root/arch/x86/math-emu/shr_Xsig.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2         .file   "shr_Xsig.S"
   3 /*---------------------------------------------------------------------------+
   4  |  shr_Xsig.S                                                               |
   5  |                                                                           |
   6  | 12 byte right shift function                                              |
   7  |                                                                           |
   8  | Copyright (C) 1992,1994,1995                                              |
   9  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
  10  |                       Australia.  E-mail billm@jacobi.maths.monash.edu.au |
  11  |                                                                           |
  12  | Call from C as:                                                           |
  13  |   void shr_Xsig(Xsig *arg, unsigned nr)                                   |
  14  |                                                                           |
  15  |   Extended shift right function.                                          |
  16  |   Fastest for small shifts.                                               |
  17  |   Shifts the 12 byte quantity pointed to by the first arg (arg)           |
  18  |   right by the number of bits specified by the second arg (nr).           |
  19  |                                                                           |
  20  +---------------------------------------------------------------------------*/
  21 
  22 #include "fpu_emu.h"
  23 
  24 .text
  25 ENTRY(shr_Xsig)
  26         push    %ebp
  27         movl    %esp,%ebp
  28         pushl   %esi
  29         movl    PARAM2,%ecx
  30         movl    PARAM1,%esi
  31         cmpl    $32,%ecx        /* shrd only works for 0..31 bits */
  32         jnc     L_more_than_31
  33 
  34 /* less than 32 bits */
  35         pushl   %ebx
  36         movl    (%esi),%eax     /* lsl */
  37         movl    4(%esi),%ebx    /* midl */
  38         movl    8(%esi),%edx    /* msl */
  39         shrd    %cl,%ebx,%eax
  40         shrd    %cl,%edx,%ebx
  41         shr     %cl,%edx
  42         movl    %eax,(%esi)
  43         movl    %ebx,4(%esi)
  44         movl    %edx,8(%esi)
  45         popl    %ebx
  46         popl    %esi
  47         leave
  48         ret
  49 
  50 L_more_than_31:
  51         cmpl    $64,%ecx
  52         jnc     L_more_than_63
  53 
  54         subb    $32,%cl
  55         movl    4(%esi),%eax    /* midl */
  56         movl    8(%esi),%edx    /* msl */
  57         shrd    %cl,%edx,%eax
  58         shr     %cl,%edx
  59         movl    %eax,(%esi)
  60         movl    %edx,4(%esi)
  61         movl    $0,8(%esi)
  62         popl    %esi
  63         leave
  64         ret
  65 
  66 L_more_than_63:
  67         cmpl    $96,%ecx
  68         jnc     L_more_than_95
  69 
  70         subb    $64,%cl
  71         movl    8(%esi),%eax    /* msl */
  72         shr     %cl,%eax
  73         xorl    %edx,%edx
  74         movl    %eax,(%esi)
  75         movl    %edx,4(%esi)
  76         movl    %edx,8(%esi)
  77         popl    %esi
  78         leave
  79         ret
  80 
  81 L_more_than_95:
  82         xorl    %eax,%eax
  83         movl    %eax,(%esi)
  84         movl    %eax,4(%esi)
  85         movl    %eax,8(%esi)
  86         popl    %esi
  87         leave
  88         ret
  89 ENDPROC(shr_Xsig)