sysdeps/i386/fpu/s_frexpf.S

   1 /* ix87 specific frexp implementation for float.
   2    Copyright (C) 1997-2020 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <machine/asm.h>
  21 #include <libm-alias-float.h>
  22
  23         .section .rodata
  24
  25         .align ALIGNARG(4)
  26         .type two25,@object
  27 two25:  .byte 0, 0, 0, 0x4c
  28         ASM_SIZE_DIRECTIVE(two25)
  29
  30 #ifdef PIC
  31 #define MO(op) op##@GOTOFF(%edx)
  32 #else
  33 #define MO(op) op
  34 #endif
  35
  36 #define PARMS   4               /* no space for saved regs */
  37 #define VAL     PARMS
  38 #define EXPP    VAL+4
  39
  40         .text
  41 ENTRY (__frexpf)
  42
  43         movl    VAL(%esp), %eax
  44         xorl    %ecx, %ecx
  45         movl    %eax, %edx
  46         andl    $0x7fffffff, %eax
  47         jz      1f
  48         cmpl    $0x7f800000, %eax
  49         jae     1f
  50
  51         cmpl    $0x00800000, %eax
  52         jae     2f
  53
  54         flds    VAL(%esp)
  55 #ifdef  PIC
  56         LOAD_PIC_REG (dx)
  57 #endif
  58         fmuls   MO(two25)
  59         movl    $-25, %ecx
  60         fstps   VAL(%esp)
  61         fwait
  62         movl    VAL(%esp), %eax
  63         movl    %eax, %edx
  64         andl    $0x7fffffff, %eax
  65
  66 2:      shrl    $23, %eax
  67         andl    $0x807fffff, %edx
  68         subl    $126, %eax
  69         orl     $0x3f000000, %edx
  70         addl    %eax, %ecx
  71         movl    %edx, VAL(%esp)
  72
  73         /* Store %ecx in the variable pointed to by the second argument,
  74            get the factor from the stack and return.  */
  75 1:      movl    EXPP(%esp), %eax
  76         flds    VAL(%esp)
  77         movl    %ecx, (%eax)
  78
  79         ret
  80 END (__frexpf)
  81 libm_alias_float (__frexp, frexp)