1 /* 2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "./vp8_rtcd.h" 12 13 /**************************************************************************** 14 * Notes: 15 * 16 * This implementation makes use of 16 bit fixed point verio of two multiply 17 * constants: 18 * 1. sqrt(2) * cos (pi/8) 19 * 2. sqrt(2) * sin (pi/8) 20 * Becuase the first constant is bigger than 1, to maintain the same 16 bit 21 * fixed point precision as the second one, we use a trick of 22 * x * a = x + x*(a-1) 23 * so 24 * x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1). 25 **************************************************************************/ 26 static const int cospi8sqrt2minus1 = 20091; 27 static const int sinpi8sqrt2 = 35468; 28 29 void vp8_short_idct4x4llm_c(short *input, unsigned char *pred_ptr, 30 int pred_stride, unsigned char *dst_ptr, 31 int dst_stride) { 32 int i; 33 int r, c; 34 int a1, b1, c1, d1; 35 short output[16]; 36 short *ip = input; 37 short *op = output; 38 int temp1, temp2; 39 int shortpitch = 4; 40 41 for (i = 0; i < 4; ++i) { 42 a1 = ip[0] + ip[8]; 43 b1 = ip[0] - ip[8]; 44 45 temp1 = (ip[4] * sinpi8sqrt2) >> 16; 46 temp2 = ip[12] + ((ip[12] * cospi8sqrt2minus1) >> 16); 47 c1 = temp1 - temp2; 48 49 temp1 = ip[4] + ((ip[4] * cospi8sqrt2minus1) >> 16); 50 temp2 = (ip[12] * sinpi8sqrt2) >> 16; 51 d1 = temp1 + temp2; 52 53 op[shortpitch * 0] = a1 + d1; 54 op[shortpitch * 3] = a1 - d1; 55 56 op[shortpitch * 1] = b1 + c1; 57 op[shortpitch * 2] = b1 - c1; 58 59 ip++; 60 op++; 61 } 62 63 ip = output; 64 op = output; 65 66 for (i = 0; i < 4; ++i) { 67 a1 = ip[0] + ip[2]; 68 b1 = ip[0] - ip[2]; 69 70 temp1 = (ip[1] * sinpi8sqrt2) >> 16; 71 temp2 = ip[3] + ((ip[3] * cospi8sqrt2minus1) >> 16); 72 c1 = temp1 - temp2; 73 74 temp1 = ip[1] + ((ip[1] * cospi8sqrt2minus1) >> 16); 75 temp2 = (ip[3] * sinpi8sqrt2) >> 16; 76 d1 = temp1 + temp2; 77 78 op[0] = (a1 + d1 + 4) >> 3; 79 op[3] = (a1 - d1 + 4) >> 3; 80 81 op[1] = (b1 + c1 + 4) >> 3; 82 op[2] = (b1 - c1 + 4) >> 3; 83 84 ip += shortpitch; 85 op += shortpitch; 86 } 87 88 ip = output; 89 for (r = 0; r < 4; ++r) { 90 for (c = 0; c < 4; ++c) { 91 int a = ip[c] + pred_ptr[c]; 92 93 if (a < 0) a = 0; 94 95 if (a > 255) a = 255; 96 97 dst_ptr[c] = (unsigned char)a; 98 } 99 ip += 4; 100 dst_ptr += dst_stride; 101 pred_ptr += pred_stride; 102 } 103 } 104 105 void vp8_dc_only_idct_add_c(short input_dc, unsigned char *pred_ptr, 106 int pred_stride, unsigned char *dst_ptr, 107 int dst_stride) { 108 int a1 = ((input_dc + 4) >> 3); 109 int r, c; 110 111 for (r = 0; r < 4; ++r) { 112 for (c = 0; c < 4; ++c) { 113 int a = a1 + pred_ptr[c]; 114 115 if (a < 0) a = 0; 116 117 if (a > 255) a = 255; 118 119 dst_ptr[c] = (unsigned char)a; 120 } 121 122 dst_ptr += dst_stride; 123 pred_ptr += pred_stride; 124 } 125 } 126 127 void vp8_short_inv_walsh4x4_c(short *input, short *mb_dqcoeff) { 128 short output[16]; 129 int i; 130 int a1, b1, c1, d1; 131 int a2, b2, c2, d2; 132 short *ip = input; 133 short *op = output; 134 135 for (i = 0; i < 4; ++i) { 136 a1 = ip[0] + ip[12]; 137 b1 = ip[4] + ip[8]; 138 c1 = ip[4] - ip[8]; 139 d1 = ip[0] - ip[12]; 140 141 op[0] = a1 + b1; 142 op[4] = c1 + d1; 143 op[8] = a1 - b1; 144 op[12] = d1 - c1; 145 ip++; 146 op++; 147 } 148 149 ip = output; 150 op = output; 151 152 for (i = 0; i < 4; ++i) { 153 a1 = ip[0] + ip[3]; 154 b1 = ip[1] + ip[2]; 155 c1 = ip[1] - ip[2]; 156 d1 = ip[0] - ip[3]; 157 158 a2 = a1 + b1; 159 b2 = c1 + d1; 160 c2 = a1 - b1; 161 d2 = d1 - c1; 162 163 op[0] = (a2 + 3) >> 3; 164 op[1] = (b2 + 3) >> 3; 165 op[2] = (c2 + 3) >> 3; 166 op[3] = (d2 + 3) >> 3; 167 168 ip += 4; 169 op += 4; 170 } 171 172 for (i = 0; i < 16; ++i) { 173 mb_dqcoeff[i * 16] = output[i]; 174 } 175 } 176 177 void vp8_short_inv_walsh4x4_1_c(short *input, short *mb_dqcoeff) { 178 int i; 179 int a1; 180 181 a1 = ((input[0] + 3) >> 3); 182 for (i = 0; i < 16; ++i) { 183 mb_dqcoeff[i * 16] = a1; 184 } 185 } 186