mirror of
https://github.com/sjlongland/atinysynth.git
synced 2025-09-13 18:13:16 +10:00
ADSR-based synthesizer for microcontrollers
Initial check-in.
This commit is contained in:
commit
84370bd932
GPG Key ID:
F954BBBB7948D546
5
.gitignore
vendored
Normal file
5
.gitignore
vendored
Normal file
@ -0,0 +1,5 @@
|
|||||||
|
.*.swp
|
||||||
|
*.swp
|
||||||
|
*.o
|
||||||
|
*.elf
|
||||||
|
*.hex
|
||||||
340
LICENSE
Normal file
340
LICENSE
Normal 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.
|
||||||
58
Makefile
Normal file
58
Makefile
Normal file
@ -0,0 +1,58 @@
|
|||||||
|
# Compiler definitions
|
||||||
|
CROSS_COMPILE ?= avr-
|
||||||
|
CC = $(CROSS_COMPILE)gcc
|
||||||
|
AR = $(CROSS_COMPILE)ar
|
||||||
|
OBJCOPY = $(CROSS_COMPILE)objcopy
|
||||||
|
OBJDUMP = $(CROSS_COMPILE)objdump
|
||||||
|
SIZE = $(CROSS_COMPILE)size
|
||||||
|
MCU ?= attiny85
|
||||||
|
CFLAGS ?= -g -mmcu=$(MCU) -O3 -Werror -Woverflow
|
||||||
|
CPPFLAGS ?= -DF_CPU=$(FREQ) -D_POLY_CFG=\"poly_cfg.h\"
|
||||||
|
LDFLAGS ?= -mmcu=$(MCU) -O3 -Wl,--as-needed
|
||||||
|
PROG ?= avrdude
|
||||||
|
PROG_ARGS ?= -B 10 -c stk500v2 -P /dev/ttyACM0
|
||||||
|
PROG_DEV ?= t85
|
||||||
|
|
||||||
|
BINDIR ?= bin
|
||||||
|
SRCDIR ?= .
|
||||||
|
OBJDIR ?= obj
|
||||||
|
|
||||||
|
LFUSE=0xc1
|
||||||
|
HFUSE=0xdf
|
||||||
|
EFUSE=0xff
|
||||||
|
FREQ=16000000
|
||||||
|
|
||||||
|
.PHONY: setfuse all clean
|
||||||
|
|
||||||
|
-include local.mk
|
||||||
|
|
||||||
|
all: bindir/synth.hex
|
||||||
|
|
||||||
|
%.hex: %.elf
|
||||||
|
$(OBJCOPY) -j .text -j .data -O ihex $< $@
|
||||||
|
|
||||||
|
$(BINDIR)/synth.elf: $(OBJDIR)/main.o $(OBJDIR)/poly.a
|
||||||
|
@[ -d $(BINDIR) ] || mkdir $(BINDIR)
|
||||||
|
$(CC) -g -o $@ $(LDFLAGS) $^
|
||||||
|
|
||||||
|
$(OBJDIR)/poly.a: $(OBJDIR)/adsr.o $(OBJDIR)/waveform.o
|
||||||
|
$(AR) rcs $@ $^
|
||||||
|
|
||||||
|
$(OBJDIR)/%.o: $(SRCDIR)/%.c
|
||||||
|
@[ -d $(OBJDIR) ] || mkdir $(OBJDIR)
|
||||||
|
$(CC) -o $@ -c $(CPPFLAGS) $(CFLAGS) $<
|
||||||
|
|
||||||
|
clean:
|
||||||
|
-rm -fr $(OBJDIR) $(BINDIR)
|
||||||
|
|
||||||
|
%.ihex: %.elf
|
||||||
|
$(OBJCOPY) -j .text -j .data -O ihex $^ $@
|
||||||
|
|
||||||
|
%.pgm: %.ihex
|
||||||
|
$(PROG) $(PROG_ARGS) -p $(PROG_DEV) -U flash:w:$^:i
|
||||||
|
|
||||||
|
setfuse:
|
||||||
|
$(PROG) $(PROG_ARGS) -p $(PROG_DEV) \
|
||||||
|
-U lfuse:w:$(LFUSE):m \
|
||||||
|
-U hfuse:w:$(HFUSE):m \
|
||||||
|
-U efuse:w:$(EFUSE):m
|
||||||
15
README.md
Normal file
15
README.md
Normal file
@ -0,0 +1,15 @@
|
|||||||
|
ADSR-based Polyphonic Synthesizer
|
||||||
|
=================================
|
||||||
|
|
||||||
|
This project is intended to be a polyphonic synthesizer for use in
|
||||||
|
embedded microcontrollers. It features multi-voice synthesis for multiple
|
||||||
|
channels.
|
||||||
|
|
||||||
|
The synthesis is inspired from the highly regarded MOS Technologies 6581
|
||||||
|
"SID" chip, which supported up to 3 voices each producing either a
|
||||||
|
square wave, triangle wave or sawtooth wave output and hardware
|
||||||
|
attack/decay/sustain/release envelope generation.
|
||||||
|
|
||||||
|
This tries to achieve the same thing in software.
|
||||||
|
|
||||||
|
Code is presently a work-in-progress.
|
||||||
227
adsr.c
Normal file
227
adsr.c
Normal file
@ -0,0 +1,227 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers. ADSR Envelope generator.
|
||||||
|
* (C) 2017 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 "adsr.h"
|
||||||
|
#include <stdlib.h>
|
||||||
|
#ifdef __AVR_ARCH__
|
||||||
|
#include <avr/pgmspace.h>
|
||||||
|
#endif
|
||||||
|
|
||||||
|
/* ADSR attack/decay adjustments */
|
||||||
|
#define ADSR_EXP_AMP_FACTOR (6)
|
||||||
|
#define ADSR_EXP_SHIFT (-8)
|
||||||
|
#define ADSR_EXP_TIME_FACTOR (1)
|
||||||
|
#define ADSR_LIN_AMP_FACTOR (6)
|
||||||
|
#define ADSR_DECAY_OFFSET (16)
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* ADSR Attack amplitude exponential shift.
|
||||||
|
*/
|
||||||
|
static uint8_t adsr_attack_shift(uint8_t sample) {
|
||||||
|
return (sample + ADSR_EXP_SHIFT)/ADSR_EXP_TIME_FACTOR
|
||||||
|
- ADSR_EXP_AMP_FACTOR;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* ADSR Release amplitude exponential shift.
|
||||||
|
*/
|
||||||
|
static uint8_t adsr_release_shift(uint8_t sample) {
|
||||||
|
return adsr_attack_shift(ADSR_DECAY_OFFSET - sample);
|
||||||
|
}
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Reset the ADSR state ready for the next note
|
||||||
|
*/
|
||||||
|
void adsr_reset(struct adsr_env_gen_t* const adsr) {
|
||||||
|
adsr->next_event = 0;
|
||||||
|
adsr->state = ADSR_STATE_IDLE;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Compute the ADSR amplitude
|
||||||
|
*/
|
||||||
|
uint8_t adsr_next(struct adsr_env_gen_t* const adsr) {
|
||||||
|
if (adsr->next_event) {
|
||||||
|
/* Still waiting for next event */
|
||||||
|
adsr->next_event--;
|
||||||
|
return adsr->amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* We use if statements here since we might want to jump
|
||||||
|
* between states. This lets us do that more easily.
|
||||||
|
*/
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_IDLE) {
|
||||||
|
/* Are registers set up? */
|
||||||
|
if (!adsr->time_scale)
|
||||||
|
return 0;
|
||||||
|
if (!(adsr->delay_time || adsr->attack_time
|
||||||
|
|| adsr->decay_time || adsr->release_time))
|
||||||
|
return 0;
|
||||||
|
if (!(adsr->peak_amp || adsr->sustain_amp))
|
||||||
|
return 0;
|
||||||
|
|
||||||
|
/* All good */
|
||||||
|
if (adsr->delay_time)
|
||||||
|
adsr->state = ADSR_STATE_DELAY_INIT;
|
||||||
|
else
|
||||||
|
adsr->state = ADSR_STATE_DELAY_EXPIRE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_DELAY_INIT) {
|
||||||
|
/* Setting up a delay */
|
||||||
|
adsr->amplitude = 0;
|
||||||
|
adsr->next_event = adsr->time_scale
|
||||||
|
* adsr->delay_time;
|
||||||
|
adsr->state = ADSR_STATE_DELAY_EXPIRE;
|
||||||
|
/* Wait for delay */
|
||||||
|
return adsr->amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_DELAY_EXPIRE) {
|
||||||
|
/* Delay has expired */
|
||||||
|
if (adsr->attack_time)
|
||||||
|
adsr->state = ADSR_STATE_ATTACK_INIT;
|
||||||
|
else
|
||||||
|
adsr->state = ADSR_STATE_ATTACK_EXPIRE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_ATTACK_INIT) {
|
||||||
|
/* Attack is divided into 16 segments */
|
||||||
|
adsr->time_step = (uint16_t)((adsr->attack_time
|
||||||
|
* adsr->time_scale) >> 4);
|
||||||
|
adsr->counter = 16;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
adsr->state = ADSR_STATE_ATTACK;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_ATTACK) {
|
||||||
|
if (adsr->counter) {
|
||||||
|
/* Change of amplitude */
|
||||||
|
uint16_t lin_amp = (16-adsr->counter)
|
||||||
|
* adsr->peak_amp;
|
||||||
|
adsr->amplitude = lin_amp
|
||||||
|
>> ADSR_LIN_AMP_FACTOR;
|
||||||
|
adsr->amplitude += adsr->peak_amp >>
|
||||||
|
adsr_attack_shift(adsr->counter);
|
||||||
|
/* Go around again */
|
||||||
|
adsr->counter--;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
return adsr->amplitude;
|
||||||
|
} else {
|
||||||
|
adsr->state = ADSR_STATE_ATTACK_EXPIRE;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_ATTACK_EXPIRE) {
|
||||||
|
if (adsr->decay_time)
|
||||||
|
adsr->state = ADSR_STATE_DECAY_INIT;
|
||||||
|
else
|
||||||
|
adsr->state = ADSR_STATE_DECAY_EXPIRE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_DECAY_INIT) {
|
||||||
|
/* We should be at full amplitude */
|
||||||
|
adsr->amplitude = adsr->peak_amp;
|
||||||
|
|
||||||
|
adsr->time_step = (uint16_t)((adsr->decay_time
|
||||||
|
* adsr->time_scale) >> 4);
|
||||||
|
adsr->counter = 16;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
adsr->state = ADSR_STATE_DECAY;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_DECAY) {
|
||||||
|
if (adsr->counter) {
|
||||||
|
/* Linear decrease in amplitude */
|
||||||
|
uint16_t delta = adsr->peak_amp
|
||||||
|
- adsr->sustain_amp;
|
||||||
|
delta *= adsr->counter;
|
||||||
|
delta >>= 4;
|
||||||
|
|
||||||
|
adsr->amplitude = adsr->sustain_amp + delta;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
adsr->counter--;
|
||||||
|
} else {
|
||||||
|
adsr->state = ADSR_STATE_DECAY_EXPIRE;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_DECAY_EXPIRE) {
|
||||||
|
if (adsr->sustain_time)
|
||||||
|
adsr->state = ADSR_STATE_SUSTAIN_INIT;
|
||||||
|
else
|
||||||
|
adsr->state = ADSR_STATE_SUSTAIN_EXPIRE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_SUSTAIN_INIT) {
|
||||||
|
adsr->amplitude = adsr->sustain_amp;
|
||||||
|
adsr->next_event = adsr->time_scale
|
||||||
|
* adsr->sustain_time;
|
||||||
|
adsr->state = ADSR_STATE_SUSTAIN_EXPIRE;
|
||||||
|
/* Wait for delay */
|
||||||
|
return adsr->amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_SUSTAIN_EXPIRE) {
|
||||||
|
if (adsr->release_time)
|
||||||
|
adsr->state = ADSR_STATE_RELEASE_INIT;
|
||||||
|
else
|
||||||
|
adsr->state = ADSR_STATE_RELEASE_EXPIRE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_RELEASE_INIT) {
|
||||||
|
adsr->time_step = (uint16_t)((adsr->release_time
|
||||||
|
* adsr->time_scale) >> 4);
|
||||||
|
adsr->counter = 16;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
adsr->state = ADSR_STATE_RELEASE;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_RELEASE) {
|
||||||
|
if (adsr->counter) {
|
||||||
|
/* Change of amplitude */
|
||||||
|
uint16_t lin_amp = adsr->counter
|
||||||
|
* adsr->peak_amp;
|
||||||
|
adsr->amplitude = lin_amp
|
||||||
|
>> ADSR_LIN_AMP_FACTOR;
|
||||||
|
adsr->amplitude += adsr->peak_amp >>
|
||||||
|
adsr_release_shift(adsr->counter);
|
||||||
|
/* Go around again */
|
||||||
|
adsr->counter--;
|
||||||
|
adsr->next_event = adsr->time_step;
|
||||||
|
} else {
|
||||||
|
adsr->state = ADSR_STATE_RELEASE_EXPIRE;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if (adsr->state == ADSR_STATE_RELEASE_EXPIRE) {
|
||||||
|
/* Reset the state */
|
||||||
|
adsr->state = ADSR_STATE_IDLE;
|
||||||
|
adsr->amplitude = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
return adsr->amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
85
adsr.h
Normal file
85
adsr.h
Normal file
@ -0,0 +1,85 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers. ADSR Envelope generator.
|
||||||
|
* (C) 2017 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
|
||||||
|
*/
|
||||||
|
#ifndef _ADSR_H
|
||||||
|
#define _ADSR_H
|
||||||
|
|
||||||
|
#include <stdint.h>
|
||||||
|
|
||||||
|
/* ADSR states */
|
||||||
|
#define ADSR_STATE_IDLE (0x00)
|
||||||
|
#define ADSR_STATE_DELAY_INIT (0x10)
|
||||||
|
#define ADSR_STATE_DELAY_EXPIRE (0x1f)
|
||||||
|
#define ADSR_STATE_ATTACK_INIT (0x20)
|
||||||
|
#define ADSR_STATE_ATTACK (0x21)
|
||||||
|
#define ADSR_STATE_ATTACK_EXPIRE (0x2f)
|
||||||
|
#define ADSR_STATE_DECAY_INIT (0x30)
|
||||||
|
#define ADSR_STATE_DECAY (0x31)
|
||||||
|
#define ADSR_STATE_DECAY_EXPIRE (0x3f)
|
||||||
|
#define ADSR_STATE_SUSTAIN_INIT (0x40)
|
||||||
|
#define ADSR_STATE_SUSTAIN_EXPIRE (0x4f)
|
||||||
|
#define ADSR_STATE_RELEASE_INIT (0x50)
|
||||||
|
#define ADSR_STATE_RELEASE (0x51)
|
||||||
|
#define ADSR_STATE_RELEASE_EXPIRE (0x5f)
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* ADSR Envelope Generator data. 20 bytes.
|
||||||
|
*/
|
||||||
|
struct adsr_env_gen_t {
|
||||||
|
/*! Time to next event, samples */
|
||||||
|
uint32_t next_event;
|
||||||
|
/*! Time step, samples */
|
||||||
|
uint16_t time_step;
|
||||||
|
/*! Time scale, samples per unit */
|
||||||
|
uint32_t time_scale;
|
||||||
|
/*! Delay period, time units */
|
||||||
|
uint8_t delay_time;
|
||||||
|
/*! Attack period, time units */
|
||||||
|
uint8_t attack_time;
|
||||||
|
/*! Decay period, time units */
|
||||||
|
uint8_t decay_time;
|
||||||
|
/*! Sustain period, time units */
|
||||||
|
uint8_t sustain_time;
|
||||||
|
/*! Release period, time units */
|
||||||
|
uint8_t release_time;
|
||||||
|
/*! Attack peak amplitude */
|
||||||
|
uint8_t peak_amp;
|
||||||
|
/*! Sustain amplitude */
|
||||||
|
uint8_t sustain_amp;
|
||||||
|
/*! Present amplitude */
|
||||||
|
uint8_t amplitude;
|
||||||
|
/*! ADSR state */
|
||||||
|
uint8_t state;
|
||||||
|
/*! ADSR counter */
|
||||||
|
uint8_t counter;
|
||||||
|
};
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Reset the ADSR state ready for the next note
|
||||||
|
*/
|
||||||
|
void adsr_reset(struct adsr_env_gen_t* const adsr);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Compute the ADSR amplitude
|
||||||
|
*/
|
||||||
|
uint8_t adsr_next(struct adsr_env_gen_t* const adsr);
|
||||||
|
#endif
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
97
synth.h
Normal file
97
synth.h
Normal file
@ -0,0 +1,97 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers.
|
||||||
|
* (C) 2017 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
|
||||||
|
*/
|
||||||
|
#ifndef _SYNTH_H
|
||||||
|
#define _SYNTH_H
|
||||||
|
#include "voice.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 SYNTH_CFG
|
||||||
|
#include SYNTH_CFG
|
||||||
|
#endif
|
||||||
|
|
||||||
|
#ifndef SYNTH_FREQ
|
||||||
|
/*!
|
||||||
|
* Sample rate for the synthesizer: this needs to be declared in the
|
||||||
|
* application.
|
||||||
|
*/
|
||||||
|
extern const uint16_t __attribute__((weak)) synth_freq;
|
||||||
|
#else
|
||||||
|
#define synth_freq SYNTH_FREQ
|
||||||
|
#endif
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer structure
|
||||||
|
*/
|
||||||
|
struct poly_synth_t {
|
||||||
|
/*! Pointer to voices. There may be up to 16 voices referenced. */
|
||||||
|
struct voice_ch_t* const voice;
|
||||||
|
/*!
|
||||||
|
* Bit-field enabling given voices. This allows selective turning
|
||||||
|
* on and off of given voice channels. If the corresponding bit is
|
||||||
|
* not a 1, then that channel is not computed.
|
||||||
|
*
|
||||||
|
* Note no bounds checking is done, if you have only defined 4
|
||||||
|
* channels, then only set bits 0-3, don't set bits 4 onwards here.
|
||||||
|
*/
|
||||||
|
uintptr_t enable;
|
||||||
|
/*!
|
||||||
|
* Bit-field muting given voices. This allows for selective adding
|
||||||
|
* of voices to the overall output. If a field is 1, then that voice
|
||||||
|
* channel is not included. (Note, disabled channels are *also*
|
||||||
|
* not included.)
|
||||||
|
*/
|
||||||
|
uintptr_t mute;
|
||||||
|
};
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Compute the next synthesizer sample.
|
||||||
|
*/
|
||||||
|
static inline int8_t poly_synth_next(struct poly_synth_t* const synth) {
|
||||||
|
int16_t sample = 0;
|
||||||
|
uintptr_t mask = 1;
|
||||||
|
uint8_t idx = 0;
|
||||||
|
|
||||||
|
while (mask) {
|
||||||
|
if (synth->enable & mask) {
|
||||||
|
/* Channel is enabled */
|
||||||
|
int8_t ch_sample = voice_ch_next(
|
||||||
|
&(synth->voice[idx]));
|
||||||
|
if (!(synth->mute & mask))
|
||||||
|
sample += ch_sample;
|
||||||
|
}
|
||||||
|
idx++;
|
||||||
|
mask <<= 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Handle clipping */
|
||||||
|
if (sample > INT8_MAX)
|
||||||
|
sample = INT8_MAX;
|
||||||
|
else if (sample < INT8_MIN)
|
||||||
|
sample = INT8_MIN;
|
||||||
|
return sample;
|
||||||
|
};
|
||||||
|
#endif
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
61
voice.h
Normal file
61
voice.h
Normal file
@ -0,0 +1,61 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers. Voice generation.
|
||||||
|
* (C) 2017 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 "waveform.h"
|
||||||
|
#include "adsr.h"
|
||||||
|
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Voice channel state. 30 bytes.
|
||||||
|
*/
|
||||||
|
struct voice_ch_t {
|
||||||
|
/*!
|
||||||
|
* ADSR Envelope generator state.
|
||||||
|
*/
|
||||||
|
struct adsr_env_gen_t adsr;
|
||||||
|
/*!
|
||||||
|
* Waveform generator state.
|
||||||
|
*/
|
||||||
|
struct voice_wf_gen_t wf;
|
||||||
|
};
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Compute the next voice channel sample.
|
||||||
|
*/
|
||||||
|
inline static int8_t voice_ch_next(struct voice_ch_t* const voice) {
|
||||||
|
uint8_t amplitude = adsr_next(&(voice->adsr));
|
||||||
|
if (!amplitude)
|
||||||
|
return 0;
|
||||||
|
|
||||||
|
int16_t value = voice_wf_next(&(voice->wf));
|
||||||
|
value *= amplitude;
|
||||||
|
|
||||||
|
/* Saturation handling */
|
||||||
|
if (value < INT8_MIN)
|
||||||
|
return INT8_MIN;
|
||||||
|
else if (value > INT8_MAX)
|
||||||
|
return INT8_MAX;
|
||||||
|
else
|
||||||
|
return value;
|
||||||
|
}
|
||||||
|
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
136
waveform.c
Normal file
136
waveform.c
Normal file
@ -0,0 +1,136 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers. Voice waveform generator.
|
||||||
|
* (C) 2017 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 "waveform.h"
|
||||||
|
#include "synth.h"
|
||||||
|
#include <stdlib.h>
|
||||||
|
|
||||||
|
/* Waveform generation modes */
|
||||||
|
#define VOICE_MODE_DC (0)
|
||||||
|
#define VOICE_MODE_SQUARE (1)
|
||||||
|
#define VOICE_MODE_SAWTOOTH (2)
|
||||||
|
#define VOICE_MODE_TRIANGLE (3)
|
||||||
|
#define VOICE_MODE_NOISE (4)
|
||||||
|
|
||||||
|
/* Amplitude scaling */
|
||||||
|
#define VOICE_WF_AMP_SCALE (8)
|
||||||
|
|
||||||
|
int8_t voice_wf_next(struct voice_wf_gen_t* const wf_gen) {
|
||||||
|
switch(wf_gen->mode) {
|
||||||
|
case VOICE_MODE_DC:
|
||||||
|
return wf_gen->amplitude;
|
||||||
|
case VOICE_MODE_NOISE:
|
||||||
|
wf_gen->sample = (rand() /
|
||||||
|
(RAND_MAX/512)) - 256;
|
||||||
|
wf_gen->sample *= wf_gen->amplitude;
|
||||||
|
break;
|
||||||
|
case VOICE_MODE_SQUARE:
|
||||||
|
if (!wf_gen->period_remain) {
|
||||||
|
/* Swap value */
|
||||||
|
wf_gen->sample = -wf_gen->sample;
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
} else {
|
||||||
|
wf_gen->period_remain--;
|
||||||
|
}
|
||||||
|
break;
|
||||||
|
case VOICE_MODE_SAWTOOTH:
|
||||||
|
if (!wf_gen->period_remain) {
|
||||||
|
/* Back to -amplitude */
|
||||||
|
wf_gen->sample = -wf_gen->amplitude
|
||||||
|
<< VOICE_WF_AMP_SCALE;
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
} else {
|
||||||
|
wf_gen->sample += wf_gen->step;
|
||||||
|
wf_gen->period_remain--;
|
||||||
|
}
|
||||||
|
break;
|
||||||
|
case VOICE_MODE_TRIANGLE:
|
||||||
|
if (!wf_gen->period_remain) {
|
||||||
|
/* Switch direction */
|
||||||
|
if (wf_gen->step > 0)
|
||||||
|
wf_gen->sample = -wf_gen->amplitude;
|
||||||
|
else
|
||||||
|
wf_gen->sample = wf_gen->amplitude;
|
||||||
|
wf_gen->step = -wf_gen->step;
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
} else {
|
||||||
|
wf_gen->sample += wf_gen->step;
|
||||||
|
wf_gen->period_remain--;
|
||||||
|
}
|
||||||
|
break;
|
||||||
|
}
|
||||||
|
|
||||||
|
return wf_gen->sample >> VOICE_WF_AMP_SCALE;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Compute frequency period (sawtooth wave) */
|
||||||
|
static uint8_t voice_wf_calc_sawtooth_period(uint16_t freq) {
|
||||||
|
return (synth_freq / freq);
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Compute frequency period (square/triangle wave) */
|
||||||
|
static uint8_t voice_wf_calc_square_period(uint16_t freq) {
|
||||||
|
return voice_wf_calc_sawtooth_period(freq) >> 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
void voice_wf_set_dc(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint8_t amplitude) {
|
||||||
|
wf_gen->mode = VOICE_MODE_DC;
|
||||||
|
wf_gen->amplitude = amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
void voice_wf_set_square(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude) {
|
||||||
|
wf_gen->mode = VOICE_MODE_SQUARE;
|
||||||
|
wf_gen->amplitude = amplitude << VOICE_WF_AMP_SCALE;
|
||||||
|
wf_gen->period = voice_wf_calc_square_period(freq);
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
wf_gen->sample = wf_gen->amplitude;
|
||||||
|
}
|
||||||
|
|
||||||
|
void voice_wf_set_sawtooth(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude) {
|
||||||
|
wf_gen->mode = VOICE_MODE_SAWTOOTH;
|
||||||
|
wf_gen->sample = wf_gen->amplitude << VOICE_WF_AMP_SCALE;
|
||||||
|
wf_gen->period = voice_wf_calc_sawtooth_period(freq);
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
wf_gen->amplitude = -wf_gen->sample;
|
||||||
|
wf_gen->step = ((int32_t)(wf_gen->amplitude << 1)) / wf_gen->period;
|
||||||
|
}
|
||||||
|
|
||||||
|
void voice_wf_set_triangle(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude) {
|
||||||
|
wf_gen->mode = VOICE_MODE_TRIANGLE;
|
||||||
|
wf_gen->sample = wf_gen->amplitude << VOICE_WF_AMP_SCALE;
|
||||||
|
wf_gen->period = voice_wf_calc_square_period(freq);
|
||||||
|
wf_gen->period_remain = wf_gen->period;
|
||||||
|
wf_gen->amplitude = -wf_gen->sample;
|
||||||
|
wf_gen->step = ((int32_t)(wf_gen->amplitude << 1)) / wf_gen->period;
|
||||||
|
}
|
||||||
|
|
||||||
|
void voice_wf_set_noise(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint8_t amplitude) {
|
||||||
|
wf_gen->mode = VOICE_MODE_SQUARE;
|
||||||
|
wf_gen->amplitude = amplitude;
|
||||||
|
}
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
83
waveform.h
Normal file
83
waveform.h
Normal file
@ -0,0 +1,83 @@
|
|||||||
|
/*!
|
||||||
|
* Polyphonic synthesizer for microcontrollers. Voice waveform generator.
|
||||||
|
* (C) 2017 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
|
||||||
|
*/
|
||||||
|
#ifndef _WAVEFORM_H
|
||||||
|
#define _WAVEFORM_H
|
||||||
|
#include <stdint.h>
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Waveform generator state. 10 bytes.
|
||||||
|
*/
|
||||||
|
struct voice_wf_gen_t {
|
||||||
|
/*! Waveform output sample in fixed-point */
|
||||||
|
int16_t sample;
|
||||||
|
/*! Amplitude sample in fixed point */
|
||||||
|
int16_t amplitude;
|
||||||
|
/*! Samples to next waveform period */
|
||||||
|
uint16_t period_remain;
|
||||||
|
/*!
|
||||||
|
* Period duration in samples.
|
||||||
|
* (Half period for SQUARE and TRIANGLE)
|
||||||
|
*/
|
||||||
|
uint16_t period;
|
||||||
|
/*! Amplitude step for TRIANGLE and SAWTOOTH */
|
||||||
|
int8_t step;
|
||||||
|
/*! Waveform generation mode */
|
||||||
|
uint8_t mode;
|
||||||
|
};
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Configure the generator for a DC offset synthesis.
|
||||||
|
*/
|
||||||
|
void voice_wf_set_dc(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint8_t amplitude);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Configure the generator for square wave synthesis.
|
||||||
|
*/
|
||||||
|
void voice_wf_set_square(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Configure the generator for sawtooth wave synthesis.
|
||||||
|
*/
|
||||||
|
void voice_wf_set_sawtooth(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Configure the generator for sawtooth wave synthesis.
|
||||||
|
*/
|
||||||
|
void voice_wf_set_triangle(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint16_t freq, uint8_t amplitude);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Configure the generator for pseudorandom noise synthesis.
|
||||||
|
*/
|
||||||
|
void voice_wf_set_noise(struct voice_wf_gen_t* const wf_gen,
|
||||||
|
uint8_t amplitude);
|
||||||
|
|
||||||
|
/*!
|
||||||
|
* Retrieve the next sample from the generator.
|
||||||
|
*/
|
||||||
|
int8_t voice_wf_next(struct voice_wf_gen_t* const wf_gen);
|
||||||
|
|
||||||
|
#endif
|
||||||
|
/*
|
||||||
|
* vim: set sw=8 ts=8 noet si tw=72
|
||||||
|
*/
|
||||||
Loading…
Reference in New Issue
Block a user