arch/x86/math-emu/shr_Xsig.S

   1         .file   "shr_Xsig.S"
   2 /*---------------------------------------------------------------------------+
   3  |  shr_Xsig.S                                                               |
   4  |                                                                           |
   5  | 12 byte right shift function                                              |
   6  |                                                                           |
   7  | Copyright (C) 1992,1994,1995                                              |
   8  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   9  |                       Australia.  E-mail billm@jacobi.maths.monash.edu.au |
  10  |                                                                           |
  11  | Call from C as:                                                           |
  12  |   void shr_Xsig(Xsig *arg, unsigned nr)                                   |
  13  |                                                                           |
  14  |   Extended shift right function.                                          |
  15  |   Fastest for small shifts.                                               |
  16  |   Shifts the 12 byte quantity pointed to by the first arg (arg)           |
  17  |   right by the number of bits specified by the second arg (nr).           |
  18  |                                                                           |
  19  +---------------------------------------------------------------------------*/
  20
  21 #include "fpu_emu.h"
  22
  23 .text
  24 ENTRY(shr_Xsig)
  25         push    %ebp
  26         movl    %esp,%ebp
  27         pushl   %esi
  28         movl    PARAM2,%ecx
  29         movl    PARAM1,%esi
  30         cmpl    $32,%ecx        /* shrd only works for 0..31 bits */
  31         jnc     L_more_than_31
  32
  33 /* less than 32 bits */
  34         pushl   %ebx
  35         movl    (%esi),%eax     /* lsl */
  36         movl    4(%esi),%ebx    /* midl */
  37         movl    8(%esi),%edx    /* msl */
  38         shrd    %cl,%ebx,%eax
  39         shrd    %cl,%edx,%ebx
  40         shr     %cl,%edx
  41         movl    %eax,(%esi)
  42         movl    %ebx,4(%esi)
  43         movl    %edx,8(%esi)
  44         popl    %ebx
  45         popl    %esi
  46         leave
  47         ret
  48
  49 L_more_than_31:
  50         cmpl    $64,%ecx
  51         jnc     L_more_than_63
  52
  53         subb    $32,%cl
  54         movl    4(%esi),%eax    /* midl */
  55         movl    8(%esi),%edx    /* msl */
  56         shrd    %cl,%edx,%eax
  57         shr     %cl,%edx
  58         movl    %eax,(%esi)
  59         movl    %edx,4(%esi)
  60         movl    $0,8(%esi)
  61         popl    %esi
  62         leave
  63         ret
  64
  65 L_more_than_63:
  66         cmpl    $96,%ecx
  67         jnc     L_more_than_95
  68
  69         subb    $64,%cl
  70         movl    8(%esi),%eax    /* msl */
  71         shr     %cl,%eax
  72         xorl    %edx,%edx
  73         movl    %eax,(%esi)
  74         movl    %edx,4(%esi)
  75         movl    %edx,8(%esi)
  76         popl    %esi
  77         leave
  78         ret
  79
  80 L_more_than_95:
  81         xorl    %eax,%eax
  82         movl    %eax,(%esi)
  83         movl    %eax,4(%esi)
  84         movl    %eax,8(%esi)
  85         popl    %esi
  86         leave
  87         ret