sysdeps/i386/fpu/s_frexpf.S

   1 /* ix87 specific frexp implementation for float.
   2    Copyright (C) 1997-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <machine/asm.h>
  20 #include <libm-alias-float.h>
  21
  22         .section .rodata
  23
  24         .align ALIGNARG(4)
  25         .type two25,@object
  26 two25:  .byte 0, 0, 0, 0x4c
  27         ASM_SIZE_DIRECTIVE(two25)
  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 VAL     PARMS
  37 #define EXPP    VAL+4
  38
  39         .text
  40 ENTRY (__frexpf)
  41
  42         movl    VAL(%esp), %eax
  43         xorl    %ecx, %ecx
  44         movl    %eax, %edx
  45         andl    $0x7fffffff, %eax
  46         jz      1f
  47         cmpl    $0x7f800000, %eax
  48         jae     1f
  49
  50         cmpl    $0x00800000, %eax
  51         jae     2f
  52
  53         flds    VAL(%esp)
  54 #ifdef  PIC
  55         LOAD_PIC_REG (dx)
  56 #endif
  57         fmuls   MO(two25)
  58         movl    $-25, %ecx
  59         fstps   VAL(%esp)
  60         fwait
  61         movl    VAL(%esp), %eax
  62         movl    %eax, %edx
  63         andl    $0x7fffffff, %eax
  64
  65 2:      shrl    $23, %eax
  66         andl    $0x807fffff, %edx
  67         subl    $126, %eax
  68         orl     $0x3f000000, %edx
  69         addl    %eax, %ecx
  70         movl    %edx, VAL(%esp)
  71
  72         /* Store %ecx in the variable pointed to by the second argument,
  73            get the factor from the stack and return.  */
  74 1:      movl    EXPP(%esp), %eax
  75         flds    VAL(%esp)
  76         movl    %ecx, (%eax)
  77
  78         ret
  79 END (__frexpf)
  80 libm_alias_float (__frexp, frexp)