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authorAl Viro <viro@zeniv.linux.org.uk>2011-08-26 22:38:50 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-11-19 11:13:28 -0500
commitf1fd306a91f875e65af0e04855b23adda6831ac9 (patch)
tree3b3c733133f76ff212f81c9b71ea977169cb4fee /fs/minix/bitmap.c
parent016e8d44bc06dd3322f26712bdd3f3a6973592d0 (diff)
minixfs: kill manual hweight(), simplify
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/minix/bitmap.c')
-rw-r--r--fs/minix/bitmap.c41
1 files changed, 14 insertions, 27 deletions
diff --git a/fs/minix/bitmap.c b/fs/minix/bitmap.c
index 7c82c29429d7..ef175cb8cfd8 100644
--- a/fs/minix/bitmap.c
+++ b/fs/minix/bitmap.c
@@ -16,39 +16,26 @@
#include <linux/bitops.h>
#include <linux/sched.h>
-static const int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };
-
static DEFINE_SPINLOCK(bitmap_lock);
-static unsigned long count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
+/*
+ * bitmap consists of blocks filled with 16bit words
+ * bit set == busy, bit clear == free
+ * endianness is a mess, but for counting zero bits it really doesn't matter...
+ */
+static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
{
- unsigned i, j, sum = 0;
- struct buffer_head *bh;
- unsigned numblocks = minix_blocks_needed(numbits, blocksize);
-
- for (i=0; i<numblocks-1; i++) {
- if (!(bh=map[i]))
- return(0);
- for (j=0; j<bh->b_size; j++)
- sum += nibblemap[bh->b_data[j] & 0xf]
- + nibblemap[(bh->b_data[j]>>4) & 0xf];
- }
+ __u32 sum = 0;
+ unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
- if (numblocks==0 || !(bh=map[numblocks-1]))
- return(0);
- i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2;
- for (j=0; j<i; j++) {
- sum += nibblemap[bh->b_data[j] & 0xf]
- + nibblemap[(bh->b_data[j]>>4) & 0xf];
+ while (blocks--) {
+ unsigned words = blocksize / 2;
+ __u16 *p = (__u16 *)(*map++)->b_data;
+ while (words--)
+ sum += 16 - hweight16(*p++);
}
- i = numbits%16;
- if (i!=0) {
- i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
- sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
- sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
- }
- return(sum);
+ return sum;
}
void minix_free_block(struct inode *inode, unsigned long block)