chromium/third_party/libvpx/source/libvpx/vp8/common/idctllm.c

/*
 *  Copyright (c) 2010 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 "./vp8_rtcd.h"

/****************************************************************************
 * Notes:
 *
 * This implementation makes use of 16 bit fixed point verio of two multiply
 * constants:
 *         1.   sqrt(2) * cos (pi/8)
 *         2.   sqrt(2) * sin (pi/8)
 * Becuase the first constant is bigger than 1, to maintain the same 16 bit
 * fixed point precision as the second one, we use a trick of
 *         x * a = x + x*(a-1)
 * so
 *         x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1).
 **************************************************************************/
static const int cospi8sqrt2minus1 = …;
static const int sinpi8sqrt2 = …;

void vp8_short_idct4x4llm_c(short *input, unsigned char *pred_ptr,
                            int pred_stride, unsigned char *dst_ptr,
                            int dst_stride) { … }

void vp8_dc_only_idct_add_c(short input_dc, unsigned char *pred_ptr,
                            int pred_stride, unsigned char *dst_ptr,
                            int dst_stride) { … }

void vp8_short_inv_walsh4x4_c(short *input, short *mb_dqcoeff) { … }

void vp8_short_inv_walsh4x4_1_c(short *input, short *mb_dqcoeff) { … }