ref: 1b3d77536626515f9040b8646cbf72daf9a59747
dir: /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 = 20091; static const int sinpi8sqrt2 = 35468; void vp8_short_idct4x4llm_c(short *input, unsigned char *pred_ptr, int pred_stride, unsigned char *dst_ptr, int dst_stride) { int i; int r, c; int a1, b1, c1, d1; short output[16]; short *ip = input; short *op = output; int temp1, temp2; int shortpitch = 4; for (i = 0; i < 4; i++) { a1 = ip[0] + ip[8]; b1 = ip[0] - ip[8]; temp1 = (ip[4] * sinpi8sqrt2) >> 16; temp2 = ip[12] + ((ip[12] * cospi8sqrt2minus1) >> 16); c1 = temp1 - temp2; temp1 = ip[4] + ((ip[4] * cospi8sqrt2minus1) >> 16); temp2 = (ip[12] * sinpi8sqrt2) >> 16; d1 = temp1 + temp2; op[shortpitch*0] = a1 + d1; op[shortpitch*3] = a1 - d1; op[shortpitch*1] = b1 + c1; op[shortpitch*2] = b1 - c1; ip++; op++; } ip = output; op = output; for (i = 0; i < 4; i++) { a1 = ip[0] + ip[2]; b1 = ip[0] - ip[2]; temp1 = (ip[1] * sinpi8sqrt2) >> 16; temp2 = ip[3] + ((ip[3] * cospi8sqrt2minus1) >> 16); c1 = temp1 - temp2; temp1 = ip[1] + ((ip[1] * cospi8sqrt2minus1) >> 16); temp2 = (ip[3] * sinpi8sqrt2) >> 16; d1 = temp1 + temp2; op[0] = (a1 + d1 + 4) >> 3; op[3] = (a1 - d1 + 4) >> 3; op[1] = (b1 + c1 + 4) >> 3; op[2] = (b1 - c1 + 4) >> 3; ip += shortpitch; op += shortpitch; } ip = output; for (r = 0; r < 4; r++) { for (c = 0; c < 4; c++) { int a = ip[c] + pred_ptr[c] ; if (a < 0) a = 0; if (a > 255) a = 255; dst_ptr[c] = (unsigned char) a ; } ip += 4; dst_ptr += dst_stride; pred_ptr += pred_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) { int a1 = ((input_dc + 4) >> 3); int r, c; for (r = 0; r < 4; r++) { for (c = 0; c < 4; c++) { int a = a1 + pred_ptr[c] ; if (a < 0) a = 0; if (a > 255) a = 255; dst_ptr[c] = (unsigned char) a ; } dst_ptr += dst_stride; pred_ptr += pred_stride; } } void vp8_short_inv_walsh4x4_c(short *input, short *mb_dqcoeff) { short output[16]; int i; int a1, b1, c1, d1; int a2, b2, c2, d2; short *ip = input; short *op = output; for (i = 0; i < 4; i++) { a1 = ip[0] + ip[12]; b1 = ip[4] + ip[8]; c1 = ip[4] - ip[8]; d1 = ip[0] - ip[12]; op[0] = a1 + b1; op[4] = c1 + d1; op[8] = a1 - b1; op[12] = d1 - c1; ip++; op++; } ip = output; op = output; for (i = 0; i < 4; i++) { a1 = ip[0] + ip[3]; b1 = ip[1] + ip[2]; c1 = ip[1] - ip[2]; d1 = ip[0] - ip[3]; a2 = a1 + b1; b2 = c1 + d1; c2 = a1 - b1; d2 = d1 - c1; op[0] = (a2 + 3) >> 3; op[1] = (b2 + 3) >> 3; op[2] = (c2 + 3) >> 3; op[3] = (d2 + 3) >> 3; ip += 4; op += 4; } for(i = 0; i < 16; i++) { mb_dqcoeff[i * 16] = output[i]; } } void vp8_short_inv_walsh4x4_1_c(short *input, short *mb_dqcoeff) { int i; int a1; a1 = ((input[0] + 3) >> 3); for(i = 0; i < 16; i++) { mb_dqcoeff[i * 16] = a1; } }