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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 02:20:36 +0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 02:20:36 +0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/bitops.h
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'include/linux/bitops.h')
-rw-r--r--include/linux/bitops.h159
1 files changed, 159 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
new file mode 100644
index 000000000000..cb3c3ef50f50
--- /dev/null
+++ b/include/linux/bitops.h
@@ -0,0 +1,159 @@
+#ifndef _LINUX_BITOPS_H
+#define _LINUX_BITOPS_H
+#include <asm/types.h>
+
+/*
+ * ffs: find first bit set. This is defined the same way as
+ * the libc and compiler builtin ffs routines, therefore
+ * differs in spirit from the above ffz (man ffs).
+ */
+
+static inline int generic_ffs(int x)
+{
+ int r = 1;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff)) {
+ x >>= 16;
+ r += 16;
+ }
+ if (!(x & 0xff)) {
+ x >>= 8;
+ r += 8;
+ }
+ if (!(x & 0xf)) {
+ x >>= 4;
+ r += 4;
+ }
+ if (!(x & 3)) {
+ x >>= 2;
+ r += 2;
+ }
+ if (!(x & 1)) {
+ x >>= 1;
+ r += 1;
+ }
+ return r;
+}
+
+/*
+ * fls: find last bit set.
+ */
+
+static __inline__ int generic_fls(int x)
+{
+ int r = 32;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff0000u)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xff000000u)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xf0000000u)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xc0000000u)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x80000000u)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+
+/*
+ * Include this here because some architectures need generic_ffs/fls in
+ * scope
+ */
+#include <asm/bitops.h>
+
+static __inline__ int get_bitmask_order(unsigned int count)
+{
+ int order;
+
+ order = fls(count);
+ return order; /* We could be slightly more clever with -1 here... */
+}
+
+/*
+ * hweightN: returns the hamming weight (i.e. the number
+ * of bits set) of a N-bit word
+ */
+
+static inline unsigned int generic_hweight32(unsigned int w)
+{
+ unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
+ res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
+ res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
+ res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
+ return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
+}
+
+static inline unsigned int generic_hweight16(unsigned int w)
+{
+ unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
+ res = (res & 0x3333) + ((res >> 2) & 0x3333);
+ res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
+ return (res & 0x00FF) + ((res >> 8) & 0x00FF);
+}
+
+static inline unsigned int generic_hweight8(unsigned int w)
+{
+ unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
+ res = (res & 0x33) + ((res >> 2) & 0x33);
+ return (res & 0x0F) + ((res >> 4) & 0x0F);
+}
+
+static inline unsigned long generic_hweight64(__u64 w)
+{
+#if BITS_PER_LONG < 64
+ return generic_hweight32((unsigned int)(w >> 32)) +
+ generic_hweight32((unsigned int)w);
+#else
+ u64 res;
+ res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul);
+ res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
+ res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful);
+ res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul);
+ res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul);
+ return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul);
+#endif
+}
+
+static inline unsigned long hweight_long(unsigned long w)
+{
+ return sizeof(w) == 4 ? generic_hweight32(w) : generic_hweight64(w);
+}
+
+/*
+ * rol32 - rotate a 32-bit value left
+ *
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline __u32 rol32(__u32 word, unsigned int shift)
+{
+ return (word << shift) | (word >> (32 - shift));
+}
+
+/*
+ * ror32 - rotate a 32-bit value right
+ *
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline __u32 ror32(__u32 word, unsigned int shift)
+{
+ return (word >> shift) | (word << (32 - shift));
+}
+
+#endif