fast-check
Version:
Property based testing framework for JavaScript (like QuickCheck)
69 lines (68 loc) • 2.4 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.EPSILON_32 = exports.MAX_VALUE_32 = exports.MIN_VALUE_32 = void 0;
exports.decomposeFloat = decomposeFloat;
exports.floatToIndex = floatToIndex;
exports.indexToFloat = indexToFloat;
const safeNegativeInfinity = Number.NEGATIVE_INFINITY;
const safePositiveInfinity = Number.POSITIVE_INFINITY;
exports.MIN_VALUE_32 = 2 ** -126 * 2 ** -23;
exports.MAX_VALUE_32 = 2 ** 127 * (1 + (2 ** 23 - 1) / 2 ** 23);
exports.EPSILON_32 = 2 ** -23;
const INDEX_POSITIVE_INFINITY = 2139095040;
const INDEX_NEGATIVE_INFINITY = -2139095041;
const f32 = new Float32Array(1);
const u32 = new Uint32Array(f32.buffer, f32.byteOffset);
function bitCastFloatToUInt32(f) {
f32[0] = f;
return u32[0];
}
function decomposeFloat(f) {
const bits = bitCastFloatToUInt32(f);
const signBit = bits >>> 31;
const exponentBits = (bits >>> 23) & 0xff;
const significandBits = bits & 0x7fffff;
const exponent = exponentBits === 0 ? -126 : exponentBits - 127;
let significand = exponentBits === 0 ? 0 : 1;
significand += significandBits / 2 ** 23;
significand *= signBit === 0 ? 1 : -1;
return { exponent, significand };
}
function indexInFloatFromDecomp(exponent, significand) {
if (exponent === -126) {
return significand * 0x800000;
}
return (exponent + 127) * 0x800000 + (significand - 1) * 0x800000;
}
function floatToIndex(f) {
if (f === safePositiveInfinity) {
return INDEX_POSITIVE_INFINITY;
}
if (f === safeNegativeInfinity) {
return INDEX_NEGATIVE_INFINITY;
}
const decomp = decomposeFloat(f);
const exponent = decomp.exponent;
const significand = decomp.significand;
if (f > 0 || (f === 0 && 1 / f === safePositiveInfinity)) {
return indexInFloatFromDecomp(exponent, significand);
}
else {
return -indexInFloatFromDecomp(exponent, -significand) - 1;
}
}
function indexToFloat(index) {
if (index < 0) {
return -indexToFloat(-index - 1);
}
if (index === INDEX_POSITIVE_INFINITY) {
return safePositiveInfinity;
}
if (index < 0x1000000) {
return index * 2 ** -149;
}
const postIndex = index - 0x1000000;
const exponent = -125 + (postIndex >> 23);
const significand = 1 + (postIndex & 0x7fffff) / 0x800000;
return significand * 2 ** exponent;
}