Files
luet/vendor/github.com/klauspost/compress/zstd/hash.go
Ettore Di Giacinto 4c788ccbd1 bump github.com/moby/buildkit to v0.13.0 (#351)
* bump github.com/moby/buildkit to v0.13.0

Signed-off-by: Nianyu Shen <nianyu@spectrocloud.com>

* fix: update dep usage based on newer version

Signed-off-by: Nianyu Shen <nianyu@spectrocloud.com>

* remove empty line

Signed-off-by: Nianyu Shen <nianyu@spectrocloud.com>

* ci: bump golang to 1.21.x

* Bump moby

* debug

---------

Signed-off-by: Nianyu Shen <nianyu@spectrocloud.com>
Co-authored-by: Nianyu Shen <nianyu@spectrocloud.com>
2024-03-15 09:26:32 +01:00

36 lines
1.1 KiB
Go

// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
const (
prime3bytes = 506832829
prime4bytes = 2654435761
prime5bytes = 889523592379
prime6bytes = 227718039650203
prime7bytes = 58295818150454627
prime8bytes = 0xcf1bbcdcb7a56463
)
// hashLen returns a hash of the lowest mls bytes of with length output bits.
// mls must be >=3 and <=8. Any other value will return hash for 4 bytes.
// length should always be < 32.
// Preferably length and mls should be a constant for inlining.
func hashLen(u uint64, length, mls uint8) uint32 {
switch mls {
case 3:
return (uint32(u<<8) * prime3bytes) >> (32 - length)
case 5:
return uint32(((u << (64 - 40)) * prime5bytes) >> (64 - length))
case 6:
return uint32(((u << (64 - 48)) * prime6bytes) >> (64 - length))
case 7:
return uint32(((u << (64 - 56)) * prime7bytes) >> (64 - length))
case 8:
return uint32((u * prime8bytes) >> (64 - length))
default:
return (uint32(u) * prime4bytes) >> (32 - length)
}
}