sysdeps/i386/fpu/s_frexp.S

   1 /* ix87 specific frexp implementation for double.
   2    Copyright (C) 1997-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <machine/asm.h>
  21
  22         .section .rodata
  23
  24         .align ALIGNARG(4)
  25         .type two54,@object
  26 two54:  .byte 0, 0, 0, 0, 0, 0, 0x50, 0x43
  27         ASM_SIZE_DIRECTIVE(two54)
  28
  29 #ifdef PIC
  30 #define MO(op) op##@GOTOFF(%edx)
  31 #else
  32 #define MO(op) op
  33 #endif
  34
  35 #define PARMS   4               /* no space for saved regs */
  36 #define VAL0    PARMS
  37 #define VAL1    VAL0+4
  38 #define EXPP    VAL1+4
  39
  40         .text
  41 ENTRY (__frexp)
  42
  43         movl    VAL0(%esp), %ecx
  44         movl    VAL1(%esp), %eax
  45         movl    %eax, %edx
  46         andl    $0x7fffffff, %eax
  47         orl     %eax, %ecx
  48         jz      1f
  49         xorl    %ecx, %ecx
  50         cmpl    $0x7ff00000, %eax
  51         jae     1f
  52
  53         cmpl    $0x00100000, %eax
  54         jae     2f
  55
  56         fldl    VAL0(%esp)
  57 #ifdef  PIC
  58         LOAD_PIC_REG (dx)
  59 #endif
  60         fmull   MO(two54)
  61         movl    $-54, %ecx
  62         fstpl   VAL0(%esp)
  63         fwait
  64         movl    VAL1(%esp), %eax
  65         movl    %eax, %edx
  66         andl    $0x7fffffff, %eax
  67
  68 2:      shrl    $20, %eax
  69         andl    $0x800fffff, %edx
  70         subl    $1022, %eax
  71         orl     $0x3fe00000, %edx
  72         addl    %eax, %ecx
  73         movl    %edx, VAL1(%esp)
  74
  75         /* Store %ecx in the variable pointed to by the second argument,
  76            get the factor from the stack and return.  */
  77 1:      movl    EXPP(%esp), %eax
  78         fldl    VAL0(%esp)
  79         movl    %ecx, (%eax)
  80
  81         ret
  82 END (__frexp)
  83 weak_alias (__frexp, frexp)