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Unified Diff: third_party/brotli/enc/prefix.h

Issue 2537133002: Update brotli to v1.0.0-snapshot. (Closed)
Patch Set: Fixed typo Created 4 years ago
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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_ */
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