libs/sig: add sig_ops_div

Included a little hack to defend against divide by zero, seems
reasonable given the intended use cases.

3 files changed, 63 insertions, 1 deletions

diff --git a/src/libs/sig/Makefile.am b/src/libs/sig/Makefile.am
index 55eccd0..7c13a16 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_add.c ops_ceil.c ops_clamp.c ops_const.c ops_expand.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 ops_sub.c sig.c sig.h
+libsig_a_SOURCES = ops_abs.c ops_add.c ops_ceil.c ops_clamp.c ops_const.c ops_div.c ops_expand.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 ops_sub.c sig.c sig.h
 libsig_a_CPPFLAGS = -I@top_srcdir@/src
diff --git a/src/libs/sig/ops_div.c b/src/libs/sig/ops_div.c
new file mode 100644
index 0000000..d0fe4e3
--- /dev/null
+++ b/src/libs/sig/ops_div.c
@@ -0,0 +1,61 @@
+#include <assert.h>
+#include <float.h>
+
+#include "sig.h"
+
+
+typedef struct ops_div_ctxt_t {
+	sig_t	*a, *b;
+} ops_div_ctxt_t;
+
+
+static size_t ops_div_size(va_list ap)
+{
+	return sizeof(ops_div_ctxt_t);
+}
+
+
+static void ops_div_init(void *context, va_list ap)
+{
+	ops_div_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	ctxt->a = va_arg(ap, sig_t *);
+	ctxt->b = va_arg(ap, sig_t *);
+}
+
+
+static void ops_div_destroy(void *context)
+{
+	ops_div_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	sig_free(ctxt->a);
+	sig_free(ctxt->b);
+}
+
+
+static float ops_div_output(void *context, unsigned ticks_ms)
+{
+	ops_div_ctxt_t	*ctxt = context;
+	float		divisor;
+
+	assert(ctxt);
+
+	/* XXX: protect against divide by zero by replacing with epsilon */
+	divisor = sig_output(ctxt->b, ticks_ms);
+	if (divisor == 0.f)
+		divisor = FLT_EPSILON;
+
+	return sig_output(ctxt->a, ticks_ms) / divisor;
+}
+
+
+sig_ops_t	sig_ops_div = {
+	.size = ops_div_size,
+	.init = ops_div_init,
+	.destroy = ops_div_destroy,
+	.output = ops_div_output,
+};
diff --git a/src/libs/sig/sig.h b/src/libs/sig/sig.h
index 653202c..57b9a90 100644
--- a/src/libs/sig/sig.h
+++ b/src/libs/sig/sig.h
@@ -31,6 +31,7 @@ extern sig_ops_t	sig_ops_abs;
 extern sig_ops_t	sig_ops_add;
 extern sig_ops_t	sig_ops_ceil;
 extern sig_ops_t	sig_ops_clamp;
+extern sig_ops_t	sig_ops_div;
 extern sig_ops_t	sig_ops_expand;
 extern sig_ops_t	sig_ops_floor;
 extern sig_ops_t	sig_ops_inv;