61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
/* $NetBSD: ieee_dze.c,v 1.1 1996/04/04 06:36:16 phil Exp $ */
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/*
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* IEEE floating point support for NS32081 and NS32381 fpus.
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* Copyright (c) 1995 Ian Dall
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* IAN DALL ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" CONDITION.
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* IAN DALL DISCLAIMS ANY LIABILITY OF ANY KIND FOR ANY DAMAGES
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* WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*/
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/*
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* File: ieee_dze.c
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* Author: Ian Dall
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* Date: November 1995
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*
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* Handle divide by zero, generating +-Infty as required.
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*
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* HISTORY
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* 14-Dec-95 Ian Dall (Ian.Dall@dsto.defence.gov.au)
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* First release.
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*
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*/
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#include "ieee_internal.h"
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int ieee_dze(struct operand *op1, struct operand *op2,
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struct operand *f0_op, int xopcode, state *state)
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{
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int user_trap = FPC_TT_NONE;
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unsigned int fsr = state->FSR;
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DP(1, "Divide by zero trap: xopcode = 0x%x\n", xopcode);
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fsr |= FPC_DZF;
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if (fsr & FPC_DZE) {
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/* Users trap handler will fix it */
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user_trap = FPC_TT_DIV0;
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}
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else {
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/* Set dest to + or - infinity ? */
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int sign1 = op2->data.d_bits.sign;
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int sign2 = op1->data.d_bits.sign;
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op2->data = infty;
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op2->data.d_bits.sign = sign1 ^ sign2;
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switch(xopcode) {
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case LOGBF:
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/* logb(0) gives a divide by zero exception according to ieee.
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* No idea if the logbf instruction conforms, but just in case...
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*/
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op2->data.d_bits.sign = 1;
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}
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}
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state->FSR = fsr;
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return user_trap;
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}
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