summaryrefslogtreecommitdiff
path: root/Build/source/texk/seetexk/search.c
blob: 70ba4282ba836abb42fa3baf35d6ecd4135d204e (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
/*
 * Copyright (c) 1987, 1989 University of Maryland
 * Department of Computer Science.  All rights reserved.
 * Permission to copy for any purpose is hereby granted
 * so long as this copyright notice remains intact.
 */

/*
 * Key search routines (for a 32 bit key)
 *
 * SCreate initializes the search control area.
 *
 * SSearch returns the address of the data area (if found or created)
 * or a null pointer (if not).  The last argument controls the disposition
 * in various cases, and is a ``value-result'' parameter.
 *
 * SEnumerate calls the given function on each data object within the
 * search table.  Note that no ordering is specified (though currently
 * it runs in increasing-key-value sequence).
 */

#include "types.h"
#include "search.h"

#if vax || mc68000 || ns32000 || pyr
#define	HARD_ALIGNMENT	4
#else
#define	HARD_ALIGNMENT	16	/* should suffice for most everyone */
#endif

static int DOffset;		/* part of alignment code */

#ifndef KPATHSEA
char	*malloc(), *realloc();
#endif

struct search *
SCreate(unsigned int dsize)
{
	register struct search *s;

	if ((s = (struct search *) malloc(sizeof *s)) == 0)
		return (0);

	if (DOffset == 0) {
#ifndef HARD_ALIGNMENT
		DOffset = sizeof(i32);
#else
		DOffset = (sizeof(i32) + HARD_ALIGNMENT - 1) &
			~(HARD_ALIGNMENT - 1);
#endif
	}
	dsize += DOffset;	/* tack on space for keys */

#ifdef HARD_ALIGNMENT
	/*
	 * For machines with strict alignment constraints, it may be
	 * necessary to align the data at a multiple of some positive power
	 * of two.  In general, it would suffice to make dsize a power of
	 * two, but this could be very space-wasteful, so instead we align it
	 * to HARD_ALIGNMENT.  64 bit machines might ``#define HARD_ALIGNMENT
	 * 8'', for example.  N.B.:  we assume that HARD_ALIGNMENT is a power
	 * of two.
	 */

	dsize = (dsize + HARD_ALIGNMENT - 1) & ~(HARD_ALIGNMENT - 1);
#endif

	s->s_dsize = dsize;	/* save data object size */
	s->s_space = 10;	/* initially, room for 10 objects */
	s->s_n = 0;		/* and none in the table */
	if ((s->s_data = malloc(s->s_space * dsize)) == 0) {
		free((char *)s);
		return (0);
	}
	return (s);
}

/*
 * We actually use a binary search right now - this may change.
 */
char *
SSearch(struct search *s, i32 key, int *disp)
{
	register char *keyaddr;
	int itemstomove;

	*disp &= S_CREATE | S_EXCL;	/* clear return codes */
	if (s->s_n) {		/* look for the key */
		register int h, l, m;

		h = s->s_n - 1;
		l = 0;
		while (l <= h) {
			m = (l + h) >> 1;
			keyaddr = s->s_data + m * s->s_dsize;
			if (*(i32 *) keyaddr > key)
				h = m - 1;
			else if (*(i32 *) keyaddr < key)
				l = m + 1;
			else {	/* found it, now what? */
				if (*disp & S_EXCL) {
					*disp |= S_COLL;
					return (0);	/* collision */
				}
				*disp |= S_FOUND;
				return (keyaddr + DOffset);
			}
		}
		keyaddr = s->s_data + l * s->s_dsize;
	} else
		keyaddr = s->s_data;

	/* keyaddr is now where the key should have been found, if anywhere */
	if ((*disp & S_CREATE) == 0)
		return (0);	/* not found */

	/* avoid using realloc so as to retain old data if out of memory */
	if (s->s_space <= 0) {	/* must expand; double it */
		register char *new;

		if ((new = malloc((s->s_n << 1) * s->s_dsize)) == 0) {
			*disp |= S_ERROR;	/* no space */
			return (0);
		}
		keyaddr = (keyaddr - s->s_data) + new;	/* relocate */
		bcopy(s->s_data, new, s->s_n * s->s_dsize);
		free(s->s_data);
		s->s_data = new;
		s->s_space = s->s_n;
	}
	/* now move any keyed data that is beyond keyaddr down */
	itemstomove = s->s_n - (keyaddr - s->s_data) / s->s_dsize;
	if (itemstomove) {
#ifndef BLOCK_COPY
		register char *from, *to;

		from = s->s_data + s->s_n * s->s_dsize;
		to = from + s->s_dsize;
		while (from > keyaddr)
			*--to = *--from;
#else
		BLOCK_COPY(keyaddr, keyaddr + s->s_dsize,
		    itemstomove * s->s_dsize);
#endif
	}
	*disp |= S_NEW;
	s->s_n++;
	s->s_space--;
	*(i32 *) keyaddr = key;
	keyaddr += DOffset;	/* now actually dataaddr */
	/* the bzero is just a frill... */
	bzero(keyaddr, s->s_dsize - DOffset);
	return (keyaddr);
}

/*
 * Call function `f' for each element in the search table `s'.
 */
void
SEnumerate(struct search *s, void(*f)(char*,i32))
{
	register int n;
	register char *p;

	n = s->s_n;
	p = s->s_data;
	while (--n >= 0) {
		(*f)(p + DOffset, *(i32 *)p);
		p += s->s_dsize;
	}
}