[pulseaudio-discuss] [PATCH] sconv: avoid multiply in ARM NEON float->s16 conversion
Peter Meerwald
pmeerw at pmeerw.net
Tue Jul 2 02:43:35 PDT 2013
From: Peter Meerwald <p.meerwald at bct-electronic.com>
optimization idea taken from libavresample
Signed-off-by: Peter Meerwald <pmeerw at pmeerw.net>
---
src/pulsecore/sconv_neon.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/src/pulsecore/sconv_neon.c b/src/pulsecore/sconv_neon.c
index ddcdcc2..110c677 100644
--- a/src/pulsecore/sconv_neon.c
+++ b/src/pulsecore/sconv_neon.c
@@ -36,12 +36,9 @@ static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t
"movs %[n], %[n], lsr #2 \n\t"
"beq 2f \n\t"
- "vdup.f32 q1, %[scale] \n\t"
-
"1: \n\t"
"vld1.32 {q0}, [%[src]]! \n\t"
- "vmul.f32 q0, q0, q1 \n\t" /* scale */
- "vcvt.s32.f32 q0, q0, #16 \n\t" /* s32<-f32 as 16:16 fixed-point */
+ "vcvt.s32.f32 q0, q0, #31 \n\t" /* s32<-f32 as 16:16 fixed-point */
"vqrshrn.s32 d0, q0, #16 \n\t" /* shift, round, narrow */
"subs %[n], %[n], #1 \n\t"
"vst1.16 {d0}, [%[dst]]! \n\t"
@@ -50,8 +47,8 @@ static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t
"2: \n\t"
: [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n) /* output operands (or input operands that get modified) */
- : [scale] "r" (32768.0f) /* input operands */
- : "memory", "cc", "q0", "q1" /* clobber list */
+ : /* input operands */
+ : "memory", "cc", "q0" /* clobber list */
);
/* leftovers */
--
1.7.9.5
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