| 1 | // Copyright 2011 Google Inc. All Rights Reserved. | 
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| 2 | // | 
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| 3 | // Use of this source code is governed by a BSD-style license | 
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| 4 | // that can be found in the COPYING file in the root of the source | 
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| 5 | // tree. An additional intellectual property rights grant can be found | 
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| 6 | // in the file PATENTS. All contributing project authors may | 
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| 7 | // be found in the AUTHORS file in the root of the source tree. | 
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| 8 | // ----------------------------------------------------------------------------- | 
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| 9 | // | 
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| 10 | // VP8Iterator: block iterator | 
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| 11 | // | 
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| 12 | // Author: Skal (pascal.massimino@gmail.com) | 
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| 13 |  | 
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| 14 | #include <string.h> | 
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| 15 |  | 
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| 16 | #include "./vp8i_enc.h" | 
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| 17 |  | 
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| 18 | //------------------------------------------------------------------------------ | 
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| 19 | // VP8Iterator | 
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| 20 | //------------------------------------------------------------------------------ | 
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| 21 |  | 
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| 22 | static void InitLeft(VP8EncIterator* const it) { | 
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| 23 | it->y_left_[-1] = it->u_left_[-1] = it->v_left_[-1] = | 
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| 24 | (it->y_ > 0) ? 129 : 127; | 
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| 25 | memset(it->y_left_, 129, 16); | 
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| 26 | memset(it->u_left_, 129, 8); | 
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| 27 | memset(it->v_left_, 129, 8); | 
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| 28 | it->left_nz_[8] = 0; | 
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| 29 | } | 
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| 30 |  | 
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| 31 | static void InitTop(VP8EncIterator* const it) { | 
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| 32 | const VP8Encoder* const enc = it->enc_; | 
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| 33 | const size_t top_size = enc->mb_w_ * 16; | 
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| 34 | memset(enc->y_top_, 127, 2 * top_size); | 
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| 35 | memset(enc->nz_, 0, enc->mb_w_ * sizeof(*enc->nz_)); | 
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| 36 | } | 
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| 37 |  | 
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| 38 | void VP8IteratorSetRow(VP8EncIterator* const it, int y) { | 
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| 39 | VP8Encoder* const enc = it->enc_; | 
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| 40 | it->x_ = 0; | 
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| 41 | it->y_ = y; | 
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| 42 | it->bw_ = &enc->parts_[y & (enc->num_parts_ - 1)]; | 
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| 43 | it->preds_ = enc->preds_ + y * 4 * enc->preds_w_; | 
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| 44 | it->nz_ = enc->nz_; | 
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| 45 | it->mb_ = enc->mb_info_ + y * enc->mb_w_; | 
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| 46 | it->y_top_ = enc->y_top_; | 
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| 47 | it->uv_top_ = enc->uv_top_; | 
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| 48 | InitLeft(it); | 
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| 49 | } | 
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| 50 |  | 
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| 51 | void VP8IteratorReset(VP8EncIterator* const it) { | 
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| 52 | VP8Encoder* const enc = it->enc_; | 
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| 53 | VP8IteratorSetRow(it, 0); | 
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| 54 | VP8IteratorSetCountDown(it, enc->mb_w_ * enc->mb_h_);  // default | 
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| 55 | InitTop(it); | 
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| 56 | memset(it->bit_count_, 0, sizeof(it->bit_count_)); | 
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| 57 | it->do_trellis_ = 0; | 
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| 58 | } | 
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| 59 |  | 
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| 60 | void VP8IteratorSetCountDown(VP8EncIterator* const it, int count_down) { | 
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| 61 | it->count_down_ = it->count_down0_ = count_down; | 
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| 62 | } | 
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| 63 |  | 
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| 64 | int VP8IteratorIsDone(const VP8EncIterator* const it) { | 
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| 65 | return (it->count_down_ <= 0); | 
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| 66 | } | 
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| 67 |  | 
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| 68 | void VP8IteratorInit(VP8Encoder* const enc, VP8EncIterator* const it) { | 
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| 69 | it->enc_ = enc; | 
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| 70 | it->yuv_in_   = (uint8_t*)WEBP_ALIGN(it->yuv_mem_); | 
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| 71 | it->yuv_out_  = it->yuv_in_ + YUV_SIZE_ENC; | 
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| 72 | it->yuv_out2_ = it->yuv_out_ + YUV_SIZE_ENC; | 
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| 73 | it->yuv_p_    = it->yuv_out2_ + YUV_SIZE_ENC; | 
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| 74 | it->lf_stats_ = enc->lf_stats_; | 
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| 75 | it->percent0_ = enc->percent_; | 
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| 76 | it->y_left_ = (uint8_t*)WEBP_ALIGN(it->yuv_left_mem_ + 1); | 
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| 77 | it->u_left_ = it->y_left_ + 16 + 16; | 
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| 78 | it->v_left_ = it->u_left_ + 16; | 
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| 79 | VP8IteratorReset(it); | 
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| 80 | } | 
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| 81 |  | 
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| 82 | int VP8IteratorProgress(const VP8EncIterator* const it, int delta) { | 
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| 83 | VP8Encoder* const enc = it->enc_; | 
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| 84 | if (delta && enc->pic_->progress_hook != NULL) { | 
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| 85 | const int done = it->count_down0_ - it->count_down_; | 
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| 86 | const int percent = (it->count_down0_ <= 0) | 
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| 87 | ? it->percent0_ | 
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| 88 | : it->percent0_ + delta * done / it->count_down0_; | 
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| 89 | return WebPReportProgress(enc->pic_, percent, &enc->percent_); | 
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| 90 | } | 
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| 91 | return 1; | 
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| 92 | } | 
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| 93 |  | 
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| 94 | //------------------------------------------------------------------------------ | 
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| 95 | // Import the source samples into the cache. Takes care of replicating | 
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| 96 | // boundary pixels if necessary. | 
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| 97 |  | 
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| 98 | static WEBP_INLINE int MinSize(int a, int b) { return (a < b) ? a : b; } | 
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| 99 |  | 
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| 100 | static void ImportBlock(const uint8_t* src, int src_stride, | 
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| 101 | uint8_t* dst, int w, int h, int size) { | 
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| 102 | int i; | 
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| 103 | for (i = 0; i < h; ++i) { | 
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| 104 | memcpy(dst, src, w); | 
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| 105 | if (w < size) { | 
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| 106 | memset(dst + w, dst[w - 1], size - w); | 
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| 107 | } | 
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| 108 | dst += BPS; | 
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| 109 | src += src_stride; | 
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| 110 | } | 
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| 111 | for (i = h; i < size; ++i) { | 
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| 112 | memcpy(dst, dst - BPS, size); | 
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| 113 | dst += BPS; | 
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| 114 | } | 
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| 115 | } | 
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| 116 |  | 
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| 117 | static void ImportLine(const uint8_t* src, int src_stride, | 
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| 118 | uint8_t* dst, int len, int total_len) { | 
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| 119 | int i; | 
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| 120 | for (i = 0; i < len; ++i, src += src_stride) dst[i] = *src; | 
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| 121 | for (; i < total_len; ++i) dst[i] = dst[len - 1]; | 
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| 122 | } | 
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| 123 |  | 
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| 124 | void VP8IteratorImport(VP8EncIterator* const it, uint8_t* tmp_32) { | 
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| 125 | const VP8Encoder* const enc = it->enc_; | 
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| 126 | const int x = it->x_, y = it->y_; | 
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| 127 | const WebPPicture* const pic = enc->pic_; | 
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| 128 | const uint8_t* const ysrc = pic->y + (y * pic->y_stride  + x) * 16; | 
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| 129 | const uint8_t* const usrc = pic->u + (y * pic->uv_stride + x) * 8; | 
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| 130 | const uint8_t* const vsrc = pic->v + (y * pic->uv_stride + x) * 8; | 
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| 131 | const int w = MinSize(pic->width - x * 16, 16); | 
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| 132 | const int h = MinSize(pic->height - y * 16, 16); | 
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| 133 | const int uv_w = (w + 1) >> 1; | 
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| 134 | const int uv_h = (h + 1) >> 1; | 
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| 135 |  | 
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| 136 | ImportBlock(ysrc, pic->y_stride,  it->yuv_in_ + Y_OFF_ENC, w, h, 16); | 
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| 137 | ImportBlock(usrc, pic->uv_stride, it->yuv_in_ + U_OFF_ENC, uv_w, uv_h, 8); | 
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| 138 | ImportBlock(vsrc, pic->uv_stride, it->yuv_in_ + V_OFF_ENC, uv_w, uv_h, 8); | 
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| 139 |  | 
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| 140 | if (tmp_32 == NULL) return; | 
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| 141 |  | 
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| 142 | // Import source (uncompressed) samples into boundary. | 
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| 143 | if (x == 0) { | 
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| 144 | InitLeft(it); | 
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| 145 | } else { | 
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| 146 | if (y == 0) { | 
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| 147 | it->y_left_[-1] = it->u_left_[-1] = it->v_left_[-1] = 127; | 
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| 148 | } else { | 
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| 149 | it->y_left_[-1] = ysrc[- 1 - pic->y_stride]; | 
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| 150 | it->u_left_[-1] = usrc[- 1 - pic->uv_stride]; | 
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| 151 | it->v_left_[-1] = vsrc[- 1 - pic->uv_stride]; | 
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| 152 | } | 
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| 153 | ImportLine(ysrc - 1, pic->y_stride,  it->y_left_, h,   16); | 
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| 154 | ImportLine(usrc - 1, pic->uv_stride, it->u_left_, uv_h, 8); | 
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| 155 | ImportLine(vsrc - 1, pic->uv_stride, it->v_left_, uv_h, 8); | 
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| 156 | } | 
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| 157 |  | 
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| 158 | it->y_top_  = tmp_32 + 0; | 
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| 159 | it->uv_top_ = tmp_32 + 16; | 
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| 160 | if (y == 0) { | 
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| 161 | memset(tmp_32, 127, 32 * sizeof(*tmp_32)); | 
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| 162 | } else { | 
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| 163 | ImportLine(ysrc - pic->y_stride,  1, tmp_32,          w,   16); | 
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| 164 | ImportLine(usrc - pic->uv_stride, 1, tmp_32 + 16,     uv_w, 8); | 
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| 165 | ImportLine(vsrc - pic->uv_stride, 1, tmp_32 + 16 + 8, uv_w, 8); | 
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| 166 | } | 
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| 167 | } | 
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| 168 |  | 
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| 169 | //------------------------------------------------------------------------------ | 
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| 170 | // Copy back the compressed samples into user space if requested. | 
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| 171 |  | 
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| 172 | static void ExportBlock(const uint8_t* src, uint8_t* dst, int dst_stride, | 
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| 173 | int w, int h) { | 
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| 174 | while (h-- > 0) { | 
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| 175 | memcpy(dst, src, w); | 
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| 176 | dst += dst_stride; | 
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| 177 | src += BPS; | 
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| 178 | } | 
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| 179 | } | 
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| 180 |  | 
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| 181 | void VP8IteratorExport(const VP8EncIterator* const it) { | 
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| 182 | const VP8Encoder* const enc = it->enc_; | 
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| 183 | if (enc->config_->show_compressed) { | 
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| 184 | const int x = it->x_, y = it->y_; | 
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| 185 | const uint8_t* const ysrc = it->yuv_out_ + Y_OFF_ENC; | 
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| 186 | const uint8_t* const usrc = it->yuv_out_ + U_OFF_ENC; | 
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| 187 | const uint8_t* const vsrc = it->yuv_out_ + V_OFF_ENC; | 
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| 188 | const WebPPicture* const pic = enc->pic_; | 
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| 189 | uint8_t* const ydst = pic->y + (y * pic->y_stride + x) * 16; | 
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| 190 | uint8_t* const udst = pic->u + (y * pic->uv_stride + x) * 8; | 
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| 191 | uint8_t* const vdst = pic->v + (y * pic->uv_stride + x) * 8; | 
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| 192 | int w = (pic->width - x * 16); | 
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| 193 | int h = (pic->height - y * 16); | 
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| 194 |  | 
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| 195 | if (w > 16) w = 16; | 
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| 196 | if (h > 16) h = 16; | 
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| 197 |  | 
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| 198 | // Luma plane | 
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| 199 | ExportBlock(ysrc, ydst, pic->y_stride, w, h); | 
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| 200 |  | 
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| 201 | {   // U/V planes | 
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| 202 | const int uv_w = (w + 1) >> 1; | 
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| 203 | const int uv_h = (h + 1) >> 1; | 
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| 204 | ExportBlock(usrc, udst, pic->uv_stride, uv_w, uv_h); | 
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| 205 | ExportBlock(vsrc, vdst, pic->uv_stride, uv_w, uv_h); | 
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| 206 | } | 
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| 207 | } | 
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| 208 | } | 
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| 209 |  | 
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| 210 | //------------------------------------------------------------------------------ | 
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| 211 | // Non-zero contexts setup/teardown | 
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| 212 |  | 
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| 213 | // Nz bits: | 
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| 214 | //  0  1  2  3  Y | 
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| 215 | //  4  5  6  7 | 
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| 216 | //  8  9 10 11 | 
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| 217 | // 12 13 14 15 | 
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| 218 | // 16 17        U | 
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| 219 | // 18 19 | 
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| 220 | // 20 21        V | 
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| 221 | // 22 23 | 
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| 222 | // 24           DC-intra16 | 
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| 223 |  | 
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| 224 | // Convert packed context to byte array | 
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| 225 | #define BIT(nz, n) (!!((nz) & (1 << (n)))) | 
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| 226 |  | 
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| 227 | void VP8IteratorNzToBytes(VP8EncIterator* const it) { | 
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| 228 | const int tnz = it->nz_[0], lnz = it->nz_[-1]; | 
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| 229 | int* const top_nz = it->top_nz_; | 
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| 230 | int* const left_nz = it->left_nz_; | 
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| 231 |  | 
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| 232 | // Top-Y | 
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| 233 | top_nz[0] = BIT(tnz, 12); | 
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| 234 | top_nz[1] = BIT(tnz, 13); | 
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| 235 | top_nz[2] = BIT(tnz, 14); | 
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| 236 | top_nz[3] = BIT(tnz, 15); | 
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| 237 | // Top-U | 
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| 238 | top_nz[4] = BIT(tnz, 18); | 
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| 239 | top_nz[5] = BIT(tnz, 19); | 
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| 240 | // Top-V | 
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| 241 | top_nz[6] = BIT(tnz, 22); | 
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| 242 | top_nz[7] = BIT(tnz, 23); | 
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| 243 | // DC | 
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| 244 | top_nz[8] = BIT(tnz, 24); | 
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| 245 |  | 
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| 246 | // left-Y | 
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| 247 | left_nz[0] = BIT(lnz,  3); | 
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| 248 | left_nz[1] = BIT(lnz,  7); | 
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| 249 | left_nz[2] = BIT(lnz, 11); | 
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| 250 | left_nz[3] = BIT(lnz, 15); | 
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| 251 | // left-U | 
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| 252 | left_nz[4] = BIT(lnz, 17); | 
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| 253 | left_nz[5] = BIT(lnz, 19); | 
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| 254 | // left-V | 
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| 255 | left_nz[6] = BIT(lnz, 21); | 
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| 256 | left_nz[7] = BIT(lnz, 23); | 
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| 257 | // left-DC is special, iterated separately | 
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| 258 | } | 
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| 259 |  | 
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| 260 | void VP8IteratorBytesToNz(VP8EncIterator* const it) { | 
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| 261 | uint32_t nz = 0; | 
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| 262 | const int* const top_nz = it->top_nz_; | 
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| 263 | const int* const left_nz = it->left_nz_; | 
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| 264 | // top | 
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| 265 | nz |= (top_nz[0] << 12) | (top_nz[1] << 13); | 
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| 266 | nz |= (top_nz[2] << 14) | (top_nz[3] << 15); | 
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| 267 | nz |= (top_nz[4] << 18) | (top_nz[5] << 19); | 
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| 268 | nz |= (top_nz[6] << 22) | (top_nz[7] << 23); | 
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| 269 | nz |= (top_nz[8] << 24);  // we propagate the _top_ bit, esp. for intra4 | 
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| 270 | // left | 
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| 271 | nz |= (left_nz[0] << 3) | (left_nz[1] << 7); | 
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| 272 | nz |= (left_nz[2] << 11); | 
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| 273 | nz |= (left_nz[4] << 17) | (left_nz[6] << 21); | 
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| 274 |  | 
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| 275 | *it->nz_ = nz; | 
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| 276 | } | 
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| 277 |  | 
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| 278 | #undef BIT | 
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| 279 |  | 
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| 280 | //------------------------------------------------------------------------------ | 
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| 281 | // Advance to the next position, doing the bookkeeping. | 
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| 282 |  | 
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| 283 | void VP8IteratorSaveBoundary(VP8EncIterator* const it) { | 
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| 284 | VP8Encoder* const enc = it->enc_; | 
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| 285 | const int x = it->x_, y = it->y_; | 
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| 286 | const uint8_t* const ysrc = it->yuv_out_ + Y_OFF_ENC; | 
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| 287 | const uint8_t* const uvsrc = it->yuv_out_ + U_OFF_ENC; | 
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| 288 | if (x < enc->mb_w_ - 1) {   // left | 
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| 289 | int i; | 
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| 290 | for (i = 0; i < 16; ++i) { | 
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| 291 | it->y_left_[i] = ysrc[15 + i * BPS]; | 
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| 292 | } | 
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| 293 | for (i = 0; i < 8; ++i) { | 
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| 294 | it->u_left_[i] = uvsrc[7 + i * BPS]; | 
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| 295 | it->v_left_[i] = uvsrc[15 + i * BPS]; | 
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| 296 | } | 
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| 297 | // top-left (before 'top'!) | 
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| 298 | it->y_left_[-1] = it->y_top_[15]; | 
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| 299 | it->u_left_[-1] = it->uv_top_[0 + 7]; | 
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| 300 | it->v_left_[-1] = it->uv_top_[8 + 7]; | 
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| 301 | } | 
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| 302 | if (y < enc->mb_h_ - 1) {  // top | 
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| 303 | memcpy(it->y_top_, ysrc + 15 * BPS, 16); | 
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| 304 | memcpy(it->uv_top_, uvsrc + 7 * BPS, 8 + 8); | 
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| 305 | } | 
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| 306 | } | 
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| 307 |  | 
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| 308 | int VP8IteratorNext(VP8EncIterator* const it) { | 
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| 309 | if (++it->x_ == it->enc_->mb_w_) { | 
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| 310 | VP8IteratorSetRow(it, ++it->y_); | 
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| 311 | } else { | 
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| 312 | it->preds_ += 4; | 
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| 313 | it->mb_ += 1; | 
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| 314 | it->nz_ += 1; | 
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| 315 | it->y_top_ += 16; | 
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| 316 | it->uv_top_ += 16; | 
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| 317 | } | 
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| 318 | return (0 < --it->count_down_); | 
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| 319 | } | 
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| 320 |  | 
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| 321 | //------------------------------------------------------------------------------ | 
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| 322 | // Helper function to set mode properties | 
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| 323 |  | 
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| 324 | void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode) { | 
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| 325 | uint8_t* preds = it->preds_; | 
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| 326 | int y; | 
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| 327 | for (y = 0; y < 4; ++y) { | 
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| 328 | memset(preds, mode, 4); | 
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| 329 | preds += it->enc_->preds_w_; | 
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| 330 | } | 
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| 331 | it->mb_->type_ = 1; | 
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| 332 | } | 
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| 333 |  | 
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| 334 | void VP8SetIntra4Mode(const VP8EncIterator* const it, const uint8_t* modes) { | 
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| 335 | uint8_t* preds = it->preds_; | 
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| 336 | int y; | 
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| 337 | for (y = 4; y > 0; --y) { | 
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| 338 | memcpy(preds, modes, 4 * sizeof(*modes)); | 
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| 339 | preds += it->enc_->preds_w_; | 
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| 340 | modes += 4; | 
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| 341 | } | 
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| 342 | it->mb_->type_ = 0; | 
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| 343 | } | 
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| 344 |  | 
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| 345 | void VP8SetIntraUVMode(const VP8EncIterator* const it, int mode) { | 
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| 346 | it->mb_->uv_mode_ = mode; | 
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| 347 | } | 
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| 348 |  | 
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| 349 | void VP8SetSkip(const VP8EncIterator* const it, int skip) { | 
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| 350 | it->mb_->skip_ = skip; | 
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| 351 | } | 
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| 352 |  | 
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| 353 | void VP8SetSegment(const VP8EncIterator* const it, int segment) { | 
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| 354 | it->mb_->segment_ = segment; | 
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| 355 | } | 
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| 356 |  | 
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| 357 | //------------------------------------------------------------------------------ | 
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| 358 | // Intra4x4 sub-blocks iteration | 
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| 359 | // | 
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| 360 | //  We store and update the boundary samples into an array of 37 pixels. They | 
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| 361 | //  are updated as we iterate and reconstructs each intra4x4 blocks in turn. | 
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| 362 | //  The position of the samples has the following snake pattern: | 
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| 363 | // | 
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| 364 | // 16|17 18 19 20|21 22 23 24|25 26 27 28|29 30 31 32|33 34 35 36  <- Top-right | 
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| 365 | // --+-----------+-----------+-----------+-----------+ | 
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| 366 | // 15|         19|         23|         27|         31| | 
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| 367 | // 14|         18|         22|         26|         30| | 
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| 368 | // 13|         17|         21|         25|         29| | 
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| 369 | // 12|13 14 15 16|17 18 19 20|21 22 23 24|25 26 27 28| | 
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| 370 | // --+-----------+-----------+-----------+-----------+ | 
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| 371 | // 11|         15|         19|         23|         27| | 
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| 372 | // 10|         14|         18|         22|         26| | 
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| 373 | //  9|         13|         17|         21|         25| | 
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| 374 | //  8| 9 10 11 12|13 14 15 16|17 18 19 20|21 22 23 24| | 
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| 375 | // --+-----------+-----------+-----------+-----------+ | 
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| 376 | //  7|         11|         15|         19|         23| | 
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| 377 | //  6|         10|         14|         18|         22| | 
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| 378 | //  5|          9|         13|         17|         21| | 
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| 379 | //  4| 5  6  7  8| 9 10 11 12|13 14 15 16|17 18 19 20| | 
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| 380 | // --+-----------+-----------+-----------+-----------+ | 
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| 381 | //  3|          7|         11|         15|         19| | 
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| 382 | //  2|          6|         10|         14|         18| | 
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| 383 | //  1|          5|          9|         13|         17| | 
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| 384 | //  0| 1  2  3  4| 5  6  7  8| 9 10 11 12|13 14 15 16| | 
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| 385 | // --+-----------+-----------+-----------+-----------+ | 
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| 386 |  | 
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| 387 | // Array to record the position of the top sample to pass to the prediction | 
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| 388 | // functions in dsp.c. | 
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| 389 | static const uint8_t VP8TopLeftI4[16] = { | 
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| 390 | 17, 21, 25, 29, | 
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| 391 | 13, 17, 21, 25, | 
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| 392 | 9,  13, 17, 21, | 
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| 393 | 5,   9, 13, 17 | 
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| 394 | }; | 
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| 395 |  | 
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| 396 | void VP8IteratorStartI4(VP8EncIterator* const it) { | 
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| 397 | const VP8Encoder* const enc = it->enc_; | 
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| 398 | int i; | 
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| 399 |  | 
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| 400 | it->i4_ = 0;    // first 4x4 sub-block | 
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| 401 | it->i4_top_ = it->i4_boundary_ + VP8TopLeftI4[0]; | 
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| 402 |  | 
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| 403 | // Import the boundary samples | 
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| 404 | for (i = 0; i < 17; ++i) {    // left | 
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| 405 | it->i4_boundary_[i] = it->y_left_[15 - i]; | 
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| 406 | } | 
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| 407 | for (i = 0; i < 16; ++i) {    // top | 
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| 408 | it->i4_boundary_[17 + i] = it->y_top_[i]; | 
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| 409 | } | 
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| 410 | // top-right samples have a special case on the far right of the picture | 
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| 411 | if (it->x_ < enc->mb_w_ - 1) { | 
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| 412 | for (i = 16; i < 16 + 4; ++i) { | 
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| 413 | it->i4_boundary_[17 + i] = it->y_top_[i]; | 
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| 414 | } | 
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| 415 | } else {    // else, replicate the last valid pixel four times | 
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| 416 | for (i = 16; i < 16 + 4; ++i) { | 
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| 417 | it->i4_boundary_[17 + i] = it->i4_boundary_[17 + 15]; | 
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| 418 | } | 
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| 419 | } | 
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| 420 | VP8IteratorNzToBytes(it);  // import the non-zero context | 
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| 421 | } | 
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| 422 |  | 
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| 423 | int VP8IteratorRotateI4(VP8EncIterator* const it, | 
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| 424 | const uint8_t* const yuv_out) { | 
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| 425 | const uint8_t* const blk = yuv_out + VP8Scan[it->i4_]; | 
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| 426 | uint8_t* const top = it->i4_top_; | 
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| 427 | int i; | 
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| 428 |  | 
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| 429 | // Update the cache with 7 fresh samples | 
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| 430 | for (i = 0; i <= 3; ++i) { | 
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| 431 | top[-4 + i] = blk[i + 3 * BPS];   // store future top samples | 
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| 432 | } | 
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| 433 | if ((it->i4_ & 3) != 3) {  // if not on the right sub-blocks #3, #7, #11, #15 | 
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| 434 | for (i = 0; i <= 2; ++i) {        // store future left samples | 
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| 435 | top[i] = blk[3 + (2 - i) * BPS]; | 
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| 436 | } | 
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| 437 | } else {  // else replicate top-right samples, as says the specs. | 
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| 438 | for (i = 0; i <= 3; ++i) { | 
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| 439 | top[i] = top[i + 4]; | 
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| 440 | } | 
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| 441 | } | 
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| 442 | // move pointers to next sub-block | 
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| 443 | ++it->i4_; | 
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| 444 | if (it->i4_ == 16) {    // we're done | 
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| 445 | return 0; | 
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| 446 | } | 
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| 447 |  | 
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| 448 | it->i4_top_ = it->i4_boundary_ + VP8TopLeftI4[it->i4_]; | 
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| 449 | return 1; | 
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| 450 | } | 
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| 451 |  | 
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| 452 | //------------------------------------------------------------------------------ | 
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| 453 |  | 
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| 454 |  | 
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