quant.h
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// Copyright 2018 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
#ifndef WEBP_DSP_QUANT_H_
#define WEBP_DSP_QUANT_H_
#include <string.h>
#include "src/dsp/dsp.h"
#include "src/webp/types.h"
#if defined(WEBP_USE_NEON) && !defined(WEBP_ANDROID_NEON) && \
!defined(WEBP_HAVE_NEON_RTCD)
#include <arm_neon.h>
#define IsFlat IsFlat_NEON
static uint32x2_t horizontal_add_uint32x4(const uint32x4_t a) {
const uint64x2_t b = vpaddlq_u32(a);
return vadd_u32(vreinterpret_u32_u64(vget_low_u64(b)),
vreinterpret_u32_u64(vget_high_u64(b)));
}
static WEBP_INLINE int IsFlat(const int16_t* levels, int num_blocks,
int thresh) {
const int16x8_t tst_ones = vdupq_n_s16(-1);
uint32x4_t sum = vdupq_n_u32(0);
for (int i = 0; i < num_blocks; ++i) {
// Set DC to zero.
const int16x8_t a_0 = vsetq_lane_s16(0, vld1q_s16(levels), 0);
const int16x8_t a_1 = vld1q_s16(levels + 8);
const uint16x8_t b_0 = vshrq_n_u16(vtstq_s16(a_0, tst_ones), 15);
const uint16x8_t b_1 = vshrq_n_u16(vtstq_s16(a_1, tst_ones), 15);
sum = vpadalq_u16(sum, b_0);
sum = vpadalq_u16(sum, b_1);
levels += 16;
}
return thresh >= (int32_t)vget_lane_u32(horizontal_add_uint32x4(sum), 0);
}
#else
#define IsFlat IsFlat_C
static WEBP_INLINE int IsFlat(const int16_t* levels, int num_blocks,
int thresh) {
int score = 0;
while (num_blocks-- > 0) { // TODO(skal): refine positional scoring?
int i;
for (i = 1; i < 16; ++i) { // omit DC, we're only interested in AC
score += (levels[i] != 0);
if (score > thresh) return 0;
}
levels += 16;
}
return 1;
}
#endif // defined(WEBP_USE_NEON) && !defined(WEBP_ANDROID_NEON) &&
// !defined(WEBP_HAVE_NEON_RTCD)
static WEBP_INLINE int IsFlatSource16(const uint8_t* src) {
const uint32_t v = src[0] * 0x01010101u;
int i;
for (i = 0; i < 16; ++i) {
if (memcmp(src + 0, &v, 4) || memcmp(src + 4, &v, 4) ||
memcmp(src + 8, &v, 4) || memcmp(src + 12, &v, 4)) {
return 0;
}
src += BPS;
}
return 1;
}
#endif // WEBP_DSP_QUANT_H_