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author | Wim <wim@42.be> | 2020-12-31 14:48:12 +0100 |
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committer | GitHub <noreply@github.com> | 2020-12-31 14:48:12 +0100 |
commit | 4f20ebead36876a88391bf033d1de3e4cf0228da (patch) | |
tree | 70b6fd79c6a5e00c958c29a7bd3926f074e76ba6 /vendor/golang.org/x/image/ccitt/writer.go | |
parent | a9f89dbc645aafc68daa9fc8d589f55104b535c7 (diff) | |
download | matterbridge-msglm-4f20ebead36876a88391bf033d1de3e4cf0228da.tar.gz matterbridge-msglm-4f20ebead36876a88391bf033d1de3e4cf0228da.tar.bz2 matterbridge-msglm-4f20ebead36876a88391bf033d1de3e4cf0228da.zip |
Update vendor for next release (#1343)
Diffstat (limited to 'vendor/golang.org/x/image/ccitt/writer.go')
-rw-r--r-- | vendor/golang.org/x/image/ccitt/writer.go | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/vendor/golang.org/x/image/ccitt/writer.go b/vendor/golang.org/x/image/ccitt/writer.go new file mode 100644 index 00000000..87130ab0 --- /dev/null +++ b/vendor/golang.org/x/image/ccitt/writer.go @@ -0,0 +1,102 @@ +// Copyright 2019 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 ccitt + +import ( + "encoding/binary" + "io" +) + +type bitWriter struct { + w io.Writer + + // order is whether to process w's bytes LSB first or MSB first. + order Order + + // The high nBits bits of the bits field hold encoded bits to be written to w. + bits uint64 + nBits uint32 + + // bytes[:bw] holds encoded bytes not yet written to w. + // Overflow protection is ensured by using a multiple of 8 as bytes length. + bw uint32 + bytes [1024]uint8 +} + +// flushBits copies 64 bits from b.bits to b.bytes. If b.bytes is then full, it +// is written to b.w. +func (b *bitWriter) flushBits() error { + binary.BigEndian.PutUint64(b.bytes[b.bw:], b.bits) + b.bits = 0 + b.nBits = 0 + b.bw += 8 + if b.bw < uint32(len(b.bytes)) { + return nil + } + b.bw = 0 + if b.order != MSB { + reverseBitsWithinBytes(b.bytes[:]) + } + _, err := b.w.Write(b.bytes[:]) + return err +} + +// close finalizes a bitcode stream by writing any +// pending bits to bitWriter's underlying io.Writer. +func (b *bitWriter) close() error { + // Write any encoded bits to bytes. + if b.nBits > 0 { + binary.BigEndian.PutUint64(b.bytes[b.bw:], b.bits) + b.bw += (b.nBits + 7) >> 3 + } + + if b.order != MSB { + reverseBitsWithinBytes(b.bytes[:b.bw]) + } + + // Write b.bw bytes to b.w. + _, err := b.w.Write(b.bytes[:b.bw]) + return err +} + +// alignToByteBoundary rounds b.nBits up to a multiple of 8. +// If all 64 bits are used, flush them to bitWriter's bytes. +func (b *bitWriter) alignToByteBoundary() error { + if b.nBits = (b.nBits + 7) &^ 7; b.nBits == 64 { + return b.flushBits() + } + return nil +} + +// writeCode writes a variable length bitcode to b's underlying io.Writer. +func (b *bitWriter) writeCode(bs bitString) error { + bits := bs.bits + nBits := bs.nBits + if 64-b.nBits >= nBits { + // b.bits has sufficient room for storing nBits bits. + b.bits |= uint64(bits) << (64 - nBits - b.nBits) + b.nBits += nBits + if b.nBits == 64 { + return b.flushBits() + } + return nil + } + + // Number of leading bits that fill b.bits. + i := 64 - b.nBits + + // Fill b.bits then flush and write remaining bits. + b.bits |= uint64(bits) >> (nBits - i) + b.nBits = 64 + + if err := b.flushBits(); err != nil { + return err + } + + nBits -= i + b.bits = uint64(bits) << (64 - nBits) + b.nBits = nBits + return nil +} |