From 87a59598ff3cf91f153ca0efd577b8f0709b4fcc Mon Sep 17 00:00:00 2001
From: Krzysztof Foltman <wdev@foltman.com>
Date: Thu, 13 Feb 2014 00:13:15 +0000
Subject: [PATCH] Framework: implementation of "seamless" bypass

---
 src/calf/bypass.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 src/calf/bypass.h

diff --git a/src/calf/bypass.h b/src/calf/bypass.h
new file mode 100644
index 0000000..ec5b841
--- /dev/null
+++ b/src/calf/bypass.h
@@ -0,0 +1,55 @@
+#ifndef CALF_BYPASS_H
+#define CALF_BYPASS_H
+
+#include "inertia.h"
+
+namespace dsp {
+
+class bypass
+{
+    inertia<linear_ramp> ramp;
+    float first_value, next_value;
+    
+public:
+    bypass(int _ramp_len = 1024)
+    : ramp(linear_ramp(_ramp_len))
+    {
+    }
+    
+    /// Pass the new state of the bypass button, and return the ramp-aware
+    /// bypass state
+    bool update(bool new_state, uint32_t nsamples)
+    {
+        ramp.set_inertia(new_state ? 1.f : 0.f);
+        first_value = ramp.get_last();
+        ramp.step_many(nsamples);
+        next_value = ramp.get_last();
+        return first_value >= 1 && next_value >= 1;
+    }
+    
+    /// Apply ramp to prevent clicking
+    void crossfade(float *inputs[], float *outputs[], uint32_t nbuffers, uint32_t offset, uint32_t nsamples)
+    {
+        if (!nsamples || (first_value + next_value) == 0)
+            return;
+        float step = (next_value - first_value) / nsamples;
+        for (uint32_t b = 0; b < nbuffers; ++b)
+        {
+            float *out = outputs[b] + offset, *in = inputs[b] + offset;
+            if (first_value >= 1 && next_value >= 1)
+                memcpy(out, in, nsamples * sizeof(float));
+            else
+            {
+                for (uint32_t i = 0; i < nsamples; ++i)
+                {
+                    float bypass_amt = first_value + i * step;
+                    out[i] += (in[i] - out[i]) * bypass_amt;
+                }
+            }
+        }
+    }
+};
+
+}
+
+#endif
-- 
2.11.4.GIT