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