From 6f4775a8eeb30d0fde622f4e89979179af47d219 Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Sun, 16 Mar 2014 08:57:04 +0100 Subject: pcm/Neon: apply bit shift during float->int conversion Avoid multiplication. This is a speedup of 20%. --- src/pcm/Neon.hxx | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/src/pcm/Neon.hxx b/src/pcm/Neon.hxx index a6f52db42..2d3a59d2b 100644 --- a/src/pcm/Neon.hxx +++ b/src/pcm/Neon.hxx @@ -68,21 +68,16 @@ struct NeonFloatTo16 { static constexpr size_t BLOCK_SIZE = 16; void Convert(int16_t *dst, const float *src, const size_t n) const { - const float32x4_t factor = - vdupq_n_f32(1 << (DstTraits::BITS - 1)); - for (unsigned i = 0; i < n / BLOCK_SIZE; ++i, src += BLOCK_SIZE, dst += BLOCK_SIZE) { /* load 16 float samples into 4 quad registers */ float32x4x4_t value = vld4q_f32(src); - /* apply factor */ - neon_x4_b(vmulq_f32, value, value, factor); - /* convert to 32 bit integer */ int32x4x4_t ivalue; - neon_x4_u(vcvtq_s32_f32, ivalue, value); + neon_x4_b(vcvtq_n_s32_f32, ivalue, value, + DstTraits::BITS - 1); /* convert to 16 bit integer with saturation */ int16x4x4_t nvalue; -- cgit v1.2.3