indicates the immediate frequency for a voice + * channel is to change to the value given in Hz, or, if the frequency is + * zero, the channel is to emit a DC or linearly varying signal. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_IFREQ (0x04 << POLY_EVT_TYPE_BIT) + +/*! + * DFREQ change event. This indicates the frequency step is to change to + * the given value in Hz. The frequency of the channel will step by this + * amount every N samples, where N is set by DSCALE. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_DFREQ (0x05 << POLY_EVT_TYPE_BIT) + +/*! + * PMOD change event. Change phase modulation configuration. + * + * If value is UINT16_MAX: Disable phase modulation + * Otherwise, modulate the phase using the channel number given. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_PMOD (0x06 << POLY_EVT_TYPE_BIT) + +/*! + * IAMP change event. This indicates the immediate amplitude of the + * channel is to be set to the value given. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_IAMP (0x08 << POLY_EVT_TYPE_BIT) + +/*! + * DAMP change event. This indicates the amplitude step is to change to + * the given value. The amplitude will change by this amount every N + * samples, where N is set by DSCALE. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_DAMP (0x09 << POLY_EVT_TYPE_BIT) + +/*! + * AMOD change event. Change amplitude modulation configuration. + * + * If value is UINT16_MAX: Disable amplitude modulation + * Otherwise, modulate the amplitude using the channel number given. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_AMOD (0x0a << POLY_EVT_TYPE_BIT) + +/*! + * ASCALE change event. Amplitudes are to be left-shifted by this number + * of bits after multiplication with a sample. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_ASCALE (0x0b << POLY_EVT_TYPE_BIT) + +/*! + * DSCALE change event. Every N samples (given here), the amplitude and + * frequency of the channel will be adjusted. + * + * Channel number is given in bits 12-8 of the flags register. + */ +#define POLY_EVT_TYPE_DSCALE (0x0f << POLY_EVT_TYPE_BIT) + +/*! + * Position of channel number field. + */ +#define POLY_CH_BIT (8) + +/*! + * Mask for channel number field. + */ +#define POLY_CH_MASK (0x0f << POLY_VOICE_CH_BIT) + +/*! + * Voice state machine. A "voice" is simply a sinusoidal channel. It + * may be modulated by a static linear function, or by taking the output + * from another channel and summing that. + * + * Each voice has its own sample timing counter which starts at zero and + * counts upwards. + */ +struct poly_voice_t { + int16_t sample; /*!< Sample last computed */ + uint16_t time; /*!< Time (samples) for voice */ + uint16_t freq; /*!< Current frequency */ + int16_t dfreq; /*!< Delta frequency */ + uint16_t dscale; /*!< Delta time scale */ + uint8_t amp; /*!< Current amplitude */ + int8_t damp; /*!< Delta amplitude */ + uint8_t ascale; /*!< Amplitude scale */ + uint8_t pmod; /*!< Phase modulation channel */ + uint8_t amod; /*!< Amplitude modulation channel */ + uint8_t flags; /*!< Flags register */ +}; + +#ifndef _POLY_NUM_CHANNELS +/*! + * Number of voice channels: this needs to be declared in the application. + * Overridden by defining _POLY_NUM_CHANNELS. + */ +extern const uint8_t __attribute__((weak)) poly_num_channels; +#else +#define poly_num_channels _POLY_NUM_CHANNELS +#endif + +#ifndef _POLY_FREQ +/*! + * Sample rate for the synthesizer: this needs to be declared in the + * application. + */ +extern const uint16_t __attribute__((weak)) poly_freq; +#else +#define poly_freq _POLY_FREQ +#endif + +#ifndef _POLY_FREQ +/*! + * Maximum frequency for the synthesizer: this needs to be declared in the + * application. This should be set at the nyquist frequency. + * (poly_freq/2) + */ +extern const uint16_t __attribute__((weak)) poly_freq_max; +#else +#define poly_freq_max (poly_freq/2) +#endif + +#ifndef _POLY_NUM_CHANNELS +/*! + * Voice channel array: this needs to be declared in the application. + */ +extern struct __attribute__((weak)) poly_voice_t poly_voice[]; +#endif + +/*! + * Number of samples remaining before the next set of events. + */ +extern volatile uint16_t poly_remain; + +/*! + * Reset the polyphonic synthesizer. + */ +void poly_reset(); + +/*! + * Load a sample event into the polyphonic registers. + * @param event Polyphonic event to load. + * @retval 0 Success + * @retval -EINVAL Bad event + * @retval -ERANGE Bad value + * @retval -EINPROGRESS Waiting for timing event + */ +int poly_load(const struct poly_evt_t* event); + +/*! + * Retrieve the next output sample from the polyphonic synthesizer. + */ +int16_t poly_next(); + +/* + * vim: set sw=8 ts=8 noet si tw=72 + */ + +#endif diff --git a/poly_cfg.h b/poly_cfg.h new file mode 100644 index 0000000..f3b777a --- /dev/null +++ b/poly_cfg.h @@ -0,0 +1,27 @@ +#ifndef _POLY_CFG_H +#define _POLY_CFG_H + +/*! + * Polyphonic synthesizer for microcontrollers. + * (C) 2016 Stuart Longland + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, + * MA 02110-1301 USA + */ + +#define _POLY_NUM_CHANNELS 16 +#define _POLY_FREQ 32000 + +#endif