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core: Add ARM NEON optimized sample conversion code

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final:
* includes some minor style fixes and build-time changes to allow
  building a single binary for neon and non-neon systems
v4:
* fix for sample length < 4
v3:
* convert from intrinsics to inline assembly
v2:
* load and store data with vld1/vld1q and vst1/vst1q, resp., to work
  around alignment issues of compiler-generated vldmia instruction
* remove redundant check for NEON flags

Ubuntu/Linaro gcc 4.6.3
arm-linux-gnueabi-gcc -O2 -mcpu=cortex-a8 -mfloat-abi=softfp -mfpu=neon

runtime on beagle-xm:

D: [pulseaudio] sconv_neon.c: checking NEON sconv_s16le_from_float
I: [pulseaudio] sconv_neon.c: NEON: 3754 usec.
I: [pulseaudio] sconv_neon.c: ref: 58594 usec.
D: [pulseaudio] sconv_neon.c: checking NEON sconv_s16le_to_float
I: [pulseaudio] sconv_neon.c: NEON: 1831 usec.
I: [pulseaudio] sconv_neon.c: ref: 10528 usec.
I: [pulseaudio] sconv_neon.c: Initialising ARM NEON optimized conversions.

conversion may be off by one for some samples due to rounding issues
This commit is contained in:
Peter Meerwald 2012-10-23 17:54:57 +02:00 • committed by Arun Raghavan
parent 4171df3019
commit 1319c4533a
6 changed files with 193 additions and 1 deletions
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110
src/pulsecore/sconv_neon.c Normal file
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/***
This file is part of PulseAudio.
Copyright 2012 Peter Meerwald <p.meerwald@bct-electronic.com>
PulseAudio is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License,
or (at your option) any later version.
PulseAudio is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <pulse/rtclock.h>
#include <pulsecore/macro.h>
#include <pulsecore/endianmacros.h>
#include "cpu-arm.h"
#include "sconv.h"
#include <math.h>
#include <arm_neon.h>
static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t *dst) {
unsigned i = n & 3;
__asm__ __volatile__ (
"movs %[n], %[n], lsr #2 \n\t"
"beq 2f \n\t"
"vdup.f32 q2, %[plusone] \n\t"
"vneg.f32 q3, q2 \n\t"
"vdup.f32 q4, %[scale] \n\t"
"vdup.u32 q5, %[mask] \n\t"
"vdup.f32 q6, %[half] \n\t"
"1: \n\t"
"vld1.32 {q0}, [%[src]]! \n\t"
"vmin.f32 q0, q0, q2 \n\t" /* clamp */
"vmax.f32 q0, q0, q3 \n\t"
"vmul.f32 q0, q0, q4 \n\t" /* scale */
"vand.u32 q1, q0, q5 \n\t"
"vorr.u32 q1, q1, q6 \n\t" /* round */
"vadd.f32 q0, q0, q1 \n\t"
"vcvt.s32.f32 q0, q0 \n\t" /* narrow */
"vmovn.i32 d0, q0 \n\t"
"subs %[n], %[n], #1 \n\t"
"vst1.16 {d0}, [%[dst]]! \n\t"
"bgt 1b \n\t"
"2: \n\t"
: [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n) /* output operands (or input operands that get modified) */
: [plusone] "r" (1.0f), [scale] "r" (32767.0f), [half] "r" (0.5f), [mask] "r" (0x80000000) /* input operands */
: "memory", "cc", "q0", "q1", "q2", "q3", "q4", "q5", "q6" /* clobber list */
);
/* leftovers */
while (i--) {
*dst++ = (int16_t) lrintf(PA_CLAMP_UNLIKELY(*src, -1.0f, 1.0f) * 0x7FFF);
src++;
}
}
static void pa_sconv_s16le_to_f32ne_neon(unsigned n, const int16_t *src, float *dst) {
unsigned i = n & 3;
const float invscale = 1.0f / 0x7FFF;
__asm__ __volatile__ (
"movs %[n], %[n], lsr #2 \n\t"
"beq 2f \n\t"
"vdup.f32 q1, %[invscale] \n\t"
"1: \n\t"
"vld1.16 {d0}, [%[src]]! \n\t"
"vmovl.s16 q0, d0 \n\t"
"vcvt.f32.s32 q0, q0 \n\t"
"vmul.f32 q0, q0, q1 \n\t"
"subs %[n], %[n], #1 \n\t"
"vst1.32 {q0}, [%[dst]]! \n\t"
"bgt 1b \n\t"
"2: \n\t"
: [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n) /* output operands (or input operands that get modified) */
: [invscale] "r" (invscale) /* input operands */
: "memory", "cc", "q0", "q1" /* clobber list */
);
/* leftovers */
while (i--) {
*dst++ = *src++ * invscale;
}
}
void pa_convert_func_init_neon(pa_cpu_arm_flag_t flags) {
pa_log_info("Initialising ARM NEON optimized conversions.");
pa_set_convert_from_float32ne_function(PA_SAMPLE_S16LE, (pa_convert_func_t) pa_sconv_s16le_from_f32ne_neon);
pa_set_convert_to_float32ne_function(PA_SAMPLE_S16LE, (pa_convert_func_t) pa_sconv_s16le_to_f32ne_neon);
}