tor-browser

bitstream.cc (15335B)

---

// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "lib/jpegli/bitstream.h"

#include <cmath>

#include "lib/jpegli/bit_writer.h"
#include "lib/jpegli/error.h"
#include "lib/jpegli/memory_manager.h"

namespace jpegli {

void WriteOutput(j_compress_ptr cinfo, const uint8_t* buf, size_t bufsize) {
 size_t pos = 0;
 while (pos < bufsize) {
   if (cinfo->dest->free_in_buffer == 0 &&
       !(*cinfo->dest->empty_output_buffer)(cinfo)) {
     JPEGLI_ERROR("Destination suspension is not supported in markers.");
   }
   size_t len = std::min<size_t>(cinfo->dest->free_in_buffer, bufsize - pos);
   memcpy(cinfo->dest->next_output_byte, buf + pos, len);
   pos += len;
   cinfo->dest->free_in_buffer -= len;
   cinfo->dest->next_output_byte += len;
 }
}

void WriteOutput(j_compress_ptr cinfo, const std::vector<uint8_t>& bytes) {
 WriteOutput(cinfo, bytes.data(), bytes.size());
}

void WriteOutput(j_compress_ptr cinfo, std::initializer_list<uint8_t> bytes) {
 WriteOutput(cinfo, bytes.begin(), bytes.size());
}

void EncodeAPP0(j_compress_ptr cinfo) {
 WriteOutput(cinfo,
             {0xff, 0xe0, 0, 16, 'J', 'F', 'I', 'F', '\0',
              cinfo->JFIF_major_version, cinfo->JFIF_minor_version,
              cinfo->density_unit, static_cast<uint8_t>(cinfo->X_density >> 8),
              static_cast<uint8_t>(cinfo->X_density & 0xff),
              static_cast<uint8_t>(cinfo->Y_density >> 8),
              static_cast<uint8_t>(cinfo->Y_density & 0xff), 0, 0});
}

void EncodeAPP14(j_compress_ptr cinfo) {
 uint8_t color_transform = cinfo->jpeg_color_space == JCS_YCbCr  ? 1
                           : cinfo->jpeg_color_space == JCS_YCCK ? 2
                                                                 : 0;
 WriteOutput(cinfo, {0xff, 0xee, 0, 14, 'A', 'd', 'o', 'b', 'e', 0, 100, 0, 0,
                     0, 0, color_transform});
}

void WriteFileHeader(j_compress_ptr cinfo) {
 WriteOutput(cinfo, {0xFF, 0xD8});  // SOI
 if (cinfo->write_JFIF_header) {
   EncodeAPP0(cinfo);
 }
 if (cinfo->write_Adobe_marker) {
   EncodeAPP14(cinfo);
 }
}

bool EncodeDQT(j_compress_ptr cinfo, bool write_all_tables) {
 uint8_t data[4 + NUM_QUANT_TBLS * (1 + 2 * DCTSIZE2)];  // 520 bytes
 size_t pos = 0;
 data[pos++] = 0xFF;
 data[pos++] = 0xDB;
 pos += 2;  // Length will be filled in later.

 int send_table[NUM_QUANT_TBLS] = {};
 if (write_all_tables) {
   for (int i = 0; i < NUM_QUANT_TBLS; ++i) {
     if (cinfo->quant_tbl_ptrs[i]) send_table[i] = 1;
   }
 } else {
   for (int c = 0; c < cinfo->num_components; ++c) {
     send_table[cinfo->comp_info[c].quant_tbl_no] = 1;
   }
 }

 bool is_baseline = true;
 for (int i = 0; i < NUM_QUANT_TBLS; ++i) {
   if (!send_table[i]) continue;
   JQUANT_TBL* quant_table = cinfo->quant_tbl_ptrs[i];
   if (quant_table == nullptr) {
     JPEGLI_ERROR("Missing quant table %d", i);
   }
   int precision = 0;
   for (UINT16 q : quant_table->quantval) {
     if (q > 255) {
       precision = 1;
       is_baseline = false;
     }
   }
   if (quant_table->sent_table) {
     continue;
   }
   data[pos++] = (precision << 4) + i;
   for (size_t j = 0; j < DCTSIZE2; ++j) {
     int val_idx = kJPEGNaturalOrder[j];
     int val = quant_table->quantval[val_idx];
     if (val == 0) {
       JPEGLI_ERROR("Invalid quantval 0.");
     }
     if (precision) {
       data[pos++] = val >> 8;
     }
     data[pos++] = val & 0xFFu;
   }
   quant_table->sent_table = TRUE;
 }
 if (pos > 4) {
   data[2] = (pos - 2) >> 8u;
   data[3] = (pos - 2) & 0xFFu;
   WriteOutput(cinfo, data, pos);
 }
 return is_baseline;
}

void EncodeSOF(j_compress_ptr cinfo, bool is_baseline) {
 if (cinfo->data_precision != kJpegPrecision) {
   JPEGLI_ERROR("Unsupported data precision %d", cinfo->data_precision);
 }
 const uint8_t marker = cinfo->progressive_mode ? 0xc2
                        : is_baseline           ? 0xc0
                                                : 0xc1;
 const size_t n_comps = cinfo->num_components;
 const size_t marker_len = 8 + 3 * n_comps;
 std::vector<uint8_t> data(marker_len + 2);
 size_t pos = 0;
 data[pos++] = 0xFF;
 data[pos++] = marker;
 data[pos++] = marker_len >> 8u;
 data[pos++] = marker_len & 0xFFu;
 data[pos++] = kJpegPrecision;
 data[pos++] = cinfo->image_height >> 8u;
 data[pos++] = cinfo->image_height & 0xFFu;
 data[pos++] = cinfo->image_width >> 8u;
 data[pos++] = cinfo->image_width & 0xFFu;
 data[pos++] = n_comps;
 for (size_t i = 0; i < n_comps; ++i) {
   jpeg_component_info* comp = &cinfo->comp_info[i];
   data[pos++] = comp->component_id;
   data[pos++] = ((comp->h_samp_factor << 4u) | (comp->v_samp_factor));
   const uint32_t quant_idx = comp->quant_tbl_no;
   if (cinfo->quant_tbl_ptrs[quant_idx] == nullptr) {
     JPEGLI_ERROR("Invalid component quant table index %u.", quant_idx);
   }
   data[pos++] = quant_idx;
 }
 WriteOutput(cinfo, data);
}

void WriteFrameHeader(j_compress_ptr cinfo) {
 jpeg_comp_master* m = cinfo->master;
 bool is_baseline = EncodeDQT(cinfo, /*write_all_tables=*/false);
 if (cinfo->progressive_mode || cinfo->arith_code ||
     cinfo->data_precision != 8) {
   is_baseline = false;
 }
 for (size_t i = 0; i < m->num_huffman_tables; ++i) {
   int slot_id = m->slot_id_map[i];
   if (slot_id > 0x11 || (slot_id > 0x01 && slot_id < 0x10)) {
     is_baseline = false;
   }
 }
 EncodeSOF(cinfo, is_baseline);
}

void EncodeDRI(j_compress_ptr cinfo) {
 WriteOutput(cinfo, {0xFF, 0xDD, 0, 4,
                     static_cast<uint8_t>(cinfo->restart_interval >> 8),
                     static_cast<uint8_t>(cinfo->restart_interval & 0xFF)});
}

void EncodeDHT(j_compress_ptr cinfo, size_t offset, size_t num) {
 jpeg_comp_master* m = cinfo->master;
 size_t marker_len = 2;
 for (size_t i = 0; i < num; ++i) {
   const JHUFF_TBL& table = m->huffman_tables[offset + i];
   if (table.sent_table) continue;
   marker_len += kJpegHuffmanMaxBitLength + 1;
   for (size_t j = 0; j <= kJpegHuffmanMaxBitLength; ++j) {
     marker_len += table.bits[j];
   }
 }
 std::vector<uint8_t> data(marker_len + 2);
 size_t pos = 0;
 data[pos++] = 0xFF;
 data[pos++] = 0xC4;
 data[pos++] = marker_len >> 8u;
 data[pos++] = marker_len & 0xFFu;
 for (size_t i = 0; i < num; ++i) {
   const JHUFF_TBL& table = m->huffman_tables[offset + i];
   if (table.sent_table) continue;
   size_t total_count = 0;
   for (size_t i = 0; i <= kJpegHuffmanMaxBitLength; ++i) {
     total_count += table.bits[i];
   }
   data[pos++] = m->slot_id_map[offset + i];
   for (size_t i = 1; i <= kJpegHuffmanMaxBitLength; ++i) {
     data[pos++] = table.bits[i];
   }
   for (size_t i = 0; i < total_count; ++i) {
     data[pos++] = table.huffval[i];
   }
 }
 if (marker_len > 2) {
   WriteOutput(cinfo, data);
 }
}

void EncodeSOS(j_compress_ptr cinfo, int scan_index) {
 jpeg_comp_master* m = cinfo->master;
 const jpeg_scan_info* scan_info = &cinfo->scan_info[scan_index];
 const size_t marker_len = 6 + 2 * scan_info->comps_in_scan;
 std::vector<uint8_t> data(marker_len + 2);
 size_t pos = 0;
 data[pos++] = 0xFF;
 data[pos++] = 0xDA;
 data[pos++] = marker_len >> 8u;
 data[pos++] = marker_len & 0xFFu;
 data[pos++] = scan_info->comps_in_scan;
 for (int i = 0; i < scan_info->comps_in_scan; ++i) {
   int comp_idx = scan_info->component_index[i];
   data[pos++] = cinfo->comp_info[comp_idx].component_id;
   int dc_slot_id = m->slot_id_map[m->context_map[comp_idx]];
   int ac_context = m->ac_ctx_offset[scan_index] + i;
   int ac_slot_id = m->slot_id_map[m->context_map[ac_context]];
   data[pos++] = (dc_slot_id << 4u) + (ac_slot_id - 16);
 }
 data[pos++] = scan_info->Ss;
 data[pos++] = scan_info->Se;
 data[pos++] = ((scan_info->Ah << 4u) | (scan_info->Al));
 WriteOutput(cinfo, data);
}

void WriteScanHeader(j_compress_ptr cinfo, int scan_index) {
 jpeg_comp_master* m = cinfo->master;
 const jpeg_scan_info* scan_info = &cinfo->scan_info[scan_index];
 cinfo->restart_interval = m->scan_token_info[scan_index].restart_interval;
 if (cinfo->restart_interval != m->last_restart_interval) {
   EncodeDRI(cinfo);
   m->last_restart_interval = cinfo->restart_interval;
 }
 size_t num_dht = 0;
 if (scan_index == 0) {
   // For the first scan we emit all DC and at most 4 AC Huffman codes.
   for (size_t i = 0, num_ac = 0; i < m->num_huffman_tables; ++i) {
     if (m->slot_id_map[i] >= 16 && num_ac++ >= 4) break;
     ++num_dht;
   }
 } else if (scan_info->Ss > 0) {
   // For multi-scan sequential and progressive DC scans we have already
   // emitted all Huffman codes that we need before the first scan. For
   // progressive AC scans we only need at most one new Huffman code.
   if (m->context_map[m->ac_ctx_offset[scan_index]] == m->next_dht_index) {
     num_dht = 1;
   }
 }
 if (num_dht > 0) {
   EncodeDHT(cinfo, m->next_dht_index, num_dht);
   m->next_dht_index += num_dht;
 }
 EncodeSOS(cinfo, scan_index);
}

void WriteBlock(const int32_t* JXL_RESTRICT symbols,
               const int32_t* JXL_RESTRICT extra_bits, const int num_nonzeros,
               const bool emit_eob,
               const HuffmanCodeTable* JXL_RESTRICT dc_code,
               const HuffmanCodeTable* JXL_RESTRICT ac_code,
               JpegBitWriter* JXL_RESTRICT bw) {
 int symbol = symbols[0];
 WriteBits(bw, dc_code->depth[symbol], dc_code->code[symbol] | extra_bits[0]);
 for (int i = 1; i < num_nonzeros; ++i) {
   symbol = symbols[i];
   if (symbol > 255) {
     WriteBits(bw, ac_code->depth[0xf0], ac_code->code[0xf0]);
     symbol -= 256;
     if (symbol > 255) {
       WriteBits(bw, ac_code->depth[0xf0], ac_code->code[0xf0]);
       symbol -= 256;
       if (symbol > 255) {
         WriteBits(bw, ac_code->depth[0xf0], ac_code->code[0xf0]);
         symbol -= 256;
       }
     }
   }
   WriteBits(bw, ac_code->depth[symbol],
             ac_code->code[symbol] | extra_bits[i]);
 }
 if (emit_eob) {
   WriteBits(bw, ac_code->depth[0], ac_code->code[0]);
 }
}

namespace {

JXL_INLINE void EmitMarker(JpegBitWriter* bw, int marker) {
 bw->data[bw->pos++] = 0xFF;
 bw->data[bw->pos++] = marker;
}

void WriteTokens(j_compress_ptr cinfo, int scan_index, JpegBitWriter* bw) {
 jpeg_comp_master* m = cinfo->master;
 HuffmanCodeTable* coding_tables = &m->coding_tables[0];
 int next_restart_marker = 0;
 const ScanTokenInfo& sti = m->scan_token_info[scan_index];
 size_t num_token_arrays = m->cur_token_array + 1;
 size_t total_tokens = 0;
 size_t restart_idx = 0;
 size_t next_restart = sti.restarts[restart_idx];
 uint8_t* context_map = m->context_map;
 for (size_t i = 0; i < num_token_arrays; ++i) {
   Token* tokens = m->token_arrays[i].tokens;
   size_t num_tokens = m->token_arrays[i].num_tokens;
   if (sti.token_offset < total_tokens + num_tokens &&
       total_tokens < sti.token_offset + sti.num_tokens) {
     size_t start_ix =
         total_tokens < sti.token_offset ? sti.token_offset - total_tokens : 0;
     size_t end_ix = std::min(sti.token_offset + sti.num_tokens - total_tokens,
                              num_tokens);
     size_t cycle_len = bw->len / 8;
     size_t next_cycle = cycle_len;
     for (size_t i = start_ix; i < end_ix; ++i) {
       if (total_tokens + i == next_restart) {
         JumpToByteBoundary(bw);
         EmitMarker(bw, 0xD0 + next_restart_marker);
         next_restart_marker += 1;
         next_restart_marker &= 0x7;
         next_restart = sti.restarts[++restart_idx];
       }
       Token t = tokens[i];
       const HuffmanCodeTable* code = &coding_tables[context_map[t.context]];
       WriteBits(bw, code->depth[t.symbol], code->code[t.symbol] | t.bits);
       if (--next_cycle == 0) {
         if (!EmptyBitWriterBuffer(bw)) {
           JPEGLI_ERROR(
               "Output suspension is not supported in "
               "finish_compress");
         }
         next_cycle = cycle_len;
       }
     }
   }
   total_tokens += num_tokens;
 }
}

void WriteACRefinementTokens(j_compress_ptr cinfo, int scan_index,
                            JpegBitWriter* bw) {
 jpeg_comp_master* m = cinfo->master;
 const ScanTokenInfo& sti = m->scan_token_info[scan_index];
 const uint8_t context = m->ac_ctx_offset[scan_index];
 const HuffmanCodeTable* code = &m->coding_tables[m->context_map[context]];
 size_t cycle_len = bw->len / 64;
 size_t next_cycle = cycle_len;
 size_t refbit_idx = 0;
 size_t eobrun_idx = 0;
 size_t restart_idx = 0;
 size_t next_restart = sti.restarts[restart_idx];
 int next_restart_marker = 0;
 for (size_t i = 0; i < sti.num_tokens; ++i) {
   if (i == next_restart) {
     JumpToByteBoundary(bw);
     EmitMarker(bw, 0xD0 + next_restart_marker);
     next_restart_marker += 1;
     next_restart_marker &= 0x7;
     next_restart = sti.restarts[++restart_idx];
   }
   RefToken t = sti.tokens[i];
   int symbol = t.symbol & 253;
   uint16_t bits = 0;
   if ((symbol & 1) == 0) {
     int r = symbol >> 4;
     if (r > 0 && r < 15) {
       bits = sti.eobruns[eobrun_idx++];
     }
   } else {
     bits = (t.symbol >> 1) & 1;
   }
   WriteBits(bw, code->depth[symbol], code->code[symbol] | bits);
   for (int j = 0; j < t.refbits; ++j) {
     WriteBits(bw, 1, sti.refbits[refbit_idx++]);
   }
   if (--next_cycle == 0) {
     if (!EmptyBitWriterBuffer(bw)) {
       JPEGLI_ERROR("Output suspension is not supported in finish_compress");
     }
     next_cycle = cycle_len;
   }
 }
}

void WriteDCRefinementBits(j_compress_ptr cinfo, int scan_index,
                          JpegBitWriter* bw) {
 jpeg_comp_master* m = cinfo->master;
 const ScanTokenInfo& sti = m->scan_token_info[scan_index];
 size_t restart_idx = 0;
 size_t next_restart = sti.restarts[restart_idx];
 int next_restart_marker = 0;
 size_t cycle_len = bw->len * 4;
 size_t next_cycle = cycle_len;
 size_t refbit_idx = 0;
 for (size_t i = 0; i < sti.num_tokens; ++i) {
   if (i == next_restart) {
     JumpToByteBoundary(bw);
     EmitMarker(bw, 0xD0 + next_restart_marker);
     next_restart_marker += 1;
     next_restart_marker &= 0x7;
     next_restart = sti.restarts[++restart_idx];
   }
   WriteBits(bw, 1, sti.refbits[refbit_idx++]);
   if (--next_cycle == 0) {
     if (!EmptyBitWriterBuffer(bw)) {
       JPEGLI_ERROR(
           "Output suspension is not supported in "
           "finish_compress");
     }
     next_cycle = cycle_len;
   }
 }
}

}  // namespace

void WriteScanData(j_compress_ptr cinfo, int scan_index) {
 const jpeg_scan_info* scan_info = &cinfo->scan_info[scan_index];
 JpegBitWriter* bw = &cinfo->master->bw;
 if (scan_info->Ah == 0) {
   WriteTokens(cinfo, scan_index, bw);
 } else if (scan_info->Ss > 0) {
   WriteACRefinementTokens(cinfo, scan_index, bw);
 } else {
   WriteDCRefinementBits(cinfo, scan_index, bw);
 }
 if (!bw->healthy) {
   JPEGLI_ERROR("Unknown Huffman coded symbol found in scan %d", scan_index);
 }
 JumpToByteBoundary(bw);
 if (!EmptyBitWriterBuffer(bw)) {
   JPEGLI_ERROR("Output suspension is not supported in finish_compress");
 }
}

}  // namespace jpegli