libs/sig: add sig_ops_inv

map 0-1 inputs to their inverse 1-0

3 files changed, 57 insertions, 1 deletions

diff --git a/src/libs/sig/Makefile.am b/src/libs/sig/Makefile.am
index 8ce9366..7e2537c 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_div.c ops_expand.c ops_floor.c ops_lerp.c ops_max.c ops_min.c ops_mult.c ops_neg.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_neg.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_inv.c b/src/libs/sig/ops_inv.c
new file mode 100644
index 0000000..99ef134
--- /dev/null
+++ b/src/libs/sig/ops_inv.c
@@ -0,0 +1,55 @@
+#include <assert.h>
+
+#include "sig.h"
+
+
+typedef struct ops_inv_ctxt_t {
+	sig_t	*x;
+} ops_inv_ctxt_t;
+
+
+static size_t ops_inv_size(va_list ap)
+{
+	return sizeof(ops_inv_ctxt_t);
+}
+
+
+/* inverts 0-1 inputs to 1-0,
+ * assumes inputs will stay within 0-1 range
+ */
+static void ops_inv_init(void *context, va_list ap)
+{
+	ops_inv_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	ctxt->x = va_arg(ap, sig_t *);
+}
+
+
+static void ops_inv_destroy(void *context)
+{
+	ops_inv_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	sig_free(ctxt->x);
+}
+
+
+static float ops_inv_output(void *context, unsigned ticks_ms)
+{
+	ops_inv_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	return 1.f - sig_output(ctxt->x, ticks_ms);
+}
+
+
+sig_ops_t	sig_ops_inv = {
+	.size = ops_inv_size,
+	.init = ops_inv_init,
+	.destroy = ops_inv_destroy,
+	.output = ops_inv_output,
+};
diff --git a/src/libs/sig/sig.h b/src/libs/sig/sig.h
index deb0ce3..635bfcc 100644
--- a/src/libs/sig/sig.h
+++ b/src/libs/sig/sig.h
@@ -34,6 +34,7 @@ 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;
 extern sig_ops_t	sig_ops_lerp;
 extern sig_ops_t	sig_ops_max;
 extern sig_ops_t	sig_ops_min;