Am Fri, 16 Aug 2013 18:33:14 +0200 schrieb "Iain Buclaw" <ibuc...@ubuntu.com>:
> I've pushed in pure implementations of functions in std.math, > removing the workaround in core.stdc.math. > > This passes for x64/x32. Can any ARM testers please report any > problems causecd by this update? > > Thanks > Iain. I found a bug in the floor implementation for 64 bit reals: int exp = (vu[F.EXPPOS_SHORT] & 0x7ff) - 0x3ff; The constants are wrong: At least 0x7ff must be 0x7ff0. (Remember, the 16 bits are s|eeeeeeeeeee|???? ) However, the results are still wrong and I don't really understand how that equation should work. The 'naive' and working way to write this is -------- int exp = ((vu[F.EXPPOS_SHORT] & 0x7ff0) >> 4) -1023; -------- I assume 0x3ff should be changed to 0x3ff0 which is 1023 << 4. But then the result is still left-shifted by 4 and needs to be right-shifted: ------- int exp = (((vu[F.EXPPOS_SHORT] & 0x7ff0)) - 0x3ff0) >> 4; ------- is also working, but I don't know what's the advantage of this version. floatTraits also has EXPBIAS = 0x3f_e_0? How was that value obtained?
