Mail Archives: djgpp/2017/12/31/15:17:52
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| Message-ID: | <5A4946EB.3090500@gmx.de>
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| Date: | Sun, 31 Dec 2017 21:22:03 +0100
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| From: | "Juan Manuel Guerrero (juan DOT guerrero AT gmx DOT de) [via djgpp AT delorie DOT com]" <djgpp AT delorie DOT com>
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| To: | djgpp AT delorie DOT com
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| Subject: | Fixing various bugs in frexp.S
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| Reply-To: | djgpp AT delorie DOT com
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This is a multi-part message in MIME format.
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Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Content-Transfer-Encoding: 7bit
The frexp function provided by libc.a has a couple of bugs:
- it sets errno to EDOM if the argument is either infinity or NaN
- it produces the wrong value if the argument is -0
- it returns NaN if the argument is infinity
- for NaN and infinity arguments no sign checks are done thus the
results are always positive
All these issues are serious deviations from the ansi/posix behavior.
With the patch below I have tried to fix these issues. If I do not get
any serious objection I will commite the patch in a couple of days.
Regards,
Juan M. Guerrero
diff -aprNU5 djgpp.orig/src/libc/ansi/math/frexp.S djgpp/src/libc/ansi/math/frexp.S
--- djgpp.orig/src/libc/ansi/math/frexp.S 2017-12-29 21:49:56 +0000
+++ djgpp/src/libc/ansi/math/frexp.S 2017-12-31 20:55:40 +0000
@@ -1,10 +1,18 @@
+/* Copyright (C) 2017 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 2011 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1999 DJ Delorie, see COPYING.DJ for details */
-NaN:
+pos_NaN:
+ .long 0x7FC00000
+neg_NaN:
.long 0xFFC00000
+pos_inf:
+ .long 0x7F800000
+neg_inf:
+ .long 0xFF800000
+
onehalf:
.float 0.5
.globl _frexp
_frexp:
@@ -17,10 +25,11 @@ _frexp:
movl 12(%esp), %edx /* Load pointer to expon. */
movl 8(%esp), %eax
+ andl $0x7FFFFFFF, %eax
testl %eax, %eax /* Is x = 0 ? */
jnz inftest
movl 4(%esp), %eax
testl %eax, %eax
@@ -31,11 +40,11 @@ _frexp:
ret
inftest:
andl $0x7FF00000, %eax
cmpl $0x7FF00000, %eax
- je badarg /* +/- inf or NaN */
+ je badarg /* +/- inf or +/- NaN */
argok:
fldl 4(%esp)
fxtract
flds onehalf
@@ -44,10 +53,30 @@ argok:
fxch
fistpl (%edx)
incl (%edx)
ret
-badarg: /* arg is NaN */
- movl $1, _errno
+badarg: /* arg is +/- inf or +/- NaN */
movl $0, (%edx)
- flds NaN
+ movl 8(%esp), %eax
+ andl $0x800FFFFF, %eax
+ testl $0x80000000, %eax
+ jnz negarg
+
+ cmpl $0x00000000, %eax
+ je infarg
+ flds pos_NaN
+ ret
+
+infarg:
+ flds pos_inf
+ ret
+
+negarg: /* arg is - inf or - NaN */
+ cmpl $0x80000000, %eax
+ jnz nanarg
+ flds neg_inf
+ ret
+
+nanarg:
+ flds neg_NaN
ret
diff -aprNU5 djgpp.orig/src/libc/ansi/math/frexp.txh djgpp/src/libc/ansi/math/frexp.txh
--- djgpp.orig/src/libc/ansi/math/frexp.txh 2003-01-29 12:26:14 +0000
+++ djgpp/src/libc/ansi/math/frexp.txh 2017-12-31 20:53:38 +0000
@@ -16,14 +16,15 @@ range @code{[0.5,1)} and an exponent e,
It returns the value of the mantissa and stores the integer exponent in
@var{*pexp}.
@subheading Return Value
-The mantissa. If the value of @var{x} is @code{NaN} or @code{Inf}, the
-return value is @code{NaN}, zero is stored in @code{*pexp}, and
-@code{errno} is set to @code{EDOM}. If @var{x} is zero, @var{*pexp} and
-the return value are also both zero.
+The mantissa. If the value of @var{x} is @code{NaN}, the return value is
+@code{NaN} and zero is stored in @code{*pexp}. If the value of @var{x} is
+@code{Inf}, the return value is @code{Inf} and zero is stored in @code{*pexp}.
+If @var{x} is zero, @var{*pexp} and the return value are also both zero.
+@code{errno} is not modified.
@subheading Portability
@portability ansi, posix
--------------070408060806090508030602
Content-Type: text/x-patch;
name="frexp.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="frexp.patch"
diff -aprNU5 djgpp.orig/src/libc/ansi/math/frexp.S djgpp/src/libc/ansi/math/frexp.S
--- djgpp.orig/src/libc/ansi/math/frexp.S 2017-12-29 21:49:56 +0000
+++ djgpp/src/libc/ansi/math/frexp.S 2017-12-31 20:55:40 +0000
@@ -1,10 +1,18 @@
+/* Copyright (C) 2017 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 2011 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1999 DJ Delorie, see COPYING.DJ for details */
-NaN:
+pos_NaN:
+ .long 0x7FC00000
+neg_NaN:
.long 0xFFC00000
+pos_inf:
+ .long 0x7F800000
+neg_inf:
+ .long 0xFF800000
+
onehalf:
.float 0.5
.globl _frexp
_frexp:
@@ -17,10 +25,11 @@ _frexp:
movl 12(%esp), %edx /* Load pointer to expon. */
movl 8(%esp), %eax
+ andl $0x7FFFFFFF, %eax
testl %eax, %eax /* Is x = 0 ? */
jnz inftest
movl 4(%esp), %eax
testl %eax, %eax
@@ -31,11 +40,11 @@ _frexp:
ret
inftest:
andl $0x7FF00000, %eax
cmpl $0x7FF00000, %eax
- je badarg /* +/- inf or NaN */
+ je badarg /* +/- inf or +/- NaN */
argok:
fldl 4(%esp)
fxtract
flds onehalf
@@ -44,10 +53,30 @@ argok:
fxch
fistpl (%edx)
incl (%edx)
ret
-badarg: /* arg is NaN */
- movl $1, _errno
+badarg: /* arg is +/- inf or +/- NaN */
movl $0, (%edx)
- flds NaN
+ movl 8(%esp), %eax
+ andl $0x800FFFFF, %eax
+ testl $0x80000000, %eax
+ jnz negarg
+
+ cmpl $0x00000000, %eax
+ je infarg
+ flds pos_NaN
+ ret
+
+infarg:
+ flds pos_inf
+ ret
+
+negarg: /* arg is - inf or - NaN */
+ cmpl $0x80000000, %eax
+ jnz nanarg
+ flds neg_inf
+ ret
+
+nanarg:
+ flds neg_NaN
ret
diff -aprNU5 djgpp.orig/src/libc/ansi/math/frexp.txh djgpp/src/libc/ansi/math/frexp.txh
--- djgpp.orig/src/libc/ansi/math/frexp.txh 2003-01-29 12:26:14 +0000
+++ djgpp/src/libc/ansi/math/frexp.txh 2017-12-31 20:53:38 +0000
@@ -16,14 +16,15 @@ range @code{[0.5,1)} and an exponent e,
It returns the value of the mantissa and stores the integer exponent in
@var{*pexp}.
@subheading Return Value
-The mantissa. If the value of @var{x} is @code{NaN} or @code{Inf}, the
-return value is @code{NaN}, zero is stored in @code{*pexp}, and
-@code{errno} is set to @code{EDOM}. If @var{x} is zero, @var{*pexp} and
-the return value are also both zero.
+The mantissa. If the value of @var{x} is @code{NaN}, the return value is
+@code{NaN} and zero is stored in @code{*pexp}. If the value of @var{x} is
+@code{Inf}, the return value is @code{Inf} and zero is stored in @code{*pexp}.
+If @var{x} is zero, @var{*pexp} and the return value are also both zero.
+@code{errno} is not modified.
@subheading Portability
@portability ansi, posix
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