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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-generic/bitops.h
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/asm-generic/bitops.h')
-rw-r--r--include/asm-generic/bitops.h81
1 files changed, 81 insertions, 0 deletions
diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h
new file mode 100644
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+++ b/include/asm-generic/bitops.h
@@ -0,0 +1,81 @@
+#ifndef _ASM_GENERIC_BITOPS_H_
+#define _ASM_GENERIC_BITOPS_H_
+
+/*
+ * For the benefit of those who are trying to port Linux to another
+ * architecture, here are some C-language equivalents. You should
+ * recode these in the native assembly language, if at all possible.
+ * To guarantee atomicity, these routines call cli() and sti() to
+ * disable interrupts while they operate. (You have to provide inline
+ * routines to cli() and sti().)
+ *
+ * Also note, these routines assume that you have 32 bit longs.
+ * You will have to change this if you are trying to port Linux to the
+ * Alpha architecture or to a Cray. :-)
+ *
+ * C language equivalents written by Theodore Ts'o, 9/26/92
+ */
+
+extern __inline__ int set_bit(int nr,long * addr)
+{
+ int mask, retval;
+
+ addr += nr >> 5;
+ mask = 1 << (nr & 0x1f);
+ cli();
+ retval = (mask & *addr) != 0;
+ *addr |= mask;
+ sti();
+ return retval;
+}
+
+extern __inline__ int clear_bit(int nr, long * addr)
+{
+ int mask, retval;
+
+ addr += nr >> 5;
+ mask = 1 << (nr & 0x1f);
+ cli();
+ retval = (mask & *addr) != 0;
+ *addr &= ~mask;
+ sti();
+ return retval;
+}
+
+extern __inline__ int test_bit(int nr, const unsigned long * addr)
+{
+ int mask;
+
+ addr += nr >> 5;
+ mask = 1 << (nr & 0x1f);
+ return ((mask & *addr) != 0);
+}
+
+/*
+ * fls: find last bit set.
+ */
+
+#define fls(x) generic_fls(x)
+
+#ifdef __KERNEL__
+
+/*
+ * 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).
+ */
+
+#define ffs(x) generic_ffs(x)
+
+/*
+ * hweightN: returns the hamming weight (i.e. the number
+ * of bits set) of a N-bit word
+ */
+
+#define hweight32(x) generic_hweight32(x)
+#define hweight16(x) generic_hweight16(x)
+#define hweight8(x) generic_hweight8(x)
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_GENERIC_BITOPS_H */