haste-compiler-0.5.3: lib/floatdecode.js

// Scratch space for byte arrays.
var rts_scratchBuf = new ArrayBuffer(8);
var rts_scratchW32 = new Uint32Array(rts_scratchBuf);
var rts_scratchFloat = new Float32Array(rts_scratchBuf);
var rts_scratchDouble = new Float64Array(rts_scratchBuf);

function decodeFloat(x) {
    if(x === 0) {
        return __decodedZeroF;
    }
    rts_scratchFloat[0] = x;
    var sign = x < 0 ? -1 : 1;
    var exp = ((rts_scratchW32[0] >> 23) & 0xff) - 150;
    var man = rts_scratchW32[0] & 0x7fffff;
    if(exp === 0) {
        ++exp;
    } else {
        man |= (1 << 23);
    }
    return {_:0, a:sign*man, b:exp};
}

var __decodedZero = {_:0,a:1,b:0,c:0,d:0};
var __decodedZeroF = {_:0,a:1,b:0};

function decodeDouble(x) {
    if(x === 0) {
        // GHC 7.10+ *really* doesn't like 0 to be represented as anything
        // but zeroes all the way.
        return __decodedZero;
    }
    rts_scratchDouble[0] = x;
    var sign = x < 0 ? -1 : 1;
    var manHigh = rts_scratchW32[1] & 0xfffff;
    var manLow = rts_scratchW32[0];
    var exp = ((rts_scratchW32[1] >> 20) & 0x7ff) - 1075;
    if(exp === 0) {
        ++exp;
    } else {
        manHigh |= (1 << 20);
    }
    return {_:0, a:sign, b:manHigh, c:manLow, d:exp};
}