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author | Danijel Andjelkovic <adanijel99@gmail.com> | 2022-03-01 21:54:41 +0100 |
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committer | Danijel Andjelkovic <adanijel99@gmail.com> | 2022-03-01 21:54:41 +0100 |
commit | 6c8128f9fd5a5d0be115806c35a21b3d683df8d6 (patch) | |
tree | f46c2f6b3b9b294ff32bd75c08ccdc9e7a8cc4ef /sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js | |
parent | 2400b84e95913665da6279114168148444b8f9ab (diff) | |
parent | 7d3640f824f46490b47bd95f1c5a16644f712068 (diff) |
Merge branch 'dev' of http://gitlab.pmf.kg.ac.rs/igrannonica/neuronstellar into logo
Diffstat (limited to 'sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js')
-rw-r--r-- | sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js b/sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js new file mode 100644 index 00000000..dd6f690b --- /dev/null +++ b/sandbox/testAppNevena/Front/node_modules/tar/lib/large-numbers.js @@ -0,0 +1,99 @@ +'use strict' +// Tar can encode large and negative numbers using a leading byte of +// 0xff for negative, and 0x80 for positive. + +const encode = (num, buf) => { + if (!Number.isSafeInteger(num)) + // The number is so large that javascript cannot represent it with integer + // precision. + throw Error('cannot encode number outside of javascript safe integer range') + else if (num < 0) + encodeNegative(num, buf) + else + encodePositive(num, buf) + return buf +} + +const encodePositive = (num, buf) => { + buf[0] = 0x80 + + for (var i = buf.length; i > 1; i--) { + buf[i - 1] = num & 0xff + num = Math.floor(num / 0x100) + } +} + +const encodeNegative = (num, buf) => { + buf[0] = 0xff + var flipped = false + num = num * -1 + for (var i = buf.length; i > 1; i--) { + var byte = num & 0xff + num = Math.floor(num / 0x100) + if (flipped) + buf[i - 1] = onesComp(byte) + else if (byte === 0) + buf[i - 1] = 0 + else { + flipped = true + buf[i - 1] = twosComp(byte) + } + } +} + +const parse = (buf) => { + const pre = buf[0] + const value = pre === 0x80 ? pos(buf.slice(1, buf.length)) + : pre === 0xff ? twos(buf) + : null + if (value === null) + throw Error('invalid base256 encoding') + + if (!Number.isSafeInteger(value)) + // The number is so large that javascript cannot represent it with integer + // precision. + throw Error('parsed number outside of javascript safe integer range') + + return value +} + +const twos = (buf) => { + var len = buf.length + var sum = 0 + var flipped = false + for (var i = len - 1; i > -1; i--) { + var byte = buf[i] + var f + if (flipped) + f = onesComp(byte) + else if (byte === 0) + f = byte + else { + flipped = true + f = twosComp(byte) + } + if (f !== 0) + sum -= f * Math.pow(256, len - i - 1) + } + return sum +} + +const pos = (buf) => { + var len = buf.length + var sum = 0 + for (var i = len - 1; i > -1; i--) { + var byte = buf[i] + if (byte !== 0) + sum += byte * Math.pow(256, len - i - 1) + } + return sum +} + +const onesComp = byte => (0xff ^ byte) & 0xff + +const twosComp = byte => ((0xff ^ byte) + 1) & 0xff + +module.exports = { + encode, + parse, +} |