function computeFloat16MantisaTable() {
    const convertMantissa = (i)=>{
        let m = i << 13;
        let e = 0;
        while((m & 0x00800000) === 0){
            e -= 0x00800000;
            m <<= 1;
        }
        m &= -8388609;
        e += 0x38800000;
        return m | e;
    };
    const mantisaTable = new Uint32Array(2048);
    mantisaTable[0] = 0;
    for(let i = 1; i < 1024; i++)mantisaTable[i] = convertMantissa(i);
    for(let i = 1024; i < 2048; i++)mantisaTable[i] = 0x38000000 + (i - 1024 << 13);
    return mantisaTable;
}
Computes mantisa table for casting Float16 to Float32
See http://www.fox-toolkit.org/ftp/fasthalffloatconversion.pdf

@returns Uint32Array, 2048 mantissa lookup values.