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authorWim <wim@42.be>2020-12-31 14:48:12 +0100
committerGitHub <noreply@github.com>2020-12-31 14:48:12 +0100
commit4f20ebead36876a88391bf033d1de3e4cf0228da (patch)
tree70b6fd79c6a5e00c958c29a7bd3926f074e76ba6 /vendor/golang.org/x/image/ccitt/writer.go
parenta9f89dbc645aafc68daa9fc8d589f55104b535c7 (diff)
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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.go102
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
+}