libs/sig: intrduce sig_ops_const

The simplest of signals: a constant value.

The immediate need for this is to convert ops_sin_ctxt_t.hz to
another sig_t enabling varying hz with time, while still being
able to have a fixed hz as well.

1 files changed, 43 insertions, 0 deletions

diff --git a/src/libs/sig/ops_const.c b/src/libs/sig/ops_const.c
new file mode 100644
index 0000000..aa7e862
--- /dev/null
+++ b/src/libs/sig/ops_const.c
@@ -0,0 +1,43 @@
+#include <assert.h>
+#include <math.h>
+
+#include "sig.h"
+
+
+typedef struct ops_const_ctxt_t {
+	float	value;
+} ops_const_ctxt_t;
+
+
+static size_t ops_const_size(va_list ap)
+{
+	return sizeof(ops_const_ctxt_t);
+}
+
+
+static void ops_const_init(void *context, va_list ap)
+{
+	ops_const_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	ctxt->value = va_arg(ap, double);
+}
+
+
+static float ops_const_output(void *context, unsigned ticks_ms)
+{
+	ops_const_ctxt_t	*ctxt = context;
+
+	assert(ctxt);
+
+	return ctxt->value;
+}
+
+
+sig_ops_t	sig_ops_const = {
+	.size = ops_const_size,
+	.init = ops_const_init,
+	.output = ops_const_output,
+};
+