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/arch/mips/math-emu/dp_tint.c

https://bitbucket.org/evzijst/gittest
C | 124 lines | 80 code | 11 blank | 33 comment | 31 complexity | 4589d05732877205b37ecaaba21815b5 MD5 | raw file
  1/* IEEE754 floating point arithmetic
  2 * double precision: common utilities
  3 */
  4/*
  5 * MIPS floating point support
  6 * Copyright (C) 1994-2000 Algorithmics Ltd.
  7 * http://www.algor.co.uk
  8 *
  9 * ########################################################################
 10 *
 11 *  This program is free software; you can distribute it and/or modify it
 12 *  under the terms of the GNU General Public License (Version 2) as
 13 *  published by the Free Software Foundation.
 14 *
 15 *  This program is distributed in the hope it will be useful, but WITHOUT
 16 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 17 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 18 *  for more details.
 19 *
 20 *  You should have received a copy of the GNU General Public License along
 21 *  with this program; if not, write to the Free Software Foundation, Inc.,
 22 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 23 *
 24 * ########################################################################
 25 */
 26
 27
 28#include <linux/kernel.h>
 29#include "ieee754dp.h"
 30
 31int ieee754dp_tint(ieee754dp x)
 32{
 33	COMPXDP;
 34
 35	CLEARCX;
 36
 37	EXPLODEXDP;
 38	FLUSHXDP;
 39
 40	switch (xc) {
 41	case IEEE754_CLASS_SNAN:
 42	case IEEE754_CLASS_QNAN:
 43	case IEEE754_CLASS_INF:
 44		SETCX(IEEE754_INVALID_OPERATION);
 45		return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
 46	case IEEE754_CLASS_ZERO:
 47		return 0;
 48	case IEEE754_CLASS_DNORM:
 49	case IEEE754_CLASS_NORM:
 50		break;
 51	}
 52	if (xe > 31) {
 53		/* Set invalid. We will only use overflow for floating
 54		   point overflow */
 55		SETCX(IEEE754_INVALID_OPERATION);
 56		return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
 57	}
 58	/* oh gawd */
 59	if (xe > DP_MBITS) {
 60		xm <<= xe - DP_MBITS;
 61	} else if (xe < DP_MBITS) {
 62		u64 residue;
 63		int round;
 64		int sticky;
 65		int odd;
 66
 67		if (xe < -1) {
 68			residue = xm;
 69			round = 0;
 70			sticky = residue != 0;
 71			xm = 0;
 72		}
 73		else {
 74			residue = xm << (64 - DP_MBITS + xe);
 75			round = (residue >> 63) != 0;
 76			sticky = (residue << 1) != 0;
 77			xm >>= DP_MBITS - xe;
 78		}
 79		/* Note: At this point upper 32 bits of xm are guaranteed
 80		   to be zero */
 81		odd = (xm & 0x1) != 0x0;
 82		switch (ieee754_csr.rm) {
 83		case IEEE754_RN:
 84			if (round && (sticky || odd))
 85				xm++;
 86			break;
 87		case IEEE754_RZ:
 88			break;
 89		case IEEE754_RU:	/* toward +Infinity */
 90			if ((round || sticky) && !xs)
 91				xm++;
 92			break;
 93		case IEEE754_RD:	/* toward -Infinity */
 94			if ((round || sticky) && xs)
 95				xm++;
 96			break;
 97		}
 98		/* look for valid corner case 0x80000000 */
 99		if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
100			/* This can happen after rounding */
101			SETCX(IEEE754_INVALID_OPERATION);
102			return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
103		}
104		if (round || sticky)
105			SETCX(IEEE754_INEXACT);
106	}
107	if (xs)
108		return -xm;
109	else
110		return xm;
111}
112
113
114unsigned int ieee754dp_tuns(ieee754dp x)
115{
116	ieee754dp hb = ieee754dp_1e31();
117
118	/* what if x < 0 ?? */
119	if (ieee754dp_lt(x, hb))
120		return (unsigned) ieee754dp_tint(x);
121
122	return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
123	    ((unsigned) 1 << 31);
124}