89 lines
3 KiB
C
89 lines
3 KiB
C
/*
|
|
** libgcc support for software floating point.
|
|
** Copyright (C) 1991 by Pipeline Associates, Inc. All rights reserved.
|
|
** Permission is granted to do *anything* you want with this file,
|
|
** commercial or otherwise, provided this message remains intact. So there!
|
|
** I would appreciate receiving any updates/patches/changes that anyone
|
|
** makes, and am willing to be the repository for said changes (am I
|
|
** making a big mistake?).
|
|
|
|
Warning! Only single-precision is actually implemented. This file
|
|
won't really be much use until double-precision is supported.
|
|
|
|
However, once that is done, this file might eventually become a
|
|
replacement for libgcc1.c. It might also make possible
|
|
cross-compilation for an IEEE target machine from a non-IEEE
|
|
host such as a VAX.
|
|
|
|
If you'd like to work on completing this, please talk to rms@gnu.ai.mit.edu.
|
|
|
|
|
|
**
|
|
** Pat Wood
|
|
** Pipeline Associates, Inc.
|
|
** pipeline!phw@motown.com or
|
|
** sun!pipeline!phw or
|
|
** uunet!motown!pipeline!phw
|
|
**
|
|
** 05/01/91 -- V1.0 -- first release to gcc mailing lists
|
|
** 05/04/91 -- V1.1 -- added float and double prototypes and return values
|
|
** -- fixed problems with adding and subtracting zero
|
|
** -- fixed rounding in truncdfsf2
|
|
** -- fixed SWAP define and tested on 386
|
|
*/
|
|
|
|
/*
|
|
** The following are routines that replace the libgcc soft floating point
|
|
** routines that are called automatically when -msoft-float is selected.
|
|
** The support single and double precision IEEE format, with provisions
|
|
** for byte-swapped machines (tested on 386). Some of the double-precision
|
|
** routines work at full precision, but most of the hard ones simply punt
|
|
** and call the single precision routines, producing a loss of accuracy.
|
|
** long long support is not assumed or included.
|
|
** Overall accuracy is close to IEEE (actually 68882) for single-precision
|
|
** arithmetic. I think there may still be a 1 in 1000 chance of a bit
|
|
** being rounded the wrong way during a multiply. I'm not fussy enough to
|
|
** bother with it, but if anyone is, knock yourself out.
|
|
**
|
|
** Efficiency has only been addressed where it was obvious that something
|
|
** would make a big difference. Anyone who wants to do this right for
|
|
** best speed should go in and rewrite in assembler.
|
|
**
|
|
** I have tested this only on a 68030 workstation and 386/ix integrated
|
|
** in with -msoft-float.
|
|
*/
|
|
|
|
/* the following deal with IEEE single-precision numbers */
|
|
#define EXCESS 126
|
|
#define SIGNBIT ((unsigned long)0x80000000)
|
|
#define HIDDEN (unsgined long)(1 << 23)
|
|
#define SIGN(fp) ((fp >> (8*sizeof(fp)-1)) & 1)
|
|
#define EXP(fp) (((fp) >> 23) & (unsigned int)0x00FF)
|
|
#define MANT(fp) (((fp) & (unsigned long)0x007FFFFF) | HIDDEN)
|
|
#define PACK(s,e,m) ((s) | ((e) << 23) | (m))
|
|
|
|
union float_long
|
|
{
|
|
float f;
|
|
long l;
|
|
};
|
|
|
|
/* compare two floats */
|
|
char
|
|
__fseq (float a1, float a2)
|
|
{
|
|
volatile union float_long fl1, fl2;
|
|
|
|
fl1.f = a1;
|
|
fl2.f = a2;
|
|
|
|
if (SIGN (fl1.l) && SIGN (fl2.l))
|
|
{
|
|
fl1.l ^= SIGNBIT;
|
|
fl2.l ^= SIGNBIT;
|
|
}
|
|
if (fl1.l == fl2.l)
|
|
return (1);
|
|
return (0);
|
|
}
|