[pulseaudio-discuss] [PATCH 6/6 v3] core: Add ARM NEON optimized sample conversion code

Peter Meerwald pmeerw at pmeerw.net
Tue Jul 24 01:20:36 PDT 2012


From: Peter Meerwald <p.meerwald at bct-electronic.com>

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

Signed-off-by: Peter Meerwald <p.meerwald at bct-electronic.com>
---
 src/Makefile.am            |    2 +-
 src/pulsecore/sconv_neon.c |  209 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 210 insertions(+), 1 deletions(-)
 create mode 100644 src/pulsecore/sconv_neon.c

diff --git a/src/Makefile.am b/src/Makefile.am
index 6b9df97..0445445 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -832,7 +832,7 @@ libpulsecore_ at PA_MAJORMINOR@_la_SOURCES = \
 		pulsecore/svolume_neon.c \
 		pulsecore/sconv-s16be.c pulsecore/sconv-s16be.h \
 		pulsecore/sconv-s16le.c pulsecore/sconv-s16le.h \
-		pulsecore/sconv_sse.c \
+		pulsecore/sconv_sse.c pulsecore/sconv_neon.c \
 		pulsecore/sconv.c pulsecore/sconv.h \
 		pulsecore/shared.c pulsecore/shared.h \
 		pulsecore/sink-input.c pulsecore/sink-input.h \
diff --git a/src/pulsecore/sconv_neon.c b/src/pulsecore/sconv_neon.c
new file mode 100644
index 0000000..94003a0
--- /dev/null
+++ b/src/pulsecore/sconv_neon.c
@@ -0,0 +1,209 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2012 Peter Meerwald <p.meerwald at 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"
+
+#if defined(__ARM_NEON__)
+
+#include <math.h>
+#include <arm_neon.h>
+
+#define RUN_TEST
+
+static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t *dst) {
+    unsigned i = n & 3;
+
+    asm volatile (
+    "mov        %[n], %[n], lsr #2\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"
+      /* output operands (or input operands that get modified) */
+    : [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n)
+    : [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 (
+    "mov        %[n], %[n], lsr #2\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"
+      /* output operands (or input operands that get modified) */
+    : [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n)
+    : [invscale] "r" (invscale) /* input operands */
+    : "memory", "cc", "q0", "q1" /* clobber list */
+    );
+
+    // leftovers
+    while (i--) {
+        *dst++ = *src++ * invscale;
+    }
+}
+
+#ifdef RUN_TEST
+#define SAMPLES 1019
+#define TIMES 300
+
+static void run_test_from(void) {
+    int16_t samples[SAMPLES];
+    int16_t samples_ref[SAMPLES];
+    float floats[SAMPLES];
+    int i;
+    pa_usec_t start, stop;
+    pa_convert_func_t func;
+
+    pa_log_debug("checking NEON sconv_s16le_from_float");
+
+    memset(samples_ref, 0, sizeof(samples_ref));
+    memset(samples, 0, sizeof(samples));
+
+    for (i = 0; i < SAMPLES; i++) {
+        floats[i] = 2.1f * (rand()/(float) RAND_MAX - 0.5f);
+    }
+
+    func = (pa_convert_func_t) pa_get_convert_from_float32ne_function(PA_SAMPLE_S16LE);
+    func(SAMPLES, floats, samples_ref);
+    pa_sconv_s16le_from_f32ne_neon(SAMPLES, floats, samples);
+
+    for (i = 0; i < SAMPLES; i++) {
+        if (abs(samples[i] - samples_ref[i]) > 0) {
+            pa_log_debug("%d: %d != %d (%f)", i, samples[i], samples_ref[i],
+                      floats[i]);
+            break;
+        }
+    }
+
+    start = pa_rtclock_now();
+    for (i = 0; i < TIMES; i++) {
+        pa_sconv_s16le_from_f32ne_neon(SAMPLES, floats, samples);
+    }
+    stop = pa_rtclock_now();
+    pa_log_info("NEON: %llu usec.", (long long unsigned int)(stop - start));
+
+    start = pa_rtclock_now();
+    for (i = 0; i < TIMES; i++) {
+        func(SAMPLES, floats, samples_ref);
+    }
+    stop = pa_rtclock_now();
+    pa_log_info("ref: %llu usec.", (long long unsigned int)(stop - start));
+}
+
+static void run_test_to(void) {
+    int16_t samples[SAMPLES];
+    float floats[SAMPLES];
+    float floats_ref[SAMPLES];
+    int i;
+    pa_usec_t start, stop;
+    pa_convert_func_t func;
+
+    pa_log_debug("checking NEON sconv_s16le_to_float");
+
+    memset(floats_ref, 0, sizeof(floats_ref));
+    memset(floats, 0, sizeof(float));
+
+    for (i = 0; i < SAMPLES; i++) {
+        samples[i] = rand() - RAND_MAX/2;
+    }
+
+    func = (pa_convert_func_t) pa_get_convert_to_float32ne_function(PA_SAMPLE_S16LE);
+    func(SAMPLES, samples, floats_ref);
+    pa_sconv_s16le_to_f32ne_neon(SAMPLES, samples, floats);
+
+    for (i = 0; i < SAMPLES; i++) {
+        if (fabsf(floats[i] - floats_ref[i]) > 0.00001) {
+            pa_log_debug("%d: %.8f != %.8f (%d)", i, floats[i], floats_ref[i],
+                      samples[i]);
+            break;
+        }
+    }
+
+    start = pa_rtclock_now();
+    for (i = 0; i < TIMES; i++) {
+        pa_sconv_s16le_to_f32ne_neon(SAMPLES, samples, floats);
+    }
+    stop = pa_rtclock_now();
+    pa_log_info("NEON: %llu usec.", (long long unsigned int)(stop - start));
+
+    start = pa_rtclock_now();
+    for (i = 0; i < TIMES; i++) {
+        func(SAMPLES, samples, floats_ref);
+    }
+    stop = pa_rtclock_now();
+    pa_log_info("ref: %llu usec.", (long long unsigned int)(stop - start));
+}
+#endif /* RUN_TEST */
+
+#endif /* defined(__ARM_NEON__) */
+
+void pa_convert_func_init_neon(pa_cpu_arm_flag_t flags) {
+#if defined (__ARM_NEON__)
+
+#ifdef RUN_TEST
+    run_test_from();
+    run_test_to();
+#endif
+
+    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);
+
+#endif /* defined (__ARM_NEON__) */
+}
-- 
1.7.5.4



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