From ba74a824658f7f59add288d28006ff48bf46b963 Mon Sep 17 00:00:00 2001 From: Vito Caputo Date: Mon, 3 Feb 2020 00:29:09 -0800 Subject: libs/sig: introduce a signal generator abstraction This adds a small framework of sorts for creating and composing signal generators. Two generators are implemented at this time; sig_ops_sin and sig_ops_mult sig_ops_sin accepts a hz variable and will produce a sine wave of that frequency. sig_ops_mult accepts two sig_t generators and multiplies their outputs Callers may construct their own sig_ops_t ops structs and supply them to sig_new(), but it's expected that libs/sig will grow a collection of commonly used generators which can then be used by simply passing their sig_ops_$foo to sig_new(). See the test code at the bottom of libs/sig/sig.c for some contrived sample usage. Note by composing multiple sig_ops_sin generators with a sig_ops_mult generator, one can already easily construct a synth-like LFO generator. Some obvious todos are to add triangle/sawtooth/square wave generators. More compositional generators may be interesting as well, like additive and subtractive for example. Those will need to implement clipping, as it's expected that the generators *always* stay within unity (0-1). No modules use this yet, but I expect to wire this up to rtv for driving knobs. --- src/Makefile.am | 2 +- src/libs/Makefile.am | 2 +- src/libs/sig/Makefile.am | 3 ++ src/libs/sig/ops_mult.c | 58 +++++++++++++++++++++++++++ src/libs/sig/ops_sin.c | 49 +++++++++++++++++++++++ src/libs/sig/sig.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++ src/libs/sig/sig.h | 30 ++++++++++++++ 7 files changed, 242 insertions(+), 2 deletions(-) create mode 100644 src/libs/sig/Makefile.am create mode 100644 src/libs/sig/ops_mult.c create mode 100644 src/libs/sig/ops_sin.c create mode 100644 src/libs/sig/sig.c create mode 100644 src/libs/sig/sig.h (limited to 'src') diff --git a/src/Makefile.am b/src/Makefile.am index cd7acf1..d13fdd0 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -4,4 +4,4 @@ rototiller_SOURCES = fb.c fb.h fps.c fps.h knobs.h rototiller.c rototiller.h sdl if ENABLE_DRM rototiller_SOURCES += drm_fb.c endif -rototiller_LDADD = modules/drizzle/libdrizzle.a modules/flui2d/libflui2d.a modules/julia/libjulia.a modules/meta2d/libmeta2d.a modules/montage/libmontage.a modules/pixbounce/libpixbounce.a modules/plasma/libplasma.a modules/ray/libray.a modules/roto/libroto.a modules/rtv/librtv.a modules/snow/libsnow.a modules/sparkler/libsparkler.a modules/spiro/libspiro.a modules/stars/libstars.a modules/submit/libsubmit.a modules/swab/libswab.a libs/grid/libgrid.a libs/puddle/libpuddle.a libs/ray/libray.a libs/txt/libtxt.a libs/ascii/libascii.a libs/din/libdin.a -lm +rototiller_LDADD = modules/drizzle/libdrizzle.a modules/flui2d/libflui2d.a modules/julia/libjulia.a modules/meta2d/libmeta2d.a modules/montage/libmontage.a modules/pixbounce/libpixbounce.a modules/plasma/libplasma.a modules/ray/libray.a modules/roto/libroto.a modules/rtv/librtv.a modules/snow/libsnow.a modules/sparkler/libsparkler.a modules/spiro/libspiro.a modules/stars/libstars.a modules/submit/libsubmit.a modules/swab/libswab.a libs/grid/libgrid.a libs/puddle/libpuddle.a libs/ray/libray.a libs/sig/libsig.a libs/txt/libtxt.a libs/ascii/libascii.a libs/din/libdin.a -lm diff --git a/src/libs/Makefile.am b/src/libs/Makefile.am index 820efef..36addcd 100644 --- a/src/libs/Makefile.am +++ b/src/libs/Makefile.am @@ -1 +1 @@ -SUBDIRS = ascii grid din puddle ray txt +SUBDIRS = ascii grid din puddle ray sig txt diff --git a/src/libs/sig/Makefile.am b/src/libs/sig/Makefile.am new file mode 100644 index 0000000..4787b5a --- /dev/null +++ b/src/libs/sig/Makefile.am @@ -0,0 +1,3 @@ +noinst_LIBRARIES = libsig.a +libsig_a_SOURCES = ops_mult.c ops_sin.c sig.c sig.h +libsig_a_CPPFLAGS = -I@top_srcdir@/src diff --git a/src/libs/sig/ops_mult.c b/src/libs/sig/ops_mult.c new file mode 100644 index 0000000..7133e25 --- /dev/null +++ b/src/libs/sig/ops_mult.c @@ -0,0 +1,58 @@ +#include + +#include "sig.h" + + +typedef struct ops_mult_ctxt_t { + sig_t *a, *b; +} ops_mult_ctxt_t; + + +static size_t ops_mult_size(va_list ap) +{ + return sizeof(ops_mult_ctxt_t); +} + + +/* supply two sig_t's to be multiplied, this sig_t takes + * ownership of them so they'll be freed by the multiplier + * on destroy when that sig_t is freed. + */ +static void ops_mult_init(void *context, va_list ap) +{ + ops_mult_ctxt_t *ctxt = context; + + assert(ctxt); + + ctxt->a = va_arg(ap, sig_t *); + ctxt->b = va_arg(ap, sig_t *); +} + + +static float ops_mult_output(void *context, unsigned ticks_ms) +{ + ops_mult_ctxt_t *ctxt = context; + + assert(ctxt); + + return sig_output(ctxt->a, ticks_ms) * sig_output(ctxt->b, ticks_ms); +} + + +static void ops_mult_destroy(void *context) +{ + ops_mult_ctxt_t *ctxt = context; + + assert(ctxt); + + sig_free(ctxt->a); + sig_free(ctxt->b); +} + + +sig_ops_t sig_ops_mult = { + .size = ops_mult_size, + .init = ops_mult_init, + .destroy = ops_mult_destroy, + .output = ops_mult_output, +}; diff --git a/src/libs/sig/ops_sin.c b/src/libs/sig/ops_sin.c new file mode 100644 index 0000000..b228b49 --- /dev/null +++ b/src/libs/sig/ops_sin.c @@ -0,0 +1,49 @@ +#include +#include + +#include "sig.h" + + +typedef struct ops_sin_ctxt_t { + float hz; +} ops_sin_ctxt_t; + + +static size_t ops_sin_size(va_list ap) +{ + return sizeof(ops_sin_ctxt_t); +} + + +static void ops_sin_init(void *context, va_list ap) +{ + ops_sin_ctxt_t *ctxt = context; + + assert(ctxt); + + ctxt->hz = va_arg(ap, double); + assert(ctxt->hz >= .0001f); +} + + +static float ops_sin_output(void *context, unsigned ticks_ms) +{ + ops_sin_ctxt_t *ctxt = context; + float rads_per_ms, rads; + unsigned ms_per_cycle; + + assert(ctxt); + + ms_per_cycle = ctxt->hz * 1000.f; + rads_per_ms = (M_PI * 2.f) * ctxt->hz * .001f; + rads = (float)(ticks_ms % ms_per_cycle) * rads_per_ms; + + return sinf(rads); +} + + +sig_ops_t sig_ops_sin = { + .size = ops_sin_size, + .init = ops_sin_init, + .output = ops_sin_output, +}; diff --git a/src/libs/sig/sig.c b/src/libs/sig/sig.c new file mode 100644 index 0000000..e3d5a7c --- /dev/null +++ b/src/libs/sig/sig.c @@ -0,0 +1,100 @@ +#include +#include +#include + +#include "sig.h" + + +typedef struct sig_t { + const sig_ops_t *ops; + void *ctxt[]; +} sig_t; + + +/* return a new signal generator of ops type, configured according to va_list */ +sig_t * sig_new(const sig_ops_t *ops, ...) +{ + static const sig_ops_t null_ops; + size_t ctxt_size = 0; + sig_t *sig; + va_list ap; + + if (!ops) + ops = &null_ops; + + va_start(ap, ops); + if (ops->size) + ctxt_size = ops->size(ap); + va_end(ap); + + sig = calloc(1, sizeof(sig_t) + ctxt_size); + if (!sig) + return NULL; + + va_start(ap, ops); + if (ops->init) + ops->init(&sig->ctxt, ap); + va_end(ap); + + sig->ops = ops; + + return sig; +} + + +/* free a signal generator, always returns NULL */ +sig_t * sig_free(sig_t *sig) +{ + if (sig) { + if (sig->ops->destroy) + sig->ops->destroy(&sig->ctxt); + + free(sig); + } + + return NULL; +} + + +/* produce the value for time ticks_ms from the supplied signal generator, + * the returned value should always be kept in the range 0-1. + */ +float sig_output(sig_t *sig, unsigned ticks_ms) +{ + assert(sig); + assert(sig->ops); + + if (sig->ops->output) + return sig->ops->output(sig->ctxt, ticks_ms); + + return 0; +} + + +#ifdef TESTING + +#include + +int main(int argc, char *argv[]) +{ + sig_t *sig; + + sig = sig_new(NULL); + printf("null output=%f\n", sig_output(sig, 0)); + sig = sig_free(sig); + + sig = sig_new(&sig_ops_sin, 2.f); + for (unsigned i = 0; i < 1000; i++) + printf("sin 2hz output %i=%f\n", i, sig_output(sig, i)); + sig = sig_free(sig); + + sig = sig_new(&sig_ops_mult, + sig_new(&sig_ops_sin, 1.f), /* LFO @ 1hz */ + sig_new(&sig_ops_sin, 100.f) /* oscillator @ 100hz */ + ); + for (unsigned i = 0; i < 1000; i++) + printf("sin 100hz * 1hz output %i=%f\n", i, sig_output(sig, i)); + sig = sig_free(sig); +} + +#endif diff --git a/src/libs/sig/sig.h b/src/libs/sig/sig.h new file mode 100644 index 0000000..cd22d4d --- /dev/null +++ b/src/libs/sig/sig.h @@ -0,0 +1,30 @@ +#ifndef _SIG_H +#define _SIG_H + +#include +#include + +typedef struct sig_t sig_t; + +typedef struct sig_ops_t { + size_t (*size)(va_list ap); /* return size of space needed for context for given ap */ + void (*init)(void *context, va_list ap); /* initialize context w/given ap */ + void (*destroy)(void *context); /* destroy initialized context */ + float (*output)(void *context, unsigned ticks_ms); /* output a value 0-1 from context appropriate @ time ticks_ms */ +} sig_ops_t; + +sig_t * sig_new(const sig_ops_t *ops, ...); +sig_t * sig_free(sig_t *sig); +float sig_output(sig_t *sig, unsigned ticks_ms); + +extern sig_ops_t sig_ops_sin; + +/* TODO: +extern sig_ops_t sig_ops_tri; +extern sig_ops_t sig_ops_saw; +extern sig_ops_t sig_ops_sqr; +*/ + +extern sig_ops_t sig_ops_mult; + +#endif -- cgit v1.2.1