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- "use strict";
- Object.defineProperty(exports, "__esModule", {
- value: true
- });
- exports.extract = extract;
- exports.inject = inject;
- exports.getSign = getSign;
- exports.highOrder = highOrder;
- function extract(buffer, bitIndex, bitLength, defaultBit) {
- if (bitLength < 0 || bitLength > 32) {
- throw new Error("Bad value for bitLength.");
- }
- if (defaultBit === undefined) {
- defaultBit = 0;
- } else if (defaultBit !== 0 && defaultBit !== 1) {
- throw new Error("Bad value for defaultBit.");
- }
- var defaultByte = defaultBit * 0xff;
- var result = 0;
-
- var lastBit = bitIndex + bitLength;
- var startByte = Math.floor(bitIndex / 8);
- var startBit = bitIndex % 8;
- var endByte = Math.floor(lastBit / 8);
- var endBit = lastBit % 8;
- if (endBit !== 0) {
-
-
- result = get(endByte) & (1 << endBit) - 1;
- }
- while (endByte > startByte) {
- endByte--;
- result = result << 8 | get(endByte);
- }
- result >>>= startBit;
- return result;
- function get(index) {
- var result = buffer[index];
- return result === undefined ? defaultByte : result;
- }
- }
- function inject(buffer, bitIndex, bitLength, value) {
- if (bitLength < 0 || bitLength > 32) {
- throw new Error("Bad value for bitLength.");
- }
- var lastByte = Math.floor((bitIndex + bitLength - 1) / 8);
- if (bitIndex < 0 || lastByte >= buffer.length) {
- throw new Error("Index out of range.");
- }
-
- var atByte = Math.floor(bitIndex / 8);
- var atBit = bitIndex % 8;
- while (bitLength > 0) {
- if (value & 1) {
- buffer[atByte] |= 1 << atBit;
- } else {
- buffer[atByte] &= ~(1 << atBit);
- }
- value >>= 1;
- bitLength--;
- atBit = (atBit + 1) % 8;
- if (atBit === 0) {
- atByte++;
- }
- }
- }
- function getSign(buffer) {
- return buffer[buffer.length - 1] >>> 7;
- }
- function highOrder(bit, buffer) {
- var length = buffer.length;
- var fullyWrongByte = (bit ^ 1) * 0xff;
- while (length > 0 && buffer[length - 1] === fullyWrongByte) {
- length--;
- }
- if (length === 0) {
-
- return -1;
- }
- var byteToCheck = buffer[length - 1];
- var result = length * 8 - 1;
- for (var i = 7; i > 0; i--) {
- if ((byteToCheck >> i & 1) === bit) {
- break;
- }
- result--;
- }
- return result;
- }
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