On 12/13/2016 08:39 AM, Andres Valloud wrote: > I would have expected the floats to be a byte object of size 8. Why is > this conversion needed? Is somehow the primitive thinking the float has > size 2? Or is the primitive hashing 32 bits at a time? The prim used > to be a C version of the byte oriented 1644525 multiplicative hash, did > this change?
The float is not a byte object of size 8, it's a word object of size 2. When you feed it to #hashBytes:startingWith: the primitive fails. (I didn't look at why -- maybe because it isn't a byte object?) The alternative Smalltalk code treats it like it was a byte object, even though it's not. So it iterates through the two words, multiplying each by 1664525, then keeping only the low-order 28 bits of the result. But since each word is a full 32 bits, the high-order four bits of each word, which include the sign bit, can never affect the hash. Regards, -Martin
