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200x-xx-xx Nathan Sidwell <nathan@codesourcery.com>

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gcc/
200x-xx-xx  Nathan Sidwell  <nathan@codesourcery.com>

	* config/m68k/fpgnulib.c (__truncdfsf2): Implement round to
	nearest even, fix denormal rounding overflow.

From-SVN: r120925
This commit is contained in:
Nathan Sidwell 2007-01-18 19:49:59 +00:00 committed by Richard Sandiford
parent 17e143a173
commit e444d54e44
2 changed files with 34 additions and 11 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2007-01-18 Nathan Sidwell <nathan@codesourcery.com>
* config/m68k/fpgnulib.c (__truncdfsf2): Implement round to
nearest even, fix denormal rounding overflow.
2007-01-18 Richard Sandiford <richard@codesourcery.com>
* config/m68k/m68k.md (movsf_cf_hard): Use fsmove instead of

40
gcc/config/m68k/fpgnulib.c
View File

@ -277,6 +277,8 @@ __truncdfsf2 (double a1)
register long mant;
register union float_long fl;
register union double_long dl1;
int sticky;
int shift;
dl1.d = a1;
@ -288,29 +290,45 @@ __truncdfsf2 (double a1)
exp = EXPD (dl1) - EXCESSD + EXCESS;
sticky = dl1.l.lower & ((1 << 22) - 1);
mant = MANTD (dl1);
/* shift double mantissa 6 bits so we can round */
mant = MANTD (dl1) >> 6;
sticky |= mant & ((1 << 6) - 1);
mant >>= 6;
/* Check for underflow and denormals. */
if (exp <= 0)
{
if (exp < -24)
mant = 0;
{
sticky |= mant;
mant = 0;
}
else
mant >>= 1 - exp;
{
sticky |= mant & ((1 << (1 - exp)) - 1);
mant >>= 1 - exp;
}
exp = 0;
}
/* now round and shift down */
mant += 1;
mant >>= 1;
/* did the round overflow? */
if (mant & 0xFF000000L)
/* now round */
shift = 1;
if ((mant & 1) && (sticky || (mant & 2)))
{
mant >>= 1;
exp++;
int rounding = exp ? 2 : 1;
mant += 1;
/* did the round overflow? */
if (mant >= (HIDDEN << rounding))
{
exp++;
shift = rounding;
}
}
/* shift down */
mant >>= shift;
mant &= ~HIDDEN;