root/lib/bitmap.c

/*
 * lib/bitmap.c
 * Helper functions for bitmap.h.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/bitmap.h>
#include <asm/bitops.h>
#include <asm/uaccess.h>

int bitmap_empty(const unsigned long *bitmap, int bits)
{
        int k, lim = bits/BITS_PER_LONG;
        for (k = 0; k < lim; ++k)
                if (bitmap[k])
                        return 0;

        if (bits % BITS_PER_LONG)
                if (bitmap[k] & ((1UL << (bits % BITS_PER_LONG)) - 1))
                        return 0;

        return 1;
}
EXPORT_SYMBOL(bitmap_empty);

int bitmap_full(const unsigned long *bitmap, int bits)
{
        int k, lim = bits/BITS_PER_LONG;
        for (k = 0; k < lim; ++k)
                if (~bitmap[k])
                        return 0;

        if (bits % BITS_PER_LONG)
                if (~bitmap[k] & ((1UL << (bits % BITS_PER_LONG)) - 1))
                        return 0;

        return 1;
}
EXPORT_SYMBOL(bitmap_full);

int bitmap_equal(const unsigned long *bitmap1,
                unsigned long *bitmap2, int bits)
{
        int k, lim = bits/BITS_PER_LONG;
        for (k = 0; k < lim; ++k)
                if (bitmap1[k] != bitmap2[k])
                        return 0;

        if (bits % BITS_PER_LONG)
                if ((bitmap1[k] ^ bitmap2[k]) &
                                ((1UL << (bits % BITS_PER_LONG)) - 1))
                        return 0;

        return 1;
}
EXPORT_SYMBOL(bitmap_equal);

void bitmap_complement(unsigned long *bitmap, int bits)
{
        int k;
        int nr = BITS_TO_LONGS(bits);

        for (k = 0; k < nr; ++k)
                bitmap[k] = ~bitmap[k];
}
EXPORT_SYMBOL(bitmap_complement);

/*
 * bitmap_shift_right - logical right shift of the bits in a bitmap
 *   @dst - destination bitmap
 *   @src - source bitmap
 *   @nbits - shift by this many bits
 *   @bits - bitmap size, in bits
 *
 * Shifting right (dividing) means moving bits in the MS -> LS bit
 * direction.  Zeros are fed into the vacated MS positions and the
 * LS bits shifted off the bottom are lost.
 */
void bitmap_shift_right(unsigned long *dst,
                        const unsigned long *src, int shift, int bits)
{
        int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
        int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
        unsigned long mask = (1UL << left) - 1;
        for (k = 0; off + k < lim; ++k) {
                unsigned long upper, lower;

                /*
                 * If shift is not word aligned, take lower rem bits of
                 * word above and make them the top rem bits of result.
                 */
                if (!rem || off + k + 1 >= lim)
                        upper = 0;
                else {
                        upper = src[off + k + 1];
                        if (off + k + 1 == lim - 1 && left)
                                upper &= mask;
                }
                lower = src[off + k];
                if (left && off + k == lim - 1)
                        lower &= mask;
                dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
                if (left && k == lim - 1)
                        dst[k] &= mask;
        }
        if (off)
                memset(&dst[lim - off], 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(bitmap_shift_right);

/*
 * bitmap_shift_left - logical left shift of the bits in a bitmap
 *   @dst - destination bitmap
 *   @src - source bitmap
 *   @nbits - shift by this many bits
 *   @bits - bitmap size, in bits
 *
 * Shifting left (multiplying) means moving bits in the LS -> MS
 * direction.  Zeros are fed into the vacated LS bit positions
 * and those MS bits shifted off the top are lost.
 */
void bitmap_shift_left(unsigned long *dst,
                        const unsigned long *src, int shift, int bits)
{
        int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
        int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
        for (k = lim - off - 1; k >= 0; --k) {
                unsigned long upper, lower;

                /*
                 * If shift is not word aligned, take upper rem bits of
                 * word below and make them the bottom rem bits of result.
                 */
                if (rem && k > 0)
                        lower = src[k - 1];
                else
                        lower = 0;
                upper = src[k];
                if (left && k == lim - 1)
                        upper &= (1UL << left) - 1;
                dst[k + off] = lower  >> (BITS_PER_LONG - rem) | upper << rem;
                if (left && k + off == lim - 1)
                        dst[k + off] &= (1UL << left) - 1;
        }
        if (off)
                memset(dst, 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(bitmap_shift_left);

void bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
                                const unsigned long *bitmap2, int bits)
{
        int k;
        int nr = BITS_TO_LONGS(bits);

        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] & bitmap2[k];
}
EXPORT_SYMBOL(bitmap_and);

void bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
                                const unsigned long *bitmap2, int bits)
{
        int k;
        int nr = BITS_TO_LONGS(bits);

        for (k = 0; k < nr; k++)
                dst[k] = bitmap1[k] | bitmap2[k];
}
EXPORT_SYMBOL(bitmap_or);

#if BITS_PER_LONG == 32
int bitmap_weight(const unsigned long *bitmap, int bits)
{
        int k, w = 0, lim = bits/BITS_PER_LONG;

        for (k = 0; k < lim; k++)
                w += hweight32(bitmap[k]);

        if (bits % BITS_PER_LONG)
                w += hweight32(bitmap[k] &
                                ((1UL << (bits % BITS_PER_LONG)) - 1));

        return w;
}
#else
int bitmap_weight(const unsigned long *bitmap, int bits)
{
        int k, w = 0, lim = bits/BITS_PER_LONG;

        for (k = 0; k < lim; k++)
                w += hweight64(bitmap[k]);

        if (bits % BITS_PER_LONG)
                w += hweight64(bitmap[k] &
                                ((1UL << (bits % BITS_PER_LONG)) - 1));

        return w;
}
#endif
EXPORT_SYMBOL(bitmap_weight);

/*
 * Bitmap printing & parsing functions: first version by Bill Irwin,
 * second version by Paul Jackson, third by Joe Korty.
 */

#define CHUNKSZ                         32
#define nbits_to_hold_value(val)        fls(val)
#define roundup_power2(val,modulus)     (((val) + (modulus) - 1) & ~((modulus) - 1))
#define unhex(c)                        (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))

/**
 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
 * @buf: byte buffer into which string is placed
 * @buflen: reserved size of @buf, in bytes
 * @maskp: pointer to bitmap to convert
 * @nmaskbits: size of bitmap, in bits
 *
 * Exactly @nmaskbits bits are displayed.  Hex digits are grouped into
 * comma-separated sets of eight digits per set.
 */
int bitmap_scnprintf(char *buf, unsigned int buflen,
        const unsigned long *maskp, int nmaskbits)
{
        int i, word, bit, len = 0;
        unsigned long val;
        const char *sep = "";
        int chunksz;
        u32 chunkmask;

        chunksz = nmaskbits & (CHUNKSZ - 1);
        if (chunksz == 0)
                chunksz = CHUNKSZ;

        i = roundup_power2(nmaskbits, CHUNKSZ) - CHUNKSZ;
        for (; i >= 0; i -= CHUNKSZ) {
                chunkmask = ((1ULL << chunksz) - 1);
                word = i / BITS_PER_LONG;
                bit = i % BITS_PER_LONG;
                val = (maskp[word] >> bit) & chunkmask;
                len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
                        (chunksz+3)/4, val);
                chunksz = CHUNKSZ;
                sep = ",";
        }
        return len;
}
EXPORT_SYMBOL(bitmap_scnprintf);

/**
 * bitmap_parse - convert an ASCII hex string into a bitmap.
 * @buf: pointer to buffer in user space containing string.
 * @buflen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Commas group hex digits into chunks.  Each chunk defines exactly 32
 * bits of the resultant bitmask.  No chunk may specify a value larger
 * than 32 bits (-EOVERFLOW), and if a chunk specifies a smaller value
 * then leading 0-bits are prepended.  -EINVAL is returned for illegal
 * characters and for grouping errors such as "1,,5", ",44", "," and "".
 * Leading and trailing whitespace accepted, but not embedded whitespace.
 */
int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
        unsigned long *maskp, int nmaskbits)
{
        int c, old_c, totaldigits, ndigits, nchunks, nbits;
        u32 chunk;

        bitmap_zero(maskp, nmaskbits);

        nchunks = nbits = totaldigits = c = 0;
        do {
                chunk = ndigits = 0;

                /* Get the next chunk of the bitmap */
                while (ubuflen) {
                        old_c = c;
                        if (get_user(c, ubuf++))
                                return -EFAULT;
                        ubuflen--;
                        if (isspace(c))
                                continue;

                        /*
                         * If the last character was a space and the current
                         * character isn't '\0', we've got embedded whitespace.
                         * This is a no-no, so throw an error.
                         */
                        if (totaldigits && c && isspace(old_c))
                                return -EINVAL;

                        /* A '\0' or a ',' signal the end of the chunk */
                        if (c == '\0' || c == ',')
                                break;

                        if (!isxdigit(c))
                                return -EINVAL;

                        /*
                         * Make sure there are at least 4 free bits in 'chunk'.
                         * If not, this hexdigit will overflow 'chunk', so
                         * throw an error.
                         */
                        if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
                                return -EOVERFLOW;

                        chunk = (chunk << 4) | unhex(c);
                        ndigits++; totaldigits++;
                }
                if (ndigits == 0)
                        return -EINVAL;
                if (nchunks == 0 && chunk == 0)
                        continue;

                bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
                *maskp |= chunk;
                nchunks++;
                nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
                if (nbits > nmaskbits)
                        return -EOVERFLOW;
        } while (ubuflen && c == ',');

        return 0;
}
EXPORT_SYMBOL(bitmap_parse);