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authorRalf Baechle <ralf@linux-mips.org>2005-07-12 12:50:30 +0000
committerRalf Baechle <ralf@linux-mips.org>2005-10-29 19:31:43 +0100
commit6590326505e3f7b4b57793e84760e9920c3c56b4 (patch)
tree920ab56cb70895393e57b356c28d6eb37932c63f
parente5de3b468795e4c58a9f0702630d28707b3ae011 (diff)
Use clz / dclz on MIPS32 / MIPS64 processors.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--include/asm-mips/bitops.h137
1 files changed, 115 insertions, 22 deletions
diff --git a/include/asm-mips/bitops.h b/include/asm-mips/bitops.h
index d9c02bd0b18..2ba20730a3e 100644
--- a/include/asm-mips/bitops.h
+++ b/include/asm-mips/bitops.h
@@ -546,17 +546,60 @@ static inline int test_bit(unsigned long nr, const volatile unsigned long *addr)
return 1UL & (addr[nr >> SZLONG_LOG] >> (nr & SZLONG_MASK));
}
+#ifdef CONFIG_CPU_MIPS32_R1
/*
- * ffz - find first zero in word.
+ * Return the bit position (0..31) of the most significant 1 bit in a word
+ * Returns -1 if no 1 bit exists
+ */
+static __inline__ int __ilog2(unsigned long x)
+{
+ int lz;
+
+ __asm__ (
+ " .set push \n"
+ " .set mips32 \n"
+ " clz %0, %1 \n"
+ " .set pop \n"
+ : "=r" (lz)
+ : "r" (x));
+
+ return 31 - lz;
+}
+#elif defined(CONFIG_CPU_MIPS64_R1)
+/*
+ * Return the bit position (0..63) of the most significant 1 bit in a word
+ * Returns -1 if no 1 bit exists
+ */
+static __inline__ int __ilog2(unsigned long x)
+{
+ int lz;
+
+ __asm__ (
+ " .set push \n"
+ " .set mips64 \n"
+ " dclz %0, %1 \n"
+ " .set pop \n"
+ : "=r" (lz)
+ : "r" (x));
+
+ return 63 - lz;
+}
+#endif
+
+/*
+ * __ffs - find first bit in word.
* @word: The word to search
*
- * Undefined if no zero exists, so code should check against ~0UL first.
+ * Returns 0..SZLONG-1
+ * Undefined if no bit exists, so code should check against 0 first.
*/
-static inline unsigned long ffz(unsigned long word)
+static inline unsigned long __ffs(unsigned long word)
{
+#if defined(CONFIG_CPU_MIPS32_R1) || defined(CONFIG_CPU_MIPS64_R1)
+ return __ilog2(word & -word);
+#else
int b = 0, s;
- word = ~word;
#ifdef CONFIG_32BIT
s = 16; if (word << 16 != 0) s = 0; b += s; word >>= s;
s = 8; if (word << 24 != 0) s = 0; b += s; word >>= s;
@@ -572,26 +615,87 @@ static inline unsigned long ffz(unsigned long word)
s = 2; if (word << 62 != 0) s = 0; b += s; word >>= s;
s = 1; if (word << 63 != 0) s = 0; b += s;
#endif
-
return b;
+#endif
}
/*
- * __ffs - find first bit in word.
+ * ffs - find first bit set.
* @word: The word to search
*
- * Undefined if no bit exists, so code should check against 0 first.
+ * Returns 1..SZLONG
+ * Returns 0 if no bit exists
*/
-static inline unsigned long __ffs(unsigned long word)
+
+static inline unsigned long ffs(unsigned long word)
{
- return ffz(~word);
+ if (!word)
+ return 0;
+
+ return __ffs(word) + 1;
}
/*
- * fls: find last bit set.
+ * ffz - find first zero in word.
+ * @word: The word to search
+ *
+ * Undefined if no zero exists, so code should check against ~0UL first.
*/
+static inline unsigned long ffz(unsigned long word)
+{
+ return __ffs (~word);
+}
+
+/*
+ * flz - find last zero in word.
+ * @word: The word to search
+ *
+ * Returns 0..SZLONG-1
+ * Undefined if no zero exists, so code should check against ~0UL first.
+ */
+static inline unsigned long flz(unsigned long word)
+{
+#if defined(CONFIG_CPU_MIPS32_R1) || defined(CONFIG_CPU_MIPS64_R1)
+ return __ilog2(~word);
+#else
+#if defined(CONFIG_32BIT)
+ int r = 31, s;
+ word = ~word;
+ s = 16; if ((word & 0xffff0000)) s = 0; r -= s; word <<= s;
+ s = 8; if ((word & 0xff000000)) s = 0; r -= s; word <<= s;
+ s = 4; if ((word & 0xf0000000)) s = 0; r -= s; word <<= s;
+ s = 2; if ((word & 0xc0000000)) s = 0; r -= s; word <<= s;
+ s = 1; if ((word & 0x80000000)) s = 0; r -= s;
+#endif
+#if defined(CONFIG_64BIT)
+ int r = 63, s;
+ word = ~word;
+ s = 32; if ((word & 0xffffffff00000000UL)) s = 0; r -= s; word <<= s;
+ s = 16; if ((word & 0xffff000000000000UL)) s = 0; r -= s; word <<= s;
+ s = 8; if ((word & 0xff00000000000000UL)) s = 0; r -= s; word <<= s;
+ s = 4; if ((word & 0xf000000000000000UL)) s = 0; r -= s; word <<= s;
+ s = 2; if ((word & 0xc000000000000000UL)) s = 0; r -= s; word <<= s;
+ s = 1; if ((word & 0x8000000000000000UL)) s = 0; r -= s;
+#endif
+ return r;
+#endif
+}
+
+/*
+ * fls - find last bit set.
+ * @word: The word to search
+ *
+ * Returns 1..SZLONG
+ * Returns 0 if no bit exists
+ */
+static inline unsigned long fls(unsigned long word)
+{
+ if (word == 0)
+ return 0;
+
+ return flz(~word) + 1;
+}
-#define fls(x) generic_fls(x)
/*
* find_next_zero_bit - find the first zero bit in a memory region
@@ -728,17 +832,6 @@ static inline int sched_find_first_bit(const unsigned long *b)
}
/*
- * 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).
- */
-
-#define ffs(x) generic_ffs(x)
-
-/*
* hweightN - returns the hamming weight of a N-bit word
* @x: the word to weigh
*