| // Copyright 2014 The PDFium Authors | 
 | // Use of this source code is governed by a BSD-style license that can be | 
 | // found in the LICENSE file. | 
 |  | 
 | // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com | 
 |  | 
 | #include "core/fxcodec/fax/faxmodule.h" | 
 |  | 
 | #include <stdint.h> | 
 |  | 
 | #include <algorithm> | 
 | #include <iterator> | 
 | #include <memory> | 
 | #include <utility> | 
 |  | 
 | #include "build/build_config.h" | 
 | #include "core/fxcodec/scanlinedecoder.h" | 
 | #include "core/fxcrt/binary_buffer.h" | 
 | #include "core/fxcrt/data_vector.h" | 
 | #include "core/fxcrt/fx_2d_size.h" | 
 | #include "core/fxcrt/fx_memory.h" | 
 | #include "core/fxge/calculate_pitch.h" | 
 | #include "third_party/base/check.h" | 
 | #include "third_party/base/check_op.h" | 
 | #include "third_party/base/cxx17_backports.h" | 
 | #include "third_party/base/numerics/safe_conversions.h" | 
 | #include "third_party/base/span.h" | 
 |  | 
 | #if BUILDFLAG(IS_WIN) | 
 | #include "core/fxcrt/span_util.h" | 
 | #include "core/fxge/dib/cfx_dibbase.h" | 
 | #endif | 
 |  | 
 | namespace fxcodec { | 
 |  | 
 | namespace { | 
 |  | 
 | const uint8_t OneLeadPos[256] = { | 
 |     8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, | 
 |     3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, | 
 |     2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, | 
 |     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, | 
 |     1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, | 
 |     1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 |     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 |     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 |     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 |     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 |     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, | 
 | }; | 
 |  | 
 | // Limit of image dimension. Use the same limit as the JBIG2 codecs. | 
 | constexpr int kFaxMaxImageDimension = 65535; | 
 |  | 
 | constexpr int kFaxBpc = 1; | 
 | constexpr int kFaxComps = 1; | 
 |  | 
 | int FindBit(pdfium::span<const uint8_t> data_buf, | 
 |             int max_pos, | 
 |             int start_pos, | 
 |             bool bit) { | 
 |   DCHECK(start_pos >= 0); | 
 |   if (start_pos >= max_pos) | 
 |     return max_pos; | 
 |  | 
 |   const uint8_t bit_xor = bit ? 0x00 : 0xff; | 
 |   int bit_offset = start_pos % 8; | 
 |   if (bit_offset) { | 
 |     const int byte_pos = start_pos / 8; | 
 |     uint8_t data = (data_buf[byte_pos] ^ bit_xor) & (0xff >> bit_offset); | 
 |     if (data) | 
 |       return byte_pos * 8 + OneLeadPos[data]; | 
 |  | 
 |     start_pos += 7; | 
 |   } | 
 |  | 
 |   const int max_byte = (max_pos + 7) / 8; | 
 |   int byte_pos = start_pos / 8; | 
 |  | 
 |   // Try reading in bigger chunks in case there are long runs to be skipped. | 
 |   static constexpr int kBulkReadSize = 8; | 
 |   if (max_byte >= kBulkReadSize && byte_pos < max_byte - kBulkReadSize) { | 
 |     static constexpr uint8_t skip_block_0[kBulkReadSize] = { | 
 |         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; | 
 |     static constexpr uint8_t skip_block_1[kBulkReadSize] = { | 
 |         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; | 
 |     const uint8_t* skip_block = bit ? skip_block_0 : skip_block_1; | 
 |     while (byte_pos < max_byte - kBulkReadSize && | 
 |            memcmp(data_buf.subspan(byte_pos).data(), skip_block, | 
 |                   kBulkReadSize) == 0) { | 
 |       byte_pos += kBulkReadSize; | 
 |     } | 
 |   } | 
 |  | 
 |   while (byte_pos < max_byte) { | 
 |     uint8_t data = data_buf[byte_pos] ^ bit_xor; | 
 |     if (data) | 
 |       return std::min(byte_pos * 8 + OneLeadPos[data], max_pos); | 
 |  | 
 |     ++byte_pos; | 
 |   } | 
 |   return max_pos; | 
 | } | 
 |  | 
 | void FaxG4FindB1B2(pdfium::span<const uint8_t> ref_buf, | 
 |                    int columns, | 
 |                    int a0, | 
 |                    bool a0color, | 
 |                    int* b1, | 
 |                    int* b2) { | 
 |   bool first_bit = a0 < 0 || (ref_buf[a0 / 8] & (1 << (7 - a0 % 8))) != 0; | 
 |   *b1 = FindBit(ref_buf, columns, a0 + 1, !first_bit); | 
 |   if (*b1 >= columns) { | 
 |     *b1 = *b2 = columns; | 
 |     return; | 
 |   } | 
 |   if (first_bit == !a0color) { | 
 |     *b1 = FindBit(ref_buf, columns, *b1 + 1, first_bit); | 
 |     first_bit = !first_bit; | 
 |   } | 
 |   if (*b1 >= columns) { | 
 |     *b1 = *b2 = columns; | 
 |     return; | 
 |   } | 
 |   *b2 = FindBit(ref_buf, columns, *b1 + 1, first_bit); | 
 | } | 
 |  | 
 | void FaxFillBits(uint8_t* dest_buf, int columns, int startpos, int endpos) { | 
 |   startpos = std::max(startpos, 0); | 
 |   endpos = pdfium::clamp(endpos, 0, columns); | 
 |   if (startpos >= endpos) | 
 |     return; | 
 |  | 
 |   int first_byte = startpos / 8; | 
 |   int last_byte = (endpos - 1) / 8; | 
 |   if (first_byte == last_byte) { | 
 |     for (int i = startpos % 8; i <= (endpos - 1) % 8; ++i) | 
 |       dest_buf[first_byte] -= 1 << (7 - i); | 
 |     return; | 
 |   } | 
 |  | 
 |   for (int i = startpos % 8; i < 8; ++i) | 
 |     dest_buf[first_byte] -= 1 << (7 - i); | 
 |   for (int i = 0; i <= (endpos - 1) % 8; ++i) | 
 |     dest_buf[last_byte] -= 1 << (7 - i); | 
 |  | 
 |   if (last_byte > first_byte + 1) | 
 |     memset(dest_buf + first_byte + 1, 0, last_byte - first_byte - 1); | 
 | } | 
 |  | 
 | inline bool NextBit(const uint8_t* src_buf, int* bitpos) { | 
 |   int pos = (*bitpos)++; | 
 |   return !!(src_buf[pos / 8] & (1 << (7 - pos % 8))); | 
 | } | 
 |  | 
 | const uint8_t kFaxBlackRunIns[] = { | 
 |     0,          2,          0x02,       3,          0,          0x03, | 
 |     2,          0,          2,          0x02,       1,          0, | 
 |     0x03,       4,          0,          2,          0x02,       6, | 
 |     0,          0x03,       5,          0,          1,          0x03, | 
 |     7,          0,          2,          0x04,       9,          0, | 
 |     0x05,       8,          0,          3,          0x04,       10, | 
 |     0,          0x05,       11,         0,          0x07,       12, | 
 |     0,          2,          0x04,       13,         0,          0x07, | 
 |     14,         0,          1,          0x18,       15,         0, | 
 |     5,          0x08,       18,         0,          0x0f,       64, | 
 |     0,          0x17,       16,         0,          0x18,       17, | 
 |     0,          0x37,       0,          0,          10,         0x08, | 
 |     0x00,       0x07,       0x0c,       0x40,       0x07,       0x0d, | 
 |     0x80,       0x07,       0x17,       24,         0,          0x18, | 
 |     25,         0,          0x28,       23,         0,          0x37, | 
 |     22,         0,          0x67,       19,         0,          0x68, | 
 |     20,         0,          0x6c,       21,         0,          54, | 
 |     0x12,       1984 % 256, 1984 / 256, 0x13,       2048 % 256, 2048 / 256, | 
 |     0x14,       2112 % 256, 2112 / 256, 0x15,       2176 % 256, 2176 / 256, | 
 |     0x16,       2240 % 256, 2240 / 256, 0x17,       2304 % 256, 2304 / 256, | 
 |     0x1c,       2368 % 256, 2368 / 256, 0x1d,       2432 % 256, 2432 / 256, | 
 |     0x1e,       2496 % 256, 2496 / 256, 0x1f,       2560 % 256, 2560 / 256, | 
 |     0x24,       52,         0,          0x27,       55,         0, | 
 |     0x28,       56,         0,          0x2b,       59,         0, | 
 |     0x2c,       60,         0,          0x33,       320 % 256,  320 / 256, | 
 |     0x34,       384 % 256,  384 / 256,  0x35,       448 % 256,  448 / 256, | 
 |     0x37,       53,         0,          0x38,       54,         0, | 
 |     0x52,       50,         0,          0x53,       51,         0, | 
 |     0x54,       44,         0,          0x55,       45,         0, | 
 |     0x56,       46,         0,          0x57,       47,         0, | 
 |     0x58,       57,         0,          0x59,       58,         0, | 
 |     0x5a,       61,         0,          0x5b,       256 % 256,  256 / 256, | 
 |     0x64,       48,         0,          0x65,       49,         0, | 
 |     0x66,       62,         0,          0x67,       63,         0, | 
 |     0x68,       30,         0,          0x69,       31,         0, | 
 |     0x6a,       32,         0,          0x6b,       33,         0, | 
 |     0x6c,       40,         0,          0x6d,       41,         0, | 
 |     0xc8,       128,        0,          0xc9,       192,        0, | 
 |     0xca,       26,         0,          0xcb,       27,         0, | 
 |     0xcc,       28,         0,          0xcd,       29,         0, | 
 |     0xd2,       34,         0,          0xd3,       35,         0, | 
 |     0xd4,       36,         0,          0xd5,       37,         0, | 
 |     0xd6,       38,         0,          0xd7,       39,         0, | 
 |     0xda,       42,         0,          0xdb,       43,         0, | 
 |     20,         0x4a,       640 % 256,  640 / 256,  0x4b,       704 % 256, | 
 |     704 / 256,  0x4c,       768 % 256,  768 / 256,  0x4d,       832 % 256, | 
 |     832 / 256,  0x52,       1280 % 256, 1280 / 256, 0x53,       1344 % 256, | 
 |     1344 / 256, 0x54,       1408 % 256, 1408 / 256, 0x55,       1472 % 256, | 
 |     1472 / 256, 0x5a,       1536 % 256, 1536 / 256, 0x5b,       1600 % 256, | 
 |     1600 / 256, 0x64,       1664 % 256, 1664 / 256, 0x65,       1728 % 256, | 
 |     1728 / 256, 0x6c,       512 % 256,  512 / 256,  0x6d,       576 % 256, | 
 |     576 / 256,  0x72,       896 % 256,  896 / 256,  0x73,       960 % 256, | 
 |     960 / 256,  0x74,       1024 % 256, 1024 / 256, 0x75,       1088 % 256, | 
 |     1088 / 256, 0x76,       1152 % 256, 1152 / 256, 0x77,       1216 % 256, | 
 |     1216 / 256, 0xff}; | 
 |  | 
 | const uint8_t kFaxWhiteRunIns[] = { | 
 |     0,          0,          0,          6,          0x07,       2, | 
 |     0,          0x08,       3,          0,          0x0B,       4, | 
 |     0,          0x0C,       5,          0,          0x0E,       6, | 
 |     0,          0x0F,       7,          0,          6,          0x07, | 
 |     10,         0,          0x08,       11,         0,          0x12, | 
 |     128,        0,          0x13,       8,          0,          0x14, | 
 |     9,          0,          0x1b,       64,         0,          9, | 
 |     0x03,       13,         0,          0x07,       1,          0, | 
 |     0x08,       12,         0,          0x17,       192,        0, | 
 |     0x18,       1664 % 256, 1664 / 256, 0x2a,       16,         0, | 
 |     0x2B,       17,         0,          0x34,       14,         0, | 
 |     0x35,       15,         0,          12,         0x03,       22, | 
 |     0,          0x04,       23,         0,          0x08,       20, | 
 |     0,          0x0c,       19,         0,          0x13,       26, | 
 |     0,          0x17,       21,         0,          0x18,       28, | 
 |     0,          0x24,       27,         0,          0x27,       18, | 
 |     0,          0x28,       24,         0,          0x2B,       25, | 
 |     0,          0x37,       256 % 256,  256 / 256,  42,         0x02, | 
 |     29,         0,          0x03,       30,         0,          0x04, | 
 |     45,         0,          0x05,       46,         0,          0x0a, | 
 |     47,         0,          0x0b,       48,         0,          0x12, | 
 |     33,         0,          0x13,       34,         0,          0x14, | 
 |     35,         0,          0x15,       36,         0,          0x16, | 
 |     37,         0,          0x17,       38,         0,          0x1a, | 
 |     31,         0,          0x1b,       32,         0,          0x24, | 
 |     53,         0,          0x25,       54,         0,          0x28, | 
 |     39,         0,          0x29,       40,         0,          0x2a, | 
 |     41,         0,          0x2b,       42,         0,          0x2c, | 
 |     43,         0,          0x2d,       44,         0,          0x32, | 
 |     61,         0,          0x33,       62,         0,          0x34, | 
 |     63,         0,          0x35,       0,          0,          0x36, | 
 |     320 % 256,  320 / 256,  0x37,       384 % 256,  384 / 256,  0x4a, | 
 |     59,         0,          0x4b,       60,         0,          0x52, | 
 |     49,         0,          0x53,       50,         0,          0x54, | 
 |     51,         0,          0x55,       52,         0,          0x58, | 
 |     55,         0,          0x59,       56,         0,          0x5a, | 
 |     57,         0,          0x5b,       58,         0,          0x64, | 
 |     448 % 256,  448 / 256,  0x65,       512 % 256,  512 / 256,  0x67, | 
 |     640 % 256,  640 / 256,  0x68,       576 % 256,  576 / 256,  16, | 
 |     0x98,       1472 % 256, 1472 / 256, 0x99,       1536 % 256, 1536 / 256, | 
 |     0x9a,       1600 % 256, 1600 / 256, 0x9b,       1728 % 256, 1728 / 256, | 
 |     0xcc,       704 % 256,  704 / 256,  0xcd,       768 % 256,  768 / 256, | 
 |     0xd2,       832 % 256,  832 / 256,  0xd3,       896 % 256,  896 / 256, | 
 |     0xd4,       960 % 256,  960 / 256,  0xd5,       1024 % 256, 1024 / 256, | 
 |     0xd6,       1088 % 256, 1088 / 256, 0xd7,       1152 % 256, 1152 / 256, | 
 |     0xd8,       1216 % 256, 1216 / 256, 0xd9,       1280 % 256, 1280 / 256, | 
 |     0xda,       1344 % 256, 1344 / 256, 0xdb,       1408 % 256, 1408 / 256, | 
 |     0,          3,          0x08,       1792 % 256, 1792 / 256, 0x0c, | 
 |     1856 % 256, 1856 / 256, 0x0d,       1920 % 256, 1920 / 256, 10, | 
 |     0x12,       1984 % 256, 1984 / 256, 0x13,       2048 % 256, 2048 / 256, | 
 |     0x14,       2112 % 256, 2112 / 256, 0x15,       2176 % 256, 2176 / 256, | 
 |     0x16,       2240 % 256, 2240 / 256, 0x17,       2304 % 256, 2304 / 256, | 
 |     0x1c,       2368 % 256, 2368 / 256, 0x1d,       2432 % 256, 2432 / 256, | 
 |     0x1e,       2496 % 256, 2496 / 256, 0x1f,       2560 % 256, 2560 / 256, | 
 |     0xff, | 
 | }; | 
 |  | 
 | int FaxGetRun(pdfium::span<const uint8_t> ins_array, | 
 |               const uint8_t* src_buf, | 
 |               int* bitpos, | 
 |               int bitsize) { | 
 |   uint32_t code = 0; | 
 |   int ins_off = 0; | 
 |   while (true) { | 
 |     uint8_t ins = ins_array[ins_off++]; | 
 |     if (ins == 0xff) | 
 |       return -1; | 
 |  | 
 |     if (*bitpos >= bitsize) | 
 |       return -1; | 
 |  | 
 |     code <<= 1; | 
 |     if (src_buf[*bitpos / 8] & (1 << (7 - *bitpos % 8))) | 
 |       ++code; | 
 |  | 
 |     ++(*bitpos); | 
 |     int next_off = ins_off + ins * 3; | 
 |     for (; ins_off < next_off; ins_off += 3) { | 
 |       if (ins_array[ins_off] == code) | 
 |         return ins_array[ins_off + 1] + ins_array[ins_off + 2] * 256; | 
 |     } | 
 |   } | 
 | } | 
 |  | 
 | void FaxG4GetRow(const uint8_t* src_buf, | 
 |                  int bitsize, | 
 |                  int* bitpos, | 
 |                  uint8_t* dest_buf, | 
 |                  pdfium::span<const uint8_t> ref_buf, | 
 |                  int columns) { | 
 |   int a0 = -1; | 
 |   bool a0color = true; | 
 |   while (true) { | 
 |     if (*bitpos >= bitsize) | 
 |       return; | 
 |  | 
 |     int a1; | 
 |     int a2; | 
 |     int b1; | 
 |     int b2; | 
 |     FaxG4FindB1B2(ref_buf, columns, a0, a0color, &b1, &b2); | 
 |  | 
 |     int v_delta = 0; | 
 |     if (!NextBit(src_buf, bitpos)) { | 
 |       if (*bitpos >= bitsize) | 
 |         return; | 
 |  | 
 |       bool bit1 = NextBit(src_buf, bitpos); | 
 |       if (*bitpos >= bitsize) | 
 |         return; | 
 |  | 
 |       bool bit2 = NextBit(src_buf, bitpos); | 
 |       if (bit1) { | 
 |         v_delta = bit2 ? 1 : -1; | 
 |       } else if (bit2) { | 
 |         int run_len1 = 0; | 
 |         while (true) { | 
 |           int run = FaxGetRun(a0color ? pdfium::make_span(kFaxWhiteRunIns) | 
 |                                       : pdfium::make_span(kFaxBlackRunIns), | 
 |                               src_buf, bitpos, bitsize); | 
 |           run_len1 += run; | 
 |           if (run < 64) | 
 |             break; | 
 |         } | 
 |         if (a0 < 0) | 
 |           ++run_len1; | 
 |         if (run_len1 < 0) | 
 |           return; | 
 |  | 
 |         a1 = a0 + run_len1; | 
 |         if (!a0color) | 
 |           FaxFillBits(dest_buf, columns, a0, a1); | 
 |  | 
 |         int run_len2 = 0; | 
 |         while (true) { | 
 |           int run = FaxGetRun(a0color ? pdfium::make_span(kFaxBlackRunIns) | 
 |                                       : pdfium::make_span(kFaxWhiteRunIns), | 
 |                               src_buf, bitpos, bitsize); | 
 |           run_len2 += run; | 
 |           if (run < 64) | 
 |             break; | 
 |         } | 
 |         if (run_len2 < 0) | 
 |           return; | 
 |         a2 = a1 + run_len2; | 
 |         if (a0color) | 
 |           FaxFillBits(dest_buf, columns, a1, a2); | 
 |  | 
 |         a0 = a2; | 
 |         if (a0 < columns) | 
 |           continue; | 
 |  | 
 |         return; | 
 |       } else { | 
 |         if (*bitpos >= bitsize) | 
 |           return; | 
 |  | 
 |         if (NextBit(src_buf, bitpos)) { | 
 |           if (!a0color) | 
 |             FaxFillBits(dest_buf, columns, a0, b2); | 
 |  | 
 |           if (b2 >= columns) | 
 |             return; | 
 |  | 
 |           a0 = b2; | 
 |           continue; | 
 |         } | 
 |  | 
 |         if (*bitpos >= bitsize) | 
 |           return; | 
 |  | 
 |         bool next_bit1 = NextBit(src_buf, bitpos); | 
 |         if (*bitpos >= bitsize) | 
 |           return; | 
 |  | 
 |         bool next_bit2 = NextBit(src_buf, bitpos); | 
 |         if (next_bit1) { | 
 |           v_delta = next_bit2 ? 2 : -2; | 
 |         } else if (next_bit2) { | 
 |           if (*bitpos >= bitsize) | 
 |             return; | 
 |  | 
 |           v_delta = NextBit(src_buf, bitpos) ? 3 : -3; | 
 |         } else { | 
 |           if (*bitpos >= bitsize) | 
 |             return; | 
 |  | 
 |           if (NextBit(src_buf, bitpos)) { | 
 |             *bitpos += 3; | 
 |             continue; | 
 |           } | 
 |           *bitpos += 5; | 
 |           return; | 
 |         } | 
 |       } | 
 |     } | 
 |     a1 = b1 + v_delta; | 
 |     if (!a0color) | 
 |       FaxFillBits(dest_buf, columns, a0, a1); | 
 |  | 
 |     if (a1 >= columns) | 
 |       return; | 
 |  | 
 |     // The position of picture element must be monotonic increasing. | 
 |     if (a0 >= a1) | 
 |       return; | 
 |  | 
 |     a0 = a1; | 
 |     a0color = !a0color; | 
 |   } | 
 | } | 
 |  | 
 | void FaxSkipEOL(const uint8_t* src_buf, int bitsize, int* bitpos) { | 
 |   int startbit = *bitpos; | 
 |   while (*bitpos < bitsize) { | 
 |     if (!NextBit(src_buf, bitpos)) | 
 |       continue; | 
 |     if (*bitpos - startbit <= 11) | 
 |       *bitpos = startbit; | 
 |     return; | 
 |   } | 
 | } | 
 |  | 
 | void FaxGet1DLine(const uint8_t* src_buf, | 
 |                   int bitsize, | 
 |                   int* bitpos, | 
 |                   uint8_t* dest_buf, | 
 |                   int columns) { | 
 |   bool color = true; | 
 |   int startpos = 0; | 
 |   while (true) { | 
 |     if (*bitpos >= bitsize) | 
 |       return; | 
 |  | 
 |     int run_len = 0; | 
 |     while (true) { | 
 |       int run = FaxGetRun(color ? pdfium::make_span(kFaxWhiteRunIns) | 
 |                                 : pdfium::make_span(kFaxBlackRunIns), | 
 |                           src_buf, bitpos, bitsize); | 
 |       if (run < 0) { | 
 |         while (*bitpos < bitsize) { | 
 |           if (NextBit(src_buf, bitpos)) | 
 |             return; | 
 |         } | 
 |         return; | 
 |       } | 
 |       run_len += run; | 
 |       if (run < 64) | 
 |         break; | 
 |     } | 
 |     if (!color) | 
 |       FaxFillBits(dest_buf, columns, startpos, startpos + run_len); | 
 |  | 
 |     startpos += run_len; | 
 |     if (startpos >= columns) | 
 |       break; | 
 |  | 
 |     color = !color; | 
 |   } | 
 | } | 
 |  | 
 | class FaxDecoder final : public ScanlineDecoder { | 
 |  public: | 
 |   FaxDecoder(pdfium::span<const uint8_t> src_span, | 
 |              int width, | 
 |              int height, | 
 |              int K, | 
 |              bool EndOfLine, | 
 |              bool EncodedByteAlign, | 
 |              bool BlackIs1); | 
 |   ~FaxDecoder() override; | 
 |  | 
 |   // ScanlineDecoder: | 
 |   bool Rewind() override; | 
 |   pdfium::span<uint8_t> GetNextLine() override; | 
 |   uint32_t GetSrcOffset() override; | 
 |  | 
 |  private: | 
 |   void InvertBuffer(); | 
 |  | 
 |   const int m_Encoding; | 
 |   int m_bitpos = 0; | 
 |   bool m_bByteAlign = false; | 
 |   const bool m_bEndOfLine; | 
 |   const bool m_bBlack; | 
 |   const pdfium::span<const uint8_t> m_SrcSpan; | 
 |   DataVector<uint8_t> m_ScanlineBuf; | 
 |   DataVector<uint8_t> m_RefBuf; | 
 | }; | 
 |  | 
 | FaxDecoder::FaxDecoder(pdfium::span<const uint8_t> src_span, | 
 |                        int width, | 
 |                        int height, | 
 |                        int K, | 
 |                        bool EndOfLine, | 
 |                        bool EncodedByteAlign, | 
 |                        bool BlackIs1) | 
 |     : ScanlineDecoder(width, | 
 |                       height, | 
 |                       width, | 
 |                       height, | 
 |                       kFaxComps, | 
 |                       kFaxBpc, | 
 |                       fxge::CalculatePitch32OrDie(kFaxBpc, width)), | 
 |       m_Encoding(K), | 
 |       m_bByteAlign(EncodedByteAlign), | 
 |       m_bEndOfLine(EndOfLine), | 
 |       m_bBlack(BlackIs1), | 
 |       m_SrcSpan(src_span), | 
 |       m_ScanlineBuf(m_Pitch), | 
 |       m_RefBuf(m_Pitch) {} | 
 |  | 
 | FaxDecoder::~FaxDecoder() { | 
 |   // Span in superclass can't outlive our buffer. | 
 |   m_pLastScanline = pdfium::span<uint8_t>(); | 
 | } | 
 |  | 
 | bool FaxDecoder::Rewind() { | 
 |   memset(m_RefBuf.data(), 0xff, m_RefBuf.size()); | 
 |   m_bitpos = 0; | 
 |   return true; | 
 | } | 
 |  | 
 | pdfium::span<uint8_t> FaxDecoder::GetNextLine() { | 
 |   int bitsize = pdfium::base::checked_cast<int>(m_SrcSpan.size() * 8); | 
 |   FaxSkipEOL(m_SrcSpan.data(), bitsize, &m_bitpos); | 
 |   if (m_bitpos >= bitsize) | 
 |     return pdfium::span<uint8_t>(); | 
 |  | 
 |   memset(m_ScanlineBuf.data(), 0xff, m_ScanlineBuf.size()); | 
 |   if (m_Encoding < 0) { | 
 |     FaxG4GetRow(m_SrcSpan.data(), bitsize, &m_bitpos, m_ScanlineBuf.data(), | 
 |                 m_RefBuf, m_OrigWidth); | 
 |     m_RefBuf = m_ScanlineBuf; | 
 |   } else if (m_Encoding == 0) { | 
 |     FaxGet1DLine(m_SrcSpan.data(), bitsize, &m_bitpos, m_ScanlineBuf.data(), | 
 |                  m_OrigWidth); | 
 |   } else { | 
 |     if (NextBit(m_SrcSpan.data(), &m_bitpos)) { | 
 |       FaxGet1DLine(m_SrcSpan.data(), bitsize, &m_bitpos, m_ScanlineBuf.data(), | 
 |                    m_OrigWidth); | 
 |     } else { | 
 |       FaxG4GetRow(m_SrcSpan.data(), bitsize, &m_bitpos, m_ScanlineBuf.data(), | 
 |                   m_RefBuf, m_OrigWidth); | 
 |     } | 
 |     m_RefBuf = m_ScanlineBuf; | 
 |   } | 
 |   if (m_bEndOfLine) | 
 |     FaxSkipEOL(m_SrcSpan.data(), bitsize, &m_bitpos); | 
 |  | 
 |   if (m_bByteAlign && m_bitpos < bitsize) { | 
 |     int bitpos0 = m_bitpos; | 
 |     int bitpos1 = FxAlignToBoundary<8>(m_bitpos); | 
 |     while (m_bByteAlign && bitpos0 < bitpos1) { | 
 |       int bit = m_SrcSpan[bitpos0 / 8] & (1 << (7 - bitpos0 % 8)); | 
 |       if (bit != 0) | 
 |         m_bByteAlign = false; | 
 |       else | 
 |         ++bitpos0; | 
 |     } | 
 |     if (m_bByteAlign) | 
 |       m_bitpos = bitpos1; | 
 |   } | 
 |   if (m_bBlack) | 
 |     InvertBuffer(); | 
 |   return m_ScanlineBuf; | 
 | } | 
 |  | 
 | uint32_t FaxDecoder::GetSrcOffset() { | 
 |   return pdfium::base::checked_cast<uint32_t>( | 
 |       std::min<size_t>((m_bitpos + 7) / 8, m_SrcSpan.size())); | 
 | } | 
 |  | 
 | void FaxDecoder::InvertBuffer() { | 
 |   DCHECK_EQ(m_Pitch, m_ScanlineBuf.size()); | 
 |   DCHECK_EQ(m_Pitch % 4, 0); | 
 |   uint32_t* data = reinterpret_cast<uint32_t*>(m_ScanlineBuf.data()); | 
 |   for (size_t i = 0; i < m_ScanlineBuf.size() / 4; ++i) | 
 |     data[i] = ~data[i]; | 
 | } | 
 |  | 
 | }  // namespace | 
 |  | 
 | // static | 
 | std::unique_ptr<ScanlineDecoder> FaxModule::CreateDecoder( | 
 |     pdfium::span<const uint8_t> src_span, | 
 |     int width, | 
 |     int height, | 
 |     int K, | 
 |     bool EndOfLine, | 
 |     bool EncodedByteAlign, | 
 |     bool BlackIs1, | 
 |     int Columns, | 
 |     int Rows) { | 
 |   int actual_width = Columns ? Columns : width; | 
 |   int actual_height = Rows ? Rows : height; | 
 |  | 
 |   // Reject invalid values. | 
 |   if (actual_width <= 0 || actual_height <= 0) | 
 |     return nullptr; | 
 |  | 
 |   // Reject unreasonable large input. | 
 |   if (actual_width > kFaxMaxImageDimension || | 
 |       actual_height > kFaxMaxImageDimension) { | 
 |     return nullptr; | 
 |   } | 
 |  | 
 |   return std::make_unique<FaxDecoder>(src_span, actual_width, actual_height, K, | 
 |                                       EndOfLine, EncodedByteAlign, BlackIs1); | 
 | } | 
 |  | 
 | // static | 
 | int FaxModule::FaxG4Decode(const uint8_t* src_buf, | 
 |                            uint32_t src_size, | 
 |                            int starting_bitpos, | 
 |                            int width, | 
 |                            int height, | 
 |                            int pitch, | 
 |                            uint8_t* dest_buf) { | 
 |   DCHECK(pitch != 0); | 
 |  | 
 |   DataVector<uint8_t> ref_buf(pitch, 0xff); | 
 |   int bitpos = starting_bitpos; | 
 |   for (int iRow = 0; iRow < height; ++iRow) { | 
 |     uint8_t* line_buf = dest_buf + iRow * pitch; | 
 |     memset(line_buf, 0xff, pitch); | 
 |     FaxG4GetRow(src_buf, src_size << 3, &bitpos, line_buf, ref_buf, width); | 
 |     memcpy(ref_buf.data(), line_buf, pitch); | 
 |   } | 
 |   return bitpos; | 
 | } | 
 |  | 
 | #if BUILDFLAG(IS_WIN) | 
 | namespace { | 
 | const uint8_t BlackRunTerminator[128] = { | 
 |     0x37, 10, 0x02, 3,  0x03, 2,  0x02, 2,  0x03, 3,  0x03, 4,  0x02, 4, | 
 |     0x03, 5,  0x05, 6,  0x04, 6,  0x04, 7,  0x05, 7,  0x07, 7,  0x04, 8, | 
 |     0x07, 8,  0x18, 9,  0x17, 10, 0x18, 10, 0x08, 10, 0x67, 11, 0x68, 11, | 
 |     0x6c, 11, 0x37, 11, 0x28, 11, 0x17, 11, 0x18, 11, 0xca, 12, 0xcb, 12, | 
 |     0xcc, 12, 0xcd, 12, 0x68, 12, 0x69, 12, 0x6a, 12, 0x6b, 12, 0xd2, 12, | 
 |     0xd3, 12, 0xd4, 12, 0xd5, 12, 0xd6, 12, 0xd7, 12, 0x6c, 12, 0x6d, 12, | 
 |     0xda, 12, 0xdb, 12, 0x54, 12, 0x55, 12, 0x56, 12, 0x57, 12, 0x64, 12, | 
 |     0x65, 12, 0x52, 12, 0x53, 12, 0x24, 12, 0x37, 12, 0x38, 12, 0x27, 12, | 
 |     0x28, 12, 0x58, 12, 0x59, 12, 0x2b, 12, 0x2c, 12, 0x5a, 12, 0x66, 12, | 
 |     0x67, 12, | 
 | }; | 
 |  | 
 | const uint8_t BlackRunMarkup[80] = { | 
 |     0x0f, 10, 0xc8, 12, 0xc9, 12, 0x5b, 12, 0x33, 12, 0x34, 12, 0x35, 12, | 
 |     0x6c, 13, 0x6d, 13, 0x4a, 13, 0x4b, 13, 0x4c, 13, 0x4d, 13, 0x72, 13, | 
 |     0x73, 13, 0x74, 13, 0x75, 13, 0x76, 13, 0x77, 13, 0x52, 13, 0x53, 13, | 
 |     0x54, 13, 0x55, 13, 0x5a, 13, 0x5b, 13, 0x64, 13, 0x65, 13, 0x08, 11, | 
 |     0x0c, 11, 0x0d, 11, 0x12, 12, 0x13, 12, 0x14, 12, 0x15, 12, 0x16, 12, | 
 |     0x17, 12, 0x1c, 12, 0x1d, 12, 0x1e, 12, 0x1f, 12, | 
 | }; | 
 |  | 
 | const uint8_t WhiteRunTerminator[128] = { | 
 |     0x35, 8, 0x07, 6, 0x07, 4, 0x08, 4, 0x0B, 4, 0x0C, 4, 0x0E, 4, 0x0F, 4, | 
 |     0x13, 5, 0x14, 5, 0x07, 5, 0x08, 5, 0x08, 6, 0x03, 6, 0x34, 6, 0x35, 6, | 
 |     0x2a, 6, 0x2B, 6, 0x27, 7, 0x0c, 7, 0x08, 7, 0x17, 7, 0x03, 7, 0x04, 7, | 
 |     0x28, 7, 0x2B, 7, 0x13, 7, 0x24, 7, 0x18, 7, 0x02, 8, 0x03, 8, 0x1a, 8, | 
 |     0x1b, 8, 0x12, 8, 0x13, 8, 0x14, 8, 0x15, 8, 0x16, 8, 0x17, 8, 0x28, 8, | 
 |     0x29, 8, 0x2a, 8, 0x2b, 8, 0x2c, 8, 0x2d, 8, 0x04, 8, 0x05, 8, 0x0a, 8, | 
 |     0x0b, 8, 0x52, 8, 0x53, 8, 0x54, 8, 0x55, 8, 0x24, 8, 0x25, 8, 0x58, 8, | 
 |     0x59, 8, 0x5a, 8, 0x5b, 8, 0x4a, 8, 0x4b, 8, 0x32, 8, 0x33, 8, 0x34, 8, | 
 | }; | 
 |  | 
 | const uint8_t WhiteRunMarkup[80] = { | 
 |     0x1b, 5,  0x12, 5,  0x17, 6,  0x37, 7,  0x36, 8,  0x37, 8,  0x64, 8, | 
 |     0x65, 8,  0x68, 8,  0x67, 8,  0xcc, 9,  0xcd, 9,  0xd2, 9,  0xd3, 9, | 
 |     0xd4, 9,  0xd5, 9,  0xd6, 9,  0xd7, 9,  0xd8, 9,  0xd9, 9,  0xda, 9, | 
 |     0xdb, 9,  0x98, 9,  0x99, 9,  0x9a, 9,  0x18, 6,  0x9b, 9,  0x08, 11, | 
 |     0x0c, 11, 0x0d, 11, 0x12, 12, 0x13, 12, 0x14, 12, 0x15, 12, 0x16, 12, | 
 |     0x17, 12, 0x1c, 12, 0x1d, 12, 0x1e, 12, 0x1f, 12, | 
 | }; | 
 |  | 
 | class FaxEncoder { | 
 |  public: | 
 |   explicit FaxEncoder(RetainPtr<CFX_DIBBase> src); | 
 |   ~FaxEncoder(); | 
 |   DataVector<uint8_t> Encode(); | 
 |  | 
 |  private: | 
 |   void FaxEncode2DLine(pdfium::span<const uint8_t> src_span); | 
 |   void FaxEncodeRun(int run, bool bWhite); | 
 |   void AddBitStream(int data, int bitlen); | 
 |  | 
 |   // Must outlive `m_RefLineSpan`. | 
 |   RetainPtr<CFX_DIBBase> const m_Src; | 
 |   int m_DestBitpos = 0; | 
 |   const int m_Cols; | 
 |   const int m_Rows; | 
 |   const int m_Pitch; | 
 |   BinaryBuffer m_DestBuf; | 
 |   // Must outlive `m_RefLineSpan`. | 
 |   const DataVector<uint8_t> m_InitialRefLine; | 
 |   DataVector<uint8_t> m_LineBuf; | 
 |   pdfium::span<const uint8_t> m_RefLineSpan; | 
 | }; | 
 |  | 
 | FaxEncoder::FaxEncoder(RetainPtr<CFX_DIBBase> src) | 
 |     : m_Src(std::move(src)), | 
 |       m_Cols(m_Src->GetWidth()), | 
 |       m_Rows(m_Src->GetHeight()), | 
 |       m_Pitch(m_Src->GetPitch()), | 
 |       m_InitialRefLine(m_Pitch, 0xff), | 
 |       m_LineBuf(Fx2DSizeOrDie(8, m_Pitch)), | 
 |       m_RefLineSpan(m_InitialRefLine) { | 
 |   DCHECK_EQ(1, m_Src->GetBPP()); | 
 |   m_DestBuf.SetAllocStep(10240); | 
 | } | 
 |  | 
 | FaxEncoder::~FaxEncoder() = default; | 
 |  | 
 | void FaxEncoder::AddBitStream(int data, int bitlen) { | 
 |   for (int i = bitlen - 1; i >= 0; --i, ++m_DestBitpos) { | 
 |     if (data & (1 << i)) | 
 |       m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |   } | 
 | } | 
 |  | 
 | void FaxEncoder::FaxEncodeRun(int run, bool bWhite) { | 
 |   while (run >= 2560) { | 
 |     AddBitStream(0x1f, 12); | 
 |     run -= 2560; | 
 |   } | 
 |   if (run >= 64) { | 
 |     int markup = run - run % 64; | 
 |     const uint8_t* p = bWhite ? WhiteRunMarkup : BlackRunMarkup; | 
 |     p += (markup / 64 - 1) * 2; | 
 |     AddBitStream(*p, p[1]); | 
 |   } | 
 |   run %= 64; | 
 |   const uint8_t* p = bWhite ? WhiteRunTerminator : BlackRunTerminator; | 
 |   p += run * 2; | 
 |   AddBitStream(*p, p[1]); | 
 | } | 
 |  | 
 | void FaxEncoder::FaxEncode2DLine(pdfium::span<const uint8_t> src_span) { | 
 |   int a0 = -1; | 
 |   bool a0color = true; | 
 |   while (1) { | 
 |     int a1 = FindBit(src_span, m_Cols, a0 + 1, !a0color); | 
 |     int b1; | 
 |     int b2; | 
 |     FaxG4FindB1B2(m_RefLineSpan, m_Cols, a0, a0color, &b1, &b2); | 
 |     if (b2 < a1) { | 
 |       m_DestBitpos += 3; | 
 |       m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |       ++m_DestBitpos; | 
 |       a0 = b2; | 
 |     } else if (a1 - b1 <= 3 && b1 - a1 <= 3) { | 
 |       int delta = a1 - b1; | 
 |       switch (delta) { | 
 |         case 0: | 
 |           m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |           break; | 
 |         case 1: | 
 |         case 2: | 
 |         case 3: | 
 |           m_DestBitpos += delta == 1 ? 1 : delta + 2; | 
 |           m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |           ++m_DestBitpos; | 
 |           m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |           break; | 
 |         case -1: | 
 |         case -2: | 
 |         case -3: | 
 |           m_DestBitpos += delta == -1 ? 1 : -delta + 2; | 
 |           m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |           ++m_DestBitpos; | 
 |           break; | 
 |       } | 
 |       ++m_DestBitpos; | 
 |       a0 = a1; | 
 |       a0color = !a0color; | 
 |     } else { | 
 |       int a2 = FindBit(src_span, m_Cols, a1 + 1, a0color); | 
 |       ++m_DestBitpos; | 
 |       ++m_DestBitpos; | 
 |       m_LineBuf[m_DestBitpos / 8] |= 1 << (7 - m_DestBitpos % 8); | 
 |       ++m_DestBitpos; | 
 |       if (a0 < 0) | 
 |         a0 = 0; | 
 |       FaxEncodeRun(a1 - a0, a0color); | 
 |       FaxEncodeRun(a2 - a1, !a0color); | 
 |       a0 = a2; | 
 |     } | 
 |     if (a0 >= m_Cols) | 
 |       return; | 
 |   } | 
 | } | 
 |  | 
 | DataVector<uint8_t> FaxEncoder::Encode() { | 
 |   m_DestBitpos = 0; | 
 |   uint8_t last_byte = 0; | 
 |   for (int i = 0; i < m_Rows; ++i) { | 
 |     pdfium::span<uint8_t> buf_span = pdfium::make_span(m_LineBuf); | 
 |     fxcrt::spanset(buf_span, 0); | 
 |     buf_span[0] = last_byte; | 
 |     pdfium::span<const uint8_t> scan_line = m_Src->GetScanline(i); | 
 |     FaxEncode2DLine(scan_line); | 
 |     m_DestBuf.AppendSpan(buf_span.first(m_DestBitpos / 8)); | 
 |     last_byte = m_LineBuf[m_DestBitpos / 8]; | 
 |     m_DestBitpos %= 8; | 
 |     m_RefLineSpan = scan_line; | 
 |   } | 
 |   if (m_DestBitpos) | 
 |     m_DestBuf.AppendUint8(last_byte); | 
 |   return m_DestBuf.DetachBuffer(); | 
 | } | 
 |  | 
 | }  // namespace | 
 |  | 
 | // static | 
 | DataVector<uint8_t> FaxModule::FaxEncode(RetainPtr<CFX_DIBBase> src) { | 
 |   DCHECK_EQ(1, src->GetBPP()); | 
 |   FaxEncoder encoder(std::move(src)); | 
 |   return encoder.Encode(); | 
 | } | 
 |  | 
 | #endif  // BUILDFLAG(IS_WIN) | 
 |  | 
 | }  // namespace fxcodec |