stuartl/polyphonic-synthesizer
1
0
Fork 0
mirror of https://github.com/sjlongland/polyphonic-synthesizer.git synced 2025-09-13 08:42:22 +10:00
Code Issues Releases Wiki Activity

Check-in of polyphonic synthesizer

Browse Source
This commit is contained in:
Stuart Longland 2017-04-01 19:38:19 +10:00
commit d3e57436f9
Signed by: stuartl
GPG Key ID: F954BBBB7948D546
10 changed files with 1544 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

340
LICENSE Normal file
View File

@ -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. (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
modification follow.
GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language. (Hereinafter, translation is included without limitation in
the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
a) You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.
c) If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License. (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,
b) Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,
c) Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.
5. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
6. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.
7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all. For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
9. The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.
10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this. Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.
NO WARRANTY
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.
12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
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
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. 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.
<signature of Ty Coon>, 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.

25
Makefile Normal file
View File

@ -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

11
Makefile.pc Normal file
View File

@ -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 $@

78
README.md Normal file
View File

@ -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.

208
fifo.h Normal file
View File

@ -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 <stdint.h>
/*!
* 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

106
main.c Normal file
View File

@ -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 <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#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<<PLOCK)));
PLLCSR |= (1<<PCKE);
fifo_init(&sample_fifo, sample_buffer, SAMPLE_LEN);
/* Reset the synthesizer */
poly_reset();
/* Enable output on PB4 (PWM out) */
DDRB |= (1 << 4) | (1 << 3);
PORTB |= (1 << 4) | (1 << 3);
/* Timer 1 configuration for PWM */
OCR1B = 128; /* Initial PWM value */
OCR1C = 255; /* Maximum PWM value */
TCCR1 = (1 << CS10); /* No prescaling, max speed */
GTCCR = (1 << PWM1B) /* Enable PWM */
| (2 << COM1B0); /* Clear output bit on match */
/* Timer 0 configuration for sample rate interrupt */
TCCR0A = (2 << WGM00); /* CTC mode */
TCCR0B = (1 << CS00); /* No prescaling */
OCR0A = F_CPU / _POLY_FREQ; /* Sample rate */
TIMSK |= (1 << OCIE0A); /* Enable interrupts */
/* Configure the synthesizer */
poly_evt.flags = POLY_EVT_TYPE_ENABLE;
poly_evt.value = 1;
poly_load(&poly_evt);
poly_evt.flags = POLY_EVT_TYPE_IFREQ;
poly_evt.value = 1000;
poly_load(&poly_evt);
poly_evt.flags = POLY_EVT_TYPE_IAMP;
poly_evt.value = 255;
poly_load(&poly_evt);
poly_evt.flags = POLY_EVT_TYPE_ASCALE;
poly_evt.value = 8;
poly_load(&poly_evt);
sei();
while(1) {
poly_evt.flags = POLY_EVT_TYPE_TIME;
poly_evt.value = 64000;
poly_load(&poly_evt);
while (poly_remain) {
while (sample_fifo.stored_sz < SAMPLE_LEN) {
int16_t s = poly_next();
fifo_write_one(&sample_fifo,
128 + (s >> 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;
}

165
pctest.c Normal file
View File

@ -0,0 +1,165 @@
#include "poly.h"
#include <stdio.h>
#include <string.h>
#include <ao/ao.h>
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;
}

332
poly.c Normal file
View File

@ -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 <string.h>
#include <assert.h>
#include <stdlib.h>
#ifdef __AVR_ARCH__
#include <avr/pgmspace.h>
#endif
#ifdef _DEBUG
#include <stdio.h>
#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
*/

252
poly.h Normal file
View File

@ -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 <stdint.h>
#include <errno.h>
/*
* _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

27
poly_cfg.h Normal file
View File

@ -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