linux-4.4.1/bitmap_find_free_region() の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-4.4.1/bitmap_find_free_region() へ行く。
  • 1 (2016-03-01 (火) 19:04:19)

参照元†

• linux-4.4.1/dma_alloc_from_coherent()

説明†

• パス: linux-4.4.1/lib/bitmap.c

• FIXME: これは何？
  • 説明

引数†

• unsigned long *bitmap
• unsigned int bits
• int order

返り値†

• int

参考†

実装†

/**
 * 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;
        }

• • linux-4.4.1/__reg_op()

        return -ENOMEM;
}
EXPORT_SYMBOL(bitmap_find_free_region);

• • linux-4.4.1/EXPORT_SYMBOL()

コメント†