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authorVito Caputo <vcaputo@pengaru.com>2020-02-03 15:59:56 -0800
committerVito Caputo <vcaputo@pengaru.com>2020-02-03 16:04:18 -0800
commit59b276edf6cd3d53fab1d45819a34ef1627e3389 (patch)
tree4beb238d5fd9a10298ed99c393709c87df1cc723
parent1c1ae5ee7243e731c7b44a11400e19bb8dab047b (diff)
libs/sig: add sig_ops_scale w/test example
This assumes the input value is always 0-1, but may be used to produce values in any signed range, mapped linearly to the input.
-rw-r--r--src/libs/sig/Makefile.am2
-rw-r--r--src/libs/sig/ops_scale.c67
-rw-r--r--src/libs/sig/sig.c13
-rw-r--r--src/libs/sig/sig.h1
4 files changed, 82 insertions, 1 deletions
diff --git a/src/libs/sig/Makefile.am b/src/libs/sig/Makefile.am
index 64715fe..e53a4bd 100644
--- a/src/libs/sig/Makefile.am
+++ b/src/libs/sig/Makefile.am
@@ -1,3 +1,3 @@
noinst_LIBRARIES = libsig.a
-libsig_a_SOURCES = ops_abs.c ops_ceil.c ops_clamp.c ops_const.c ops_floor.c ops_inv.c ops_lerp.c ops_max.c ops_min.c ops_mult.c ops_pow.c ops_rand.c ops_round.c ops_sin.c sig.c sig.h
+libsig_a_SOURCES = ops_abs.c ops_ceil.c ops_clamp.c ops_const.c ops_floor.c ops_inv.c ops_lerp.c ops_max.c ops_min.c ops_mult.c ops_pow.c ops_rand.c ops_round.c ops_scale.c ops_sin.c sig.c sig.h
libsig_a_CPPFLAGS = -I@top_srcdir@/src
diff --git a/src/libs/sig/ops_scale.c b/src/libs/sig/ops_scale.c
new file mode 100644
index 0000000..22c0363
--- /dev/null
+++ b/src/libs/sig/ops_scale.c
@@ -0,0 +1,67 @@
+#include <assert.h>
+
+#include "sig.h"
+
+
+typedef struct ops_scale_ctxt_t {
+ sig_t *value, *min, *max;
+} ops_scale_ctxt_t;
+
+
+static size_t ops_scale_size(va_list ap)
+{
+ return sizeof(ops_scale_ctxt_t);
+}
+
+
+/* expects three sig_t's: value, min, max.
+ * min is assumed to be always <= max,
+ * and value is assumed to always be 0-1
+ */
+static void ops_scale_init(void *context, va_list ap)
+{
+ ops_scale_ctxt_t *ctxt = context;
+
+ assert(ctxt);
+
+ ctxt->value = va_arg(ap, sig_t *);
+ ctxt->min = va_arg(ap, sig_t *);
+ ctxt->max = va_arg(ap, sig_t *);
+}
+
+
+static void ops_scale_destroy(void *context)
+{
+ ops_scale_ctxt_t *ctxt = context;
+
+ assert(ctxt);
+
+ sig_free(ctxt->value);
+ sig_free(ctxt->min);
+ sig_free(ctxt->max);
+}
+
+
+static float ops_scale_output(void *context, unsigned ticks_ms)
+{
+ ops_scale_ctxt_t *ctxt = context;
+ float value, min, max;
+
+ assert(ctxt);
+
+ value = sig_output(ctxt->value, ticks_ms);
+ min = sig_output(ctxt->min, ticks_ms);
+ max = sig_output(ctxt->max, ticks_ms);
+
+ assert(max >= min);
+
+ return value * (max - min) + min;
+}
+
+
+sig_ops_t sig_ops_scale = {
+ .size = ops_scale_size,
+ .init = ops_scale_init,
+ .destroy = ops_scale_destroy,
+ .output = ops_scale_output,
+};
diff --git a/src/libs/sig/sig.c b/src/libs/sig/sig.c
index 4146cd3..c68a420 100644
--- a/src/libs/sig/sig.c
+++ b/src/libs/sig/sig.c
@@ -132,6 +132,19 @@ int main(int argc, char *argv[])
for (unsigned i = 0; i < 1000; i++)
printf("sin 10hz ^ (sin 1hz * 50) output %i=%f\n", i, sig_output(sig, i));
sig = sig_free(sig);
+
+ sig = sig_new(&sig_ops_scale, /* scale a */
+ sig_new(&sig_ops_lerp, /* linear interpolation */
+ sig_new(&sig_ops_sin, sig_new(&sig_ops_const, 10.f)), /* between one 10hz oscillator */
+ sig_new(&sig_ops_sin, sig_new(&sig_ops_const, 33.f)), /* and another 33hz oscillator */
+ sig_new(&sig_ops_sin, sig_new(&sig_ops_const, 2.f)) /* weighted by a 2hz oscillator */
+ ),
+ sig_new(&sig_ops_const, -100.f), sig_new(&sig_ops_const, 100.f) /* to the range -100 .. +100 */
+ );
+ for (unsigned i = 0; i < 1000; i++)
+ printf("scale(lerp(sin(10hz), sin(33hz), sin(2hz)), -100, +100) 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
index 3456af9..b54bfb7 100644
--- a/src/libs/sig/sig.h
+++ b/src/libs/sig/sig.h
@@ -38,5 +38,6 @@ extern sig_ops_t sig_ops_min;
extern sig_ops_t sig_ops_mult;
extern sig_ops_t sig_ops_pow;
extern sig_ops_t sig_ops_round;
+extern sig_ops_t sig_ops_scale;
#endif
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