X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Ffind_next_bit.c;h=24c59ded47a05d5617e2fe2501077f990de1ec4b;hb=dfb0ae091479240c19bef4382026671776ca204e;hp=9c90853b4472b85eb9b7d17e56ae69182f718467;hpb=c7f612cdf091def01454e7e132c7d7a3f419fbc4;p=linux-2.6 diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c index 9c90853b44..24c59ded47 100644 --- a/lib/find_next_bit.c +++ b/lib/find_next_bit.c @@ -12,17 +12,16 @@ #include #include #include +#include #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) -/** - * find_next_bit - find the next set bit in a memory region - * @addr: The address to base the search on - * @offset: The bitnumber to start searching at - * @size: The maximum size to search +#ifdef CONFIG_GENERIC_FIND_NEXT_BIT +/* + * Find the next set bit in a memory region. */ unsigned long find_next_bit(const unsigned long *addr, unsigned long size, - unsigned long offset) + unsigned long offset) { const unsigned long *p = addr + BITOP_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG-1); @@ -59,7 +58,6 @@ found_first: found_middle: return result + __ffs(tmp); } - EXPORT_SYMBOL(find_next_bit); /* @@ -67,7 +65,7 @@ EXPORT_SYMBOL(find_next_bit); * Linus' asm-alpha/bitops.h. */ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, - unsigned long offset) + unsigned long offset) { const unsigned long *p = addr + BITOP_WORD(offset); unsigned long result = offset & ~(BITS_PER_LONG-1); @@ -104,5 +102,174 @@ found_first: found_middle: return result + ffz(tmp); } - EXPORT_SYMBOL(find_next_zero_bit); +#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */ + +#ifdef CONFIG_GENERIC_FIND_FIRST_BIT +/* + * Find the first set bit in a memory region. + */ +unsigned long find_first_bit(const unsigned long *addr, unsigned long size) +{ + const unsigned long *p = addr; + unsigned long result = 0; + unsigned long tmp; + + while (size & ~(BITS_PER_LONG-1)) { + if ((tmp = *(p++))) + goto found; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + + tmp = (*p) & (~0UL >> (BITS_PER_LONG - size)); + if (tmp == 0UL) /* Are any bits set? */ + return result + size; /* Nope. */ +found: + return result + __ffs(tmp); +} +EXPORT_SYMBOL(find_first_bit); + +/* + * Find the first cleared bit in a memory region. + */ +unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) +{ + const unsigned long *p = addr; + unsigned long result = 0; + unsigned long tmp; + + while (size & ~(BITS_PER_LONG-1)) { + if (~(tmp = *(p++))) + goto found; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + + tmp = (*p) | (~0UL << size); + if (tmp == ~0UL) /* Are any bits zero? */ + return result + size; /* Nope. */ +found: + return result + ffz(tmp); +} +EXPORT_SYMBOL(find_first_zero_bit); +#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */ + +#ifdef __BIG_ENDIAN + +/* include/linux/byteorder does not support "unsigned long" type */ +static inline unsigned long ext2_swabp(const unsigned long * x) +{ +#if BITS_PER_LONG == 64 + return (unsigned long) __swab64p((u64 *) x); +#elif BITS_PER_LONG == 32 + return (unsigned long) __swab32p((u32 *) x); +#else +#error BITS_PER_LONG not defined +#endif +} + +/* include/linux/byteorder doesn't support "unsigned long" type */ +static inline unsigned long ext2_swab(const unsigned long y) +{ +#if BITS_PER_LONG == 64 + return (unsigned long) __swab64((u64) y); +#elif BITS_PER_LONG == 32 + return (unsigned long) __swab32((u32) y); +#else +#error BITS_PER_LONG not defined +#endif +} + +unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned + long size, unsigned long offset) +{ + const unsigned long *p = addr + BITOP_WORD(offset); + unsigned long result = offset & ~(BITS_PER_LONG - 1); + unsigned long tmp; + + if (offset >= size) + return size; + size -= result; + offset &= (BITS_PER_LONG - 1UL); + if (offset) { + tmp = ext2_swabp(p++); + tmp |= (~0UL >> (BITS_PER_LONG - offset)); + if (size < BITS_PER_LONG) + goto found_first; + if (~tmp) + goto found_middle; + size -= BITS_PER_LONG; + result += BITS_PER_LONG; + } + + while (size & ~(BITS_PER_LONG - 1)) { + if (~(tmp = *(p++))) + goto found_middle_swap; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + tmp = ext2_swabp(p); +found_first: + tmp |= ~0UL << size; + if (tmp == ~0UL) /* Are any bits zero? */ + return result + size; /* Nope. Skip ffz */ +found_middle: + return result + ffz(tmp); + +found_middle_swap: + return result + ffz(ext2_swab(tmp)); +} + +EXPORT_SYMBOL(generic_find_next_zero_le_bit); + +unsigned long generic_find_next_le_bit(const unsigned long *addr, unsigned + long size, unsigned long offset) +{ + const unsigned long *p = addr + BITOP_WORD(offset); + unsigned long result = offset & ~(BITS_PER_LONG - 1); + unsigned long tmp; + + if (offset >= size) + return size; + size -= result; + offset &= (BITS_PER_LONG - 1UL); + if (offset) { + tmp = ext2_swabp(p++); + tmp &= (~0UL << offset); + if (size < BITS_PER_LONG) + goto found_first; + if (tmp) + goto found_middle; + size -= BITS_PER_LONG; + result += BITS_PER_LONG; + } + + while (size & ~(BITS_PER_LONG - 1)) { + tmp = *(p++); + if (tmp) + goto found_middle_swap; + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) + return result; + tmp = ext2_swabp(p); +found_first: + tmp &= (~0UL >> (BITS_PER_LONG - size)); + if (tmp == 0UL) /* Are any bits set? */ + return result + size; /* Nope. */ +found_middle: + return result + __ffs(tmp); + +found_middle_swap: + return result + __ffs(ext2_swab(tmp)); +} +EXPORT_SYMBOL(generic_find_next_le_bit); +#endif /* __BIG_ENDIAN */