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					86 lines
				
				2.1 KiB
			
		
		
			
		
	
	
					86 lines
				
				2.1 KiB
			| 
											3 years ago
										 | /*! ieee754. BSD-3-Clause License. Feross Aboukhadijeh <https://feross.org/opensource> */ | ||
|  | exports.read = function (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) | ||
|  | } | ||
|  | 
 | ||
|  | exports.write = function (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 | ||
|  | } |