diff options
Diffstat (limited to 'internal/compress/zlib/writer_header.go')
| -rw-r--r-- | internal/compress/zlib/writer_header.go | 71 |
1 files changed, 0 insertions, 71 deletions
diff --git a/internal/compress/zlib/writer_header.go b/internal/compress/zlib/writer_header.go deleted file mode 100644 index 43d3bdf5..00000000 --- a/internal/compress/zlib/writer_header.go +++ /dev/null @@ -1,71 +0,0 @@ -// Copyright 2009 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. - -package zlib - -import ( - "encoding/binary" - - "codeberg.org/lindenii/furgit/internal/adler32" - "codeberg.org/lindenii/furgit/internal/compress/flate" -) - -// writeHeader writes the ZLIB header. -func (z *Writer) writeHeader() (err error) { - z.wroteHeader = true - // ZLIB has a two-byte header (as documented in RFC 1950). - // The first four bits is the CINFO (compression info), which is 7 for the default deflate window size. - // The next four bits is the CM (compression method), which is 8 for deflate. - z.scratch[0] = 0x78 - // The next two bits is the FLEVEL (compression level). The four values are: - // 0=fastest, 1=fast, 2=default, 3=best. - // The next bit, FDICT, is set if a dictionary is given. - // The final five FCHECK bits form a mod-31 checksum. - switch z.level { - case -2, 0, 1: - z.scratch[1] = 0 << 6 - case 2, 3, 4, 5: - z.scratch[1] = 1 << 6 - case 6, -1: - z.scratch[1] = 2 << 6 - case 7, 8, 9: - z.scratch[1] = 3 << 6 - default: - panic("unreachable") - } - - if z.dict != nil { - z.scratch[1] |= 1 << 5 - } - - z.scratch[1] += uint8(31 - binary.BigEndian.Uint16(z.scratch[:2])%31) //#nosec G115 - - _, err = z.w.Write(z.scratch[0:2]) - if err != nil { - return err - } - - if z.dict != nil { - // The next four bytes are the Adler-32 checksum of the dictionary. - binary.BigEndian.PutUint32(z.scratch[:], adler32.Checksum(z.dict)) - - _, err = z.w.Write(z.scratch[0:4]) - if err != nil { - return err - } - } - - if z.compressor == nil { - // Initialize deflater unless the Writer is being reused - // after a Reset call. - z.compressor, err = flate.NewWriterDict(z.w, z.level, z.dict) - if err != nil { - return err - } - - z.digest = adler32.New() - } - - return nil -} |
