Author: James Robertson
Date: 14:08:54 06/18/00
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On June 18, 2000 at 16:08:20, Robert Hyatt wrote: >On June 18, 2000 at 15:25:23, James Robertson wrote: > >>I cannot remember how to do a shift in assembler and save any bits shifted off. >>Specifically, I want to shift a 64-bit integer. What is the assembler equivalent >>of: >> >>unsigned __int64 x; >>x <<= shift; >> >>Thanks, >>James > > >I don't follow. x <<= shift simply shifts x "shift" bits to the left and >gives you the result. Not the bits shifted off. To get the bits you are >going to shift off, create a mask with "shift" bits in the left-most end, >AND this with the value, and then save them. Those are the bits that would >have been lost. I guess my message is unclear. What I meant to say is: how do you do a shift of a 64-bit integer with a 32-bit processor? I think you must use two shift operations, one for the lower 32 bits, and one for the upper 32 bits. Unfortunately, I don't know how to do the shift on the lower 32 bits and move any bits shifted off the end of the lower 32 bit integer into the upper 32 bit integer. James
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