opus: arm asm for C_MULC

speeds up decoding of a 64kbps test_file by 1.5MHz on c200 (pp)
and 1.9MHz on fuzev1 (amsv1)

Change-Id: I1db460b634eba608c3e00541d96fc93d5a05710b
Signed-off-by: Nils Wallménius <nils@rockbox.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libopus/celt/_kiss_fft_guts.h b/lib/rbcodec/codecs/libopus/celt/_kiss_fft_guts.h
index 6e806bbc23..b1fe8fbeb7 100644
--- a/lib/rbcodec/codecs/libopus/celt/_kiss_fft_guts.h
+++ b/lib/rbcodec/codecs/libopus/celt/_kiss_fft_guts.h
@@ -80,6 +80,28 @@
                    : [ap] "a" (&(a)), [bp] "a" (&(b)) \
                    : "d0", "d1", "d2", "d3", "cc"); \
     }
+#elif defined(CPU_ARM)
+#   define C_MULC(m,a,b) \
+    { \
+      asm volatile( \
+                   "ldmia %[ap], {r0,r1}                  \n\t" \
+                   "ldrsh r2, [%[bp], #0]                 \n\t" \
+                   "ldrsh r3, [%[bp], #2]                 \n\t" \
+                   \
+                   "smull r4, %[mr], r0, r2               \n\t" \
+                   "smlal r4, %[mr], r1, r3               \n\t" \
+                   "mov   r4, r4, lsr #15                 \n\t" \
+                   "orr   %[mr], r4, %[mr], lsl #17       \n\t" \
+                   \
+                   "smull r4, %[mi], r1, r2               \n\t" \
+                   "rsb   r3, r3, #0                      \n\t" \
+                   "smlal r4, %[mi], r0, r3               \n\t" \
+                   "mov   r4, r4, lsr #15                 \n\t" \
+                   "orr   %[mi], r4, %[mi], lsl #17       \n\t" \
+                   : [mr] "=r" ((m).r), [mi] "=r" ((m).i) \
+                   : [ap] "r" (&(a)), [bp] "r" (&(b)) \
+                   : "r0", "r1", "r2", "r3", "r4"); \
+}
 #else
 #   define C_MULC(m,a,b) \
       do{ (m).r = ADD32(S_MUL((a).r,(b).r) , S_MUL((a).i,(b).i)); \