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[PATCH] Fix formatting of denormal IBM long double numbers
- From: Andreas Schwab <schwab at linux-m68k dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 23 Apr 2012 22:30:16 +0200
- Subject: [PATCH] Fix formatting of denormal IBM long double numbers
[BZ #13941]
* sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c
(__mpn_extract_long_double): Use DBL_MIN_EXP instead of
LDBL_MIN_EXP.
---
sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c b/sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c
index 3162bbd..ed0c872 100644
--- a/sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c
+++ b/sysdeps/ieee754/ldbl-128ibm/ldbl2mpn.c
@@ -1,5 +1,4 @@
-/* Copyright (C) 1995,1996,1997,1998,1999,2002,2003,2006
- Free Software Foundation, Inc.
+/* Copyright (C) 1995-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -104,7 +103,10 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
else
{
/* It is a denormal number, meaning it has no implicit leading
- one bit, and its exponent is in fact the format minimum. */
+ one bit, and its exponent is in fact the format minimum. We
+ use DBL_MIN_EXP instead of LDBL_MIN_EXP below because the
+ latter describes the properies of the both parts together,
+ but the exponent is computed from the high part only. */
int cnt;
#if N == 2
@@ -115,7 +117,7 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
res_ptr[N - 1] = res_ptr[N - 1] << cnt
| (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt));
res_ptr[0] <<= cnt;
- *expt = LDBL_MIN_EXP - 1 - cnt;
+ *expt = DBL_MIN_EXP - 1 - cnt;
}
else
{
@@ -130,7 +132,7 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
res_ptr[N - 1] = res_ptr[0] >> (NUM_LEADING_ZEROS - cnt);
res_ptr[0] <<= BITS_PER_MP_LIMB - (NUM_LEADING_ZEROS - cnt);
}
- *expt = LDBL_MIN_EXP - 1
+ *expt = DBL_MIN_EXP - 1
- (BITS_PER_MP_LIMB - NUM_LEADING_ZEROS) - cnt;
}
#else
@@ -161,7 +163,7 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
for (; k >= 0; k--)
res_ptr[k] = 0;
- *expt = LDBL_MIN_EXP - 1 - l * BITS_PER_MP_LIMB - cnt;
+ *expt = DBL_MIN_EXP - 1 - l * BITS_PER_MP_LIMB - cnt;
#endif
}
}
--
1.7.10
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."