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authorCatalin Marinas <catalin.marinas@arm.com>2012-09-12 23:00:53 +0200
committerCatalin Marinas <catalin.marinas@arm.com>2012-09-14 18:15:41 +0200
commit048fa2df92c325cb4425dccd66c8922c8342b507 (patch)
treea76ddbd3f05752f27e0867906a34e102cb76b4e4 /include/asm-generic
parentfs: Build sys_stat64() and friends if __ARCH_WANT_COMPAT_STAT64 (diff)
downloadlinux-048fa2df92c325cb4425dccd66c8922c8342b507.tar.xz
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generic: Implement generic ffs/fls using __builtin_* functions
This patch implements ffs, __ffs, fls, __fls using __builtin_* gcc functions. These header files can be used by other architectures that rely on the gcc builtins. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/bitops/builtin-__ffs.h15
-rw-r--r--include/asm-generic/bitops/builtin-__fls.h15
-rw-r--r--include/asm-generic/bitops/builtin-ffs.h17
-rw-r--r--include/asm-generic/bitops/builtin-fls.h16
4 files changed, 63 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/builtin-__ffs.h b/include/asm-generic/bitops/builtin-__ffs.h
new file mode 100644
index 000000000000..90041e3a41f0
--- /dev/null
+++ b/include/asm-generic/bitops/builtin-__ffs.h
@@ -0,0 +1,15 @@
+#ifndef _ASM_GENERIC_BITOPS_BUILTIN___FFS_H_
+#define _ASM_GENERIC_BITOPS_BUILTIN___FFS_H_
+
+/**
+ * __ffs - find first bit in word.
+ * @word: The word to search
+ *
+ * Undefined if no bit exists, so code should check against 0 first.
+ */
+static __always_inline unsigned long __ffs(unsigned long word)
+{
+ return __builtin_ctzl(word);
+}
+
+#endif
diff --git a/include/asm-generic/bitops/builtin-__fls.h b/include/asm-generic/bitops/builtin-__fls.h
new file mode 100644
index 000000000000..0248f386635f
--- /dev/null
+++ b/include/asm-generic/bitops/builtin-__fls.h
@@ -0,0 +1,15 @@
+#ifndef _ASM_GENERIC_BITOPS_BUILTIN___FLS_H_
+#define _ASM_GENERIC_BITOPS_BUILTIN___FLS_H_
+
+/**
+ * __fls - find last (most-significant) set bit in a long word
+ * @word: the word to search
+ *
+ * Undefined if no set bit exists, so code should check against 0 first.
+ */
+static __always_inline unsigned long __fls(unsigned long word)
+{
+ return (sizeof(word) * 8) - 1 - __builtin_clzl(word);
+}
+
+#endif
diff --git a/include/asm-generic/bitops/builtin-ffs.h b/include/asm-generic/bitops/builtin-ffs.h
new file mode 100644
index 000000000000..064825829e1c
--- /dev/null
+++ b/include/asm-generic/bitops/builtin-ffs.h
@@ -0,0 +1,17 @@
+#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
+#define _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
+
+/**
+ * ffs - find first bit set
+ * @x: the word to search
+ *
+ * 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 __always_inline int ffs(int x)
+{
+ return __builtin_ffs(x);
+}
+
+#endif
diff --git a/include/asm-generic/bitops/builtin-fls.h b/include/asm-generic/bitops/builtin-fls.h
new file mode 100644
index 000000000000..eda652d0ac7f
--- /dev/null
+++ b/include/asm-generic/bitops/builtin-fls.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_
+#define _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_
+
+/**
+ * fls - find last (most-significant) bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as ffs.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ */
+static __always_inline int fls(int x)
+{
+ return x ? sizeof(x) * 8 - __builtin_clz(x) : 0;
+}
+
+#endif