blob: 0559b628c87a473ad10053b17fad8d6d3b222ae4 [file] [log] [blame]
/* This is a stripped down version of floatlib.c. It supplies only those
functions which exist in libgcc, but for which there is not assembly
language versions in m68k/lb1sf68.asm.
It also includes simplistic support for extended floats (by working in
double precision). You must compile this file again with -DEXTFLOAT
to get this support. */
/*
** gnulib 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?).
**
** 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 gnulib 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 126L
#define SIGNBIT 0x80000000L
#define HIDDEN (1L << 23L)
#define SIGN(fp) ((fp) & SIGNBIT)
#define EXP(fp) (((fp) >> 23L) & 0xFF)
#define MANT(fp) (((fp) & 0x7FFFFFL) | HIDDEN)
#define PACK(s,e,m) ((s) | ((e) << 23L) | (m))
/* the following deal with IEEE double-precision numbers */
#define EXCESSD 1022
#define HIDDEND (1L << 20L)
#define EXPDBITS 11
#define EXPDMASK 0x7FF
#define EXPD(fp) (((fp.l.upper) >> 20L) & 0x7FFL)
#define SIGND(fp) ((fp.l.upper) & SIGNBIT)
#define MANTD(fp) (((((fp.l.upper) & 0xFFFFF) | HIDDEND) << 10) | \
(fp.l.lower >> 22))
#define MANTDMASK 0xFFFFF /* mask of upper part */
/* the following deal with IEEE extended-precision numbers */
#define EXCESSX 16382
#define HIDDENX (1L << 31L)
#define EXPXBITS 15
#define EXPXMASK 0x7FFF
#define EXPX(fp) (((fp.l.upper) >> 16) & EXPXMASK)
#define SIGNX(fp) ((fp.l.upper) & SIGNBIT)
#define MANTXMASK 0x7FFFFFFF /* mask of upper part */
union double_long
{
double d;
struct {
long upper;
unsigned long lower;
} l;
};
union float_long {
float f;
long l;
};
union long_double_long
{
long double ld;
struct
{
long upper;
unsigned long middle;
unsigned long lower;
} l;
};
#ifndef EXTFLOAT
/* convert int to double */
double
__floatsidf (int a1)
{
long sign = 0, exp = 31 + EXCESSD;
union double_long dl;
if (!a1)
{
dl.l.upper = dl.l.lower = 0;
return dl.d;
}
if (a1 < 0)
{
sign = SIGNBIT;
a1 = -a1;
if (a1 < 0)
{
dl.l.upper = SIGNBIT | ((32 + EXCESSD) << 20L);
dl.l.lower = 0;
return dl.d;
}
}
while (a1 < 0x1000000)
{
a1 <<= 4;
exp -= 4;
}
while (a1 < 0x40000000)
{
a1 <<= 1;
exp--;
}
/* pack up and go home */
dl.l.upper = sign;
dl.l.upper |= exp << 20L;
dl.l.upper |= (a1 >> 10L) & ~HIDDEND;
dl.l.lower = a1 << 22L;
return dl.d;
}
/* convert int to float */
float
__floatsisf (int l)
{
double foo = __floatsidf (l);
return foo;
}
/* convert float to double */
double
__extendsfdf2 (float a1)
{
register union float_long fl1;
register union double_long dl;
register long exp;
fl1.f = a1;
if (!fl1.l)
{
dl.l.upper = dl.l.lower = 0;
return dl.d;
}
dl.l.upper = SIGN (fl1.l);
exp = EXP (fl1.l) - EXCESS + EXCESSD;
dl.l.upper |= exp << 20;
dl.l.upper |= (MANT (fl1.l) & ~HIDDEN) >> 3;
dl.l.lower = MANT (fl1.l) << 29;
return dl.d;
}
/* convert double to float */
float
__truncdfsf2 (double a1)
{
register long exp;
register long mant;
register union float_long fl;
register union double_long dl1;
dl1.d = a1;
if (!dl1.l.upper && !dl1.l.lower)
return 0;
exp = EXPD (dl1) - EXCESSD + EXCESS;
/* shift double mantissa 6 bits so we can round */
mant = MANTD (dl1) >> 6;
/* now round and shift down */
mant += 1;
mant >>= 1;
/* did the round overflow? */
if (mant & 0xFF000000)
{
mant >>= 1;
exp++;
}
mant &= ~HIDDEN;
/* pack up and go home */
fl.l = PACK (SIGND (dl1), exp, mant);
return (fl.f);
}
/* convert double to int */
int
__fixdfsi (double a1)
{
register union double_long dl1;
register long exp;
register long l;
dl1.d = a1;
if (!dl1.l.upper && !dl1.l.lower)
return 0;
exp = EXPD (dl1) - EXCESSD - 31;
l = MANTD (dl1);
if (exp > 0)
{
/* Return largest integer. */
return SIGND (dl1) ? 0x80000000 : 0x7fffffff;
}
if (exp <= -32)
return 0;
/* shift down until exp = 0 */
if (exp < 0)
l >>= -exp;
return (SIGND (dl1) ? -l : l);
}
/* convert float to int */
int
__fixsfsi (float a1)
{
double foo = a1;
return __fixdfsi (foo);
}
#else /* EXTFLOAT */
/* Primitive extended precision floating point support.
We assume all numbers are normalized, don't do any rounding, etc. */
/* Prototypes for the above in case we use them. */
double __floatsidf (int);
float __floatsisf (int);
double __extendsfdf2 (float);
float __truncdfsf2 (double);
int __fixdfsi (double);
int __fixsfsi (float);
/* convert double to long double */
long double
__extenddfxf2 (double d)
{
register union double_long dl;
register union long_double_long ldl;
register long exp;
dl.d = d;
/*printf ("dfxf in: %g\n", d);*/
if (!dl.l.upper && !dl.l.lower)
return 0;
ldl.l.upper = SIGND (dl);
exp = EXPD (dl) - EXCESSD + EXCESSX;
ldl.l.upper |= exp << 16;
ldl.l.middle = HIDDENX;
/* 31-20: # mantissa bits in ldl.l.middle - # mantissa bits in dl.l.upper */
ldl.l.middle |= (dl.l.upper & MANTDMASK) << (31 - 20);
/* 1+20: explicit-integer-bit + # mantissa bits in dl.l.upper */
ldl.l.middle |= dl.l.lower >> (1 + 20);
/* 32 - 21: # bits of dl.l.lower in ldl.l.middle */
ldl.l.lower = dl.l.lower << (32 - 21);
/*printf ("dfxf out: %s\n", dumpxf (ldl.ld));*/
return ldl.ld;
}
/* convert long double to double */
double
__truncxfdf2 (long double ld)
{
register long exp;
register union double_long dl;
register union long_double_long ldl;
ldl.ld = ld;
/*printf ("xfdf in: %s\n", dumpxf (ld));*/
if (!ldl.l.upper && !ldl.l.middle && !ldl.l.lower)
return 0;
exp = EXPX (ldl) - EXCESSX + EXCESSD;
/* ??? quick and dirty: keep `exp' sane */
if (exp >= EXPDMASK)
exp = EXPDMASK - 1;
dl.l.upper = SIGNX (ldl);
dl.l.upper |= exp << (32 - (EXPDBITS + 1));
/* +1-1: add one for sign bit, but take one off for explicit-integer-bit */
dl.l.upper |= (ldl.l.middle & MANTXMASK) >> (EXPDBITS + 1 - 1);
dl.l.lower = (ldl.l.middle & MANTXMASK) << (32 - (EXPDBITS + 1 - 1));
dl.l.lower |= ldl.l.lower >> (EXPDBITS + 1 - 1);
/*printf ("xfdf out: %g\n", dl.d);*/
return dl.d;
}
/* convert a float to a long double */
long double
__extendsfxf2 (float f)
{
long double foo = __extenddfxf2 (__extendsfdf2 (f));
return foo;
}
/* convert a long double to a float */
float
__truncxfsf2 (long double ld)
{
float foo = __truncdfsf2 (__truncxfdf2 (ld));
return foo;
}
/* convert an int to a long double */
long double
__floatsixf (int l)
{
double foo = __floatsidf (l);
return foo;
}
/* convert a long double to an int */
int
__fixxfsi (long double ld)
{
int foo = __fixdfsi ((double) ld);
return foo;
}
/* The remaining provide crude math support by working in double precision. */
long double
__addxf3 (long double x1, long double x2)
{
return (double) x1 + (double) x2;
}
long double
__subxf3 (long double x1, long double x2)
{
return (double) x1 - (double) x2;
}
long double
__mulxf3 (long double x1, long double x2)
{
return (double) x1 * (double) x2;
}
long double
__divxf3 (long double x1, long double x2)
{
return (double) x1 / (double) x2;
}
long double
__negxf2 (long double x1)
{
return - (double) x1;
}
long
__cmpxf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__eqxf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__nexf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__ltxf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__lexf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__gtxf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
long
__gexf2 (long double x1, long double x2)
{
return __cmpdf2 ((double) x1, (double) x2);
}
#endif /* EXTFLOAT */