88 lines
3.8 KiB
Go
88 lines
3.8 KiB
Go
package brotli
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/* Copyright 2013 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Function to find backward reference copies. */
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/* Copyright 2013 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Function to find backward reference copies. */
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/* "commands" points to the next output command to write to, "*num_commands" is
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initially the total amount of commands output by previous
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CreateBackwardReferences calls, and must be incremented by the amount written
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by this call. */
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func ComputeDistanceCode(distance uint, max_distance uint, dist_cache []int) uint {
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if distance <= max_distance {
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var distance_plus_3 uint = distance + 3
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var offset0 uint = distance_plus_3 - uint(dist_cache[0])
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var offset1 uint = distance_plus_3 - uint(dist_cache[1])
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if distance == uint(dist_cache[0]) {
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return 0
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} else if distance == uint(dist_cache[1]) {
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return 1
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} else if offset0 < 7 {
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return (0x9750468 >> (4 * offset0)) & 0xF
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} else if offset1 < 7 {
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return (0xFDB1ACE >> (4 * offset1)) & 0xF
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} else if distance == uint(dist_cache[2]) {
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return 2
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} else if distance == uint(dist_cache[3]) {
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return 3
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}
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}
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return distance + BROTLI_NUM_DISTANCE_SHORT_CODES - 1
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}
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func BrotliCreateBackwardReferences(num_bytes uint, position uint, ringbuffer []byte, ringbuffer_mask uint, params *BrotliEncoderParams, hasher HasherHandle, dist_cache []int, last_insert_len *uint, commands []Command, num_commands *uint, num_literals *uint) {
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switch params.hasher.type_ {
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case 2:
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CreateBackwardReferencesNH2(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 3:
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CreateBackwardReferencesNH3(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 4:
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CreateBackwardReferencesNH4(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 5:
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CreateBackwardReferencesNH5(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 6:
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CreateBackwardReferencesNH6(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 40:
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CreateBackwardReferencesNH40(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 41:
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CreateBackwardReferencesNH41(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 42:
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CreateBackwardReferencesNH42(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 54:
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CreateBackwardReferencesNH54(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 35:
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CreateBackwardReferencesNH35(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 55:
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CreateBackwardReferencesNH55(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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case 65:
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CreateBackwardReferencesNH65(num_bytes, position, ringbuffer, ringbuffer_mask, params, hasher, dist_cache, last_insert_len, commands, num_commands, num_literals)
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return
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default:
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break
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}
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}
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