vpx/vp9/common/x86/vp9_idctllm_x86.c
Yunqing Wang 35bc02c6eb Optimize vp9_dc_only_idct_add_c function
Wrote SSE2 version of vp9_dc_only_idct_add_c function. In order to
improve performance, clipped the absolute diff values to [0, 255].
This allowed us to keep the additions/subtractions in 8 bits.
Test showed an over 2% decoder performance increase.

Change-Id: Ie1a236d23d207e4ffcd1fc9f3d77462a9c7fe09d
2013-02-26 17:16:13 -08:00

77 lines
2.4 KiB
C

/*
* Copyright (c) 2012 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE 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.
*/
#include <assert.h>
#include <emmintrin.h> // SSE2
#include "./vpx_config.h"
#include "vpx/vpx_integer.h"
#include "vp9/common/vp9_common.h"
#include "vp9/common/vp9_idct.h"
#if HAVE_SSE2
// In order to improve performance, clip absolute diff values to [0, 255],
// which allows to keep the additions/subtractions in 8 bits.
void vp9_dc_only_idct_add_sse2(int input_dc, uint8_t *pred_ptr,
uint8_t *dst_ptr, int pitch, int stride) {
int a1;
int16_t out;
uint8_t abs_diff;
__m128i p0, p1, p2, p3;
unsigned int extended_diff;
__m128i diff;
out = dct_const_round_shift(input_dc * cospi_16_64);
out = dct_const_round_shift(out * cospi_16_64);
a1 = ROUND_POWER_OF_TWO(out, 4);
// Read prediction data.
p0 = _mm_cvtsi32_si128 (*(const int *)(pred_ptr + 0 * pitch));
p1 = _mm_cvtsi32_si128 (*(const int *)(pred_ptr + 1 * pitch));
p2 = _mm_cvtsi32_si128 (*(const int *)(pred_ptr + 2 * pitch));
p3 = _mm_cvtsi32_si128 (*(const int *)(pred_ptr + 3 * pitch));
// Unpack prediction data, and store 4x4 array in 1 XMM register.
p0 = _mm_unpacklo_epi32(p0, p1);
p2 = _mm_unpacklo_epi32(p2, p3);
p0 = _mm_unpacklo_epi64(p0, p2);
// Clip dc value to [0, 255] range. Then, do addition or subtraction
// according to its sign.
if (a1 >= 0) {
abs_diff = (a1 > 255) ? 255 : a1;
extended_diff = abs_diff * 0x01010101u;
diff = _mm_shuffle_epi32(_mm_cvtsi32_si128((int)extended_diff), 0);
p1 = _mm_adds_epu8(p0, diff);
} else {
abs_diff = (a1 < -255) ? 255 : -a1;
extended_diff = abs_diff * 0x01010101u;
diff = _mm_shuffle_epi32(_mm_cvtsi32_si128((int)extended_diff), 0);
p1 = _mm_subs_epu8(p0, diff);
}
// Store results to dst.
*(int *)dst_ptr = _mm_cvtsi128_si32(p1);
dst_ptr += stride;
p1 = _mm_srli_si128(p1, 4);
*(int *)dst_ptr = _mm_cvtsi128_si32(p1);
dst_ptr += stride;
p1 = _mm_srli_si128(p1, 4);
*(int *)dst_ptr = _mm_cvtsi128_si32(p1);
dst_ptr += stride;
p1 = _mm_srli_si128(p1, 4);
*(int *)dst_ptr = _mm_cvtsi128_si32(p1);
}
#endif