/** 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/export.h>#include <linux/thread_info.h>#include <linux/ctype.h>#include <linux/errno.h>#include <linux/bitmap.h>#include <linux/bitops.h>#include <linux/bug.h>#include <asm/page.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, unsigned int bits){unsigned 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, unsigned int bits){unsigned 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, unsigned int bits){unsigned 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, unsigned int bits){unsigned 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];}EXPORT_SYMBOL(__bitmap_complement);/*** __bitmap_shift_right - logical right shift of the bits in a bitmap* @dst : destination bitmap* @src : source bitmap* @shift : shift by this many bits* @nbits : 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,unsigned shift, unsigned nbits){unsigned k, lim = BITS_TO_LONGS(nbits);unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);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)upper &= mask;upper <<= (BITS_PER_LONG - rem);}lower = src[off + k];if (off + k == lim - 1)lower &= mask;lower >>= rem;dst[k] = lower | upper;}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* @shift : shift by this many bits* @nbits : 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,unsigned int shift, unsigned int nbits){int k;unsigned int lim = BITS_TO_LONGS(nbits);unsigned 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] >> (BITS_PER_LONG - rem);elselower = 0;upper = src[k] << rem;dst[k + off] = lower | upper;}if (off)memset(dst, 0, off*sizeof(unsigned long));}EXPORT_SYMBOL(__bitmap_shift_left);int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,const unsigned long *bitmap2, unsigned int bits){unsigned int k;unsigned int lim = bits/BITS_PER_LONG;unsigned long result = 0;for (k = 0; k < lim; k++)result |= (dst[k] = bitmap1[k] & bitmap2[k]);if (bits % BITS_PER_LONG)result |= (dst[k] = bitmap1[k] & bitmap2[k] &BITMAP_LAST_WORD_MASK(bits));return result != 0;}EXPORT_SYMBOL(__bitmap_and);void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,const unsigned long *bitmap2, unsigned int bits){unsigned int k;unsigned 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, unsigned int bits){unsigned int k;unsigned int nr = BITS_TO_LONGS(bits);for (k = 0; k < nr; k++)dst[k] = bitmap1[k] ^ bitmap2[k];}EXPORT_SYMBOL(__bitmap_xor);int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,const unsigned long *bitmap2, unsigned int bits){unsigned int k;unsigned int lim = bits/BITS_PER_LONG;unsigned long result = 0;for (k = 0; k < lim; k++)result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);if (bits % BITS_PER_LONG)result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &BITMAP_LAST_WORD_MASK(bits));return result != 0;}EXPORT_SYMBOL(__bitmap_andnot);int __bitmap_intersects(const unsigned long *bitmap1,const unsigned long *bitmap2, unsigned int bits){unsigned 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, unsigned int bits){unsigned 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, unsigned int bits){unsigned int k, lim = bits/BITS_PER_LONG;int w = 0;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);void bitmap_set(unsigned long *map, unsigned int start, int len){unsigned long *p = map + BIT_WORD(start);const unsigned int size = start + len;int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);while (len - bits_to_set >= 0) {*p |= mask_to_set;len -= bits_to_set;bits_to_set = BITS_PER_LONG;mask_to_set = ~0UL;p++;}if (len) {mask_to_set &= BITMAP_LAST_WORD_MASK(size);*p |= mask_to_set;}}EXPORT_SYMBOL(bitmap_set);void bitmap_clear(unsigned long *map, unsigned int start, int len){unsigned long *p = map + BIT_WORD(start);const unsigned int size = start + len;int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);while (len - bits_to_clear >= 0) {*p &= ~mask_to_clear;len -= bits_to_clear;bits_to_clear = BITS_PER_LONG;mask_to_clear = ~0UL;p++;}if (len) {mask_to_clear &= BITMAP_LAST_WORD_MASK(size);*p &= ~mask_to_clear;}}EXPORT_SYMBOL(bitmap_clear);/*** bitmap_find_next_zero_area_off - find a contiguous aligned zero area* @map: The address to base the search on* @size: The bitmap size in bits* @start: The bitnumber to start searching at* @nr: The number of zeroed bits we're looking for* @align_mask: Alignment mask for zero area* @align_offset: Alignment offset for zero area.** The @align_mask should be one less than a power of 2; the effect is that* the bit offset of all zero areas this function finds plus @align_offset* is multiple of that power of 2.*/unsigned long bitmap_find_next_zero_area_off(unsigned long *map,unsigned long size,unsigned long start,unsigned int nr,unsigned long align_mask,unsigned long align_offset){unsigned long index, end, i;again:index = find_next_zero_bit(map, size, start);/* Align allocation */index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;end = index + nr;if (end > size)return end;i = find_next_bit(map, end, index);if (i < end) {start = i + 1;goto again;}return index;}EXPORT_SYMBOL(bitmap_find_next_zero_area_off);/** Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,* second version by Paul Jackson, third by Joe Korty.*/#define CHUNKSZ 32#define nbits_to_hold_value(val) fls(val)#define BASEDEC 10 /* fancier cpuset lists input in decimal *//*** __bitmap_parse - convert an ASCII hex string into a bitmap.* @buf: pointer to buffer containing string.* @buflen: buffer size in bytes. If string is smaller than this* then it must be terminated with a 0円.* @is_user: location of buffer, 0 indicates kernel space* @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 *buf, unsigned int buflen,int is_user, unsigned long *maskp,int nmaskbits){int c, old_c, totaldigits, ndigits, nchunks, nbits;u32 chunk;const char __user __force *ubuf = (const char __user __force *)buf;bitmap_zero(maskp, nmaskbits);nchunks = nbits = totaldigits = c = 0;do {chunk = ndigits = 0;/* Get the next chunk of the bitmap */while (buflen) {old_c = c;if (is_user) {if (__get_user(c, ubuf++))return -EFAULT;}elsec = *buf++;buflen--;if (isspace(c))continue;/** If the last character was a space and the current* character isn't '0円', we've got embedded whitespace.* This is a no-no, so throw an error.*/if (totaldigits && c && isspace(old_c))return -EINVAL;/* A '0円' or a ',' signal the end of the chunk */if (c == '0円' || 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) | hex_to_bin(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 (buflen && c == ',');return 0;}EXPORT_SYMBOL(__bitmap_parse);/*** bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap** @ubuf: pointer to user buffer containing string.* @ulen: buffer size in bytes. If string is smaller than this* then it must be terminated with a 0円.* @maskp: pointer to bitmap array that will contain result.* @nmaskbits: size of bitmap, in bits.** Wrapper for __bitmap_parse(), providing it with user buffer.** We cannot have this as an inline function in bitmap.h because it needs* linux/uaccess.h to get the access_ok() declaration and this causes* cyclic dependencies.*/int bitmap_parse_user(const char __user *ubuf,unsigned int ulen, unsigned long *maskp,int nmaskbits){if (!access_ok(VERIFY_READ, ubuf, ulen))return -EFAULT;return __bitmap_parse((const char __force *)ubuf,ulen, 1, maskp, nmaskbits);}EXPORT_SYMBOL(bitmap_parse_user);/*** bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string* @list: indicates whether the bitmap must be list* @buf: page aligned buffer into which string is placed* @maskp: pointer to bitmap to convert* @nmaskbits: size of bitmap, in bits** Output format is a comma-separated list of decimal numbers and* ranges if list is specified or hex digits grouped into comma-separated* sets of 8 digits/set. Returns the number of characters written to buf.*/int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,int nmaskbits){ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;int n = 0;if (len > 1) {n = list ? scnprintf(buf, len, "%*pbl", nmaskbits, maskp) :scnprintf(buf, len, "%*pb", nmaskbits, maskp);buf[n++] = '\n';buf[n] = '0円';}return n;}EXPORT_SYMBOL(bitmap_print_to_pagebuf);/*** __bitmap_parselist - convert list format ASCII string to bitmap* @buf: read nul-terminated user string from this buffer* @buflen: buffer size in bytes. If string is smaller than this* then it must be terminated with a 0円.* @is_user: location of buffer, 0 indicates kernel space* @maskp: 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.* Error values:* %-EINVAL: second number in range smaller than first* %-EINVAL: invalid character in string* %-ERANGE: bit number specified too large for mask*/static int __bitmap_parselist(const char *buf, unsigned int buflen,int is_user, unsigned long *maskp,int nmaskbits){unsigned a, b;int c, old_c, totaldigits;const char __user __force *ubuf = (const char __user __force *)buf;int exp_digit, in_range;totaldigits = c = 0;bitmap_zero(maskp, nmaskbits);do {exp_digit = 1;in_range = 0;a = b = 0;/* Get the next cpu# or a range of cpu#'s */while (buflen) {old_c = c;if (is_user) {if (__get_user(c, ubuf++))return -EFAULT;} elsec = *buf++;buflen--;if (isspace(c))continue;/** If the last character was a space and the current* character isn't '0円', we've got embedded whitespace.* This is a no-no, so throw an error.*/if (totaldigits && c && isspace(old_c))return -EINVAL;/* A '0円' or a ',' signal the end of a cpu# or range */if (c == '0円' || c == ',')break;if (c == '-') {if (exp_digit || in_range)return -EINVAL;b = 0;in_range = 1;exp_digit = 1;continue;}if (!isdigit(c))return -EINVAL;b = b * 10 + (c - '0');if (!in_range)a = b;exp_digit = 0;totaldigits++;}if (!(a <= b))return -EINVAL;if (b >= nmaskbits)return -ERANGE;while (a <= b) {set_bit(a, maskp);a++;}} while (buflen && c == ',');return 0;}int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits){char *nl = strchrnul(bp, '\n');int len = nl - bp;return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);}EXPORT_SYMBOL(bitmap_parselist);/*** bitmap_parselist_user()** @ubuf: pointer to user buffer containing string.* @ulen: buffer size in bytes. If string is smaller than this* then it must be terminated with a 0円.* @maskp: pointer to bitmap array that will contain result.* @nmaskbits: size of bitmap, in bits.** Wrapper for bitmap_parselist(), providing it with user buffer.** We cannot have this as an inline function in bitmap.h because it needs* linux/uaccess.h to get the access_ok() declaration and this causes* cyclic dependencies.*/int bitmap_parselist_user(const char __user *ubuf,unsigned int ulen, unsigned long *maskp,int nmaskbits){if (!access_ok(VERIFY_READ, ubuf, ulen))return -EFAULT;return __bitmap_parselist((const char __force *)ubuf,ulen, 1, maskp, nmaskbits);}EXPORT_SYMBOL(bitmap_parselist_user);/*** bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap* @buf: pointer to a bitmap* @pos: a bit position in @buf (0 <= @pos < @nbits)* @nbits: number of valid bit positions in @buf** Map the bit at position @pos in @buf (of length @nbits) 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 -1. 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, unsigned int pos, unsigned int nbits){if (pos >= nbits || !test_bit(pos, buf))return -1;return __bitmap_weight(buf, pos);}/*** bitmap_ord_to_pos - find position of n-th set bit in bitmap* @buf: pointer to bitmap* @ord: ordinal bit position (n-th set bit, n >= 0)* @nbits: 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). If @ord* >= weight(buf), returns @nbits.** 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 returns @nbits. 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 @nbits-1 are valid positions in @buf.*/unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits){unsigned int pos;for (pos = find_first_bit(buf, nbits);pos < nbits && ord;pos = find_next_bit(buf, nbits, pos + 1))ord--;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* @nbits: 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,unsigned int nbits){unsigned int oldbit, w;if (dst == src) /* following doesn't handle inplace remaps */return;bitmap_zero(dst, nbits);w = bitmap_weight(new, nbits);for_each_set_bit(oldbit, src, nbits) {int n = bitmap_pos_to_ord(old, oldbit, nbits);if (n < 0 || w == 0)set_bit(oldbit, dst); /* identity map */elseset_bit(bitmap_ord_to_pos(new, n % w, nbits), 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;elsereturn bitmap_ord_to_pos(new, n % w, bits);}EXPORT_SYMBOL(bitmap_bitremap);/*** bitmap_onto - translate one bitmap relative to another* @dst: resulting translated bitmap* @orig: original untranslated bitmap* @relmap: bitmap relative to which translated* @bits: number of bits in each of these bitmaps** Set the n-th bit of @dst iff there exists some m such that the* n-th bit of @relmap is set, the m-th bit of @orig is set, and* the n-th bit of @relmap is also the m-th _set_ bit of @relmap.* (If you understood the previous sentence the first time your* read it, you're overqualified for your current job.)** In other words, @orig is mapped onto (surjectively) @dst,* using the map { <n, m> | the n-th bit of @relmap is the* m-th set bit of @relmap }.** Any set bits in @orig above bit number W, where W is the* weight of (number of set bits in) @relmap are mapped nowhere.* In particular, if for all bits m set in @orig, m >= W, then* @dst will end up empty. In situations where the possibility* of such an empty result is not desired, one way to avoid it is* to use the bitmap_fold() operator, below, to first fold the* @orig bitmap over itself so that all its set bits x are in the* range 0 <= x < W. The bitmap_fold() operator does this by* setting the bit (m % W) in @dst, for each bit (m) set in @orig.** Example [1] for bitmap_onto():* Let's say @relmap has bits 30-39 set, and @orig has bits* 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,* @dst will have bits 31, 33, 35, 37 and 39 set.** When bit 0 is set in @orig, it means turn on the bit in* @dst corresponding to whatever is the first bit (if any)* that is turned on in @relmap. Since bit 0 was off in the* above example, we leave off that bit (bit 30) in @dst.** When bit 1 is set in @orig (as in the above example), it* means turn on the bit in @dst corresponding to whatever* is the second bit that is turned on in @relmap. The second* bit in @relmap that was turned on in the above example was* bit 31, so we turned on bit 31 in @dst.** Similarly, we turned on bits 33, 35, 37 and 39 in @dst,* because they were the 4th, 6th, 8th and 10th set bits* set in @relmap, and the 4th, 6th, 8th and 10th bits of* @orig (i.e. bits 3, 5, 7 and 9) were also set.** When bit 11 is set in @orig, it means turn on the bit in* @dst corresponding to whatever is the twelfth bit that is* turned on in @relmap. In the above example, there were* only ten bits turned on in @relmap (30..39), so that bit* 11 was set in @orig had no affect on @dst.** Example [2] for bitmap_fold() + bitmap_onto():* Let's say @relmap has these ten bits set:* 40 41 42 43 45 48 53 61 74 95* (for the curious, that's 40 plus the first ten terms of the* Fibonacci sequence.)** Further lets say we use the following code, invoking* bitmap_fold() then bitmap_onto, as suggested above to* avoid the possibility of an empty @dst result:** unsigned long *tmp; // a temporary bitmap's bits** bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);* bitmap_onto(dst, tmp, relmap, bits);** Then this table shows what various values of @dst would be, for* various @orig's. I list the zero-based positions of each set bit.* The tmp column shows the intermediate result, as computed by* using bitmap_fold() to fold the @orig bitmap modulo ten* (the weight of @relmap).** @orig tmp @dst* 0 0 40* 1 1 41* 9 9 95* 10 0 40 (*)* 1 3 5 7 1 3 5 7 41 43 48 61* 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45* 0 9 18 27 0 9 8 7 40 61 74 95* 0 10 20 30 0 40* 0 11 22 33 0 1 2 3 40 41 42 43* 0 12 24 36 0 2 4 6 40 42 45 53* 78 102 211 1 2 8 41 42 74 (*)** (*) For these marked lines, if we hadn't first done bitmap_fold()* into tmp, then the @dst result would have been empty.** If either of @orig or @relmap is empty (no set bits), then @dst* will be returned empty.** If (as explained above) the only set bits in @orig are in positions* m where m >= W, (where W is the weight of @relmap) then @dst will* once again be returned empty.** All bits in @dst not set by the above rule are cleared.*/void bitmap_onto(unsigned long *dst, const unsigned long *orig,const unsigned long *relmap, unsigned int bits){unsigned int n, m; /* same meaning as in above comment */if (dst == orig) /* following doesn't handle inplace mappings */return;bitmap_zero(dst, bits);/** The following code is a more efficient, but less* obvious, equivalent to the loop:* for (m = 0; m < bitmap_weight(relmap, bits); m++) {* n = bitmap_ord_to_pos(orig, m, bits);* if (test_bit(m, orig))* set_bit(n, dst);* }*/m = 0;for_each_set_bit(n, relmap, bits) {/* m == bitmap_pos_to_ord(relmap, n, bits) */if (test_bit(m, orig))set_bit(n, dst);m++;}}EXPORT_SYMBOL(bitmap_onto);/*** bitmap_fold - fold larger bitmap into smaller, modulo specified size* @dst: resulting smaller bitmap* @orig: original larger bitmap* @sz: specified size* @nbits: number of bits in each of these bitmaps** For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.* Clear all other bits in @dst. See further the comment and* Example [2] for bitmap_onto() for why and how to use this.*/void bitmap_fold(unsigned long *dst, const unsigned long *orig,unsigned int sz, unsigned int nbits){unsigned int oldbit;if (dst == orig) /* following doesn't handle inplace mappings */return;bitmap_zero(dst, nbits);for_each_set_bit(oldbit, orig, nbits)set_bit(oldbit % sz, dst);}EXPORT_SYMBOL(bitmap_fold);/** 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, unsigned 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, unsigned int bits, int order){unsigned int pos, end; /* scans bitmap by regions of size order */for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))continue;__reg_op(bitmap, pos, order, REG_OP_ALLOC);return pos;}return -ENOMEM;}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, unsigned 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, unsigned int pos, int order){if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))return -EBUSY;return __reg_op(bitmap, pos, order, REG_OP_ALLOC);}EXPORT_SYMBOL(bitmap_allocate_region);/*** bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.* @dst: destination buffer* @src: bitmap to copy* @nbits: number of bits in the bitmap** Require nbits % BITS_PER_LONG == 0.*/#ifdef __BIG_ENDIANvoid bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits){unsigned int i;for (i = 0; i < nbits/BITS_PER_LONG; i++) {if (BITS_PER_LONG == 64)dst[i] = cpu_to_le64(src[i]);elsedst[i] = cpu_to_le32(src[i]);}}EXPORT_SYMBOL(bitmap_copy_le);#endif
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