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

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
C | 128 lines | 83 code | 11 blank | 34 comment | 31 complexity | c9d7864cc231654ed4ce5cf0627aece7 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/* IEEE754 floating point arithmetic
  2 * single precision
  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 "ieee754sp.h"
 30
 31int ieee754sp_tint(ieee754sp x)
 32{
 33	COMPXSP;
 34
 35	CLEARCX;
 36
 37	EXPLODEXSP;
 38	FLUSHXSP;
 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(), "sp_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		/* look for valid corner case */
 54		if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
 55			return -0x80000000;
 56		/* Set invalid. We will only use overflow for floating
 57		   point overflow */
 58		SETCX(IEEE754_INVALID_OPERATION);
 59		return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
 60	}
 61	/* oh gawd */
 62	if (xe > SP_MBITS) {
 63		xm <<= xe - SP_MBITS;
 64	} else {
 65		u32 residue;
 66		int round;
 67		int sticky;
 68		int odd;
 69
 70		if (xe < -1) {
 71			residue = xm;
 72			round = 0;
 73			sticky = residue != 0;
 74			xm = 0;
 75		}
 76		else {
 77			/* Shifting a u32 32 times does not work,
 78			* so we do it in two steps. Be aware that xe
 79			* may be -1 */
 80			residue = xm << (xe + 1);
 81			residue <<= 31 - SP_MBITS;
 82			round = (residue >> 31) != 0;
 83			sticky = (residue << 1) != 0;
 84			xm >>= SP_MBITS - xe;
 85		}
 86		odd = (xm & 0x1) != 0x0;
 87		switch (ieee754_csr.rm) {
 88		case IEEE754_RN:
 89			if (round && (sticky || odd))
 90				xm++;
 91			break;
 92		case IEEE754_RZ:
 93			break;
 94		case IEEE754_RU:	/* toward +Infinity */
 95			if ((round || sticky) && !xs)
 96				xm++;
 97			break;
 98		case IEEE754_RD:	/* toward -Infinity */
 99			if ((round || sticky) && xs)
100				xm++;
101			break;
102		}
103		if ((xm >> 31) != 0) {
104			/* This can happen after rounding */
105			SETCX(IEEE754_INVALID_OPERATION);
106			return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
107		}
108		if (round || sticky)
109			SETCX(IEEE754_INEXACT);
110	}
111	if (xs)
112		return -xm;
113	else
114		return xm;
115}
116
117
118unsigned int ieee754sp_tuns(ieee754sp x)
119{
120	ieee754sp hb = ieee754sp_1e31();
121
122	/* what if x < 0 ?? */
123	if (ieee754sp_lt(x, hb))
124		return (unsigned) ieee754sp_tint(x);
125
126	return (unsigned) ieee754sp_tint(ieee754sp_sub(x, hb)) |
127	    ((unsigned) 1 << 31);
128}