summaryrefslogtreecommitdiffstats
path: root/arch/parisc/math-emu/sfrem.c
blob: 3a1b7a34d87aa28062d31d60195a5d507324688f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * BEGIN_DESC
 *
 *  File:
 *	@(#)	pa/spmath/sfrem.c		$Revision: 1.1 $
 *
 *  Purpose:
 *	Single Precision Floating-point Remainder
 *
 *  External Interfaces:
 *	sgl_frem(srcptr1,srcptr2,dstptr,status)
 *
 *  Internal Interfaces:
 *
 *  Theory:
 *	<<please update with a overview of the operation of this file>>
 *
 * END_DESC
*/



#include "float.h"
#include "sgl_float.h"

/*
 *  Single Precision Floating-point Remainder
 */

int
sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
	  sgl_floating_point * dstptr, unsigned int *status)
{
	register unsigned int opnd1, opnd2, result;
	register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
	register boolean roundup = FALSE;

	opnd1 = *srcptr1;
	opnd2 = *srcptr2;
	/*
	 * check first operand for NaN's or infinity
	 */
	if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd1)) {
			if (Sgl_isnotnan(opnd2)) {
				/* invalid since first operand is infinity */
				if (Is_invalidtrap_enabled()) 
                                	return(INVALIDEXCEPTION);
                                Set_invalidflag();
                                Sgl_makequietnan(result);
				*dstptr = result;
				return(NOEXCEPTION);
			}
		}
		else {
                	/*
                 	 * is NaN; signaling or quiet?
                 	 */
                	if (Sgl_isone_signaling(opnd1)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd1);
                	}
			/* 
			 * is second operand a signaling NaN? 
			 */
			else if (Sgl_is_signalingnan(opnd2)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd2);
                		*dstptr = opnd2;
                		return(NOEXCEPTION);
			}
                	/*
                 	 * return quiet NaN
                 	 */
                	*dstptr = opnd1;
                	return(NOEXCEPTION);
		}
	} 
	/*
	 * check second operand for NaN's or infinity
	 */
	if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd2)) {
			/*
			 * return first operand
			 */
                	*dstptr = opnd1;
			return(NOEXCEPTION);
		}
                /*
                 * is NaN; signaling or quiet?
                 */
                if (Sgl_isone_signaling(opnd2)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        /* make NaN quiet */
                        Set_invalidflag();
                        Sgl_set_quiet(opnd2);
                }
                /*
                 * return quiet NaN
                 */
                *dstptr = opnd2;
                return(NOEXCEPTION);
	}
	/*
	 * check second operand for zero
	 */
	if (Sgl_iszero_exponentmantissa(opnd2)) {
		/* invalid since second operand is zero */
		if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                Set_invalidflag();
                Sgl_makequietnan(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	/* 
	 * get sign of result
	 */
	result = opnd1;  

	/* 
	 * check for denormalized operands
	 */
	if (opnd1_exponent == 0) {
		/* check for zero */
		if (Sgl_iszero_mantissa(opnd1)) {
			*dstptr = opnd1;
			return(NOEXCEPTION);
		}
		/* normalize, then continue */
		opnd1_exponent = 1;
		Sgl_normalize(opnd1,opnd1_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd1);
	}
	if (opnd2_exponent == 0) {
		/* normalize, then continue */
		opnd2_exponent = 1;
		Sgl_normalize(opnd2,opnd2_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd2);
	}

	/* find result exponent and divide step loop count */
	dest_exponent = opnd2_exponent - 1;
	stepcount = opnd1_exponent - opnd2_exponent;

	/*
	 * check for opnd1/opnd2 < 1
	 */
	if (stepcount < 0) {
		/*
		 * check for opnd1/opnd2 > 1/2
		 *
		 * In this case n will round to 1, so 
		 *    r = opnd1 - opnd2 
		 */
		if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
			Sgl_all(result) = ~Sgl_all(result);   /* set sign */
			/* align opnd2 with opnd1 */
			Sgl_leftshiftby1(opnd2); 
			Sgl_subtract(opnd2,opnd1,opnd2);
			/* now normalize */
                	while (Sgl_iszero_hidden(opnd2)) {
                        	Sgl_leftshiftby1(opnd2);
                        	dest_exponent--;
			}
			Sgl_set_exponentmantissa(result,opnd2);
			goto testforunderflow;
		}
		/*
		 * opnd1/opnd2 <= 1/2
		 *
		 * In this case n will round to zero, so 
		 *    r = opnd1
		 */
		Sgl_set_exponentmantissa(result,opnd1);
		dest_exponent = opnd1_exponent;
		goto testforunderflow;
	}

	/*
	 * Generate result
	 *
	 * Do iterative subtract until remainder is less than operand 2.
	 */
	while (stepcount-- > 0 && Sgl_all(opnd1)) {
		if (Sgl_isnotlessthan(opnd1,opnd2))
			Sgl_subtract(opnd1,opnd2,opnd1);
		Sgl_leftshiftby1(opnd1);
	}
	/*
	 * Do last subtract, then determine which way to round if remainder 
	 * is exactly 1/2 of opnd2 
	 */
	if (Sgl_isnotlessthan(opnd1,opnd2)) {
		Sgl_subtract(opnd1,opnd2,opnd1);
		roundup = TRUE;
	}
	if (stepcount > 0 || Sgl_iszero(opnd1)) {
		/* division is exact, remainder is zero */
		Sgl_setzero_exponentmantissa(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	/* 
	 * Check for cases where opnd1/opnd2 < n 
	 *
	 * In this case the result's sign will be opposite that of
	 * opnd1.  The mantissa also needs some correction.
	 */
	Sgl_leftshiftby1(opnd1);
	if (Sgl_isgreaterthan(opnd1,opnd2)) {
		Sgl_invert_sign(result);
		Sgl_subtract((opnd2<<1),opnd1,opnd1);
	}
	/* check for remainder being exactly 1/2 of opnd2 */
	else if (Sgl_isequal(opnd1,opnd2) && roundup) { 
		Sgl_invert_sign(result);
	}

	/* normalize result's mantissa */
        while (Sgl_iszero_hidden(opnd1)) {
                dest_exponent--;
                Sgl_leftshiftby1(opnd1);
        }
	Sgl_set_exponentmantissa(result,opnd1);

        /* 
         * Test for underflow
         */
    testforunderflow:
	if (dest_exponent <= 0) {
                /* trap if UNDERFLOWTRAP enabled */
                if (Is_underflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,unfl);
			*dstptr = result;
			/* frem is always exact */
			return(UNDERFLOWEXCEPTION);
                }
                /*
                 * denormalize result or set to signed zero
                 */
                if (dest_exponent >= (1 - SGL_P)) {
			Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
                }
                else {
			Sgl_setzero_exponentmantissa(result);
		}
	}
	else Sgl_set_exponent(result,dest_exponent);
	*dstptr = result;
	return(NOEXCEPTION);
}
OpenPOWER on IntegriCloud