Function tdefl_compress_lz_codes

SampleFramework12/v1.00/TinyEXR.cpp:2995–3088

#if MINIZ_USE_UNALIGNED_LOADS_AND_STORES && MINIZ_LITTLE_ENDIAN &&             \
    MINIZ_HAS_64BIT_REGISTERS
static mz_bool tdefl_compress_lz_codes(tdefl_compressor *d) {
  mz_uint flags;
  mz_uint8 *pLZ_codes;
  mz_uint8 *pOutput_buf = d->m_pOutput_buf;
  mz_uint8 *pLZ_code_buf_end = d->m_pLZ_code_buf;
  mz_uint64 bit_buffer = d->m_bit_buffer;
  mz_uint bits_in = d->m_bits_in;

#define TDEFL_PUT_BITS_FAST(b, l)                                              \
  {                                                                            \
    bit_buffer |= (((mz_uint64)(b)) << bits_in);                               \
    bits_in += (l);                                                            \
  }

  flags = 1;
  for (pLZ_codes = d->m_lz_code_buf; pLZ_codes < pLZ_code_buf_end;
       flags >>= 1) {
    if (flags == 1)
      flags = *pLZ_codes++ | 0x100;

    if (flags & 1) {
      mz_uint s0, s1, n0, n1, sym, num_extra_bits;
      mz_uint match_len = pLZ_codes[0],
              match_dist = *(const mz_uint16 *)(pLZ_codes + 1);
      pLZ_codes += 3;

      MZ_ASSERT(d->m_huff_code_sizes[0][s_tdefl_len_sym[match_len]]);
      TDEFL_PUT_BITS_FAST(d->m_huff_codes[0][s_tdefl_len_sym[match_len]],
                          d->m_huff_code_sizes[0][s_tdefl_len_sym[match_len]]);
      TDEFL_PUT_BITS_FAST(match_len & mz_bitmasks[s_tdefl_len_extra[match_len]],
                          s_tdefl_len_extra[match_len]);

      // This sequence coaxes MSVC into using cmov's vs. jmp's.
      s0 = s_tdefl_small_dist_sym[match_dist & 511];
      n0 = s_tdefl_small_dist_extra[match_dist & 511];
      s1 = s_tdefl_large_dist_sym[match_dist >> 8];
      n1 = s_tdefl_large_dist_extra[match_dist >> 8];
      sym = (match_dist < 512) ? s0 : s1;
      num_extra_bits = (match_dist < 512) ? n0 : n1;

      MZ_ASSERT(d->m_huff_code_sizes[1][sym]);
      TDEFL_PUT_BITS_FAST(d->m_huff_codes[1][sym],
                          d->m_huff_code_sizes[1][sym]);
      TDEFL_PUT_BITS_FAST(match_dist & mz_bitmasks[num_extra_bits],
                          num_extra_bits);
    } else {
      mz_uint lit = *pLZ_codes++;
      MZ_ASSERT(d->m_huff_code_sizes[0][lit]);
      TDEFL_PUT_BITS_FAST(d->m_huff_codes[0][lit],
                          d->m_huff_code_sizes[0][lit]);

      if (((flags & 2) == 0) && (pLZ_codes < pLZ_code_buf_end)) {
        flags >>= 1;
        lit = *pLZ_codes++;
        MZ_ASSERT(d->m_huff_code_sizes[0][lit]);
        TDEFL_PUT_BITS_FAST(d->m_huff_codes[0][lit],
                            d->m_huff_code_sizes[0][lit]);