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authorUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
committerUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
commitabfbdde177c3a7155070dda1b2cdc8292054cc26 (patch)
treee021306b596381fbf8311d2b7eb294e918ff17c8 /sysdeps/i386/fpu/s_expm1f.S
parent86421aa57ecfd70963ae66848bd6a6dd3b8e0fe6 (diff)
downloadglibc-abfbdde177c3a7155070dda1b2cdc8292054cc26.tar.gz
Update.
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+/* ix87 specific implementation of exp(x)-1.
+ Copyright (C) 1996, 1997 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
+ Based on code by John C. Bowman <bowman@ipp-garching.mpg.de>.
+ Corrections by H.J. Lu (hjl@gnu.ai.mit.edu), 1997.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+ /* Using: e^x - 1 = 2^(x * log2(e)) - 1 */
+
+#include <machine/asm.h>
+
+#ifdef __ELF__
+ .section .rodata
+#else
+ .text
+#endif
+ .align ALIGNARG(4)
+ ASM_TYPE_DIRECTIVE(minus1,@object)
+minus1: .double -1.0
+ ASM_SIZE_DIRECTIVE(minus1)
+ ASM_TYPE_DIRECTIVE(one,@object)
+one: .double 1.0
+ ASM_SIZE_DIRECTIVE(one)
+ ASM_TYPE_DIRECTIVE(l2e,@object)
+l2e: .tfloat 1.442695040888963407359924681002
+ ASM_SIZE_DIRECTIVE(l2e)
+
+#ifdef PIC
+#define MO(op) op##@GOTOFF(%edx)
+#else
+#define MO(op) op
+#endif
+
+ .text
+ENTRY(__expm1f)
+ flds 4(%esp) // x
+ fxam // Is NaN or +-Inf?
+ fstsw %ax
+ movb $0x45, %ch
+ andb %ah, %ch
+ cmpb $0x40, %ch
+ je 3f // If +-0, jump.
+#ifdef PIC
+ call 1f
+1: popl %edx
+ addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
+#endif
+ cmpb $0x05, %ch
+ je 2f // If +-Inf, jump.
+
+ fldt MO(l2e) // log2(e) : x
+ fmulp // log2(e)*x
+ fld %st // log2(e)*x : log2(e)*x
+ frndint // int(log2(e)*x) : log2(e)*x
+ fsubr %st, %st(1) // int(log2(e)*x) : fract(log2(e)*x)
+ fxch // fract(log2(e)*x) : int(log2(e)*x)
+ f2xm1 // 2^fract(log2(e)*x)-1 : int(log2(e)*x)
+ fscale // 2^(log2(e)*x)-2^int(log2(e)*x) : int(log2(e)*x)
+ fxch // int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
+ fldl MO(one) // 1 : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
+ fscale // 2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
+ fsubrl MO(one) // 1-2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
+ fstp %st(1) // 1-2^int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)
+ fsubrp %st, %st(1) // 2^(log2(e)*x)
+ ret
+
+2: testl $0x200, %eax // Test sign.
+ jz 3f // If positive, jump.
+ fstp %st
+ fldl MO(minus1) // Set result to -1.0.
+3: ret
+END(__expm1f)
+weak_alias (__expm1f, expm1f)