summaryrefslogtreecommitdiffstats
path: root/tools/power/cpupower/utils/helpers/bitmask.c
blob: 60f4d69bb20d04a6d6b5ef818f1f74e3cd021ee6 (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
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <helpers/bitmask.h>

/* How many bits in an unsigned long */
#define bitsperlong (8 * sizeof(unsigned long))

/* howmany(a,b) : how many elements of size b needed to hold all of a */
#define howmany(x,y) (((x)+((y)-1))/(y))

/* How many longs in mask of n bits */
#define longsperbits(n) howmany(n, bitsperlong)

#define max(a,b) ((a) > (b) ? (a) : (b))

/*
 * Allocate and free `struct bitmask *`
 */

/* Allocate a new `struct bitmask` with a size of n bits */
struct bitmask *bitmask_alloc(unsigned int n)
{
	struct bitmask *bmp;

	bmp = malloc(sizeof(*bmp));
	if (bmp == 0)
		return 0;
	bmp->size = n;
	bmp->maskp = calloc(longsperbits(n), sizeof(unsigned long));
	if (bmp->maskp == 0) {
		free(bmp);
		return 0;
	}
	return bmp;
}

/* Free `struct bitmask` */
void bitmask_free(struct bitmask *bmp)
{
	if (bmp == 0)
		return;
	free(bmp->maskp);
	bmp->maskp = (unsigned long *)0xdeadcdef;  /* double free tripwire */
	free(bmp);
}

/*
 * The routines _getbit() and _setbit() are the only
 * routines that actually understand the layout of bmp->maskp[].
 *
 * On little endian architectures, this could simply be an array of
 * bytes.  But the kernel layout of bitmasks _is_ visible to userspace
 * via the sched_(set/get)affinity calls in Linux 2.6, and on big
 * endian architectures, it is painfully obvious that this is an
 * array of unsigned longs.
 */

/* Return the value (0 or 1) of bit n in bitmask bmp */
static unsigned int _getbit(const struct bitmask *bmp, unsigned int n)
{
	if (n < bmp->size)
		return (bmp->maskp[n/bitsperlong] >> (n % bitsperlong)) & 1;
	else
		return 0;
}

/* Set bit n in bitmask bmp to value v (0 or 1) */
static void _setbit(struct bitmask *bmp, unsigned int n, unsigned int v)
{
	if (n < bmp->size) {
		if (v)
			bmp->maskp[n/bitsperlong] |= 1UL << (n % bitsperlong);
		else
			bmp->maskp[n/bitsperlong] &= ~(1UL << (n % bitsperlong));
	}
}

/*
 * When parsing bitmask lists, only allow numbers, separated by one
 * of the allowed next characters.
 *
 * The parameter 'sret' is the return from a sscanf "%u%c".  It is
 * -1 if the sscanf input string was empty.  It is 0 if the first
 * character in the sscanf input string was not a decimal number.
 * It is 1 if the unsigned number matching the "%u" was the end of the
 * input string.  It is 2 if one or more additional characters followed
 * the matched unsigned number.  If it is 2, then 'nextc' is the first
 * character following the number.  The parameter 'ok_next_chars'
 * is the nul-terminated list of allowed next characters.
 *
 * The mask term just scanned was ok if and only if either the numbers
 * matching the %u were all of the input or if the next character in
 * the input past the numbers was one of the allowed next characters.
 */
static int scan_was_ok(int sret, char nextc, const char *ok_next_chars)
{
	return sret == 1 ||
		(sret == 2 && strchr(ok_next_chars, nextc) != NULL);
}

static const char *nexttoken(const char *q,  int sep)
{
	if (q)
		q = strchr(q, sep);
	if (q)
		q++;
	return q;
}

/* Set a single bit i in bitmask */
struct bitmask *bitmask_setbit(struct bitmask *bmp, unsigned int i)
{
	_setbit(bmp, i, 1);
	return bmp;
}

/* Set all bits in bitmask: bmp = ~0 */
struct bitmask *bitmask_setall(struct bitmask *bmp)
{
	unsigned int i;
	for (i = 0; i < bmp->size; i++)
		_setbit(bmp, i, 1);
	return bmp;
}

/* Clear all bits in bitmask: bmp = 0 */
struct bitmask *bitmask_clearall(struct bitmask *bmp)
{
	unsigned int i;
	for (i = 0; i < bmp->size; i++)
		_setbit(bmp, i, 0);
	return bmp;
}

/* True if all bits are clear */
int bitmask_isallclear(const struct bitmask *bmp)
{
	unsigned int i;
	for (i = 0; i < bmp->size; i++)
		if (_getbit(bmp, i))
			return 0;
	return 1;
}

/* True if specified bit i is set */
int bitmask_isbitset(const struct bitmask *bmp, unsigned int i)
{
	return _getbit(bmp, i);
}

/* Number of lowest set bit (min) */
unsigned int bitmask_first(const struct bitmask *bmp)
{
	return bitmask_next(bmp, 0);
}

/* Number of highest set bit (max) */
unsigned int bitmask_last(const struct bitmask *bmp)
{
	unsigned int i;
	unsigned int m = bmp->size;
	for (i = 0; i < bmp->size; i++)
		if (_getbit(bmp, i))
			m = i;
	return m;
}

/* Number of next set bit at or above given bit i */
unsigned int bitmask_next(const struct bitmask *bmp, unsigned int i)
{
	unsigned int n;
	for (n = i; n < bmp->size; n++)
		if (_getbit(bmp, n))
			break;
	return n;
}

/*
 * Parses a comma-separated list of numbers and ranges of numbers,
 * with optional ':%u' strides modifying ranges, into provided bitmask.
 * Some examples of input lists and their equivalent simple list:
 *	Input		Equivalent to
 *	0-3		0,1,2,3
 *	0-7:2		0,2,4,6
 *	1,3,5-7		1,3,5,6,7
 *	0-3:2,8-15:4	0,2,8,12	
 */
int bitmask_parselist(const char *buf, struct bitmask *bmp)
{
	const char *p, *q;

	bitmask_clearall(bmp);

	q = buf;
	while (p = q, q = nexttoken(q, ','), p) {
		unsigned int a;		/* begin of range */
		unsigned int b;		/* end of range */
		unsigned int s;		/* stride */
		const char *c1, *c2;	/* next tokens after '-' or ',' */
		char nextc;		/* char after sscanf %u match */
		int sret;		/* sscanf return (number of matches) */

		sret = sscanf(p, "%u%c", &a, &nextc);
		if (!scan_was_ok(sret, nextc, ",-"))
			goto err;
		b = a;
		s = 1;
		c1 = nexttoken(p, '-');
		c2 = nexttoken(p, ',');
		if (c1 != NULL && (c2 == NULL || c1 < c2)) {
			sret = sscanf(c1, "%u%c", &b, &nextc);
			if (!scan_was_ok(sret, nextc, ",:"))
				goto err;
			c1 = nexttoken(c1, ':');
			if (c1 != NULL && (c2 == NULL || c1 < c2)) {
				sret = sscanf(c1, "%u%c", &s, &nextc);
				if (!scan_was_ok(sret, nextc, ","))
					goto err;
			}
		}
		if (!(a <= b))
			goto err;
		if (b >= bmp->size)
			goto err;
		while (a <= b) {
			_setbit(bmp, a, 1);
			a += s;
		}
	}
	return 0;
err:
	bitmask_clearall(bmp);
	return -1;
}

/*
 * emit(buf, buflen, rbot, rtop, len)
 *
 * Helper routine for bitmask_displaylist().  Write decimal number
 * or range to buf+len, suppressing output past buf+buflen, with optional
 * comma-prefix.  Return len of what would be written to buf, if it
 * all fit.
 */

static inline int emit(char *buf, int buflen, int rbot, int rtop, int len)
{
	if (len > 0)
		len += snprintf(buf + len, max(buflen - len, 0), ",");
	if (rbot == rtop)
		len += snprintf(buf + len, max(buflen - len, 0), "%d", rbot);
	else
		len += snprintf(buf + len, max(buflen - len, 0), "%d-%d", rbot, rtop);
	return len;
}

/*
 * Write decimal list representation of bmp to buf.
 *
 * Output format is a comma-separated list of decimal numbers and
 * ranges.  Consecutively set bits are shown as two hyphen-separated
 * decimal numbers, the smallest and largest bit numbers set in
 * the range.  Output format is compatible with the format
 * accepted as input by bitmap_parselist().
 *
 * The return value is the number of characters which would be
 * generated for the given input, excluding the trailing '\0', as
 * per ISO C99.
 */

int bitmask_displaylist(char *buf, int buflen, const struct bitmask *bmp)
{
	int len = 0;
	/* current bit is 'cur', most recently seen range is [rbot, rtop] */
	unsigned int cur, rbot, rtop;

	if (buflen > 0)
		*buf = 0;
	rbot = cur = bitmask_first(bmp);
	while (cur < bmp->size) {
		rtop = cur;
		cur = bitmask_next(bmp, cur+1);
		if (cur >= bmp->size || cur > rtop + 1) {
			len = emit(buf, buflen, rbot, rtop, len);
			rbot = cur;
		}
	}
	return len;
}