HC11 32-bit by 32-bit multiplication routine

2009-05-16 00:43 by Ian

No big write up, just a couple quick subroutines that give an HC11 the means to get a 64-bit product from two 32-bit factors. I wrote it down on paper while I was sitting in my calculus class and copied it into my assembler verbatim when I got home, so there aren’t any optimizations for factors that don’t extend past certain boundaries. Doesn’t use any static memory locations, but instead uses the stack to pass and return values, giving the programmer the option of using it recursively, or in ISR’s without worry.