diff options
Diffstat (limited to 'libgo/go/hash/crc64/crc64.go')
| -rw-r--r-- | libgo/go/hash/crc64/crc64.go | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/libgo/go/hash/crc64/crc64.go b/libgo/go/hash/crc64/crc64.go index a799a017c93..063c63c6a3b 100644 --- a/libgo/go/hash/crc64/crc64.go +++ b/libgo/go/hash/crc64/crc64.go @@ -10,6 +10,7 @@ package crc64 import ( "errors" "hash" + "sync" ) // The size of a CRC-64 checksum in bytes. @@ -28,13 +29,24 @@ const ( type Table [256]uint64 var ( - slicing8TableISO = makeSlicingBy8Table(makeTable(ISO)) - slicing8TableECMA = makeSlicingBy8Table(makeTable(ECMA)) + slicing8TablesBuildOnce sync.Once + slicing8TableISO *[8]Table + slicing8TableECMA *[8]Table ) +func buildSlicing8TablesOnce() { + slicing8TablesBuildOnce.Do(buildSlicing8Tables) +} + +func buildSlicing8Tables() { + slicing8TableISO = makeSlicingBy8Table(makeTable(ISO)) + slicing8TableECMA = makeSlicingBy8Table(makeTable(ECMA)) +} + // MakeTable returns a Table constructed from the specified polynomial. // The contents of this Table must not be modified. func MakeTable(poly uint64) *Table { + buildSlicing8TablesOnce() switch poly { case ISO: return &slicing8TableISO[0] @@ -141,6 +153,7 @@ func readUint64(b []byte) uint64 { } func update(crc uint64, tab *Table, p []byte) uint64 { + buildSlicing8TablesOnce() crc = ^crc // Table comparison is somewhat expensive, so avoid it for small sizes for len(p) >= 64 { |