On Sunday 22 April 2007 14:08, Uri Guttman wrote: > >>>>> "JP" == Joerg Plate <[EMAIL PROTECTED]> writes: > >> > >> const int slot = (reg_alloc + 7) >> 3; reg_alloc = slot << 3; > >> > >> This is where I start not to understand. Why reg_alloc + 7? Why > >> shift left and right by 3? > > JP> That's just a rounding up (if necessary) to a multiple of 8 (2<<3). > > and those sort of things should be macros as they are confusing > otherwise and annoying to change. and named something like > ROUND_UP_TO_BOUNDARY. as others have said it is a common idiom. and i > agree that there should be comments on WHY the rounding is used/needed.
I figured it was a rounding, but I saw two magic numbers and didn't want to guess what it was. Any volunteers to macroize this? Also, is anyone *sure* that this boundary is effective on both 32- and 64-bit platforms? I hate to make assumptions about alignment. -- c
