#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;
}
