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authorVito Caputo <vcaputo@pengaru.com>2020-02-10 23:47:34 -0800
committerVito Caputo <vcaputo@pengaru.com>2020-02-10 23:47:34 -0800
commit8ff41d060344af4d045bdd79bb826231d6739c7f (patch)
treee7e688c2d06d498b86838367c7e59203a58fb650 /src/libs
parent64a0fe99038b9c58a815a92db2eb2ded1fd2801a (diff)
libs/sig: triangle wave; sig_ops_tri / sig_new_tri()
Added a triangle wave
Diffstat (limited to 'src/libs')
-rw-r--r--src/libs/sig/ops_sin.c23
-rw-r--r--src/libs/sig/sig.c6
-rw-r--r--src/libs/sig/sig.h3
3 files changed, 31 insertions, 1 deletions
diff --git a/src/libs/sig/ops_sin.c b/src/libs/sig/ops_sin.c
index da5b371..4acc8e5 100644
--- a/src/libs/sig/ops_sin.c
+++ b/src/libs/sig/ops_sin.c
@@ -50,6 +50,15 @@ static float output_sqr(float rads)
}
+static float output_tri(float rads)
+{
+ /* This approximation comes from:
+ * https://calculushowto.com/triangle-wave-function/
+ */
+ return M_2_PI * asinf(fabsf(sinf(M_PI * rads)));
+}
+
+
static float output(void *context, unsigned ticks_ms, float (*output_fn)(float rads))
{
ops_sin_ctxt_t *ctxt = context;
@@ -87,6 +96,12 @@ static float ops_sqr_output(void *context, unsigned ticks_ms)
}
+static float ops_tri_output(void *context, unsigned ticks_ms)
+{
+ return output(context, ticks_ms, output_tri);
+}
+
+
sig_ops_t sig_ops_sin = {
.size = ops_sin_size,
.init = ops_sin_init,
@@ -101,3 +116,11 @@ sig_ops_t sig_ops_sqr = {
.destroy = ops_sin_destroy,
.output = ops_sqr_output,
};
+
+
+sig_ops_t sig_ops_tri = {
+ .size = ops_sin_size,
+ .init = ops_sin_init,
+ .destroy = ops_sin_destroy,
+ .output = ops_tri_output,
+};
diff --git a/src/libs/sig/sig.c b/src/libs/sig/sig.c
index 87a76c4..203a37a 100644
--- a/src/libs/sig/sig.c
+++ b/src/libs/sig/sig.c
@@ -240,6 +240,12 @@ sig_t * sig_new_sqr(sig_t *hz)
}
+sig_t * sig_new_tri(sig_t *hz)
+{
+ return sig_new(&sig_ops_tri, hz);
+}
+
+
sig_t * sig_new_sub(sig_t *a, sig_t *b)
{
return sig_new(&sig_ops_sub, a, b);
diff --git a/src/libs/sig/sig.h b/src/libs/sig/sig.h
index 917dbc4..9be3012 100644
--- a/src/libs/sig/sig.h
+++ b/src/libs/sig/sig.h
@@ -38,15 +38,16 @@ sig_t * sig_new_round(sig_t *x);
sig_t * sig_new_scale(sig_t *x, sig_t *min, sig_t *max);
sig_t * sig_new_sin(sig_t *hz);
sig_t * sig_new_sqr(sig_t *hz);
+sig_t * sig_new_tri(sig_t *hz);
sig_t * sig_new_sub(sig_t *a, sig_t *b);
extern sig_ops_t sig_ops_const;
extern sig_ops_t sig_ops_rand;
extern sig_ops_t sig_ops_sin;
extern sig_ops_t sig_ops_sqr;
+extern sig_ops_t sig_ops_tri;
/* TODO:
-extern sig_ops_t sig_ops_tri;
extern sig_ops_t sig_ops_saw;
*/
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