##crc32_execute
if !HaveCRCExt() then
    UnallocatedEncoding();
end

bits(32)      acc     = X[n];   // accumulator
bits(size)    val     = X[m];   // input value
bits(32)      poly    = (if crc32c then 0x1EDC6F41 else 0x04C11DB7)<31:0>;

bits(32+size) tempacc = BitReverse(acc) : Zeros(size);
bits(size+32) tempval = BitReverse(val) : Zeros(32);

// Poly32Mod2 on a bitstring does a polynomial Modulus over {0,1} operation
X[d] = BitReverse(Poly32Mod2(tempacc EOR tempval, poly));
@@