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author | Dmitry Torokhov <dtor_core@ameritech.net> | 2006-04-02 07:08:05 +0200 |
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committer | Dmitry Torokhov <dtor_core@ameritech.net> | 2006-04-02 07:08:05 +0200 |
commit | 95d465fd750897ab32462a6702fbfe1b122cbbc0 (patch) | |
tree | 65c38b2f11c51bb6932e44dd6c92f15b0091abfe /lib/bitmap.c | |
parent | Input: gameport - fix memory leak (diff) | |
parent | Merge master.kernel.org:/home/rmk/linux-2.6-serial (diff) | |
download | linux-95d465fd750897ab32462a6702fbfe1b122cbbc0.tar.xz linux-95d465fd750897ab32462a6702fbfe1b122cbbc0.zip |
Manual merge with Linus.
Conflicts:
arch/powerpc/kernel/setup-common.c
drivers/input/keyboard/hil_kbd.c
drivers/input/mouse/hil_ptr.c
Diffstat (limited to 'lib/bitmap.c')
-rw-r--r-- | lib/bitmap.c | 182 |
1 files changed, 113 insertions, 69 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c index 48e708381d44..ed2ae3b0cd06 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -253,33 +253,18 @@ int __bitmap_subset(const unsigned long *bitmap1, } EXPORT_SYMBOL(__bitmap_subset); -#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]); + w += hweight_long(bitmap[k]); if (bits % BITS_PER_LONG) - w += hweight32(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); + w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits)); 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] & BITMAP_LAST_WORD_MASK(bits)); - - return w; -} -#endif EXPORT_SYMBOL(__bitmap_weight); /* @@ -676,84 +661,143 @@ int bitmap_bitremap(int oldbit, const unsigned long *old, } EXPORT_SYMBOL(bitmap_bitremap); -/** - * bitmap_find_free_region - find a contiguous aligned mem region - * @bitmap: an array of unsigned longs corresponding to the bitmap - * @bits: number of bits in the bitmap - * @order: region size to find (size is actually 1<<order) +/* + * 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 * - * This is used to allocate a memory region from a bitmap. The idea is - * that the region has to be 1<<order sized and 1<<order aligned (this - * makes the search algorithm much faster). + * Can set, verify and/or release a region of bits in a bitmap, + * depending on which combination of REG_OP_* flag bits is set. * - * The region is marked as set bits in the bitmap if a free one is - * found. + * 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 either beginning of region or negative error + * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). + * Returns 0 in all other cases and reg_ops. */ -int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) -{ - unsigned long mask; - int pages = 1 << order; - int i; - if(pages > BITS_PER_LONG) - return -EINVAL; +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 */ +}; - /* make a mask of the order */ - mask = (1ul << (pages - 1)); +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; - /* run up the bitmap pages bits at a time */ - for (i = 0; i < bits; i += pages) { - int index = i/BITS_PER_LONG; - int offset = i - (index * BITS_PER_LONG); - if((bitmap[index] & (mask << offset)) == 0) { - /* set region in bimap */ - bitmap[index] |= (mask << offset); - return i; + 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; } - return -ENOMEM; +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: a pointer to the bitmap - * @pos: the beginning of the region - * @order: the order of the bits to release (number is 1<<order) + * 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) { - int pages = 1 << order; - unsigned long mask = (1ul << (pages - 1)); - int index = pos/BITS_PER_LONG; - int offset = pos - (index * BITS_PER_LONG); - mask += mask - 1; - bitmap[index] &= ~(mask << offset); + __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) { - int pages = 1 << order; - unsigned long mask = (1ul << (pages - 1)); - int index = pos/BITS_PER_LONG; - int offset = pos - (index * BITS_PER_LONG); - - /* We don't do regions of pages > BITS_PER_LONG. The - * algorithm would be a simple look for multiple zeros in the - * array, but there's no driver today that needs this. If you - * trip this BUG(), you get to code it... */ - BUG_ON(pages > BITS_PER_LONG); - mask += mask - 1; - if (bitmap[index] & (mask << offset)) + if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE)) return -EBUSY; - bitmap[index] |= (mask << offset); + __reg_op(bitmap, pos, order, REG_OP_ALLOC); return 0; } EXPORT_SYMBOL(bitmap_allocate_region); |