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/*---------------------------------------------------------------------------+

 |  fpu_aux.c                                                                |

 |                                                                           |

 | Code to implement some of the FPU auxiliary instructions.                 |

 |                                                                           |

 | Copyright (C) 1992,1993,1994                                              |

 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |

 |                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au    |

 |                                                                           |

 |                                                                           |

 +---------------------------------------------------------------------------*/

#include "fpu_system.h"

#include "exception.h"

#include "fpu_emu.h"

#include "status_w.h"

#include "control_w.h"

static void fnop(void)

{

}

void fclex(void)

{

  partial_status &= ~(SW_Backward|SW_Summary|SW_Stack_Fault|SW_Precision|

                   SW_Underflow|SW_Overflow|SW_Zero_Div|SW_Denorm_Op|

                   SW_Invalid);

  no_ip_update = 1;

}

/* Needs to be externally visible */

void finit()

{

  int r;

  control_word = 0x037f;

  partial_status = 0;

  top = 0;            /* We don't keep top in the status word internally. */

  for (r = 0; r < 8; r++)

    {

      regs[r].tag = TW_Empty;

    }

  /* The behaviour is different to that detailed in

     Section 15.1.6 of the Intel manual */

  operand_address.offset = 0;

  operand_address.selector = 0;

  instruction_address.offset = 0;

  instruction_address.selector = 0;

  instruction_address.opcode = 0;

  no_ip_update = 1;

}

/*

 * These are nops on the i387..

 */

#define feni fnop

#define fdisi fnop

#define fsetpm fnop

static FUNC const finit_table[] = {

  feni, fdisi, fclex, finit,

  fsetpm, FPU_illegal, FPU_illegal, FPU_illegal

};

void finit_()

{

  (finit_table[FPU_rm])();

}

static void fstsw_ax(void)

{

  *(short *) &FPU_EAX = status_word();

  no_ip_update = 1;

}

static FUNC const fstsw_table[] = {

  fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,

  FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal

};

void fstsw_()

{

  (fstsw_table[FPU_rm])();

}

static FUNC const fp_nop_table[] = {

  fnop, FPU_illegal, FPU_illegal, FPU_illegal,

  FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal

};

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 & CW_Invalid )

        {

          /* The masked response */

          stack_underflow();

        }

      else

        EXCEPTION(EX_StackUnder);

    }

}

void fxch_i()

{

  /* fxch st(i) */

  FPU_REG t;

  register FPU_REG *sti_ptr = &st(FPU_rm), *st0_ptr = &st(0);

  if ( st0_ptr->tag == TW_Empty )

    {

      if ( sti_ptr->tag == TW_Empty )

        {

          stack_underflow();

          stack_underflow_i(FPU_rm);

          return;

        }

      if ( control_word & CW_Invalid )

        reg_move(sti_ptr, st0_ptr);   /* Masked response */

      stack_underflow_i(FPU_rm);

      return;

    }

  if ( sti_ptr->tag == TW_Empty )

    {

      if ( control_word & CW_Invalid )

        reg_move(st0_ptr, sti_ptr);   /* Masked response */

      stack_underflow();

      return;

    }

  clear_C1();

  reg_move(st0_ptr, &t);

  reg_move(sti_ptr, 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(&st(0), &st(FPU_rm));

}

void fstp_i()

{

  /* fstp st(i) */

  reg_move(&st(0), &st(FPU_rm));

  pop();

}