1/* $NetBSD: arithchk.c,v 1.2 2006/01/25 15:27:42 kleink Exp $ */
2
3/****************************************************************
4Copyright (C) 1997, 1998 Lucent Technologies
5All Rights Reserved
6
7Permission to use, copy, modify, and distribute this software and
8its documentation for any purpose and without fee is hereby
9granted, provided that the above copyright notice appear in all
10copies and that both that the copyright notice and this
11permission notice and warranty disclaimer appear in supporting
12documentation, and that the name of Lucent or any of its entities
13not be used in advertising or publicity pertaining to
14distribution of the software without specific, written prior
15permission.
16
17LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
18INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
19IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
20SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
21WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
22IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
23ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
24THIS SOFTWARE.
25****************************************************************/
26
27/* Try to deduce arith.h from arithmetic properties. */
28
29#include <stdio.h>
30
31 static int dalign;
32 typedef struct
33Akind {
34	char *name;
35	int   kind;
36	} Akind;
37
38 static Akind
39IEEE_LITTLE_ENDIAN	= { "IEEE_LITTLE_ENDIAN", 1 },
40IEEE_BIG_ENDIAN		= { "IEEE_BIG_ENDIAN", 2 },
41IBM			= { "IBM", 3 },
42VAX			= { "VAX", 4 },
43CRAY			= { "CRAY", 5};
44
45 static Akind *
46Lcheck()
47{
48	union {
49		double d;
50		long L[2];
51		} u;
52	struct {
53		double d;
54		long L;
55		} x[2];
56
57	if (sizeof(x) > 2*(sizeof(double) + sizeof(long)))
58		dalign = 1;
59	u.L[0] = u.L[1] = 0;
60	u.d = 1e13;
61	if (u.L[0] == 1117925532 && u.L[1] == -448790528)
62		return &IEEE_BIG_ENDIAN;
63	if (u.L[1] == 1117925532 && u.L[0] == -448790528)
64		return &IEEE_LITTLE_ENDIAN;
65	if (u.L[0] == -2065213935 && u.L[1] == 10752)
66		return &VAX;
67	if (u.L[0] == 1267827943 && u.L[1] == 704643072)
68		return &IBM;
69	return 0;
70	}
71
72 static Akind *
73icheck()
74{
75	union {
76		double d;
77		int L[2];
78		} u;
79	struct {
80		double d;
81		int L;
82		} x[2];
83
84	if (sizeof(x) > 2*(sizeof(double) + sizeof(int)))
85		dalign = 1;
86	u.L[0] = u.L[1] = 0;
87	u.d = 1e13;
88	if (u.L[0] == 1117925532 && u.L[1] == -448790528)
89		return &IEEE_BIG_ENDIAN;
90	if (u.L[1] == 1117925532 && u.L[0] == -448790528)
91		return &IEEE_LITTLE_ENDIAN;
92	if (u.L[0] == -2065213935 && u.L[1] == 10752)
93		return &VAX;
94	if (u.L[0] == 1267827943 && u.L[1] == 704643072)
95		return &IBM;
96	return 0;
97	}
98
99char *emptyfmt = "";	/* avoid possible warning message with printf("") */
100
101 static Akind *
102ccheck()
103{
104	union {
105		double d;
106		long L;
107		} u;
108	long Cray1;
109
110	/* Cray1 = 4617762693716115456 -- without overflow on non-Crays */
111	Cray1 = printf(emptyfmt) < 0 ? 0 : 4617762;
112	if (printf(emptyfmt, Cray1) >= 0)
113		Cray1 = 1000000*Cray1 + 693716;
114	if (printf(emptyfmt, Cray1) >= 0)
115		Cray1 = 1000000*Cray1 + 115456;
116	u.d = 1e13;
117	if (u.L == Cray1)
118		return &CRAY;
119	return 0;
120	}
121
122 static int
123fzcheck()
124{
125	double a, b;
126	int i;
127
128	a = 1.;
129	b = .1;
130	for(i = 155;; b *= b, i >>= 1) {
131		if (i & 1) {
132			a *= b;
133			if (i == 1)
134				break;
135			}
136		}
137	b = a * a;
138	return b == 0.;
139	}
140
141 int
142main()
143{
144	Akind *a = 0;
145	int Ldef = 0;
146	FILE *f;
147
148#ifdef WRITE_ARITH_H	/* for Symantec's buggy "make" */
149	f = fopen("arith.h", "w");
150	if (!f) {
151		printf("Cannot open arith.h\n");
152		return 1;
153		}
154#else
155	f = stdout;
156#endif
157
158	if (sizeof(double) == 2*sizeof(long))
159		a = Lcheck();
160	else if (sizeof(double) == 2*sizeof(int)) {
161		Ldef = 1;
162		a = icheck();
163		}
164	else if (sizeof(double) == sizeof(long))
165		a = ccheck();
166	if (a) {
167		fprintf(f, "#define %s\n#define Arith_Kind_ASL %d\n",
168			a->name, a->kind);
169		if (Ldef)
170			fprintf(f, "#define Long int\n#define Intcast (int)(long)\n");
171		if (dalign)
172			fprintf(f, "#define Double_Align\n");
173		if (sizeof(char*) == 8)
174			fprintf(f, "#define X64_bit_pointers\n");
175#ifndef NO_LONG_LONG
176		if (sizeof(long long) < 8)
177#endif
178			fprintf(f, "#define NO_LONG_LONG\n");
179		if (a->kind <= 2 && fzcheck())
180			fprintf(f, "#define Sudden_Underflow\n");
181#ifdef WRITE_ARITH_H
182		fclose(f);
183#endif
184		return 0;
185		}
186	fprintf(f, "/* Unknown arithmetic */\n");
187#ifdef WRITE_ARITH_H
188	fclose(f);
189#endif
190	return 1;
191	}
192