arch/x86/math-emu/round_Xsig.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*---------------------------------------------------------------------------+
   3  |  round_Xsig.S                                                             |
   4  |                                                                           |
   5  | Copyright (C) 1992,1993,1994,1995                                         |
   6  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   7  |                       Australia.  E-mail billm@jacobi.maths.monash.edu.au |
   8  |                                                                           |
   9  | Normalize and round a 12 byte quantity.                                   |
  10  | Call from C as:                                                           |
  11  |   int round_Xsig(Xsig *n)                                                 |
  12  |                                                                           |
  13  | Normalize a 12 byte quantity.                                             |
  14  | Call from C as:                                                           |
  15  |   int norm_Xsig(Xsig *n)                                                  |
  16  |                                                                           |
  17  | Each function returns the size of the shift (nr of bits).                 |
  18  |                                                                           |
  19  +---------------------------------------------------------------------------*/
  20         .file   "round_Xsig.S"
  21
  22 #include "fpu_emu.h"
  23
  24
  25 .text
  26 ENTRY(round_Xsig)
  27         pushl   %ebp
  28         movl    %esp,%ebp
  29         pushl   %ebx            /* Reserve some space */
  30         pushl   %ebx
  31         pushl   %esi
  32
  33         movl    PARAM1,%esi
  34
  35         movl    8(%esi),%edx
  36         movl    4(%esi),%ebx
  37         movl    (%esi),%eax
  38
  39         movl    $0,-4(%ebp)
  40
  41         orl     %edx,%edx       /* ms bits */
  42         js      L_round         /* Already normalized */
  43         jnz     L_shift_1       /* Shift left 1 - 31 bits */
  44
  45         movl    %ebx,%edx
  46         movl    %eax,%ebx
  47         xorl    %eax,%eax
  48         movl    $-32,-4(%ebp)
  49
  50 /* We need to shift left by 1 - 31 bits */
  51 L_shift_1:
  52         bsrl    %edx,%ecx       /* get the required shift in %ecx */
  53         subl    $31,%ecx
  54         negl    %ecx
  55         subl    %ecx,-4(%ebp)
  56         shld    %cl,%ebx,%edx
  57         shld    %cl,%eax,%ebx
  58         shl     %cl,%eax
  59
  60 L_round:
  61         testl   $0x80000000,%eax
  62         jz      L_exit
  63
  64         addl    $1,%ebx
  65         adcl    $0,%edx
  66         jnz     L_exit
  67
  68         movl    $0x80000000,%edx
  69         incl    -4(%ebp)
  70
  71 L_exit:
  72         movl    %edx,8(%esi)
  73         movl    %ebx,4(%esi)
  74         movl    %eax,(%esi)
  75
  76         movl    -4(%ebp),%eax
  77
  78         popl    %esi
  79         popl    %ebx
  80         leave
  81         ret
  82 ENDPROC(round_Xsig)
  83
  84
  85
  86 ENTRY(norm_Xsig)
  87         pushl   %ebp
  88         movl    %esp,%ebp
  89         pushl   %ebx            /* Reserve some space */
  90         pushl   %ebx
  91         pushl   %esi
  92
  93         movl    PARAM1,%esi
  94
  95         movl    8(%esi),%edx
  96         movl    4(%esi),%ebx
  97         movl    (%esi),%eax
  98
  99         movl    $0,-4(%ebp)
 100
 101         orl     %edx,%edx       /* ms bits */
 102         js      L_n_exit                /* Already normalized */
 103         jnz     L_n_shift_1     /* Shift left 1 - 31 bits */
 104
 105         movl    %ebx,%edx
 106         movl    %eax,%ebx
 107         xorl    %eax,%eax
 108         movl    $-32,-4(%ebp)
 109
 110         orl     %edx,%edx       /* ms bits */
 111         js      L_n_exit        /* Normalized now */
 112         jnz     L_n_shift_1     /* Shift left 1 - 31 bits */
 113
 114         movl    %ebx,%edx
 115         movl    %eax,%ebx
 116         xorl    %eax,%eax
 117         addl    $-32,-4(%ebp)
 118         jmp     L_n_exit        /* Might not be normalized,
 119                                    but shift no more. */
 120
 121 /* We need to shift left by 1 - 31 bits */
 122 L_n_shift_1:
 123         bsrl    %edx,%ecx       /* get the required shift in %ecx */
 124         subl    $31,%ecx
 125         negl    %ecx
 126         subl    %ecx,-4(%ebp)
 127         shld    %cl,%ebx,%edx
 128         shld    %cl,%eax,%ebx
 129         shl     %cl,%eax
 130
 131 L_n_exit:
 132         movl    %edx,8(%esi)
 133         movl    %ebx,4(%esi)
 134         movl    %eax,(%esi)
 135
 136         movl    -4(%ebp),%eax
 137
 138         popl    %esi
 139         popl    %ebx
 140         leave
 141         ret
 142 ENDPROC(norm_Xsig)