opus: replace copy loops with calls to memcpy

speeds up decoding of a 64kbps test file by 0.5Hz on h300 (cf)
0.9MHz on c200 (pp) and 0.2MHz on fuzev1 (amsv1)

Change-Id: Ib537c2393fa6dca0b61e4e9f80eef5e688c2c2bd
Signed-off-by: Nils Wallménius <nils@rockbox.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/lib/rbcodec/codecs/libopus/celt/mdct.c b/lib/rbcodec/codecs/libopus/celt/mdct.c
index 8fc1b54db7..0f9af9eac4 100644
--- a/lib/rbcodec/codecs/libopus/celt/mdct.c
+++ b/lib/rbcodec/codecs/libopus/celt/mdct.c
@@ -305,12 +305,11 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
       kiss_fft_scalar * OPUS_RESTRICT yp1 = out+N4-overlap/2;
       const opus_val16 * OPUS_RESTRICT wp1 = window;
       const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
-      for(i = 0; i< N4-overlap/2; i++)
-      {
-         *xp1 = *fp1;
-         xp1--;
-         fp1--;
-      }
+
+      i = N4-overlap/2;
+      xp1 -= N4-overlap/2;
+      fp1 -= N4-overlap/2;
+      OPUS_COPY(xp1+1, fp1+1, N4-overlap/2);
       for(; i < N4; i++)
       {
          kiss_fft_scalar x1;
@@ -327,12 +326,11 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
       kiss_fft_scalar * OPUS_RESTRICT yp2 = out+N-1-(N4-overlap/2);
       const opus_val16 * OPUS_RESTRICT wp1 = window;
       const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
-      for(i = 0; i< N4-overlap/2; i++)
-      {
-         *xp2 = *fp2;
-         xp2++;
-         fp2++;
-      }
+
+      i = N4-overlap/2;
+      OPUS_COPY(xp2, fp2, N4-overlap/2);
+      xp2 += N4-overlap/2;
+      fp2 += N4-overlap/2;
       for(; i < N4; i++)
       {
          kiss_fft_scalar x2;