Copyright changes per the author.

[unix-history] / sys / gnu / fpemul / fpu_etc.c

/*
*  fpu_etc.c
*
* Implement a few FPU instructions.
*
*
* Copyright (C) 1992,1993,1994
*                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
*                       Australia.  E-mail   billm@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, FreeBSD and NetBSD operating systems. 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.
*
*
* The purpose of this copyright, based upon the Berkeley copyright, is to
* ensure that the covered software remains freely available to everyone.
*
* The software (with necessary differences) is also available, but under
* the terms of the GNU copyleft, for the Linux operating system and for
* the djgpp ms-dos extender.
*
* W. Metzenthen   June 1994.
*
*
*    $Id: fpu_etc.c,v 1.2 1994/04/29 21:16:22 gclarkii Exp $
*
*/

#include "param.h"
#include "proc.h"
#include "machine/cpu.h"
#include "machine/pcb.h"

#include "fpu_emu.h"
#include "fpu_system.h"
#include "exception.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]) ();
}