kernel/FPU-emu/reg

/* */
This source file includes following definitions.
reg_mul
   1 /*---------------------------------------------------------------------------+
   2  |  reg_mul.c                                                                |
   3  |                                                                           |
   4  | Multiply one FPU_REG by another, put the result in a destination FPU_REG. |
   5  |                                                                           |
   6  | Copyright (C) 1992    W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   7  |                       Australia.  E-mail apm233m@vaxc.cc.monash.edu.au    |
   8  |                                                                           |
   9  |                                                                           |
  10  +---------------------------------------------------------------------------*/
  11 
  12 /*---------------------------------------------------------------------------+
  13  | The destination may be any FPU_REG, including one of the source FPU_REGs. |
  14  +---------------------------------------------------------------------------*/
  15 
  16 #include "exception.h"
  17 #include "reg_constant.h"
  18 #include "fpu_emu.h"
  19 
  20 
  21 /* This routine must be called with non-empty registers */
  22 void reg_mul(FPU_REG *a, FPU_REG *b, FPU_REG *dest)
     /*  */
  23 {
  24   if (!(a->tag | b->tag))
  25     {
  26       /* This should be the most common case */
  27       reg_u_mul(a, b, dest);
  28       dest->exp += - EXP_BIAS + 1;
  29       dest->sign = (a->sign ^ b->sign);
  30       dest->tag = TW_Valid;
  31       if ( dest->exp <= EXP_UNDER )
  32         { arith_underflow(FPU_st0_ptr); }
  33       else if ( dest->exp >= EXP_OVER )
  34         { arith_overflow(FPU_st0_ptr); }
  35       return;
  36     }
  37   else if ((a->tag <= TW_Zero) && (b->tag <= TW_Zero))
  38     {
  39       /* Must have either both arguments == zero, or
  40          one valid and the other zero.
  41          The result is therefore zero. */
  42       reg_move(&CONST_Z, dest);
  43     }
  44   else if ((a->tag <= TW_Denormal) && (b->tag <= TW_Denormal))
  45     {
  46       /* One or both arguments are de-normalized */
  47       /* Internal de-normalized numbers are not supported yet */
  48       EXCEPTION(EX_INTERNAL|0x105);
  49       reg_move(&CONST_Z, dest);
  50     }
  51   else
  52     {
  53       /* Must have infinities, NaNs, etc */
  54       if ( (a->tag == TW_NaN) || (b->tag == TW_NaN) )
  55         { real_2op_NaN(a, b, dest); return; }
  56       else if (a->tag == TW_Infinity)
  57         {
  58           if (b->tag == TW_Zero)
  59             { arith_invalid(dest); return; }
  60           else
  61             {
  62               reg_move(a, dest);
  63               dest->sign = a->sign == b->sign ? SIGN_POS : SIGN_NEG;
  64             }
  65         }
  66       else if (b->tag == TW_Infinity)
  67         {
  68           if (a->tag == TW_Zero)
  69             { arith_invalid(dest); return; }
  70           else
  71             {
  72               reg_move(b, dest);
  73               dest->sign = a->sign == b->sign ? SIGN_POS : SIGN_NEG;
  74             }
  75         }
  76 #ifdef PARANOID
  77       else
  78         {
  79           EXCEPTION(EX_INTERNAL|0x102);
  80         }
  81 #endif PARANOID
  82       dest->sign = (a->sign ^ b->sign);
  83     }
  84 }
/* */
root/kernel/FPU-emu/reg_mul.c

DEFINITIONS
