In article <87pmvbobbn....@igel.home>, Andreas Schwab <sch...@linux-m68k.org> wrote:
> On Jul 21 2021, Nelson H. F. Beebe wrote: > > The Intel IA-64 Application Developer's Architecture Guide, May 1999, > > (Order Number: 245188-001) on page 5-1, in Table 5-1 has > > > >>> ... > >>> Total memory format width (bits) 32 64 80 128 > >>> Exponent bias +127 +1023 +16383 +16383 > That are the biases for normalized numbers. What does it say about > denormalized numbers? Note that the i387 format does not allow for a > biased exponent of zero when the explicit integer bit is one, unlike the > m68881 format. As this has been discussed in the GNU MPFR mailing-list a few days ago, I've found that https://www.nxp.com/docs/en/reference-manual/M68000PM.pdf (MOTOROLA M68000 FAMILY – Programmer's Reference Manual) confirms the difference with the i387 format: Page 1-18, Section 1.6.1 "Normalized Numbers" says: In extended precision, the mantissa's MSB, the explicit integer bit, can only be a one (see Figure 1-13); and the exponent can be zero. and Section 1.6.2 "Denormalized Numbers" says: In extended precision, the mantissa's MSB, the explicit integer bit, can only be a zero (see Figure 1-14). So on m86k, emin is one less the Intel x87 emin, and the printf output is correct. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
