minixfs: kill manual hweight(), simplify

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

2 files changed, 15 insertions, 28 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)
diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index 6415fe0d2385..26bbd55e82ea 100644
--- 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;