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| author | 2025-11-05 21:58:38 +0100 | |
|---|---|---|
| committer | 2025-11-17 14:12:41 +0100 | |
| commit | d0c551acb5ab79efafd325f5b19c76a3de835356 (patch) | |
| tree | ba9462cdc5081015fbd6bf5d98d9f39334d13207 /vendor/github.com/klauspost/crc32/crc32_generic.go | |
| parent | [performance] when transforming media, perform read operations of large files... (diff) | |
| download | gotosocial-d0c551acb5ab79efafd325f5b19c76a3de835356.tar.xz | |
[chore] update dependencies (#4542)
- github.com/minio/minio-go/v7: v7.0.95 -> v7.0.97
- github.com/ncruces/go-sqlite3: v0.29.1 -> v0.30.0
- github.com/tdewolff/minify/v2: v2.24.5 -> v2.24.6
- codeberg.org/gruf/go-mmap: fixes build for BSD platforms
Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4542
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>
Diffstat (limited to 'vendor/github.com/klauspost/crc32/crc32_generic.go')
| -rw-r--r-- | vendor/github.com/klauspost/crc32/crc32_generic.go | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/crc32/crc32_generic.go b/vendor/github.com/klauspost/crc32/crc32_generic.go new file mode 100644 index 000000000..d1cf69cf4 --- /dev/null +++ b/vendor/github.com/klauspost/crc32/crc32_generic.go @@ -0,0 +1,91 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This file contains CRC32 algorithms that are not specific to any architecture +// and don't use hardware acceleration. +// +// The simple (and slow) CRC32 implementation only uses a 256*4 bytes table. +// +// The slicing-by-8 algorithm is a faster implementation that uses a bigger +// table (8*256*4 bytes). + +package crc32 + +import "encoding/binary" + +// simpleMakeTable allocates and constructs a Table for the specified +// polynomial. The table is suitable for use with the simple algorithm +// (simpleUpdate). +func simpleMakeTable(poly uint32) *Table { + t := new(Table) + simplePopulateTable(poly, t) + return t +} + +// simplePopulateTable constructs a Table for the specified polynomial, suitable +// for use with simpleUpdate. +func simplePopulateTable(poly uint32, t *Table) { + for i := 0; i < 256; i++ { + crc := uint32(i) + for j := 0; j < 8; j++ { + if crc&1 == 1 { + crc = (crc >> 1) ^ poly + } else { + crc >>= 1 + } + } + t[i] = crc + } +} + +// simpleUpdate uses the simple algorithm to update the CRC, given a table that +// was previously computed using simpleMakeTable. +func simpleUpdate(crc uint32, tab *Table, p []byte) uint32 { + crc = ^crc + for _, v := range p { + crc = tab[byte(crc)^v] ^ (crc >> 8) + } + return ^crc +} + +// Use slicing-by-8 when payload >= this value. +const slicing8Cutoff = 16 + +// slicing8Table is array of 8 Tables, used by the slicing-by-8 algorithm. +type slicing8Table [8]Table + +// slicingMakeTable constructs a slicing8Table for the specified polynomial. The +// table is suitable for use with the slicing-by-8 algorithm (slicingUpdate). +func slicingMakeTable(poly uint32) *slicing8Table { + t := new(slicing8Table) + simplePopulateTable(poly, &t[0]) + for i := 0; i < 256; i++ { + crc := t[0][i] + for j := 1; j < 8; j++ { + crc = t[0][crc&0xFF] ^ (crc >> 8) + t[j][i] = crc + } + } + return t +} + +// slicingUpdate uses the slicing-by-8 algorithm to update the CRC, given a +// table that was previously computed using slicingMakeTable. +func slicingUpdate(crc uint32, tab *slicing8Table, p []byte) uint32 { + if len(p) >= slicing8Cutoff { + crc = ^crc + for len(p) > 8 { + crc ^= binary.LittleEndian.Uint32(p) + crc = tab[0][p[7]] ^ tab[1][p[6]] ^ tab[2][p[5]] ^ tab[3][p[4]] ^ + tab[4][crc>>24] ^ tab[5][(crc>>16)&0xFF] ^ + tab[6][(crc>>8)&0xFF] ^ tab[7][crc&0xFF] + p = p[8:] + } + crc = ^crc + } + if len(p) == 0 { + return crc + } + return simpleUpdate(crc, &tab[0], p) +} |
