mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-11-27 09:11:53 -05:00
31 lines
1.3 KiB
Go
31 lines
1.3 KiB
Go
|
package brotli
|
||
|
|
|
||
|
|
/* Copyright 2013 Google Inc. All Rights Reserved.
|
||
|
|
|
||
|
|
Distributed under MIT license.
|
||
|
|
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. */
|
||
|
|
|
||
|
|
/* 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. */
|
||
|
|
func prefixEncodeCopyDistance(distance_code uint, num_direct_codes uint, postfix_bits uint, code *uint16, extra_bits *uint32) {
|
||
|
|
if distance_code < numDistanceShortCodes+num_direct_codes {
|
||
|
|
*code = uint16(distance_code)
|
||
|
|
*extra_bits = 0
|
||
|
|
return
|
||
|
|
} else {
|
||
|
|
var dist uint = (uint(1) << (postfix_bits + 2)) + (distance_code - numDistanceShortCodes - num_direct_codes)
|
||
|
|
var bucket uint = uint(log2FloorNonZero(dist) - 1)
|
||
|
|
var postfix_mask uint = (1 << postfix_bits) - 1
|
||
|
|
var postfix uint = dist & postfix_mask
|
||
|
|
var prefix uint = (dist >> bucket) & 1
|
||
|
|
var offset uint = (2 + prefix) << bucket
|
||
|
|
var nbits uint = bucket - postfix_bits
|
||
|
|
*code = uint16(nbits<<10 | (numDistanceShortCodes + num_direct_codes + ((2*(nbits-1) + prefix) << postfix_bits) + postfix))
|
||
|
|
*extra_bits = uint32((dist - offset) >> postfix_bits)
|
||
|
|
}
|
||
|
|
}
|