| /* ix87 specific implementation of exp(x)-1. |
| Copyright (C) 1996-2014 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 Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* Using: e^x - 1 = 2^(x * log2(e)) - 1 */ |
| |
| #include <sysdep.h> |
| #include <machine/asm.h> |
| |
| .section .rodata |
| |
| .align ALIGNARG(4) |
| .type minus1,@object |
| minus1: .double -1.0 |
| ASM_SIZE_DIRECTIVE(minus1) |
| .type one,@object |
| one: .double 1.0 |
| ASM_SIZE_DIRECTIVE(one) |
| .type 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(__expm1) |
| movzwl 4+6(%esp), %eax |
| xorb $0x80, %ah // invert sign bit (now 1 is "positive") |
| cmpl $0xc086, %eax // is num >= 704? |
| jae HIDDEN_JUMPTARGET (__exp) |
| |
| fldl 4(%esp) // x |
| fxam // Is NaN, +-Inf or +-0? |
| xorb $0x80, %ah |
| cmpl $0xc043, %eax // is num <= -38.0? |
| fstsw %ax |
| movb $0x45, %ch |
| jb 4f |
| |
| // Below -38.0 (may be -NaN or -Inf). |
| andb %ah, %ch |
| #ifdef PIC |
| LOAD_PIC_REG (dx) |
| #endif |
| cmpb $0x01, %ch |
| je 5f // If -NaN, jump. |
| jmp 2f // -large, possibly -Inf. |
| |
| 4: // In range -38.0 to 704.0 (may be +-0 but not NaN or +-Inf). |
| andb %ah, %ch |
| cmpb $0x40, %ch |
| je 3f // If +-0, jump. |
| #ifdef PIC |
| LOAD_PIC_REG (dx) |
| #endif |
| |
| 5: fldt MO(l2e) // log2(e) : x |
| fmulp // log2(e)*x |
| fld %st // log2(e)*x : log2(e)*x |
| // Set round-to-nearest temporarily. |
| subl $8, %esp |
| cfi_adjust_cfa_offset (8) |
| fstcw 4(%esp) |
| movl $0xf3ff, %ecx |
| andl 4(%esp), %ecx |
| movl %ecx, (%esp) |
| fldcw (%esp) |
| frndint // int(log2(e)*x) : log2(e)*x |
| fldcw 4(%esp) |
| addl $8, %esp |
| cfi_adjust_cfa_offset (-8) |
| 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: fstp %st |
| fldl MO(minus1) // Set result to -1.0. |
| 3: ret |
| END(__expm1) |
| weak_alias (__expm1, expm1) |
