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 * The Universal Permissive License (UPL), Version 1.0
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 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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package com.oracle.truffle.js.nodes.cast;

import java.math.BigInteger;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.js.nodes.JavaScriptBaseNode;
import com.oracle.truffle.js.runtime.BigInt;
import com.oracle.truffle.js.runtime.Errors;
import com.oracle.truffle.js.runtime.JSRuntime;

public abstract class JSNumberToBigIntNode extends JavaScriptBaseNode {

    public abstract Object execute(Object value);

    public final BigInt executeBigInt(Object value) {
        return (BigInt) execute(value);
    }

    public static JSNumberToBigIntNode create() {
        return JSNumberToBigIntNodeGen.create();
    }

    @Specialization
    protected BigInt doInteger(int value) {
        return BigInt.valueOf(value);
    }

    @Specialization(guards = "isDoubleRepresentableAsLong(value)")
    protected BigInt doDoubleAsLong(double value) {
        return BigInt.valueOf((long) value);
    }

    @TruffleBoundary
    @Specialization(guards = "!isDoubleRepresentableAsLong(value)")
    protected BigInt doDoubleOther(double value) {
        if (!JSRuntime.isInteger(value)) {
            throw Errors.createRangeError("BigInt out of range");
        }
        long bits = Double.doubleToRawLongBits(value);
        boolean negative = (bits & 0x8000000000000000L) != 0;
        int exponentOffset = 1023;
        int mantissaLength = 52;
        int exponent = (int) ((bits & 0x7ff0000000000000L) >> mantissaLength) - exponentOffset - mantissaLength;
        long mantissa = (bits & 0x000fffffffffffffL) | 0x0010000000000000L;
        BigInteger bigInteger = BigInteger.valueOf(negative ? -mantissa : mantissa).shiftLeft(exponent);
        return new BigInt(bigInteger);
    }

    @Specialization(guards = "isJSNull(value)")
    protected static BigInt doNull(@SuppressWarnings("unused") Object value) {
        return BigInt.ZERO;
    }
}