/*
 *  fpu_etc.c
 *
 * Implement a few FPU instructions.
 *
 *
 * Copyright (C) 1992, 1993  W. Metzenthen, 22 Parker St, Ormond,
 *                           Vic 3163, Australia.
 *                           E-mail apm233m@vaxc.cc.monash.edu.au
 * All rights reserved.
 *
 * This copyright notice covers the redistribution and use of the
 * FPU emulator developed by W. Metzenthen. It covers only its use
 * in the 386BSD operating system. Any other use is not permitted
 * under this copyright.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must include information specifying
 *    that source code for the emulator is freely available and include
 *    either:
 *      a) an offer to provide the source code for a nominal distribution
 *         fee, or
 *      b) list at least two alternative methods whereby the source
 *         can be obtained, e.g. a publically accessible bulletin board
 *         and an anonymous ftp site from which the software can be
 *         downloaded.
 * 3. All advertising materials specifically mentioning features or use of
 *    this emulator must acknowledge that it was developed by W. Metzenthen.
 * 4. The name of W. Metzenthen may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifdef __386BSD__
#include "sys/param.h"
#include "sys/user.h"
/*#include "sys/signal.h"*/
/*#include "sys/errno.h"*/
#include "systm.h"
#include "proc.h"
#include "machine/cpu.h"
#include "prototypes.h"
#endif

#include "fpu_system.h"
#include "exception.h"
#include "fpu_emu.h"
#include "status_w.h"
#include "reg_constant.h"


static void fchs(void)
{
  if ( NOT_EMPTY_0 )
    {
      FPU_st0_ptr->sign ^= SIGN_POS^SIGN_NEG;
      status_word &= ~SW_C1;
    }
  else
    stack_underflow();
}

static void fabs(void)
{
  if ( FPU_st0_tag ^ TW_Empty )
    {
      FPU_st0_ptr->sign = SIGN_POS;
      status_word &= ~SW_C1;
    }
  else
    stack_underflow();
}


static void ftst_(void)
{
  switch (FPU_st0_tag)
    {
    case TW_Zero:
      setcc(SW_C3);
      break;
    case TW_Valid:

#ifdef DENORM_OPERAND
      if ( (FPU_st0_ptr->exp <= EXP_UNDER) && (denormal_operand()) )
	return;
#endif DENORM_OPERAND

      if (FPU_st0_ptr->sign == SIGN_POS)
        setcc(0);
      else
        setcc(SW_C0);
      break;
    case TW_NaN:
      setcc(SW_C0|SW_C2|SW_C3);   /* Operand is not comparable */ 
      EXCEPTION(EX_Invalid);
      break;
    case TW_Infinity:
      if (FPU_st0_ptr->sign == SIGN_POS)
        setcc(0);
      else
        setcc(SW_C0);
      EXCEPTION(EX_Invalid);
      break;
    case TW_Empty:
      setcc(SW_C0|SW_C2|SW_C3);
      EXCEPTION(EX_StackUnder);
      break;
    default:
      setcc(SW_C0|SW_C2|SW_C3);   /* Operand is not comparable */ 
      EXCEPTION(EX_INTERNAL|0x14);
      break;
    }
}

static void fxam(void)
{
  int c=0;
  switch (FPU_st0_tag)
    {
    case TW_Empty:
      c = SW_C3|SW_C0;
      break;
    case TW_Zero:
      c = SW_C3;
      break;
    case TW_Valid:
      /* This will need to be changed if TW_Denormal is ever used. */
      if ( FPU_st0_ptr->exp <= EXP_UNDER )
        c = SW_C2|SW_C3;  /* Denormal */
      else
        c = SW_C3;
      break;
    case TW_NaN:
      c = SW_C0;
      break;
    case TW_Infinity:
      c = SW_C2|SW_C0;
      break;
    }
  if (FPU_st0_ptr->sign == SIGN_NEG)
    c |= SW_C1;
  setcc(c);
}

static FUNC fp_etc_table[] = {
  fchs, fabs, Un_impl, Un_impl, ftst_, fxam, Un_impl, Un_impl
};

void fp_etc()
{
  (fp_etc_table[FPU_rm])();
}
