libs/sig: add sig_ops_inv

map 0-1 inputs to their inverse 1-0

1 files changed, 55 insertions, 0 deletions

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,
+};