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-rw-r--r--vendor/github.com/klauspost/compress/huff0/compress.go64
1 files changed, 64 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/huff0/compress.go b/vendor/github.com/klauspost/compress/huff0/compress.go
index 0823c928c..8323dc053 100644
--- a/vendor/github.com/klauspost/compress/huff0/compress.go
+++ b/vendor/github.com/klauspost/compress/huff0/compress.go
@@ -161,6 +161,70 @@ func compress(in []byte, s *Scratch, compressor func(src []byte) ([]byte, error)
return s.Out, false, nil
}
+// EstimateSizes will estimate the data sizes
+func EstimateSizes(in []byte, s *Scratch) (tableSz, dataSz, reuseSz int, err error) {
+ s, err = s.prepare(in)
+ if err != nil {
+ return 0, 0, 0, err
+ }
+
+ // Create histogram, if none was provided.
+ tableSz, dataSz, reuseSz = -1, -1, -1
+ maxCount := s.maxCount
+ var canReuse = false
+ if maxCount == 0 {
+ maxCount, canReuse = s.countSimple(in)
+ } else {
+ canReuse = s.canUseTable(s.prevTable)
+ }
+
+ // We want the output size to be less than this:
+ wantSize := len(in)
+ if s.WantLogLess > 0 {
+ wantSize -= wantSize >> s.WantLogLess
+ }
+
+ // Reset for next run.
+ s.clearCount = true
+ s.maxCount = 0
+ if maxCount >= len(in) {
+ if maxCount > len(in) {
+ return 0, 0, 0, fmt.Errorf("maxCount (%d) > length (%d)", maxCount, len(in))
+ }
+ if len(in) == 1 {
+ return 0, 0, 0, ErrIncompressible
+ }
+ // One symbol, use RLE
+ return 0, 0, 0, ErrUseRLE
+ }
+ if maxCount == 1 || maxCount < (len(in)>>7) {
+ // Each symbol present maximum once or too well distributed.
+ return 0, 0, 0, ErrIncompressible
+ }
+
+ // Calculate new table.
+ err = s.buildCTable()
+ if err != nil {
+ return 0, 0, 0, err
+ }
+
+ if false && !s.canUseTable(s.cTable) {
+ panic("invalid table generated")
+ }
+
+ tableSz, err = s.cTable.estTableSize(s)
+ if err != nil {
+ return 0, 0, 0, err
+ }
+ if canReuse {
+ reuseSz = s.prevTable.estimateSize(s.count[:s.symbolLen])
+ }
+ dataSz = s.cTable.estimateSize(s.count[:s.symbolLen])
+
+ // Restore
+ return tableSz, dataSz, reuseSz, nil
+}
+
func (s *Scratch) compress1X(src []byte) ([]byte, error) {
return s.compress1xDo(s.Out, src)
}