libs/sig: square wave; sig_ops_sqr / sig_new_sqr()

This builds minimally upon the existing sine wave code,
just use the sign to drive the signal high or low.

Wikipedia shows a third state for 0 values, but that's for a -1..+1
signal.  I'm producing all 0-1 signals as it's more convenient for
this application, but it seems like it would be awkward to return
.5f for the 0 case.  So 0 is being treated as just another positive
value; high.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libs/sig/sig.c b/src/libs/sig/sig.c
index 2c3452c..87a76c4 100644
--- a/src/libs/sig/sig.c
+++ b/src/libs/sig/sig.c
@@ -234,6 +234,12 @@ sig_t * sig_new_sin(sig_t *hz)
 }
 
 
+sig_t * sig_new_sqr(sig_t *hz)
+{
+	return sig_new(&sig_ops_sqr, hz);
+}
+
+
 sig_t * sig_new_sub(sig_t *a, sig_t *b)
 {
 	return sig_new(&sig_ops_sub, a, b);