Eugene Klyuchnikov | 771eb10 | 2015-11-27 11:27:11 +0100 | [diff] [blame] | 1 | /* Copyright 2013 Google Inc. All Rights Reserved. |
| 2 | |
Eugene Klyuchnikov | 24ffa78 | 2015-12-11 11:11:51 +0100 | [diff] [blame] | 3 | Distributed under MIT license. |
Eugene Klyuchnikov | 771eb10 | 2015-11-27 11:27:11 +0100 | [diff] [blame] | 4 | See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
| 5 | */ |
| 6 | |
Zoltan Szabadka | c66e4e3 | 2013-10-23 13:06:13 +0200 | [diff] [blame] | 7 | // This class models a sequence of literals and a backward reference copy. |
| 8 | |
| 9 | #ifndef BROTLI_ENC_COMMAND_H_ |
| 10 | #define BROTLI_ENC_COMMAND_H_ |
| 11 | |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 12 | #include "./fast_log.h" |
Lode Vandevenne | 6511d6b | 2015-08-28 16:09:23 +0200 | [diff] [blame] | 13 | #include "./prefix.h" |
Zoltan Szabadka | 4a7024d | 2015-10-01 12:08:14 +0200 | [diff] [blame] | 14 | #include "./types.h" |
Zoltan Szabadka | c66e4e3 | 2013-10-23 13:06:13 +0200 | [diff] [blame] | 15 | |
| 16 | namespace brotli { |
| 17 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 18 | static uint32_t kInsBase[] = { 0, 1, 2, 3, 4, 5, 6, 8, 10, 14, 18, 26, 34, 50, |
| 19 | 66, 98, 130, 194, 322, 578, 1090, 2114, 6210, 22594 }; |
| 20 | static uint32_t kInsExtra[] = { 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, |
| 21 | 5, 5, 6, 7, 8, 9, 10, 12, 14, 24 }; |
| 22 | static uint32_t kCopyBase[] = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 18, 22, 30, |
| 23 | 38, 54, 70, 102, 134, 198, 326, 582, 1094, 2118 }; |
| 24 | static uint32_t kCopyExtra[] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, |
| 25 | 4, 4, 5, 5, 6, 7, 8, 9, 10, 24 }; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 26 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 27 | static inline uint16_t GetInsertLengthCode(size_t insertlen) { |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 28 | if (insertlen < 6) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 29 | return static_cast<uint16_t>(insertlen); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 30 | } else if (insertlen < 130) { |
| 31 | insertlen -= 2; |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 32 | uint32_t nbits = Log2FloorNonZero(insertlen) - 1u; |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 33 | return static_cast<uint16_t>((nbits << 1) + (insertlen >> nbits) + 2); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 34 | } else if (insertlen < 2114) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 35 | return static_cast<uint16_t>(Log2FloorNonZero(insertlen - 66) + 10); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 36 | } else if (insertlen < 6210) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 37 | return 21u; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 38 | } else if (insertlen < 22594) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 39 | return 22u; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 40 | } else { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 41 | return 23u; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 42 | } |
| 43 | } |
| 44 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 45 | static inline uint16_t GetCopyLengthCode(size_t copylen) { |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 46 | if (copylen < 10) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 47 | return static_cast<uint16_t>(copylen - 2); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 48 | } else if (copylen < 134) { |
| 49 | copylen -= 6; |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 50 | uint32_t nbits = Log2FloorNonZero(copylen) - 1u; |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 51 | return static_cast<uint16_t>((nbits << 1) + (copylen >> nbits) + 4); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 52 | } else if (copylen < 2118) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 53 | return static_cast<uint16_t>(Log2FloorNonZero(copylen - 70) + 12); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 54 | } else { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 55 | return 23u; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 56 | } |
| 57 | } |
| 58 | |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 59 | static inline uint16_t CombineLengthCodes( |
| 60 | uint16_t inscode, uint16_t copycode, bool use_last_distance) { |
| 61 | uint16_t bits64 = |
| 62 | static_cast<uint16_t>((copycode & 0x7u) | ((inscode & 0x7u) << 3)); |
| 63 | if (use_last_distance && inscode < 8 && copycode < 16) { |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 64 | return (copycode < 8) ? bits64 : (bits64 | 64); |
| 65 | } else { |
| 66 | // "To convert an insert-and-copy length code to an insert length code and |
| 67 | // a copy length code, the following table can be used" |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 68 | static const uint16_t cells[9] = { 128u, 192u, 384u, 256u, 320u, 512u, |
| 69 | 448u, 576u, 640u }; |
| 70 | return cells[(copycode >> 3) + 3 * (inscode >> 3)] | bits64; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 71 | } |
| 72 | } |
| 73 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 74 | static inline void GetLengthCode(size_t insertlen, size_t copylen, |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 75 | bool use_last_distance, |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 76 | uint16_t* code, uint64_t* extra) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 77 | uint16_t inscode = GetInsertLengthCode(insertlen); |
| 78 | uint16_t copycode = GetCopyLengthCode(copylen); |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 79 | uint64_t insnumextra = kInsExtra[inscode]; |
| 80 | uint64_t numextra = insnumextra + kCopyExtra[copycode]; |
| 81 | uint64_t insextraval = insertlen - kInsBase[inscode]; |
| 82 | uint64_t copyextraval = copylen - kCopyBase[copycode]; |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 83 | *code = CombineLengthCodes(inscode, copycode, use_last_distance); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 84 | *extra = (numextra << 48) | (copyextraval << insnumextra) | insextraval; |
| 85 | } |
| 86 | |
| 87 | struct Command { |
Zoltan Szabadka | 12eb9bf | 2015-05-07 17:40:00 +0200 | [diff] [blame] | 88 | // distance_code is e.g. 0 for same-as-last short code, or 16 for offset 1. |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 89 | Command(size_t insertlen, size_t copylen, size_t copylen_code, |
| 90 | size_t distance_code) |
| 91 | : insert_len_(static_cast<uint32_t>(insertlen)) |
| 92 | , copy_len_(static_cast<uint32_t>(copylen)) { |
Lode Vandevenne | 6511d6b | 2015-08-28 16:09:23 +0200 | [diff] [blame] | 93 | // The distance prefix and extra bits are stored in this Command as if |
| 94 | // npostfix and ndirect were 0, they are only recomputed later after the |
| 95 | // clustering if needed. |
| 96 | PrefixEncodeCopyDistance(distance_code, 0, 0, &dist_prefix_, &dist_extra_); |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 97 | GetLengthCode(insertlen, copylen_code, dist_prefix_ == 0, |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 98 | &cmd_prefix_, &cmd_extra_); |
| 99 | } |
| 100 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 101 | explicit Command(size_t insertlen) |
| 102 | : insert_len_(static_cast<uint32_t>(insertlen)) |
Zoltan Szabadka | 14d6ae7 | 2016-01-26 11:25:53 +0100 | [diff] [blame] | 103 | , copy_len_(0), dist_extra_(0), dist_prefix_(16) { |
Zoltan Szabadka | ea48ce5 | 2015-10-28 17:44:47 +0100 | [diff] [blame] | 104 | GetLengthCode(insertlen, 4, dist_prefix_ == 0, &cmd_prefix_, &cmd_extra_); |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 105 | } |
| 106 | |
Eugene Kliuchnikov | 25e3796 | 2016-02-29 14:41:24 +0100 | [diff] [blame^] | 107 | uint32_t DistanceCode(void) const { |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 108 | if (dist_prefix_ < 16) { |
Zoltan Szabadka | 12eb9bf | 2015-05-07 17:40:00 +0200 | [diff] [blame] | 109 | return dist_prefix_; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 110 | } |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 111 | uint32_t nbits = dist_extra_ >> 24; |
| 112 | uint32_t extra = dist_extra_ & 0xffffff; |
| 113 | uint32_t prefix = dist_prefix_ - 12 - 2 * nbits; |
Zoltan Szabadka | 12eb9bf | 2015-05-07 17:40:00 +0200 | [diff] [blame] | 114 | return (prefix << nbits) + extra + 12; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 115 | } |
| 116 | |
Eugene Kliuchnikov | 25e3796 | 2016-02-29 14:41:24 +0100 | [diff] [blame^] | 117 | uint32_t DistanceContext(void) const { |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 118 | uint32_t r = cmd_prefix_ >> 6; |
| 119 | uint32_t c = cmd_prefix_ & 7; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 120 | if ((r == 0 || r == 2 || r == 4 || r == 7) && (c <= 2)) { |
| 121 | return c; |
| 122 | } |
| 123 | return 3; |
| 124 | } |
| 125 | |
Zoltan Szabadka | 8844b7f | 2016-01-07 16:27:49 +0100 | [diff] [blame] | 126 | uint32_t insert_len_; |
| 127 | uint32_t copy_len_; |
Zoltan Szabadka | b4f39bf | 2014-10-28 13:25:22 +0100 | [diff] [blame] | 128 | uint64_t cmd_extra_; |
| 129 | uint32_t dist_extra_; |
Zoltan Szabadka | 14d6ae7 | 2016-01-26 11:25:53 +0100 | [diff] [blame] | 130 | uint16_t cmd_prefix_; |
| 131 | uint16_t dist_prefix_; |
Zoltan Szabadka | c66e4e3 | 2013-10-23 13:06:13 +0200 | [diff] [blame] | 132 | }; |
| 133 | |
| 134 | } // namespace brotli |
| 135 | |
| 136 | #endif // BROTLI_ENC_COMMAND_H_ |