minixfs: kill manual hweight(), simplify

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/minix/bitmap.c b/fs/minix/bitmap.c
index 7c82c29..ef175cb 100644 (file)
--- 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)

diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index 6415fe0..26bbd55 100644 (file)
--- a/fs/minix/minix.h
+++ b/fs/minix/minix.h
@@ -130,7 +130,7 @@ static inline int minix_find_first_zero_bit(const void *vaddr, unsigned size)
        if (!size)
                return 0;
 
-       size = (size >> 4) + ((size & 15) > 0);
+       size >>= 4;
        while (*p++ == 0xffff) {
                if (--size == 0)
                        return (p - addr) << 4;