/*
 *  fpu_aux.c
 *
 * Code to implement some of the FPU auxiliary 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"



void fclex(void)
{
  status_word &= ~(SW_Backward|SW_Summary|SW_Stack_Fault|SW_Precision|
		   SW_Underflow|SW_Overflow|SW_Zero_Div|SW_Denorm_Op|
		   SW_Invalid);
  FPU_entry_eip = ip_offset;               /* We want no net effect */
}

/* Needs to be externally visible */
void finit()
{
  int r;
  control_word = 0x037f;
  status_word = 0;
  top = 0;            /* We don't keep top in the status word internally. */
  for (r = 0; r < 8; r++)
    {
      regs[r].tag = TW_Empty;
    }
  FPU_entry_eip = ip_offset = 0;
}

static FUNC finit_table[] = {
  Un_impl, Un_impl, fclex, finit, Un_impl, Un_impl, Un_impl, Un_impl
};

void finit_()
{
  (finit_table[FPU_rm])();
}


static void fstsw_ax(void)
{

  status_word &= ~SW_Top;
  status_word |= (top&7) << SW_Top_Shift;

  *(short *) &FPU_EAX = status_word;

}

static FUNC fstsw_table[] = {
  fstsw_ax, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl
};

void fstsw_()
{
  (fstsw_table[FPU_rm])();
}



static void fnop(void)
{
}

FUNC fp_nop_table[] = {
  fnop, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl, Un_impl
};

void fp_nop()
{
  (fp_nop_table[FPU_rm])();
}


void fld_i_()
{
  FPU_REG *st_new_ptr;

  if ( STACK_OVERFLOW )
    { stack_overflow(); return; }

  /* fld st(i) */
  if ( NOT_EMPTY(FPU_rm) )
    { reg_move(&st(FPU_rm), st_new_ptr); push(); }
  else
    {
      if ( control_word & EX_Invalid )
	{
	  /* The masked response */
	  push();
	  stack_underflow();
	}
      else
	EXCEPTION(EX_StackUnder);
    }

}


void fxch_i()
{
  /* fxch st(i) */
  FPU_REG t;
  register FPU_REG *sti_ptr = &st(FPU_rm);

  if ( FPU_st0_tag == TW_Empty )
    {
      if ( sti_ptr->tag == TW_Empty )
	{
	  stack_underflow();
	  stack_underflow_i(FPU_rm);
	  return;
	}
      reg_move(sti_ptr, FPU_st0_ptr);
      stack_underflow_i(FPU_rm);
      return;
    }
  if ( sti_ptr->tag == TW_Empty )
    {
      reg_move(FPU_st0_ptr, sti_ptr);
      stack_underflow();
      return;
    }
  reg_move(FPU_st0_ptr, &t);
  reg_move(sti_ptr, FPU_st0_ptr);
  reg_move(&t, sti_ptr);
}


void ffree_()
{
  /* ffree st(i) */
  st(FPU_rm).tag = TW_Empty;
}


void ffreep()
{
  /* ffree st(i) + pop - unofficial code */
  st(FPU_rm).tag = TW_Empty;
  pop();
}


void fst_i_()
{
  /* fst st(i) */
  reg_move(FPU_st0_ptr, &st(FPU_rm));
}


void fstp_i()
{
  /* fstp st(i) */
  reg_move(FPU_st0_ptr, &st(FPU_rm));
  pop();
}

