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Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c')
-rw-r--r--sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c75
1 files changed, 62 insertions, 13 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c
index 8a2d45e2d8..21d1e62dab 100644
--- a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004, 2006
+/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004, 2006, 2007
Free Software Foundation, Inc.
This file is part of the GNU C Library.
@@ -31,19 +31,20 @@ long double
__mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
{
union ibm_extended_long_double u;
- unsigned long hidden2, lzcount;
+ unsigned long lzcount;
unsigned long long hi, lo;
+ int exponent2;
u.ieee.negative = sign;
u.ieee.negative2 = sign;
u.ieee.exponent = expt + IBM_EXTENDED_LONG_DOUBLE_BIAS;
- u.ieee.exponent2 = expt - 53 + IBM_EXTENDED_LONG_DOUBLE_BIAS;
+ u.ieee.exponent2 = 0;
+ exponent2 = expt - 53 + IBM_EXTENDED_LONG_DOUBLE_BIAS;
#if BITS_PER_MP_LIMB == 32
/* The low order 53 bits (52 + hidden) go into the lower double */
lo = frac_ptr[0];
lo |= (frac_ptr[1] & ((1LL << (53 - 32)) - 1)) << 32;
- hidden2 = (frac_ptr[1] >> (52 - 32)) & ((mp_limb_t) 1);
/* The high order 53 bits (52 + hidden) go into the upper double */
hi = (frac_ptr[1] >> (53 - 32)) & ((1 << 11) - 1);
hi |= ((unsigned long long) frac_ptr[2]) << 11;
@@ -51,7 +52,6 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
#elif BITS_PER_MP_LIMB == 64
/* The low order 53 bits (52 + hidden) go into the lower double */
lo = frac_ptr[0] & (((mp_limb_t) 1 << 53) - 1);
- hidden2 = (frac_ptr[0] >> 52) & ((mp_limb_t) 1);
/* The high order 53 bits (52 + hidden) go into the upper double */
hi = (frac_ptr[0] >> 53) & (((mp_limb_t) 1 << 11) - 1);
hi |= (frac_ptr[1] << 11);
@@ -59,14 +59,62 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
#error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
#endif
+ if ((hi & (1LL << 52)) == 0 && (hi | lo) != 0)
+ {
+ /* denormal number */
+ unsigned long long val = hi ? hi : lo;
+
+ if (sizeof (val) == sizeof (long))
+ lzcount = __builtin_clzl (val);
+ else if ((val >> 32) != 0)
+ lzcount = __builtin_clzl ((long) (val >> 32));
+ else
+ lzcount = __builtin_clzl ((long) val) + 32;
+ if (hi)
+ lzcount = lzcount - 11;
+ else
+ lzcount = lzcount + 42;
+
+ if (lzcount > u.ieee.exponent)
+ {
+ lzcount = u.ieee.exponent;
+ u.ieee.exponent = 0;
+ exponent2 -= lzcount;
+ }
+ else
+ {
+ u.ieee.exponent -= (lzcount - 1);
+ exponent2 -= (lzcount - 1);
+ }
+
+ if (lzcount <= 53)
+ {
+ hi = (hi << lzcount) | (lo >> (53 - lzcount));
+ lo = (lo << lzcount) & ((1LL << 53) - 1);
+ }
+ else
+ {
+ hi = lo << (lzcount - 53);
+ lo = 0;
+ }
+ }
+
if (lo != 0L)
{
/* hidden2 bit of low double controls rounding of the high double.
- If hidden2 is '1' then round up hi and adjust lo (2nd mantissa)
+ If hidden2 is '1' and either the explicit mantissa is non-zero
+ or hi is odd, then round up hi and adjust lo (2nd mantissa)
plus change the sign of the low double to compensate. */
- if (hidden2)
+ if ((lo & (1LL << 52)) != 0
+ && ((hi & 1) != 0 || (lo & ((1LL << 52) - 1))))
{
hi++;
+ if ((hi & ((1LL << 52) - 1)) == 0)
+ {
+ if ((hi & (1LL << 53)) != 0)
+ hi -= 1LL << 52;
+ u.ieee.exponent++;
+ }
u.ieee.negative2 = !sign;
lo = (1LL << 53) - lo;
}
@@ -85,17 +133,18 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
if (lzcount > 0)
{
lo = lo << lzcount;
- u.ieee.exponent2 = u.ieee.exponent2 - lzcount;
+ exponent2 = exponent2 - lzcount;
}
+ if (exponent2 > 0)
+ u.ieee.exponent2 = exponent2;
+ else
+ lo >>= 1 - exponent2;
}
else
- {
- u.ieee.negative2 = 0;
- u.ieee.exponent2 = 0;
- }
+ u.ieee.negative2 = 0;
u.ieee.mantissa3 = lo & 0xffffffffLL;
- u.ieee.mantissa2 = (lo >> 32) & 0xffffff;
+ u.ieee.mantissa2 = (lo >> 32) & 0xfffff;
u.ieee.mantissa1 = hi & 0xffffffffLL;
u.ieee.mantissa0 = (hi >> 32) & ((1LL << (LDBL_MANT_DIG - 86)) - 1);