ChangeSet 1.1589, 2005/05/29 14:57:27+01:00, kaf24@xxxxxxxxxxxxxxxxxxxx
More bitop cleanups and code improvements.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
arch/x86/bitops.c | 99 ++++++++++++++++++++++++++++++++++
include/asm-x86/bitops.h | 134 ++++++++++++++---------------------------------
2 files changed, 140 insertions(+), 93 deletions(-)
diff -Nru a/xen/arch/x86/bitops.c b/xen/arch/x86/bitops.c
--- /dev/null Wed Dec 31 16:00:00 196900
+++ b/xen/arch/x86/bitops.c 2005-05-29 10:02:35 -04:00
@@ -0,0 +1,99 @@
+
+#include <xen/bitops.h>
+#include <xen/lib.h>
+
+unsigned long __find_first_bit(
+ const unsigned long *addr, unsigned long size)
+{
+ unsigned long d0, d1, res;
+
+ __asm__ __volatile__ (
+ " xor %%eax,%%eax\n\t" /* also ensures ZF==1 if size==0 */
+ " repe; scas"__OS"\n\t"
+ " je 1f\n\t"
+ " lea -"STR(BITS_PER_LONG/8)"(%2),%2\n\t"
+ " bsf (%2),%0\n"
+ "1: sub %5,%2\n\t"
+ " shl $3,%2\n\t"
+ " add %2,%0"
+ : "=&a" (res), "=&c" (d0), "=&D" (d1)
+ : "1" ((size + BITS_PER_LONG - 1) / BITS_PER_LONG),
+ "2" (addr), "b" (addr) : "memory" );
+
+ return res;
+}
+
+unsigned long __find_next_bit(
+ const unsigned long *addr, unsigned long size, unsigned long offset)
+{
+ const unsigned long *p = addr + (offset / BITS_PER_LONG);
+ unsigned long set, bit = offset & (BITS_PER_LONG - 1);
+
+ ASSERT(offset < size);
+
+ if ( bit != 0 )
+ {
+ /* Look for a bit in the first word. */
+ __asm__ ( "bsf %1,%0"
+ : "=r" (set) : "r" (*p >> bit), "0" (BITS_PER_LONG) );
+ if ( set < (BITS_PER_LONG - bit) )
+ return (offset + set);
+ offset += BITS_PER_LONG - bit;
+ p++;
+ }
+
+ if ( offset >= size )
+ return size;
+
+ /* Search remaining full words for a bit. */
+ set = __find_first_bit(p, size - offset);
+ return (offset + set);
+}
+
+unsigned long __find_first_zero_bit(
+ const unsigned long *addr, unsigned long size)
+{
+ unsigned long d0, d1, d2, res;
+
+ __asm__ (
+ " xor %%edx,%%edx\n\t" /* also ensures ZF==1 if size==0 */
+ " repe; scas"__OS"\n\t"
+ " je 1f\n\t"
+ " lea -"STR(BITS_PER_LONG/8)"(%2),%2\n\t"
+ " xor (%2),%3\n\t"
+ " bsf %3,%0\n"
+ "1: sub %6,%2\n\t"
+ " shl $3,%2\n\t"
+ " add %2,%0"
+ : "=&d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
+ : "1" ((size + BITS_PER_LONG - 1) / BITS_PER_LONG),
+ "2" (addr), "b" (addr), "3" (-1L) : "memory" );
+
+ return res;
+}
+
+unsigned long __find_next_zero_bit(
+ const unsigned long *addr, unsigned long size, unsigned long offset)
+{
+ const unsigned long *p = addr + (offset / BITS_PER_LONG);
+ unsigned long set, bit = offset & (BITS_PER_LONG - 1);
+
+ ASSERT(offset < size);
+
+ if ( bit != 0 )
+ {
+ /* Look for zero in the first word. */
+ __asm__ ( "bsf %1,%0" : "=r" (set) : "r" (~(*p >> bit)) );
+ if ( set < (BITS_PER_LONG - bit) )
+ return (offset + set);
+ offset += BITS_PER_LONG - bit;
+ p++;
+ }
+
+ if ( offset >= size )
+ return size;
+
+ /* Search remaining full words for a zero. */
+ set = __find_first_zero_bit(p, size - offset);
+ return (offset + set);
+}
diff -Nru a/xen/include/asm-x86/bitops.h b/xen/include/asm-x86/bitops.h
--- a/xen/include/asm-x86/bitops.h 2005-05-29 10:02:35 -04:00
+++ b/xen/include/asm-x86/bitops.h 2005-05-29 10:02:35 -04:00
@@ -248,46 +248,23 @@
constant_test_bit((nr),(addr)) : \
variable_test_bit((nr),(addr)))
-/**
- * find_first_zero_bit - find the first zero bit in a memory region
- * @addr: The address to start the search at
- * @size: The maximum size to search
- *
- * Returns the bit-number of the first zero bit, not the number of the byte
- * containing a bit.
- */
-static inline long find_first_zero_bit(
- const unsigned long *addr, unsigned size)
-{
- long d0, d1, d2;
- long res;
+extern unsigned long __find_first_bit(
+ const unsigned long *addr, unsigned long size);
+extern unsigned long __find_next_bit(
+ const unsigned long *addr, unsigned long size, unsigned long offset);
+extern unsigned long __find_first_zero_bit(
+ const unsigned long *addr, unsigned long size);
+extern unsigned long __find_next_zero_bit(
+ const unsigned long *addr, unsigned long size, unsigned long offset);
- __asm__ __volatile__(
- "mov $-1,%%"__OP"ax\n\t"
- "xor %%edx,%%edx\n\t"
- "repe; scas"__OS"\n\t"
- "je 1f\n\t"
- "lea -"STR(BITS_PER_LONG/8)"(%%"__OP"di),%%"__OP"di\n\t"
- "xor (%%"__OP"di),%%"__OP"ax\n\t"
- "bsf %%"__OP"ax,%%"__OP"dx\n"
- "1:\tsub %%"__OP"bx,%%"__OP"di\n\t"
- "shl $3,%%"__OP"di\n\t"
- "add %%"__OP"di,%%"__OP"dx"
- :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
- :"1" ((size + BITS_PER_LONG - 1) / BITS_PER_LONG),
- "2" (addr), "b" (addr) : "memory");
- return res;
+/* return index of first bit set in val or BITS_PER_LONG when no bit is set */
+static inline unsigned long __scanbit(unsigned long val)
+{
+ __asm__ ( "bsf %1,%0" : "=r" (val) : "r" (val), "0" (BITS_PER_LONG) );
+ return val;
}
/**
- * find_next_zero_bit - find the first zero bit in a memory region
- * @addr: The address to base the search on
- * @offset: The bitnumber to start searching at
- * @size: The maximum size to search
- */
-long find_next_zero_bit(const unsigned long *addr, int size, int offset);
-
-/**
* find_first_bit - find the first set bit in a memory region
* @addr: The address to start the search at
* @size: The maximum size to search
@@ -295,26 +272,10 @@
* Returns the bit-number of the first set bit, not the number of the byte
* containing a bit.
*/
-static inline long find_first_bit(
- const unsigned long *addr, unsigned size)
-{
- long d0, d1;
- long res;
-
- __asm__ __volatile__(
- "xor %%eax,%%eax\n\t"
- "repe; scas"__OS"\n\t"
- "je 1f\n\t"
- "lea -"STR(BITS_PER_LONG/8)"(%%"__OP"di),%%"__OP"di\n\t"
- "bsf (%%"__OP"di),%%"__OP"ax\n"
- "1:\tsub %%"__OP"bx,%%"__OP"di\n\t"
- "shl $3,%%"__OP"di\n\t"
- "add %%"__OP"di,%%"__OP"ax"
- :"=a" (res), "=&c" (d0), "=&D" (d1)
- :"1" ((size + BITS_PER_LONG - 1) / BITS_PER_LONG),
- "2" (addr), "b" (addr) : "memory");
- return res;
-}
+#define find_first_bit(addr,size) \
+((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
+ (__scanbit(*(unsigned long *)addr)) : \
+ __find_first_bit(addr,size)))
/**
* find_next_bit - find the first set bit in a memory region
@@ -322,45 +283,46 @@
* @offset: The bitnumber to start searching at
* @size: The maximum size to search
*/
-long find_next_bit(const unsigned long *addr, int size, int offset);
-
-/* return index of first bet set in val or BITS_PER_LONG when no bit is set */
-static inline unsigned long __scanbit(unsigned long val)
-{
- asm("bsf %1,%0" : "=&r" (val) : "r" (val), "0" (BITS_PER_LONG));
- return val;
-}
-
-#define find_first_bit(addr,size) \
-((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
- (__scanbit(*(unsigned long *)addr)) : \
- find_first_bit(addr,size)))
-
#define find_next_bit(addr,size,off) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
((off) + (__scanbit((*(unsigned long *)addr) >> (off)))) : \
- find_next_bit(addr,size,off)))
+ __find_next_bit(addr,size,off)))
+/**
+ * find_first_zero_bit - find the first zero bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum size to search
+ *
+ * Returns the bit-number of the first zero bit, not the number of the byte
+ * containing a bit.
+ */
#define find_first_zero_bit(addr,size) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
(__scanbit(~*(unsigned long *)addr)) : \
- find_first_zero_bit(addr,size)))
+ __find_first_zero_bit(addr,size)))
+/**
+ * find_next_zero_bit - find the first zero bit in a memory region
+ * @addr: The address to base the search on
+ * @offset: The bitnumber to start searching at
+ * @size: The maximum size to search
+ */
#define find_next_zero_bit(addr,size,off) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
((off)+(__scanbit(~(((*(unsigned long *)addr)) >> (off))))) : \
- find_next_zero_bit(addr,size,off)))
+ __find_next_zero_bit(addr,size,off)))
-/*
- * Return index of first non-zero bit in @word (counting l.s.b. as 0).
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