arch/i386/math-emu/round

/* */
   1 /*---------------------------------------------------------------------------+
   2  |  round_Xsig.S                                                             |
   3  |                                                                           |
   4  | Copyright (C) 1992,1993,1994                                              |
   5  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   6  |                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au    |
   7  |                                                                           |
   8  | Normalize and round a 12 byte quantity.                                   |
   9  | Call from C as:                                                           |
  10  |   int round_Xsig(Xsig *n)                                                 |
  11  |                                                                           |
  12  | Normalize a 12 byte quantity.                                             |
  13  | Call from C as:                                                           |
  14  |   int norm_Xsig(Xsig *n)                                                  |
  15  |                                                                           |
  16  | Each function returns the size of the shift (nr of bits).                 |
  17  |                                                                           |
  18  +---------------------------------------------------------------------------*/
  19         .file   "round_Xsig.S"
  20 
  21 #include "fpu_asm.h"
  22 
  23 
  24 .text
  25 ENTRY(round_Xsig)
  26         pushl   %ebp
  27         movl    %esp,%ebp
  28         pushl   %ebx            /* Reserve some space */
  29         pushl   %ebx
  30         pushl   %esi
  31 
  32         movl    PARAM1,%esi
  33 
  34         movl    8(%esi),%edx
  35         movl    4(%esi),%ebx
  36         movl    (%esi),%eax
  37 
  38         movl    $0,-4(%ebp)
  39 
  40         orl     %edx,%edx       /* ms bits */
  41         js      L_round         /* Already normalized */
  42         jnz     L_shift_1       /* Shift left 1 - 31 bits */
  43 
  44         movl    %ebx,%edx
  45         movl    %eax,%ebx
  46         xorl    %eax,%eax
  47         movl    $-32,-4(%ebp)
  48 
  49 /* We need to shift left by 1 - 31 bits */
  50 L_shift_1:
  51         bsrl    %edx,%ecx       /* get the required shift in %ecx */
  52         subl    $31,%ecx
  53         negl    %ecx
  54         subl    %ecx,-4(%ebp)
  55         shld    %cl,%ebx,%edx
  56         shld    %cl,%eax,%ebx
  57         shl     %cl,%eax
  58 
  59 L_round:
  60         testl   $0x80000000,%eax
  61         jz      L_exit
  62 
  63         addl    $1,%ebx
  64         adcl    $0,%edx
  65         jnz     L_exit
  66 
  67         movl    $0x80000000,%edx
  68         incl    -4(%ebp)
  69 
  70 L_exit:
  71         movl    %edx,8(%esi)
  72         movl    %ebx,4(%esi)
  73         movl    %eax,(%esi)
  74 
  75         movl    -4(%ebp),%eax
  76 
  77         popl    %esi
  78         popl    %ebx
  79         leave
  80         ret
  81 
  82 
  83 
  84 
  85 ENTRY(norm_Xsig)
  86         pushl   %ebp
  87         movl    %esp,%ebp
  88         pushl   %ebx            /* Reserve some space */
  89         pushl   %ebx
  90         pushl   %esi
  91 
  92         movl    PARAM1,%esi
  93 
  94         movl    8(%esi),%edx
  95         movl    4(%esi),%ebx
  96         movl    (%esi),%eax
  97 
  98         movl    $0,-4(%ebp)
  99 
 100         orl     %edx,%edx       /* ms bits */
 101         js      L_n_exit                /* Already normalized */
 102         jnz     L_n_shift_1     /* Shift left 1 - 31 bits */
 103 
 104         movl    %ebx,%edx
 105         movl    %eax,%ebx
 106         xorl    %eax,%eax
 107         movl    $-32,-4(%ebp)
 108 
 109         orl     %edx,%edx       /* ms bits */
 110         js      L_n_exit        /* Normalized now */
 111         jnz     L_n_shift_1     /* Shift left 1 - 31 bits */
 112 
 113         movl    %ebx,%edx
 114         movl    %eax,%ebx
 115         xorl    %eax,%eax
 116         addl    $-32,-4(%ebp)
 117         jmp     L_n_exit        /* Might not be normalized,
 118                                    but shift no more. */
 119 
 120 /* We need to shift left by 1 - 31 bits */
 121 L_n_shift_1:
 122         bsrl    %edx,%ecx       /* get the required shift in %ecx */
 123         subl    $31,%ecx
 124         negl    %ecx
 125         subl    %ecx,-4(%ebp)
 126         shld    %cl,%ebx,%edx
 127         shld    %cl,%eax,%ebx
 128         shl     %cl,%eax
 129 
 130 L_n_exit:
 131         movl    %edx,8(%esi)
 132         movl    %ebx,4(%esi)
 133         movl    %eax,(%esi)
 134 
 135         movl    -4(%ebp),%eax
 136 
 137         popl    %esi
 138         popl    %ebx
 139         leave
 140         ret
 141
/* */
root/arch/i386/math-emu/round_Xsig.S
