/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*namespace com.google.zxing.common {*/
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import IllegalArgumentException from '../IllegalArgumentException';
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/**
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* <p>This provides an easy abstraction to read bits at a time from a sequence of bytes, where the
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* number of bits read is not often a multiple of 8.</p>
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*
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* <p>This class is thread-safe but not reentrant -- unless the caller modifies the bytes array
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* it passed in, in which case all bets are off.</p>
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*
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* @author Sean Owen
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*/
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var BitSource = /** @class */ (function () {
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/**
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* @param bytes bytes from which this will read bits. Bits will be read from the first byte first.
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* Bits are read within a byte from most-significant to least-significant bit.
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*/
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function BitSource(bytes) {
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this.bytes = bytes;
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this.byteOffset = 0;
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this.bitOffset = 0;
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}
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/**
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* @return index of next bit in current byte which would be read by the next call to {@link #readBits(int)}.
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*/
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BitSource.prototype.getBitOffset = function () {
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return this.bitOffset;
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};
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/**
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* @return index of next byte in input byte array which would be read by the next call to {@link #readBits(int)}.
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*/
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BitSource.prototype.getByteOffset = function () {
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return this.byteOffset;
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};
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/**
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* @param numBits number of bits to read
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* @return int representing the bits read. The bits will appear as the least-significant
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* bits of the int
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* @throws IllegalArgumentException if numBits isn't in [1,32] or more than is available
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*/
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BitSource.prototype.readBits = function (numBits /*int*/) {
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if (numBits < 1 || numBits > 32 || numBits > this.available()) {
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throw new IllegalArgumentException('' + numBits);
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}
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var result = 0;
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var bitOffset = this.bitOffset;
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var byteOffset = this.byteOffset;
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var bytes = this.bytes;
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// First, read remainder from current byte
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if (bitOffset > 0) {
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var bitsLeft = 8 - bitOffset;
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var toRead = numBits < bitsLeft ? numBits : bitsLeft;
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var bitsToNotRead = bitsLeft - toRead;
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var mask = (0xFF >> (8 - toRead)) << bitsToNotRead;
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result = (bytes[byteOffset] & mask) >> bitsToNotRead;
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numBits -= toRead;
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bitOffset += toRead;
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if (bitOffset === 8) {
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bitOffset = 0;
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byteOffset++;
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}
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}
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// Next read whole bytes
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if (numBits > 0) {
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while (numBits >= 8) {
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result = (result << 8) | (bytes[byteOffset] & 0xFF);
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byteOffset++;
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numBits -= 8;
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}
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// Finally read a partial byte
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if (numBits > 0) {
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var bitsToNotRead = 8 - numBits;
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var mask = (0xFF >> bitsToNotRead) << bitsToNotRead;
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result = (result << numBits) | ((bytes[byteOffset] & mask) >> bitsToNotRead);
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bitOffset += numBits;
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}
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}
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this.bitOffset = bitOffset;
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this.byteOffset = byteOffset;
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return result;
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};
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/**
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* @return number of bits that can be read successfully
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*/
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BitSource.prototype.available = function () {
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return 8 * (this.bytes.length - this.byteOffset) - this.bitOffset;
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};
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return BitSource;
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}());
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export default BitSource;
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