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1// Tar can encode large and negative numbers using a leading byte of2// 0xff for negative, and 0x80 for positive.3export const encode = (num, buf) => {4    if (!Number.isSafeInteger(num)) {5        // The number is so large that javascript cannot represent it with integer6        // precision.7        throw Error('cannot encode number outside of javascript safe integer range');8    }9    else if (num < 0) {10        encodeNegative(num, buf);11    }12    else {13        encodePositive(num, buf);14    }15    return buf;16};17const encodePositive = (num, buf) => {18    buf[0] = 0x80;19    for (var i = buf.length; i > 1; i--) {20        buf[i - 1] = num & 0xff;21        num = Math.floor(num / 0x100);22    }23};24const encodeNegative = (num, buf) => {25    buf[0] = 0xff;26    var flipped = false;27    num = num * -1;28    for (var i = buf.length; i > 1; i--) {29        var byte = num & 0xff;30        num = Math.floor(num / 0x100);31        if (flipped) {32            buf[i - 1] = onesComp(byte);33        }34        else if (byte === 0) {35            buf[i - 1] = 0;36        }37        else {38            flipped = true;39            buf[i - 1] = twosComp(byte);40        }41    }42};43export const parse = (buf) => {44    const pre = buf[0];45    const value = pre === 0x80 ? pos(buf.subarray(1, buf.length))46        : pre === 0xff ? twos(buf)47            : null;48    if (value === null) {49        throw Error('invalid base256 encoding');50    }51    if (!Number.isSafeInteger(value)) {52        // The number is so large that javascript cannot represent it with integer53        // precision.54        throw Error('parsed number outside of javascript safe integer range');55    }56    return value;57};58const twos = (buf) => {59    var len = buf.length;60    var sum = 0;61    var flipped = false;62    for (var i = len - 1; i > -1; i--) {63        var byte = Number(buf[i]);64        var f;65        if (flipped) {66            f = onesComp(byte);67        }68        else if (byte === 0) {69            f = byte;70        }71        else {72            flipped = true;73            f = twosComp(byte);74        }75        if (f !== 0) {76            sum -= f * Math.pow(256, len - i - 1);77        }78    }79    return sum;80};81const pos = (buf) => {82    var len = buf.length;83    var sum = 0;84    for (var i = len - 1; i > -1; i--) {85        var byte = Number(buf[i]);86        if (byte !== 0) {87            sum += byte * Math.pow(256, len - i - 1);88        }89    }90    return sum;91};92const onesComp = (byte) => (0xff ^ byte) & 0xff;93const twosComp = (byte) => ((0xff ^ byte) + 1) & 0xff;94//# sourceMappingURL=large-numbers.js.map