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vendor/github.com/andybalholm/brotli/bitwriter.go

@@ -0,0 +1,56 @@
+package brotli
+
+/* Copyright 2010 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Write bits into a byte array. */
+
+type bitWriter struct {
+	dst []byte
+
+	// Data waiting to be written is the low nbits of bits.
+	bits  uint64
+	nbits uint
+}
+
+func (w *bitWriter) writeBits(nb uint, b uint64) {
+	w.bits |= b << w.nbits
+	w.nbits += nb
+	if w.nbits >= 32 {
+		bits := w.bits
+		w.bits >>= 32
+		w.nbits -= 32
+		w.dst = append(w.dst,
+			byte(bits),
+			byte(bits>>8),
+			byte(bits>>16),
+			byte(bits>>24),
+		)
+	}
+}
+
+func (w *bitWriter) writeSingleBit(bit bool) {
+	if bit {
+		w.writeBits(1, 1)
+	} else {
+		w.writeBits(1, 0)
+	}
+}
+
+func (w *bitWriter) jumpToByteBoundary() {
+	dst := w.dst
+	for w.nbits != 0 {
+		dst = append(dst, byte(w.bits))
+		w.bits >>= 8
+		if w.nbits > 8 { // Avoid underflow
+			w.nbits -= 8
+		} else {
+			w.nbits = 0
+		}
+	}
+	w.bits = 0
+	w.dst = dst
+}