Index: third_party/brotli/enc/prefix.h |
diff --git a/third_party/brotli/enc/prefix.h b/third_party/brotli/enc/prefix.h |
index 86fff8d522dd8127d27b1e8e3d36b3155a6bc57c..e279ffe7f880218446a57da85270860d7364f4a7 100644 |
--- a/third_party/brotli/enc/prefix.h |
+++ b/third_party/brotli/enc/prefix.h |
@@ -4,76 +4,51 @@ |
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
*/ |
-// Functions for encoding of integers into prefix codes the amount of extra |
-// bits, and the actual values of the extra bits. |
+/* Functions for encoding of integers into prefix codes the amount of extra |
+ bits, and the actual values of the extra bits. */ |
#ifndef BROTLI_ENC_PREFIX_H_ |
#define BROTLI_ENC_PREFIX_H_ |
+#include "../common/constants.h" |
+#include <brotli/port.h> |
+#include <brotli/types.h> |
#include "./fast_log.h" |
-#include "./types.h" |
-namespace brotli { |
- |
-static const uint32_t kNumInsertLenPrefixes = 24; |
-static const uint32_t kNumCopyLenPrefixes = 24; |
-static const uint32_t kNumCommandPrefixes = 704; |
-static const uint32_t kNumBlockLenPrefixes = 26; |
-static const uint32_t kNumDistanceShortCodes = 16; |
-static const uint32_t kNumDistancePrefixes = 520; |
- |
-// Represents the range of values belonging to a prefix code: |
-// [offset, offset + 2^nbits) |
-struct PrefixCodeRange { |
- uint32_t offset; |
- uint32_t nbits; |
-}; |
- |
-static const PrefixCodeRange kBlockLengthPrefixCode[kNumBlockLenPrefixes] = { |
- { 1, 2}, { 5, 2}, { 9, 2}, { 13, 2}, |
- { 17, 3}, { 25, 3}, { 33, 3}, { 41, 3}, |
- { 49, 4}, { 65, 4}, { 81, 4}, { 97, 4}, |
- { 113, 5}, { 145, 5}, { 177, 5}, { 209, 5}, |
- { 241, 6}, { 305, 6}, { 369, 7}, { 497, 8}, |
- { 753, 9}, { 1265, 10}, {2289, 11}, {4337, 12}, |
- {8433, 13}, {16625, 24} |
-}; |
- |
-inline void GetBlockLengthPrefixCode(uint32_t len, uint32_t* code, |
- uint32_t* n_extra, uint32_t* extra) { |
- *code = 0; |
- while (*code < 25 && len >= kBlockLengthPrefixCode[*code + 1].offset) { |
- ++(*code); |
- } |
- *n_extra = kBlockLengthPrefixCode[*code].nbits; |
- *extra = len - kBlockLengthPrefixCode[*code].offset; |
-} |
- |
-inline void PrefixEncodeCopyDistance(size_t distance_code, |
- size_t num_direct_codes, |
- size_t postfix_bits, |
- uint16_t* code, |
- uint32_t* extra_bits) { |
- if (distance_code < kNumDistanceShortCodes + num_direct_codes) { |
- *code = static_cast<uint16_t>(distance_code); |
+#if defined(__cplusplus) || defined(c_plusplus) |
+extern "C" { |
+#endif |
+ |
+/* Here distance_code is an intermediate code, i.e. one of the special codes or |
+ the actual distance increased by BROTLI_NUM_DISTANCE_SHORT_CODES - 1. */ |
+static BROTLI_INLINE void PrefixEncodeCopyDistance(size_t distance_code, |
+ size_t num_direct_codes, |
+ size_t postfix_bits, |
+ uint16_t* code, |
+ uint32_t* extra_bits) { |
+ if (distance_code < BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes) { |
+ *code = (uint16_t)distance_code; |
*extra_bits = 0; |
return; |
+ } else { |
+ size_t dist = ((size_t)1 << (postfix_bits + 2u)) + |
+ (distance_code - BROTLI_NUM_DISTANCE_SHORT_CODES - num_direct_codes); |
+ size_t bucket = Log2FloorNonZero(dist) - 1; |
+ size_t postfix_mask = (1u << postfix_bits) - 1; |
+ size_t postfix = dist & postfix_mask; |
+ size_t prefix = (dist >> bucket) & 1; |
+ size_t offset = (2 + prefix) << bucket; |
+ size_t nbits = bucket - postfix_bits; |
+ *code = (uint16_t)( |
+ (BROTLI_NUM_DISTANCE_SHORT_CODES + num_direct_codes + |
+ ((2 * (nbits - 1) + prefix) << postfix_bits) + postfix)); |
+ *extra_bits = (uint32_t)( |
+ (nbits << 24) | ((dist - offset) >> postfix_bits)); |
} |
- distance_code -= kNumDistanceShortCodes + num_direct_codes; /* >= 0 */ |
- distance_code += (1u << (postfix_bits + 2u)); /* > 0 */ |
- size_t bucket = Log2FloorNonZero(distance_code) - 1; |
- size_t postfix_mask = (1 << postfix_bits) - 1; |
- size_t postfix = distance_code & postfix_mask; |
- size_t prefix = (distance_code >> bucket) & 1; |
- size_t offset = (2 + prefix) << bucket; |
- size_t nbits = bucket - postfix_bits; |
- *code = static_cast<uint16_t>( |
- (kNumDistanceShortCodes + num_direct_codes + |
- ((2 * (nbits - 1) + prefix) << postfix_bits) + postfix)); |
- *extra_bits = static_cast<uint32_t>( |
- (nbits << 24) | ((distance_code - offset) >> postfix_bits)); |
} |
-} // namespace brotli |
+#if defined(__cplusplus) || defined(c_plusplus) |
+} /* extern "C" */ |
+#endif |
-#endif // BROTLI_ENC_PREFIX_H_ |
+#endif /* BROTLI_ENC_PREFIX_H_ */ |