gree_leran/node_modules/@xtuc/ieee754/dist/index.cjs.js

97 lines
2.1 KiB
JavaScript
Raw Normal View History

2024-06-14 01:11:29 +00:00
"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.read = read;
exports.write = write;
function read(buffer, offset, isLE, mLen, nBytes) {
var e, m;
var eLen = nBytes * 8 - mLen - 1;
var eMax = (1 << eLen) - 1;
var eBias = eMax >> 1;
var nBits = -7;
var i = isLE ? nBytes - 1 : 0;
var d = isLE ? -1 : 1;
var s = buffer[offset + i];
i += d;
e = s & (1 << -nBits) - 1;
s >>= -nBits;
nBits += eLen;
for (; nBits > 0; e = e * 256 + buffer[offset + i], i += d, nBits -= 8) {}
m = e & (1 << -nBits) - 1;
e >>= -nBits;
nBits += mLen;
for (; nBits > 0; m = m * 256 + buffer[offset + i], i += d, nBits -= 8) {}
if (e === 0) {
e = 1 - eBias;
} else if (e === eMax) {
return m ? NaN : (s ? -1 : 1) * Infinity;
} else {
m = m + Math.pow(2, mLen);
e = e - eBias;
}
return (s ? -1 : 1) * m * Math.pow(2, e - mLen);
}
function write(buffer, value, offset, isLE, mLen, nBytes) {
var e, m, c;
var eLen = nBytes * 8 - mLen - 1;
var eMax = (1 << eLen) - 1;
var eBias = eMax >> 1;
var rt = mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0;
var i = isLE ? 0 : nBytes - 1;
var d = isLE ? 1 : -1;
var s = value < 0 || value === 0 && 1 / value < 0 ? 1 : 0;
value = Math.abs(value);
if (isNaN(value) || value === Infinity) {
m = isNaN(value) ? 1 : 0;
e = eMax;
} else {
e = Math.floor(Math.log(value) / Math.LN2);
if (value * (c = Math.pow(2, -e)) < 1) {
e--;
c *= 2;
}
if (e + eBias >= 1) {
value += rt / c;
} else {
value += rt * Math.pow(2, 1 - eBias);
}
if (value * c >= 2) {
e++;
c /= 2;
}
if (e + eBias >= eMax) {
m = 0;
e = eMax;
} else if (e + eBias >= 1) {
m = (value * c - 1) * Math.pow(2, mLen);
e = e + eBias;
} else {
m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen);
e = 0;
}
}
for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8) {}
e = e << mLen | m;
eLen += mLen;
for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8) {}
buffer[offset + i - d] |= s * 128;
}