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authorwdenk <wdenk>2000-08-21 15:05:47 +0000
committerwdenk <wdenk>2000-08-21 15:05:47 +0000
commitb15cbc0be004d352d4dd661546847bd52fbf8a28 (patch)
tree73d4277296a2d00ca9b090c784584d94b3bc5bf8 /include/linux/bitops.h
parent40c855574cff21a97c01d8f8d2ee2b8436eebce2 (diff)
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Initial revision
Diffstat (limited to 'include/linux/bitops.h')
-rw-r--r--include/linux/bitops.h72
1 files changed, 72 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
new file mode 100644
index 0000000..b155b77
--- /dev/null
+++ b/include/linux/bitops.h
@@ -0,0 +1,72 @@
+#ifndef _LINUX_BITOPS_H
+#define _LINUX_BITOPS_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;
+}
+
+/*
+ * 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);
+}
+
+#include <asm/bitops.h>
+
+
+#endif