Have GPUTracer process traces during CommandBuffer Idle time.
[chromium-blink-merge.git] / third_party / libwebp / dec / vp8l.c
blobe2780e5b2d62834245d869a3ffb3f10ec4f965c5
1 // Copyright 2012 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // main entry for the decoder
12 // Authors: Vikas Arora (vikaas.arora@gmail.com)
13 // Jyrki Alakuijala (jyrki@google.com)
15 #include <stdlib.h>
17 #include "./alphai.h"
18 #include "./vp8li.h"
19 #include "../dsp/dsp.h"
20 #include "../dsp/lossless.h"
21 #include "../dsp/yuv.h"
22 #include "../utils/huffman.h"
23 #include "../utils/utils.h"
25 #define NUM_ARGB_CACHE_ROWS 16
27 static const int kCodeLengthLiterals = 16;
28 static const int kCodeLengthRepeatCode = 16;
29 static const int kCodeLengthExtraBits[3] = { 2, 3, 7 };
30 static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 };
32 // -----------------------------------------------------------------------------
33 // Five Huffman codes are used at each meta code:
34 // 1. green + length prefix codes + color cache codes,
35 // 2. alpha,
36 // 3. red,
37 // 4. blue, and,
38 // 5. distance prefix codes.
39 typedef enum {
40 GREEN = 0,
41 RED = 1,
42 BLUE = 2,
43 ALPHA = 3,
44 DIST = 4
45 } HuffIndex;
47 static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = {
48 NUM_LITERAL_CODES + NUM_LENGTH_CODES,
49 NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
50 NUM_DISTANCE_CODES
54 #define NUM_CODE_LENGTH_CODES 19
55 static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = {
56 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
59 #define CODE_TO_PLANE_CODES 120
60 static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = {
61 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
62 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
63 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
64 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
65 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
66 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
67 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
68 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
69 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
70 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
71 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
72 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70
75 static int DecodeImageStream(int xsize, int ysize,
76 int is_level0,
77 VP8LDecoder* const dec,
78 uint32_t** const decoded_data);
80 //------------------------------------------------------------------------------
82 int VP8LCheckSignature(const uint8_t* const data, size_t size) {
83 return (size >= VP8L_FRAME_HEADER_SIZE &&
84 data[0] == VP8L_MAGIC_BYTE &&
85 (data[4] >> 5) == 0); // version
88 static int ReadImageInfo(VP8LBitReader* const br,
89 int* const width, int* const height,
90 int* const has_alpha) {
91 if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0;
92 *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
93 *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
94 *has_alpha = VP8LReadBits(br, 1);
95 if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0;
96 return 1;
99 int VP8LGetInfo(const uint8_t* data, size_t data_size,
100 int* const width, int* const height, int* const has_alpha) {
101 if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) {
102 return 0; // not enough data
103 } else if (!VP8LCheckSignature(data, data_size)) {
104 return 0; // bad signature
105 } else {
106 int w, h, a;
107 VP8LBitReader br;
108 VP8LInitBitReader(&br, data, data_size);
109 if (!ReadImageInfo(&br, &w, &h, &a)) {
110 return 0;
112 if (width != NULL) *width = w;
113 if (height != NULL) *height = h;
114 if (has_alpha != NULL) *has_alpha = a;
115 return 1;
119 //------------------------------------------------------------------------------
121 static WEBP_INLINE int GetCopyDistance(int distance_symbol,
122 VP8LBitReader* const br) {
123 int extra_bits, offset;
124 if (distance_symbol < 4) {
125 return distance_symbol + 1;
127 extra_bits = (distance_symbol - 2) >> 1;
128 offset = (2 + (distance_symbol & 1)) << extra_bits;
129 return offset + VP8LReadBits(br, extra_bits) + 1;
132 static WEBP_INLINE int GetCopyLength(int length_symbol,
133 VP8LBitReader* const br) {
134 // Length and distance prefixes are encoded the same way.
135 return GetCopyDistance(length_symbol, br);
138 static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) {
139 if (plane_code > CODE_TO_PLANE_CODES) {
140 return plane_code - CODE_TO_PLANE_CODES;
141 } else {
142 const int dist_code = kCodeToPlane[plane_code - 1];
143 const int yoffset = dist_code >> 4;
144 const int xoffset = 8 - (dist_code & 0xf);
145 const int dist = yoffset * xsize + xoffset;
146 return (dist >= 1) ? dist : 1; // dist<1 can happen if xsize is very small
150 //------------------------------------------------------------------------------
151 // Decodes the next Huffman code from bit-stream.
152 // FillBitWindow(br) needs to be called at minimum every second call
153 // to ReadSymbol, in order to pre-fetch enough bits.
154 static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree,
155 VP8LBitReader* const br) {
156 const HuffmanTreeNode* node = tree->root_;
157 uint32_t bits = VP8LPrefetchBits(br);
158 int bitpos = br->bit_pos_;
159 // Check if we find the bit combination from the Huffman lookup table.
160 const int lut_ix = bits & (HUFF_LUT - 1);
161 const int lut_bits = tree->lut_bits_[lut_ix];
162 if (lut_bits <= HUFF_LUT_BITS) {
163 VP8LSetBitPos(br, bitpos + lut_bits);
164 return tree->lut_symbol_[lut_ix];
166 node += tree->lut_jump_[lut_ix];
167 bitpos += HUFF_LUT_BITS;
168 bits >>= HUFF_LUT_BITS;
170 // Decode the value from a binary tree.
171 assert(node != NULL);
172 do {
173 node = HuffmanTreeNextNode(node, bits & 1);
174 bits >>= 1;
175 ++bitpos;
176 } while (HuffmanTreeNodeIsNotLeaf(node));
177 VP8LSetBitPos(br, bitpos);
178 return node->symbol_;
181 static int ReadHuffmanCodeLengths(
182 VP8LDecoder* const dec, const int* const code_length_code_lengths,
183 int num_symbols, int* const code_lengths) {
184 int ok = 0;
185 VP8LBitReader* const br = &dec->br_;
186 int symbol;
187 int max_symbol;
188 int prev_code_len = DEFAULT_CODE_LENGTH;
189 HuffmanTree tree;
190 int huff_codes[NUM_CODE_LENGTH_CODES] = { 0 };
192 if (!VP8LHuffmanTreeBuildImplicit(&tree, code_length_code_lengths,
193 huff_codes, NUM_CODE_LENGTH_CODES)) {
194 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
195 return 0;
198 if (VP8LReadBits(br, 1)) { // use length
199 const int length_nbits = 2 + 2 * VP8LReadBits(br, 3);
200 max_symbol = 2 + VP8LReadBits(br, length_nbits);
201 if (max_symbol > num_symbols) {
202 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
203 goto End;
205 } else {
206 max_symbol = num_symbols;
209 symbol = 0;
210 while (symbol < num_symbols) {
211 int code_len;
212 if (max_symbol-- == 0) break;
213 VP8LFillBitWindow(br);
214 code_len = ReadSymbol(&tree, br);
215 if (code_len < kCodeLengthLiterals) {
216 code_lengths[symbol++] = code_len;
217 if (code_len != 0) prev_code_len = code_len;
218 } else {
219 const int use_prev = (code_len == kCodeLengthRepeatCode);
220 const int slot = code_len - kCodeLengthLiterals;
221 const int extra_bits = kCodeLengthExtraBits[slot];
222 const int repeat_offset = kCodeLengthRepeatOffsets[slot];
223 int repeat = VP8LReadBits(br, extra_bits) + repeat_offset;
224 if (symbol + repeat > num_symbols) {
225 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
226 goto End;
227 } else {
228 const int length = use_prev ? prev_code_len : 0;
229 while (repeat-- > 0) code_lengths[symbol++] = length;
233 ok = 1;
235 End:
236 VP8LHuffmanTreeFree(&tree);
237 if (!ok) dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
238 return ok;
241 // 'code_lengths' is pre-allocated temporary buffer, used for creating Huffman
242 // tree.
243 static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec,
244 int* const code_lengths, int* const huff_codes,
245 HuffmanTree* const tree) {
246 int ok = 0;
247 VP8LBitReader* const br = &dec->br_;
248 const int simple_code = VP8LReadBits(br, 1);
250 if (simple_code) { // Read symbols, codes & code lengths directly.
251 int symbols[2];
252 int codes[2];
253 const int num_symbols = VP8LReadBits(br, 1) + 1;
254 const int first_symbol_len_code = VP8LReadBits(br, 1);
255 // The first code is either 1 bit or 8 bit code.
256 symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8);
257 codes[0] = 0;
258 code_lengths[0] = num_symbols - 1;
259 // The second code (if present), is always 8 bit long.
260 if (num_symbols == 2) {
261 symbols[1] = VP8LReadBits(br, 8);
262 codes[1] = 1;
263 code_lengths[1] = num_symbols - 1;
265 ok = VP8LHuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols,
266 alphabet_size, num_symbols);
267 } else { // Decode Huffman-coded code lengths.
268 int i;
269 int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
270 const int num_codes = VP8LReadBits(br, 4) + 4;
271 if (num_codes > NUM_CODE_LENGTH_CODES) {
272 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
273 return 0;
276 memset(code_lengths, 0, alphabet_size * sizeof(*code_lengths));
278 for (i = 0; i < num_codes; ++i) {
279 code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3);
281 ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size,
282 code_lengths);
283 ok = ok && VP8LHuffmanTreeBuildImplicit(tree, code_lengths, huff_codes,
284 alphabet_size);
286 ok = ok && !br->error_;
287 if (!ok) {
288 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
289 return 0;
291 return 1;
294 static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
295 int color_cache_bits, int allow_recursion) {
296 int i, j;
297 VP8LBitReader* const br = &dec->br_;
298 VP8LMetadata* const hdr = &dec->hdr_;
299 uint32_t* huffman_image = NULL;
300 HTreeGroup* htree_groups = NULL;
301 int num_htree_groups = 1;
302 int max_alphabet_size = 0;
303 int* code_lengths = NULL;
304 int* huff_codes = NULL;
306 if (allow_recursion && VP8LReadBits(br, 1)) {
307 // use meta Huffman codes.
308 const int huffman_precision = VP8LReadBits(br, 3) + 2;
309 const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision);
310 const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision);
311 const int huffman_pixs = huffman_xsize * huffman_ysize;
312 if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec,
313 &huffman_image)) {
314 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
315 goto Error;
317 hdr->huffman_subsample_bits_ = huffman_precision;
318 for (i = 0; i < huffman_pixs; ++i) {
319 // The huffman data is stored in red and green bytes.
320 const int group = (huffman_image[i] >> 8) & 0xffff;
321 huffman_image[i] = group;
322 if (group >= num_htree_groups) {
323 num_htree_groups = group + 1;
328 if (br->error_) goto Error;
330 // Find maximum alphabet size for the htree group.
331 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
332 int alphabet_size = kAlphabetSize[j];
333 if (j == 0 && color_cache_bits > 0) {
334 alphabet_size += 1 << color_cache_bits;
336 if (max_alphabet_size < alphabet_size) {
337 max_alphabet_size = alphabet_size;
341 htree_groups = VP8LHtreeGroupsNew(num_htree_groups);
342 code_lengths =
343 (int*)WebPSafeCalloc((uint64_t)max_alphabet_size, sizeof(*code_lengths));
344 huff_codes =
345 (int*)WebPSafeMalloc((uint64_t)max_alphabet_size, sizeof(*huff_codes));
347 if (htree_groups == NULL || code_lengths == NULL || huff_codes == NULL) {
348 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
349 goto Error;
352 for (i = 0; i < num_htree_groups; ++i) {
353 HuffmanTree* const htrees = htree_groups[i].htrees_;
354 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
355 int alphabet_size = kAlphabetSize[j];
356 HuffmanTree* const htree = htrees + j;
357 if (j == 0 && color_cache_bits > 0) {
358 alphabet_size += 1 << color_cache_bits;
360 if (!ReadHuffmanCode(alphabet_size, dec, code_lengths, huff_codes,
361 htree)) {
362 goto Error;
366 WebPSafeFree(huff_codes);
367 WebPSafeFree(code_lengths);
369 // All OK. Finalize pointers and return.
370 hdr->huffman_image_ = huffman_image;
371 hdr->num_htree_groups_ = num_htree_groups;
372 hdr->htree_groups_ = htree_groups;
373 return 1;
375 Error:
376 WebPSafeFree(huff_codes);
377 WebPSafeFree(code_lengths);
378 WebPSafeFree(huffman_image);
379 VP8LHtreeGroupsFree(htree_groups, num_htree_groups);
380 return 0;
383 //------------------------------------------------------------------------------
384 // Scaling.
386 static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
387 const int num_channels = 4;
388 const int in_width = io->mb_w;
389 const int out_width = io->scaled_width;
390 const int in_height = io->mb_h;
391 const int out_height = io->scaled_height;
392 const uint64_t work_size = 2 * num_channels * (uint64_t)out_width;
393 int32_t* work; // Rescaler work area.
394 const uint64_t scaled_data_size = num_channels * (uint64_t)out_width;
395 uint32_t* scaled_data; // Temporary storage for scaled BGRA data.
396 const uint64_t memory_size = sizeof(*dec->rescaler) +
397 work_size * sizeof(*work) +
398 scaled_data_size * sizeof(*scaled_data);
399 uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory));
400 if (memory == NULL) {
401 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
402 return 0;
404 assert(dec->rescaler_memory == NULL);
405 dec->rescaler_memory = memory;
407 dec->rescaler = (WebPRescaler*)memory;
408 memory += sizeof(*dec->rescaler);
409 work = (int32_t*)memory;
410 memory += work_size * sizeof(*work);
411 scaled_data = (uint32_t*)memory;
413 WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data,
414 out_width, out_height, 0, num_channels,
415 in_width, out_width, in_height, out_height, work);
416 return 1;
419 //------------------------------------------------------------------------------
420 // Export to ARGB
422 // We have special "export" function since we need to convert from BGRA
423 static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
424 int rgba_stride, uint8_t* const rgba) {
425 uint32_t* const src = (uint32_t*)rescaler->dst;
426 const int dst_width = rescaler->dst_width;
427 int num_lines_out = 0;
428 while (WebPRescalerHasPendingOutput(rescaler)) {
429 uint8_t* const dst = rgba + num_lines_out * rgba_stride;
430 WebPRescalerExportRow(rescaler, 0);
431 WebPMultARGBRow(src, dst_width, 1);
432 VP8LConvertFromBGRA(src, dst_width, colorspace, dst);
433 ++num_lines_out;
435 return num_lines_out;
438 // Emit scaled rows.
439 static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec,
440 uint8_t* in, int in_stride, int mb_h,
441 uint8_t* const out, int out_stride) {
442 const WEBP_CSP_MODE colorspace = dec->output_->colorspace;
443 int num_lines_in = 0;
444 int num_lines_out = 0;
445 while (num_lines_in < mb_h) {
446 uint8_t* const row_in = in + num_lines_in * in_stride;
447 uint8_t* const row_out = out + num_lines_out * out_stride;
448 const int lines_left = mb_h - num_lines_in;
449 const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
450 assert(needed_lines > 0 && needed_lines <= lines_left);
451 WebPMultARGBRows(row_in, in_stride,
452 dec->rescaler->src_width, needed_lines, 0);
453 WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride);
454 num_lines_in += needed_lines;
455 num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out);
457 return num_lines_out;
460 // Emit rows without any scaling.
461 static int EmitRows(WEBP_CSP_MODE colorspace,
462 const uint8_t* row_in, int in_stride,
463 int mb_w, int mb_h,
464 uint8_t* const out, int out_stride) {
465 int lines = mb_h;
466 uint8_t* row_out = out;
467 while (lines-- > 0) {
468 VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out);
469 row_in += in_stride;
470 row_out += out_stride;
472 return mb_h; // Num rows out == num rows in.
475 //------------------------------------------------------------------------------
476 // Export to YUVA
478 // TODO(skal): should be in yuv.c
479 static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos,
480 const WebPDecBuffer* const output) {
481 const WebPYUVABuffer* const buf = &output->u.YUVA;
482 // first, the luma plane
484 int i;
485 uint8_t* const y = buf->y + y_pos * buf->y_stride;
486 for (i = 0; i < width; ++i) {
487 const uint32_t p = src[i];
488 y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff,
489 YUV_HALF);
493 // then U/V planes
495 uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride;
496 uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride;
497 const int uv_width = width >> 1;
498 int i;
499 for (i = 0; i < uv_width; ++i) {
500 const uint32_t v0 = src[2 * i + 0];
501 const uint32_t v1 = src[2 * i + 1];
502 // VP8RGBToU/V expects four accumulated pixels. Hence we need to
503 // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less.
504 const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe);
505 const int g = ((v0 >> 7) & 0x1fe) + ((v1 >> 7) & 0x1fe);
506 const int b = ((v0 << 1) & 0x1fe) + ((v1 << 1) & 0x1fe);
507 if (!(y_pos & 1)) { // even lines: store values
508 u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
509 v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
510 } else { // odd lines: average with previous values
511 const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
512 const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
513 // Approximated average-of-four. But it's an acceptable diff.
514 u[i] = (u[i] + tmp_u + 1) >> 1;
515 v[i] = (v[i] + tmp_v + 1) >> 1;
518 if (width & 1) { // last pixel
519 const uint32_t v0 = src[2 * i + 0];
520 const int r = (v0 >> 14) & 0x3fc;
521 const int g = (v0 >> 6) & 0x3fc;
522 const int b = (v0 << 2) & 0x3fc;
523 if (!(y_pos & 1)) { // even lines
524 u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
525 v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
526 } else { // odd lines (note: we could just skip this)
527 const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
528 const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
529 u[i] = (u[i] + tmp_u + 1) >> 1;
530 v[i] = (v[i] + tmp_v + 1) >> 1;
534 // Lastly, store alpha if needed.
535 if (buf->a != NULL) {
536 int i;
537 uint8_t* const a = buf->a + y_pos * buf->a_stride;
538 for (i = 0; i < width; ++i) a[i] = (src[i] >> 24);
542 static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
543 WebPRescaler* const rescaler = dec->rescaler;
544 uint32_t* const src = (uint32_t*)rescaler->dst;
545 const int dst_width = rescaler->dst_width;
546 int num_lines_out = 0;
547 while (WebPRescalerHasPendingOutput(rescaler)) {
548 WebPRescalerExportRow(rescaler, 0);
549 WebPMultARGBRow(src, dst_width, 1);
550 ConvertToYUVA(src, dst_width, y_pos, dec->output_);
551 ++y_pos;
552 ++num_lines_out;
554 return num_lines_out;
557 static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec,
558 uint8_t* in, int in_stride, int mb_h) {
559 int num_lines_in = 0;
560 int y_pos = dec->last_out_row_;
561 while (num_lines_in < mb_h) {
562 const int lines_left = mb_h - num_lines_in;
563 const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
564 WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0);
565 WebPRescalerImport(dec->rescaler, lines_left, in, in_stride);
566 num_lines_in += needed_lines;
567 in += needed_lines * in_stride;
568 y_pos += ExportYUVA(dec, y_pos);
570 return y_pos;
573 static int EmitRowsYUVA(const VP8LDecoder* const dec,
574 const uint8_t* in, int in_stride,
575 int mb_w, int num_rows) {
576 int y_pos = dec->last_out_row_;
577 while (num_rows-- > 0) {
578 ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_);
579 in += in_stride;
580 ++y_pos;
582 return y_pos;
585 //------------------------------------------------------------------------------
586 // Cropping.
588 // Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and
589 // crop options. Also updates the input data pointer, so that it points to the
590 // start of the cropped window. Note that pixels are in ARGB format even if
591 // 'in_data' is uint8_t*.
592 // Returns true if the crop window is not empty.
593 static int SetCropWindow(VP8Io* const io, int y_start, int y_end,
594 uint8_t** const in_data, int pixel_stride) {
595 assert(y_start < y_end);
596 assert(io->crop_left < io->crop_right);
597 if (y_end > io->crop_bottom) {
598 y_end = io->crop_bottom; // make sure we don't overflow on last row.
600 if (y_start < io->crop_top) {
601 const int delta = io->crop_top - y_start;
602 y_start = io->crop_top;
603 *in_data += delta * pixel_stride;
605 if (y_start >= y_end) return 0; // Crop window is empty.
607 *in_data += io->crop_left * sizeof(uint32_t);
609 io->mb_y = y_start - io->crop_top;
610 io->mb_w = io->crop_right - io->crop_left;
611 io->mb_h = y_end - y_start;
612 return 1; // Non-empty crop window.
615 //------------------------------------------------------------------------------
617 static WEBP_INLINE int GetMetaIndex(
618 const uint32_t* const image, int xsize, int bits, int x, int y) {
619 if (bits == 0) return 0;
620 return image[xsize * (y >> bits) + (x >> bits)];
623 static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr,
624 int x, int y) {
625 const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_,
626 hdr->huffman_subsample_bits_, x, y);
627 assert(meta_index < hdr->num_htree_groups_);
628 return hdr->htree_groups_ + meta_index;
631 //------------------------------------------------------------------------------
632 // Main loop, with custom row-processing function
634 typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row);
636 static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows,
637 const uint32_t* const rows) {
638 int n = dec->next_transform_;
639 const int cache_pixs = dec->width_ * num_rows;
640 const int start_row = dec->last_row_;
641 const int end_row = start_row + num_rows;
642 const uint32_t* rows_in = rows;
643 uint32_t* const rows_out = dec->argb_cache_;
645 // Inverse transforms.
646 // TODO: most transforms only need to operate on the cropped region only.
647 memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out));
648 while (n-- > 0) {
649 VP8LTransform* const transform = &dec->transforms_[n];
650 VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out);
651 rows_in = rows_out;
655 // Special method for paletted alpha data.
656 static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows,
657 const uint8_t* const rows) {
658 const int start_row = dec->last_row_;
659 const int end_row = start_row + num_rows;
660 const uint8_t* rows_in = rows;
661 uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row;
662 VP8LTransform* const transform = &dec->transforms_[0];
663 assert(dec->next_transform_ == 1);
664 assert(transform->type_ == COLOR_INDEXING_TRANSFORM);
665 VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in,
666 rows_out);
669 // Processes (transforms, scales & color-converts) the rows decoded after the
670 // last call.
671 static void ProcessRows(VP8LDecoder* const dec, int row) {
672 const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_;
673 const int num_rows = row - dec->last_row_;
675 if (num_rows <= 0) return; // Nothing to be done.
676 ApplyInverseTransforms(dec, num_rows, rows);
678 // Emit output.
680 VP8Io* const io = dec->io_;
681 uint8_t* rows_data = (uint8_t*)dec->argb_cache_;
682 const int in_stride = io->width * sizeof(uint32_t); // in unit of RGBA
683 if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) {
684 // Nothing to output (this time).
685 } else {
686 const WebPDecBuffer* const output = dec->output_;
687 if (output->colorspace < MODE_YUV) { // convert to RGBA
688 const WebPRGBABuffer* const buf = &output->u.RGBA;
689 uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride;
690 const int num_rows_out = io->use_scaling ?
691 EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h,
692 rgba, buf->stride) :
693 EmitRows(output->colorspace, rows_data, in_stride,
694 io->mb_w, io->mb_h, rgba, buf->stride);
695 // Update 'last_out_row_'.
696 dec->last_out_row_ += num_rows_out;
697 } else { // convert to YUVA
698 dec->last_out_row_ = io->use_scaling ?
699 EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) :
700 EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h);
702 assert(dec->last_out_row_ <= output->height);
706 // Update 'last_row_'.
707 dec->last_row_ = row;
708 assert(dec->last_row_ <= dec->height_);
711 // Row-processing for the special case when alpha data contains only one
712 // transform (color indexing), and trivial non-green literals.
713 static int Is8bOptimizable(const VP8LMetadata* const hdr) {
714 int i;
715 if (hdr->color_cache_size_ > 0) return 0;
716 // When the Huffman tree contains only one symbol, we can skip the
717 // call to ReadSymbol() for red/blue/alpha channels.
718 for (i = 0; i < hdr->num_htree_groups_; ++i) {
719 const HuffmanTree* const htrees = hdr->htree_groups_[i].htrees_;
720 if (htrees[RED].num_nodes_ > 1) return 0;
721 if (htrees[BLUE].num_nodes_ > 1) return 0;
722 if (htrees[ALPHA].num_nodes_ > 1) return 0;
724 return 1;
727 static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) {
728 const int num_rows = row - dec->last_row_;
729 const uint8_t* const in =
730 (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_;
731 if (num_rows > 0) {
732 ApplyInverseTransformsAlpha(dec, num_rows, in);
734 dec->last_row_ = dec->last_out_row_ = row;
737 static int DecodeAlphaData(VP8LDecoder* const dec, uint8_t* const data,
738 int width, int height, int last_row) {
739 int ok = 1;
740 int row = dec->last_pixel_ / width;
741 int col = dec->last_pixel_ % width;
742 VP8LBitReader* const br = &dec->br_;
743 VP8LMetadata* const hdr = &dec->hdr_;
744 const HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
745 int pos = dec->last_pixel_; // current position
746 const int end = width * height; // End of data
747 const int last = width * last_row; // Last pixel to decode
748 const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
749 const int mask = hdr->huffman_mask_;
750 assert(htree_group != NULL);
751 assert(pos < end);
752 assert(last_row <= height);
753 assert(Is8bOptimizable(hdr));
755 while (!br->eos_ && pos < last) {
756 int code;
757 // Only update when changing tile.
758 if ((col & mask) == 0) {
759 htree_group = GetHtreeGroupForPos(hdr, col, row);
761 VP8LFillBitWindow(br);
762 code = ReadSymbol(&htree_group->htrees_[GREEN], br);
763 if (code < NUM_LITERAL_CODES) { // Literal
764 data[pos] = code;
765 ++pos;
766 ++col;
767 if (col >= width) {
768 col = 0;
769 ++row;
770 if (row % NUM_ARGB_CACHE_ROWS == 0) {
771 ExtractPalettedAlphaRows(dec, row);
774 } else if (code < len_code_limit) { // Backward reference
775 int dist_code, dist;
776 const int length_sym = code - NUM_LITERAL_CODES;
777 const int length = GetCopyLength(length_sym, br);
778 const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
779 VP8LFillBitWindow(br);
780 dist_code = GetCopyDistance(dist_symbol, br);
781 dist = PlaneCodeToDistance(width, dist_code);
782 if (pos >= dist && end - pos >= length) {
783 int i;
784 for (i = 0; i < length; ++i) data[pos + i] = data[pos + i - dist];
785 } else {
786 ok = 0;
787 goto End;
789 pos += length;
790 col += length;
791 while (col >= width) {
792 col -= width;
793 ++row;
794 if (row % NUM_ARGB_CACHE_ROWS == 0) {
795 ExtractPalettedAlphaRows(dec, row);
798 if (pos < last && (col & mask)) {
799 htree_group = GetHtreeGroupForPos(hdr, col, row);
801 } else { // Not reached
802 ok = 0;
803 goto End;
805 assert(br->eos_ == VP8LIsEndOfStream(br));
806 ok = !br->error_;
807 if (!ok) goto End;
809 // Process the remaining rows corresponding to last row-block.
810 ExtractPalettedAlphaRows(dec, row);
812 End:
813 if (br->error_ || !ok || (br->eos_ && pos < end)) {
814 ok = 0;
815 dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
816 : VP8_STATUS_BITSTREAM_ERROR;
817 } else {
818 dec->last_pixel_ = (int)pos;
819 if (pos == end) dec->state_ = READ_DATA;
821 return ok;
824 static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data,
825 int width, int height, int last_row,
826 ProcessRowsFunc process_func) {
827 int ok = 1;
828 int row = dec->last_pixel_ / width;
829 int col = dec->last_pixel_ % width;
830 VP8LBitReader* const br = &dec->br_;
831 VP8LMetadata* const hdr = &dec->hdr_;
832 HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
833 uint32_t* src = data + dec->last_pixel_;
834 uint32_t* last_cached = src;
835 uint32_t* const src_end = data + width * height; // End of data
836 uint32_t* const src_last = data + width * last_row; // Last pixel to decode
837 const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
838 const int color_cache_limit = len_code_limit + hdr->color_cache_size_;
839 VP8LColorCache* const color_cache =
840 (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL;
841 const int mask = hdr->huffman_mask_;
842 assert(htree_group != NULL);
843 assert(src < src_end);
844 assert(src_last <= src_end);
846 while (!br->eos_ && src < src_last) {
847 int code;
848 // Only update when changing tile. Note we could use this test:
849 // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed
850 // but that's actually slower and needs storing the previous col/row.
851 if ((col & mask) == 0) {
852 htree_group = GetHtreeGroupForPos(hdr, col, row);
854 VP8LFillBitWindow(br);
855 code = ReadSymbol(&htree_group->htrees_[GREEN], br);
856 if (code < NUM_LITERAL_CODES) { // Literal
857 int red, green, blue, alpha;
858 red = ReadSymbol(&htree_group->htrees_[RED], br);
859 green = code;
860 VP8LFillBitWindow(br);
861 blue = ReadSymbol(&htree_group->htrees_[BLUE], br);
862 alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br);
863 *src = ((uint32_t)alpha << 24) | (red << 16) | (green << 8) | blue;
864 AdvanceByOne:
865 ++src;
866 ++col;
867 if (col >= width) {
868 col = 0;
869 ++row;
870 if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
871 process_func(dec, row);
873 if (color_cache != NULL) {
874 while (last_cached < src) {
875 VP8LColorCacheInsert(color_cache, *last_cached++);
879 } else if (code < len_code_limit) { // Backward reference
880 int dist_code, dist;
881 const int length_sym = code - NUM_LITERAL_CODES;
882 const int length = GetCopyLength(length_sym, br);
883 const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
884 VP8LFillBitWindow(br);
885 dist_code = GetCopyDistance(dist_symbol, br);
886 dist = PlaneCodeToDistance(width, dist_code);
887 if (src - data < (ptrdiff_t)dist || src_end - src < (ptrdiff_t)length) {
888 ok = 0;
889 goto End;
890 } else {
891 int i;
892 for (i = 0; i < length; ++i) src[i] = src[i - dist];
893 src += length;
895 col += length;
896 while (col >= width) {
897 col -= width;
898 ++row;
899 if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
900 process_func(dec, row);
903 if (src < src_end) {
904 if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
905 if (color_cache != NULL) {
906 while (last_cached < src) {
907 VP8LColorCacheInsert(color_cache, *last_cached++);
911 } else if (code < color_cache_limit) { // Color cache
912 const int key = code - len_code_limit;
913 assert(color_cache != NULL);
914 while (last_cached < src) {
915 VP8LColorCacheInsert(color_cache, *last_cached++);
917 *src = VP8LColorCacheLookup(color_cache, key);
918 goto AdvanceByOne;
919 } else { // Not reached
920 ok = 0;
921 goto End;
923 assert(br->eos_ == VP8LIsEndOfStream(br));
924 ok = !br->error_;
925 if (!ok) goto End;
927 // Process the remaining rows corresponding to last row-block.
928 if (process_func != NULL) process_func(dec, row);
930 End:
931 if (br->error_ || !ok || (br->eos_ && src < src_end)) {
932 ok = 0;
933 dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
934 : VP8_STATUS_BITSTREAM_ERROR;
935 } else {
936 dec->last_pixel_ = (int)(src - data);
937 if (src == src_end) dec->state_ = READ_DATA;
939 return ok;
942 // -----------------------------------------------------------------------------
943 // VP8LTransform
945 static void ClearTransform(VP8LTransform* const transform) {
946 WebPSafeFree(transform->data_);
947 transform->data_ = NULL;
950 // For security reason, we need to remap the color map to span
951 // the total possible bundled values, and not just the num_colors.
952 static int ExpandColorMap(int num_colors, VP8LTransform* const transform) {
953 int i;
954 const int final_num_colors = 1 << (8 >> transform->bits_);
955 uint32_t* const new_color_map =
956 (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors,
957 sizeof(*new_color_map));
958 if (new_color_map == NULL) {
959 return 0;
960 } else {
961 uint8_t* const data = (uint8_t*)transform->data_;
962 uint8_t* const new_data = (uint8_t*)new_color_map;
963 new_color_map[0] = transform->data_[0];
964 for (i = 4; i < 4 * num_colors; ++i) {
965 // Equivalent to AddPixelEq(), on a byte-basis.
966 new_data[i] = (data[i] + new_data[i - 4]) & 0xff;
968 for (; i < 4 * final_num_colors; ++i)
969 new_data[i] = 0; // black tail.
970 WebPSafeFree(transform->data_);
971 transform->data_ = new_color_map;
973 return 1;
976 static int ReadTransform(int* const xsize, int const* ysize,
977 VP8LDecoder* const dec) {
978 int ok = 1;
979 VP8LBitReader* const br = &dec->br_;
980 VP8LTransform* transform = &dec->transforms_[dec->next_transform_];
981 const VP8LImageTransformType type =
982 (VP8LImageTransformType)VP8LReadBits(br, 2);
984 // Each transform type can only be present once in the stream.
985 if (dec->transforms_seen_ & (1U << type)) {
986 return 0; // Already there, let's not accept the second same transform.
988 dec->transforms_seen_ |= (1U << type);
990 transform->type_ = type;
991 transform->xsize_ = *xsize;
992 transform->ysize_ = *ysize;
993 transform->data_ = NULL;
994 ++dec->next_transform_;
995 assert(dec->next_transform_ <= NUM_TRANSFORMS);
997 switch (type) {
998 case PREDICTOR_TRANSFORM:
999 case CROSS_COLOR_TRANSFORM:
1000 transform->bits_ = VP8LReadBits(br, 3) + 2;
1001 ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_,
1002 transform->bits_),
1003 VP8LSubSampleSize(transform->ysize_,
1004 transform->bits_),
1005 0, dec, &transform->data_);
1006 break;
1007 case COLOR_INDEXING_TRANSFORM: {
1008 const int num_colors = VP8LReadBits(br, 8) + 1;
1009 const int bits = (num_colors > 16) ? 0
1010 : (num_colors > 4) ? 1
1011 : (num_colors > 2) ? 2
1012 : 3;
1013 *xsize = VP8LSubSampleSize(transform->xsize_, bits);
1014 transform->bits_ = bits;
1015 ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_);
1016 ok = ok && ExpandColorMap(num_colors, transform);
1017 break;
1019 case SUBTRACT_GREEN:
1020 break;
1021 default:
1022 assert(0); // can't happen
1023 break;
1026 return ok;
1029 // -----------------------------------------------------------------------------
1030 // VP8LMetadata
1032 static void InitMetadata(VP8LMetadata* const hdr) {
1033 assert(hdr);
1034 memset(hdr, 0, sizeof(*hdr));
1037 static void ClearMetadata(VP8LMetadata* const hdr) {
1038 assert(hdr);
1040 WebPSafeFree(hdr->huffman_image_);
1041 VP8LHtreeGroupsFree(hdr->htree_groups_, hdr->num_htree_groups_);
1042 VP8LColorCacheClear(&hdr->color_cache_);
1043 InitMetadata(hdr);
1046 // -----------------------------------------------------------------------------
1047 // VP8LDecoder
1049 VP8LDecoder* VP8LNew(void) {
1050 VP8LDecoder* const dec = (VP8LDecoder*)WebPSafeCalloc(1ULL, sizeof(*dec));
1051 if (dec == NULL) return NULL;
1052 dec->status_ = VP8_STATUS_OK;
1053 dec->action_ = READ_DIM;
1054 dec->state_ = READ_DIM;
1056 VP8LDspInit(); // Init critical function pointers.
1058 return dec;
1061 void VP8LClear(VP8LDecoder* const dec) {
1062 int i;
1063 if (dec == NULL) return;
1064 ClearMetadata(&dec->hdr_);
1066 WebPSafeFree(dec->pixels_);
1067 dec->pixels_ = NULL;
1068 for (i = 0; i < dec->next_transform_; ++i) {
1069 ClearTransform(&dec->transforms_[i]);
1071 dec->next_transform_ = 0;
1072 dec->transforms_seen_ = 0;
1074 WebPSafeFree(dec->rescaler_memory);
1075 dec->rescaler_memory = NULL;
1077 dec->output_ = NULL; // leave no trace behind
1080 void VP8LDelete(VP8LDecoder* const dec) {
1081 if (dec != NULL) {
1082 VP8LClear(dec);
1083 WebPSafeFree(dec);
1087 static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) {
1088 VP8LMetadata* const hdr = &dec->hdr_;
1089 const int num_bits = hdr->huffman_subsample_bits_;
1090 dec->width_ = width;
1091 dec->height_ = height;
1093 hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits);
1094 hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1;
1097 static int DecodeImageStream(int xsize, int ysize,
1098 int is_level0,
1099 VP8LDecoder* const dec,
1100 uint32_t** const decoded_data) {
1101 int ok = 1;
1102 int transform_xsize = xsize;
1103 int transform_ysize = ysize;
1104 VP8LBitReader* const br = &dec->br_;
1105 VP8LMetadata* const hdr = &dec->hdr_;
1106 uint32_t* data = NULL;
1107 int color_cache_bits = 0;
1109 // Read the transforms (may recurse).
1110 if (is_level0) {
1111 while (ok && VP8LReadBits(br, 1)) {
1112 ok = ReadTransform(&transform_xsize, &transform_ysize, dec);
1116 // Color cache
1117 if (ok && VP8LReadBits(br, 1)) {
1118 color_cache_bits = VP8LReadBits(br, 4);
1119 ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS);
1120 if (!ok) {
1121 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
1122 goto End;
1126 // Read the Huffman codes (may recurse).
1127 ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize,
1128 color_cache_bits, is_level0);
1129 if (!ok) {
1130 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
1131 goto End;
1134 // Finish setting up the color-cache
1135 if (color_cache_bits > 0) {
1136 hdr->color_cache_size_ = 1 << color_cache_bits;
1137 if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) {
1138 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
1139 ok = 0;
1140 goto End;
1142 } else {
1143 hdr->color_cache_size_ = 0;
1145 UpdateDecoder(dec, transform_xsize, transform_ysize);
1147 if (is_level0) { // level 0 complete
1148 dec->state_ = READ_HDR;
1149 goto End;
1153 const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize;
1154 data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data));
1155 if (data == NULL) {
1156 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
1157 ok = 0;
1158 goto End;
1162 // Use the Huffman trees to decode the LZ77 encoded data.
1163 ok = DecodeImageData(dec, data, transform_xsize, transform_ysize,
1164 transform_ysize, NULL);
1165 ok = ok && !br->error_;
1167 End:
1169 if (!ok) {
1170 WebPSafeFree(data);
1171 ClearMetadata(hdr);
1172 // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the
1173 // status appropriately.
1174 if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) {
1175 dec->status_ = VP8_STATUS_SUSPENDED;
1177 } else {
1178 if (decoded_data != NULL) {
1179 *decoded_data = data;
1180 } else {
1181 // We allocate image data in this function only for transforms. At level 0
1182 // (that is: not the transforms), we shouldn't have allocated anything.
1183 assert(data == NULL);
1184 assert(is_level0);
1186 dec->last_pixel_ = 0; // Reset for future DECODE_DATA_FUNC() calls.
1187 if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind.
1189 return ok;
1192 //------------------------------------------------------------------------------
1193 // Allocate internal buffers dec->pixels_ and dec->argb_cache_.
1194 static int AllocateInternalBuffers32b(VP8LDecoder* const dec, int final_width) {
1195 const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_;
1196 // Scratch buffer corresponding to top-prediction row for transforming the
1197 // first row in the row-blocks. Not needed for paletted alpha.
1198 const uint64_t cache_top_pixels = (uint16_t)final_width;
1199 // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha.
1200 const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS;
1201 const uint64_t total_num_pixels =
1202 num_pixels + cache_top_pixels + cache_pixels;
1204 assert(dec->width_ <= final_width);
1205 dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint32_t));
1206 if (dec->pixels_ == NULL) {
1207 dec->argb_cache_ = NULL; // for sanity check
1208 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
1209 return 0;
1211 dec->argb_cache_ = dec->pixels_ + num_pixels + cache_top_pixels;
1212 return 1;
1215 static int AllocateInternalBuffers8b(VP8LDecoder* const dec) {
1216 const uint64_t total_num_pixels = (uint64_t)dec->width_ * dec->height_;
1217 dec->argb_cache_ = NULL; // for sanity check
1218 dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint8_t));
1219 if (dec->pixels_ == NULL) {
1220 dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
1221 return 0;
1223 return 1;
1226 //------------------------------------------------------------------------------
1228 // Special row-processing that only stores the alpha data.
1229 static void ExtractAlphaRows(VP8LDecoder* const dec, int row) {
1230 const int num_rows = row - dec->last_row_;
1231 const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_;
1233 if (num_rows <= 0) return; // Nothing to be done.
1234 ApplyInverseTransforms(dec, num_rows, in);
1236 // Extract alpha (which is stored in the green plane).
1238 const int width = dec->io_->width; // the final width (!= dec->width_)
1239 const int cache_pixs = width * num_rows;
1240 uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_;
1241 const uint32_t* const src = dec->argb_cache_;
1242 int i;
1243 for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff;
1245 dec->last_row_ = dec->last_out_row_ = row;
1248 int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec,
1249 const uint8_t* const data, size_t data_size,
1250 uint8_t* const output) {
1251 int ok = 0;
1252 VP8LDecoder* dec;
1253 VP8Io* io;
1254 assert(alph_dec != NULL);
1255 alph_dec->vp8l_dec_ = VP8LNew();
1256 if (alph_dec->vp8l_dec_ == NULL) return 0;
1257 dec = alph_dec->vp8l_dec_;
1259 dec->width_ = alph_dec->width_;
1260 dec->height_ = alph_dec->height_;
1261 dec->io_ = &alph_dec->io_;
1262 io = dec->io_;
1264 VP8InitIo(io);
1265 WebPInitCustomIo(NULL, io); // Just a sanity Init. io won't be used.
1266 io->opaque = output;
1267 io->width = alph_dec->width_;
1268 io->height = alph_dec->height_;
1270 dec->status_ = VP8_STATUS_OK;
1271 VP8LInitBitReader(&dec->br_, data, data_size);
1273 dec->action_ = READ_HDR;
1274 if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) {
1275 goto Err;
1278 // Special case: if alpha data uses only the color indexing transform and
1279 // doesn't use color cache (a frequent case), we will use DecodeAlphaData()
1280 // method that only needs allocation of 1 byte per pixel (alpha channel).
1281 if (dec->next_transform_ == 1 &&
1282 dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM &&
1283 Is8bOptimizable(&dec->hdr_)) {
1284 alph_dec->use_8b_decode = 1;
1285 ok = AllocateInternalBuffers8b(dec);
1286 } else {
1287 // Allocate internal buffers (note that dec->width_ may have changed here).
1288 alph_dec->use_8b_decode = 0;
1289 ok = AllocateInternalBuffers32b(dec, alph_dec->width_);
1292 if (!ok) goto Err;
1294 dec->action_ = READ_DATA;
1295 return 1;
1297 Err:
1298 VP8LDelete(alph_dec->vp8l_dec_);
1299 alph_dec->vp8l_dec_ = NULL;
1300 return 0;
1303 int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) {
1304 VP8LDecoder* const dec = alph_dec->vp8l_dec_;
1305 assert(dec != NULL);
1306 assert(dec->action_ == READ_DATA);
1307 assert(last_row <= dec->height_);
1309 if (dec->last_pixel_ == dec->width_ * dec->height_) {
1310 return 1; // done
1313 // Decode (with special row processing).
1314 return alph_dec->use_8b_decode ?
1315 DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_,
1316 last_row) :
1317 DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
1318 last_row, ExtractAlphaRows);
1321 //------------------------------------------------------------------------------
1323 int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) {
1324 int width, height, has_alpha;
1326 if (dec == NULL) return 0;
1327 if (io == NULL) {
1328 dec->status_ = VP8_STATUS_INVALID_PARAM;
1329 return 0;
1332 dec->io_ = io;
1333 dec->status_ = VP8_STATUS_OK;
1334 VP8LInitBitReader(&dec->br_, io->data, io->data_size);
1335 if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) {
1336 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
1337 goto Error;
1339 dec->state_ = READ_DIM;
1340 io->width = width;
1341 io->height = height;
1343 dec->action_ = READ_HDR;
1344 if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error;
1345 return 1;
1347 Error:
1348 VP8LClear(dec);
1349 assert(dec->status_ != VP8_STATUS_OK);
1350 return 0;
1353 int VP8LDecodeImage(VP8LDecoder* const dec) {
1354 VP8Io* io = NULL;
1355 WebPDecParams* params = NULL;
1357 // Sanity checks.
1358 if (dec == NULL) return 0;
1360 dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
1361 assert(dec->hdr_.htree_groups_ != NULL);
1362 assert(dec->hdr_.num_htree_groups_ > 0);
1364 io = dec->io_;
1365 assert(io != NULL);
1366 params = (WebPDecParams*)io->opaque;
1367 assert(params != NULL);
1368 dec->output_ = params->output;
1369 assert(dec->output_ != NULL);
1371 // Initialization.
1372 if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) {
1373 dec->status_ = VP8_STATUS_INVALID_PARAM;
1374 goto Err;
1377 if (!AllocateInternalBuffers32b(dec, io->width)) goto Err;
1379 if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err;
1381 if (io->use_scaling || WebPIsPremultipliedMode(dec->output_->colorspace)) {
1382 // need the alpha-multiply functions for premultiplied output or rescaling
1383 WebPInitAlphaProcessing();
1386 // Decode.
1387 dec->action_ = READ_DATA;
1388 if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
1389 dec->height_, ProcessRows)) {
1390 goto Err;
1393 // Cleanup.
1394 params->last_y = dec->last_out_row_;
1395 VP8LClear(dec);
1396 return 1;
1398 Err:
1399 VP8LClear(dec);
1400 assert(dec->status_ != VP8_STATUS_OK);
1401 return 0;
1404 //------------------------------------------------------------------------------