--- /dev/null
+/*
+ * 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 <lwk/kernel.h>
+#include <lwk/ctype.h>
+#include <lwk/errno.h>
+#include <lwk/bitmap.h>
+#include <lwk/bitops.h>
+#include <lwk/linux_compat.h>
+//#include <asm/uaccess.h>
+
+/*
+ * bitmaps provide an array of bits, implemented using an an
+ * array of unsigned longs. The number of valid bits in a
+ * given bitmap does _not_ need to be an exact multiple of
+ * BITS_PER_LONG.
+ *
+ * The possible unused bits in the last, partially used word
+ * of a bitmap are 'don't care'. The implementation makes
+ * no particular effort to keep them zero. It ensures that
+ * their value will not affect the results of any operation.
+ * The bitmap operations that return Boolean (bitmap_empty,
+ * for example) or scalar (bitmap_weight, for example) results
+ * carefully filter out these unused bits from impacting their
+ * results.
+ *
+ * These operations actually hold to a slightly stronger rule:
+ * if you don't input any bitmaps to these ops that have some
+ * unused bits set, then they won't output any set unused bits
+ * in output bitmaps.
+ *
+ * The byte ordering of bitmaps is more natural on little
+ * endian architectures. See the big-endian headers
+ * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
+ * for the best explanations of this ordering.
+ */
+
+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] & BITMAP_LAST_WORD_MASK(bits))
+ 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] & BITMAP_LAST_WORD_MASK(bits))
+ return 0;
+
+ return 1;
+}
+EXPORT_SYMBOL(__bitmap_full);
+
+int __bitmap_equal(const unsigned long *bitmap1,
+ const 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]) & BITMAP_LAST_WORD_MASK(bits))
+ return 0;
+
+ return 1;
+}
+EXPORT_SYMBOL(__bitmap_equal);
+
+void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
+{
+ int k, lim = bits/BITS_PER_LONG;
+ for (k = 0; k < lim; ++k)
+ dst[k] = ~src[k];
+
+ if (bits % BITS_PER_LONG)
+ dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
+}
+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);
+
+void __bitmap_xor(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_xor);
+
+void __bitmap_andnot(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_andnot);
+
+int __bitmap_intersects(const unsigned long *bitmap1,
+ const unsigned long *bitmap2, int bits)
+{
+ int k, lim = bits/BITS_PER_LONG;
+ for (k = 0; k < lim; ++k)
+ if (bitmap1[k] & bitmap2[k])
+ return 1;
+
+ if (bits % BITS_PER_LONG)
+ if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
+ return 1;
+ return 0;
+}
+EXPORT_SYMBOL(__bitmap_intersects);
+
+int __bitmap_subset(const unsigned long *bitmap1,
+ const 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]) & BITMAP_LAST_WORD_MASK(bits))
+ return 0;
+ return 1;
+}
+EXPORT_SYMBOL(__bitmap_subset);
+
+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 += hweight_long(bitmap[k]);
+
+ if (bits % BITS_PER_LONG)
+ w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
+
+ return w;
+}
+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 unhex(c) (isdigit(c) ? (c - '0') : (toupper(c) - 'A' + 10))
+#define BASEDEC 10 /* fancier cpuset lists input in decimal */
+
+/**
+ * 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 = ALIGN(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);
+
+#if 0
+/**
+ * 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);
+#endif
+
+/*
+ * bscnl_emit(buf, buflen, rbot, rtop, bp)
+ *
+ * Helper routine for bitmap_scnlistprintf(). Write decimal number
+ * or range to buf, 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 bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
+{
+ if (len > 0)
+ len += scnprintf(buf + len, buflen - len, ",");
+ if (rbot == rtop)
+ len += scnprintf(buf + len, buflen - len, "%d", rbot);
+ else
+ len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
+ return len;
+}
+
+/**
+ * bitmap_scnlistprintf - convert bitmap to list format ASCII 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
+ *
+ * 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 bitmap_scnlistprintf(char *buf, unsigned int buflen,
+ const unsigned long *maskp, int nmaskbits)
+{
+ int len = 0;
+ /* current bit is 'cur', most recently seen range is [rbot, rtop] */
+ int cur, rbot, rtop;
+
+ rbot = cur = find_first_bit(maskp, nmaskbits);
+ while (cur < nmaskbits) {
+ rtop = cur;
+ cur = find_next_bit(maskp, nmaskbits, cur+1);
+ if (cur >= nmaskbits || cur > rtop + 1) {
+ len = bscnl_emit(buf, buflen, rbot, rtop, len);
+ rbot = cur;
+ }
+ }
+ return len;
+}
+EXPORT_SYMBOL(bitmap_scnlistprintf);
+
+/**
+ * bitmap_parselist - convert list format ASCII string to bitmap
+ * @buf: read nul-terminated user string from this buffer
+ * @mask: write resulting mask here
+ * @nmaskbits: number of bits in mask to be written
+ *
+ * Input 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.
+ *
+ * Returns 0 on success, -errno on invalid input strings:
+ * -EINVAL: second number in range smaller than first
+ * -EINVAL: invalid character in string
+ * -ERANGE: bit number specified too large for mask
+ */
+int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
+{
+ unsigned a, b;
+
+ bitmap_zero(maskp, nmaskbits);
+ do {
+ if (!isdigit(*bp))
+ return -EINVAL;
+ b = a = simple_strtoul(bp, (char **)&bp, BASEDEC);
+ if (*bp == '-') {
+ bp++;
+ if (!isdigit(*bp))
+ return -EINVAL;
+ b = simple_strtoul(bp, (char **)&bp, BASEDEC);
+ }
+ if (!(a <= b))
+ return -EINVAL;
+ if (b >= nmaskbits)
+ return -ERANGE;
+ while (a <= b) {
+ set_bit(a, maskp);
+ a++;
+ }
+ if (*bp == ',')
+ bp++;
+ } while (*bp != '\0' && *bp != '\n');
+ return 0;
+}
+EXPORT_SYMBOL(bitmap_parselist);
+
+/*
+ * bitmap_pos_to_ord(buf, pos, bits)
+ * @buf: pointer to a bitmap
+ * @pos: a bit position in @buf (0 <= @pos < @bits)
+ * @bits: number of valid bit positions in @buf
+ *
+ * Map the bit at position @pos in @buf (of length @bits) to the
+ * ordinal of which set bit it is. If it is not set or if @pos
+ * is not a valid bit position, map to -1.
+ *
+ * If for example, just bits 4 through 7 are set in @buf, then @pos
+ * values 4 through 7 will get mapped to 0 through 3, respectively,
+ * and other @pos values will get mapped to 0. When @pos value 7
+ * gets mapped to (returns) @ord value 3 in this example, that means
+ * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
+ *
+ * The bit positions 0 through @bits are valid positions in @buf.
+ */
+static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
+{
+ int i, ord;
+
+ if (pos < 0 || pos >= bits || !test_bit(pos, buf))
+ return -1;
+
+ i = find_first_bit(buf, bits);
+ ord = 0;
+ while (i < pos) {
+ i = find_next_bit(buf, bits, i + 1);
+ ord++;
+ }
+ BUG_ON(i != pos);
+
+ return ord;
+}
+
+/**
+ * bitmap_ord_to_pos(buf, ord, bits)
+ * @buf: pointer to bitmap
+ * @ord: ordinal bit position (n-th set bit, n >= 0)
+ * @bits: number of valid bit positions in @buf
+ *
+ * Map the ordinal offset of bit @ord in @buf to its position in @buf.
+ * Value of @ord should be in range 0 <= @ord < weight(buf), else
+ * results are undefined.
+ *
+ * If for example, just bits 4 through 7 are set in @buf, then @ord
+ * values 0 through 3 will get mapped to 4 through 7, respectively,
+ * and all other @ord values return undefined values. When @ord value 3
+ * gets mapped to (returns) @pos value 7 in this example, that means
+ * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
+ *
+ * The bit positions 0 through @bits are valid positions in @buf.
+ */
+static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
+{
+ int pos = 0;
+
+ if (ord >= 0 && ord < bits) {
+ int i;
+
+ for (i = find_first_bit(buf, bits);
+ i < bits && ord > 0;
+ i = find_next_bit(buf, bits, i + 1))
+ ord--;
+ if (i < bits && ord == 0)
+ pos = i;
+ }
+
+ return pos;
+}
+
+/**
+ * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
+ * @dst: remapped result
+ * @src: subset to be remapped
+ * @old: defines domain of map
+ * @new: defines range of map
+ * @bits: number of bits in each of these bitmaps
+ *
+ * Let @old and @new define a mapping of bit positions, such that
+ * whatever position is held by the n-th set bit in @old is mapped
+ * to the n-th set bit in @new. In the more general case, allowing
+ * for the possibility that the weight 'w' of @new is less than the
+ * weight of @old, map the position of the n-th set bit in @old to
+ * the position of the m-th set bit in @new, where m == n % w.
+ *
+ * If either of the @old and @new bitmaps are empty, or if @src and
+ * @dst point to the same location, then this routine copies @src
+ * to @dst.
+ *
+ * The positions of unset bits in @old are mapped to themselves
+ * (the identify map).
+ *
+ * Apply the above specified mapping to @src, placing the result in
+ * @dst, clearing any bits previously set in @dst.
+ *
+ * For example, lets say that @old has bits 4 through 7 set, and
+ * @new has bits 12 through 15 set. This defines the mapping of bit
+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
+ * bit positions unchanged. So if say @src comes into this routine
+ * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
+ * 13 and 15 set.
+ */
+void bitmap_remap(unsigned long *dst, const unsigned long *src,
+ const unsigned long *old, const unsigned long *new,
+ int bits)
+{
+ int oldbit, w;
+
+ if (dst == src) /* following doesn't handle inplace remaps */
+ return;
+ bitmap_zero(dst, bits);
+
+ w = bitmap_weight(new, bits);
+ for (oldbit = find_first_bit(src, bits);
+ oldbit < bits;
+ oldbit = find_next_bit(src, bits, oldbit + 1)) {
+ int n = bitmap_pos_to_ord(old, oldbit, bits);
+ if (n < 0 || w == 0)
+ set_bit(oldbit, dst); /* identity map */
+ else
+ set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
+ }
+}
+EXPORT_SYMBOL(bitmap_remap);
+
+/**
+ * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
+ * @oldbit - bit position to be mapped
+ * @old: defines domain of map
+ * @new: defines range of map
+ * @bits: number of bits in each of these bitmaps
+ *
+ * Let @old and @new define a mapping of bit positions, such that
+ * whatever position is held by the n-th set bit in @old is mapped
+ * to the n-th set bit in @new. In the more general case, allowing
+ * for the possibility that the weight 'w' of @new is less than the
+ * weight of @old, map the position of the n-th set bit in @old to
+ * the position of the m-th set bit in @new, where m == n % w.
+ *
+ * The positions of unset bits in @old are mapped to themselves
+ * (the identify map).
+ *
+ * Apply the above specified mapping to bit position @oldbit, returning
+ * the new bit position.
+ *
+ * For example, lets say that @old has bits 4 through 7 set, and
+ * @new has bits 12 through 15 set. This defines the mapping of bit
+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
+ * bit positions unchanged. So if say @oldbit is 5, then this routine
+ * returns 13.
+ */
+int bitmap_bitremap(int oldbit, const unsigned long *old,
+ const unsigned long *new, int bits)
+{
+ int w = bitmap_weight(new, bits);
+ int n = bitmap_pos_to_ord(old, oldbit, bits);
+ if (n < 0 || w == 0)
+ return oldbit;
+ else
+ return bitmap_ord_to_pos(new, n % w, bits);
+}
+EXPORT_SYMBOL(bitmap_bitremap);
+
+/*
+ * Common code for bitmap_*_region() routines.
+ * bitmap: array of unsigned longs corresponding to the bitmap
+ * pos: the beginning of the region
+ * order: region size (log base 2 of number of bits)
+ * reg_op: operation(s) to perform on that region of bitmap
+ *
+ * Can set, verify and/or release a region of bits in a bitmap,
+ * depending on which combination of REG_OP_* flag bits is set.
+ *
+ * A region of a bitmap is a sequence of bits in the bitmap, of
+ * some size '1 << order' (a power of two), aligned to that same
+ * '1 << order' power of two.
+ *
+ * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
+ * Returns 0 in all other cases and reg_ops.
+ */
+
+enum {
+ REG_OP_ISFREE, /* true if region is all zero bits */
+ REG_OP_ALLOC, /* set all bits in region */
+ REG_OP_RELEASE, /* clear all bits in region */
+};
+
+static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
+{
+ int nbits_reg; /* number of bits in region */
+ int index; /* index first long of region in bitmap */
+ int offset; /* bit offset region in bitmap[index] */
+ int nlongs_reg; /* num longs spanned by region in bitmap */
+ int nbitsinlong; /* num bits of region in each spanned long */
+ unsigned long mask; /* bitmask for one long of region */
+ int i; /* scans bitmap by longs */
+ int ret = 0; /* return value */
+
+ /*
+ * Either nlongs_reg == 1 (for small orders that fit in one long)
+ * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
+ */
+ nbits_reg = 1 << order;
+ index = pos / BITS_PER_LONG;
+ offset = pos - (index * BITS_PER_LONG);
+ nlongs_reg = BITS_TO_LONGS(nbits_reg);
+ nbitsinlong = min(nbits_reg, BITS_PER_LONG);
+
+ /*
+ * Can't do "mask = (1UL << nbitsinlong) - 1", as that
+ * overflows if nbitsinlong == BITS_PER_LONG.
+ */
+ mask = (1UL << (nbitsinlong - 1));
+ mask += mask - 1;
+ mask <<= offset;
+
+ switch (reg_op) {
+ case REG_OP_ISFREE:
+ for (i = 0; i < nlongs_reg; i++) {
+ if (bitmap[index + i] & mask)
+ goto done;
+ }
+ ret = 1; /* all bits in region free (zero) */
+ break;
+
+ case REG_OP_ALLOC:
+ for (i = 0; i < nlongs_reg; i++)
+ bitmap[index + i] |= mask;
+ break;
+
+ case REG_OP_RELEASE:
+ for (i = 0; i < nlongs_reg; i++)
+ bitmap[index + i] &= ~mask;
+ break;
+ }
+done:
+ return ret;
+}
+
+/**
+ * bitmap_find_free_region - find a contiguous aligned mem region
+ * @bitmap: array of unsigned longs corresponding to the bitmap
+ * @bits: number of bits in the bitmap
+ * @order: region size (log base 2 of number of bits) to find
+ *
+ * Find a region of free (zero) bits in a @bitmap of @bits bits and
+ * allocate them (set them to one). Only consider regions of length
+ * a power (@order) of two, aligned to that power of two, which
+ * makes the search algorithm much faster.
+ *
+ * Return the bit offset in bitmap of the allocated region,
+ * or -errno on failure.
+ */
+int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
+{
+ int pos; /* scans bitmap by regions of size order */
+
+ for (pos = 0; pos < bits; pos += (1 << order))
+ if (__reg_op(bitmap, pos, order, REG_OP_ISFREE))
+ break;
+ if (pos == bits)
+ return -ENOMEM;
+ __reg_op(bitmap, pos, order, REG_OP_ALLOC);
+ return pos;
+}
+EXPORT_SYMBOL(bitmap_find_free_region);
+
+/**
+ * bitmap_release_region - release allocated bitmap region
+ * @bitmap: array of unsigned longs corresponding to the bitmap
+ * @pos: beginning of bit region to release
+ * @order: region size (log base 2 of number of bits) to release
+ *
+ * This is the complement to __bitmap_find_free_region and releases
+ * the found region (by clearing it in the bitmap).
+ *
+ * No return value.
+ */
+void bitmap_release_region(unsigned long *bitmap, int pos, int order)
+{
+ __reg_op(bitmap, pos, order, REG_OP_RELEASE);
+}
+EXPORT_SYMBOL(bitmap_release_region);
+
+/**
+ * bitmap_allocate_region - allocate bitmap region
+ * @bitmap: array of unsigned longs corresponding to the bitmap
+ * @pos: beginning of bit region to allocate
+ * @order: region size (log base 2 of number of bits) to allocate
+ *
+ * Allocate (set bits in) a specified region of a bitmap.
+ *
+ * Return 0 on success, or -EBUSY if specified region wasn't
+ * free (not all bits were zero).
+ */
+int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
+{
+ if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
+ return -EBUSY;
+ __reg_op(bitmap, pos, order, REG_OP_ALLOC);
+ return 0;
+}
+EXPORT_SYMBOL(bitmap_allocate_region);
