From 1c1ae5ee7243e731c7b44a11400e19bb8dab047b Mon Sep 17 00:00:00 2001
From: Vito Caputo <vcaputo@pengaru.com>
Date: Mon, 3 Feb 2020 15:30:53 -0800
Subject: libs/sig: add sig_ops_inv for additive inverse

aka negation
---
 src/libs/sig/Makefile.am |  2 +-
 src/libs/sig/ops_inv.c   | 52 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/libs/sig/sig.h       |  1 +
 3 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 src/libs/sig/ops_inv.c

diff --git a/src/libs/sig/Makefile.am b/src/libs/sig/Makefile.am
index efec325..64715fe 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_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_sin.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..abb1102
--- /dev/null
+++ b/src/libs/sig/ops_inv.c
@@ -0,0 +1,52 @@
+#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);
+}
+
+
+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 -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 bc2b28b..3456af9 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_ceil;
 extern sig_ops_t	sig_ops_clamp;
 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;
-- 
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