sia mining algo

[fatrat1117]

I look at sia.cl and find search use ulong for the target type

search(__global unsigned char* block, volatile __global uint* output, const ulong target)

just curious why target length is 8 bytes used in search function? is it supposed to be 32 bytes like 0x0000000007547ff5d321871ff4fb4f118b8d13a30a1ff7b317f3c5b20629578a?

Thanks!