Optimize zresampler for no re-sampling case.

diff --git a/libs/zita-resampler/vmresampler.cc b/libs/zita-resampler/vmresampler.cc
index b7442c7d15f6e44c2b0ac10fd241950ef524ef32..4e10ac78544640cb7488a061815d7b71db9bd4b8 100644 (file)
--- a/libs/zita-resampler/vmresampler.cc
+++ b/libs/zita-resampler/vmresampler.cc
@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <math.h>
+#include <algorithm>
 
 #include "zita-resampler/vmresampler.h"
 
@@ -173,6 +174,44 @@ VMResampler::process (void)
        ph = _phase;
        dp = _pstep;
        n = 2 * hl - nr;
+
+#if 1
+       /* optimized full-cycle no-resampling */
+       if (dp == np && _qstep == np && nr == 1 && inp_count == out_count) {
+
+               if (out_count >= n) {
+                       const unsigned int h1 = hl - 1;
+                       const unsigned int head = out_count - h1;
+                       const unsigned int tail = out_count - n;
+
+                       memcpy (out_data, &_buff[in + hl], h1 * sizeof (float));
+                       memcpy (&out_data[h1], inp_data, head * sizeof (float));
+                       memcpy (_buff, &inp_data[tail], n * sizeof (float));
+                       _index = 0;
+                       inp_count = 0;
+                       out_count = 0;
+                       return 0;
+               }
+
+               while (out_count) {
+                       unsigned int to_proc = std::min (out_count, _inmax - in);
+                       memcpy (&_buff[in + n], inp_data, to_proc * sizeof (float));
+                       memcpy (out_data, &_buff[in + hl], to_proc * sizeof (float));
+                       inp_data  += to_proc;
+                       out_data  += to_proc;
+                       out_count -= to_proc;
+                       in        += to_proc;
+                       if (in >= _inmax) {
+                               memcpy (_buff, _buff + in, (2 * hl - 1) * sizeof (float));
+                               in = 0;
+                       }
+               }
+               inp_count = out_count;
+               _index = in;
+               return 0;
+       }
+#endif
+
        p1 = _buff + in;
        p2 = p1 + n;