ducha-qianduan/node_modules/@xtuc/ieee754/dist/index.cjs.js

"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;
}