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[/] [or1k_old/] [trunk/] [rc203soc/] [sw/] [uClinux/] [arch/] [i386/] [math-emu/] [reg_mul.c] - Blame information for rev 1782

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Line No. Rev Author Line
1 1623 jcastillo
/*---------------------------------------------------------------------------+
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 |  reg_mul.c                                                                |
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 |                                                                           |
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 | Multiply one FPU_REG by another, put the result in a destination FPU_REG. |
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 |                                                                           |
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 | Copyright (C) 1992,1993                                                   |
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 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
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 |                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au    |
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 |                                                                           |
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 |                                                                           |
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 +---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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 | The destination may be any FPU_REG, including one of the source FPU_REGs. |
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 +---------------------------------------------------------------------------*/
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#include "exception.h"
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#include "reg_constant.h"
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#include "fpu_emu.h"
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#include "fpu_system.h"
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/* This routine must be called with non-empty source registers */
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int reg_mul(FPU_REG const *a, FPU_REG const *b,
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            FPU_REG *dest, unsigned int control_w)
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{
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  char saved_sign = dest->sign;
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  char sign = (a->sign ^ b->sign);
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  if (!(a->tag | b->tag))
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    {
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      /* Both regs Valid, this should be the most common case. */
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      dest->sign = sign;
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      if ( reg_u_mul(a, b, dest, control_w) )
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        {
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          dest->sign = saved_sign;
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          return 1;
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        }
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      return 0;
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    }
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  else if ((a->tag <= TW_Zero) && (b->tag <= TW_Zero))
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    {
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#ifdef DENORM_OPERAND
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      if ( ((b->tag == TW_Valid) && (b->exp <= EXP_UNDER)) ||
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          ((a->tag == TW_Valid) && (a->exp <= EXP_UNDER)) )
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        {
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          if ( denormal_operand() ) return 1;
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        }
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#endif DENORM_OPERAND
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      /* Must have either both arguments == zero, or
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         one valid and the other zero.
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         The result is therefore zero. */
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      reg_move(&CONST_Z, dest);
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      /* The 80486 book says that the answer is +0, but a real
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         80486 behaves this way.
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         IEEE-754 apparently says it should be this way. */
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      dest->sign = sign;
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      return 0;
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    }
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  else
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    {
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      /* Must have infinities, NaNs, etc */
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      if ( (a->tag == TW_NaN) || (b->tag == TW_NaN) )
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        { return real_2op_NaN(a, b, dest); }
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      else if (a->tag == TW_Infinity)
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        {
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          if (b->tag == TW_Zero)
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            { return arith_invalid(dest); }  /* Zero*Infinity is invalid */
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          else
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            {
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#ifdef DENORM_OPERAND
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              if ( (b->tag == TW_Valid) && (b->exp <= EXP_UNDER) &&
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                  denormal_operand() )
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                return 1;
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#endif DENORM_OPERAND
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              reg_move(a, dest);
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              dest->sign = sign;
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            }
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          return 0;
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        }
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      else if (b->tag == TW_Infinity)
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        {
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          if (a->tag == TW_Zero)
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            { return arith_invalid(dest); }  /* Zero*Infinity is invalid */
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          else
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            {
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#ifdef DENORM_OPERAND
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              if ( (a->tag == TW_Valid) && (a->exp <= EXP_UNDER) &&
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                  denormal_operand() )
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                return 1;
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#endif DENORM_OPERAND
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              reg_move(b, dest);
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              dest->sign = sign;
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            }
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          return 0;
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        }
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#ifdef PARANOID
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      else
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        {
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          EXCEPTION(EX_INTERNAL|0x102);
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          return 1;
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        }
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#endif PARANOID
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    }
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}

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