Messages in this thread Patch in this message | | | Date | Fri, 20 Aug 2004 17:05:26 +1000 | From | Paul Mackerras <> | Subject | [PATCH] PPC64 Better little-endian bitops |
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Below patch reuses the big-endian bitops for the little endian ones, and moves the ext2_{set,clear}_bit_atomic functions to be truly atomic instead of lock based.
This requires that the bitmaps passed to the ext2_* bitop functions are 8-byte aligned. I have been assured that they will be 512-byte or 1024-byte aligned, and sparc and ppc32 also impose an alignment requirement on the bitmap.
Signed-off-by: Olof Johansson <olof@austin.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
diff -puN include/asm-ppc64/bitops.h~ext2-set-bit include/asm-ppc64/bitops.h --- linux-2.5/include/asm-ppc64/bitops.h~ext2-set-bit 2004-08-18 12:04:43.208963520 -0500 +++ linux-2.5-olof/include/asm-ppc64/bitops.h 2004-08-18 15:11:57.088963696 -0500 @@ -22,6 +22,15 @@ * it will be a bad memory reference since we want to store in chunks * of unsigned long (64 bits here) size. * + * There are a few little-endian macros used mostly for filesystem bitmaps, + * these work on similar bit arrays layouts, but byte-oriented: + * + * |7...0|15...8|23...16|31...24|39...32|47...40|55...48|63...56| + * + * The main difference is that bit 3-5 in the bit number field needs to be + * reversed compared to the big-endian bit fields. This can be achieved + * by XOR with 0b111000 (0x38). + * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version @@ -306,71 +315,34 @@ static __inline__ int test_le_bit(unsign return (ADDR[nr >> 3] >> (nr & 7)) & 1; } +#define test_and_clear_le_bit(nr, addr) \ + test_and_clear_bit((nr) ^ 0x38, (addr)) +#define test_and_set_le_bit(nr, addr) \ + test_and_set_bit((nr) ^ 0x38, (addr)) + /* * non-atomic versions */ -static __inline__ void __set_le_bit(unsigned long nr, unsigned long *addr) -{ - unsigned char *ADDR = (unsigned char *)addr; - ADDR += nr >> 3; - *ADDR |= 1 << (nr & 0x07); -} - -static __inline__ void __clear_le_bit(unsigned long nr, unsigned long *addr) -{ - unsigned char *ADDR = (unsigned char *)addr; - - ADDR += nr >> 3; - *ADDR &= ~(1 << (nr & 0x07)); -} - -static __inline__ int __test_and_set_le_bit(unsigned long nr, unsigned long *addr) -{ - int mask, retval; - unsigned char *ADDR = (unsigned char *)addr; - - ADDR += nr >> 3; - mask = 1 << (nr & 0x07); - retval = (mask & *ADDR) != 0; - *ADDR |= mask; - return retval; -} - -static __inline__ int __test_and_clear_le_bit(unsigned long nr, unsigned long *addr) -{ - int mask, retval; - unsigned char *ADDR = (unsigned char *)addr; - - ADDR += nr >> 3; - mask = 1 << (nr & 0x07); - retval = (mask & *ADDR) != 0; - *ADDR &= ~mask; - return retval; -} +#define __set_le_bit(nr, addr) \ + __set_bit((nr) ^ 0x38, (addr)) +#define __clear_le_bit(nr, addr) \ + __clear_bit((nr) ^ 0x38, (addr)) +#define __test_and_clear_le_bit(nr, addr) \ + __test_and_clear_bit((nr) ^ 0x38, (addr)) +#define __test_and_set_le_bit(nr, addr) \ + __test_and_set_bit((nr) ^ 0x38, (addr)) #define ext2_set_bit(nr,addr) \ - __test_and_set_le_bit((nr),(unsigned long*)addr) + __test_and_set_le_bit((nr), (unsigned long*)addr) #define ext2_clear_bit(nr, addr) \ - __test_and_clear_le_bit((nr),(unsigned long*)addr) + __test_and_clear_le_bit((nr), (unsigned long*)addr) + +#define ext2_set_bit_atomic(lock, nr, addr) \ + test_and_set_le_bit((nr), (unsigned long*)addr) +#define ext2_clear_bit_atomic(lock, nr, addr) \ + test_and_clear_le_bit((nr), (unsigned long*)addr) -#define ext2_set_bit_atomic(lock, nr, addr) \ - ({ \ - int ret; \ - spin_lock(lock); \ - ret = ext2_set_bit((nr), (addr)); \ - spin_unlock(lock); \ - ret; \ - }) - -#define ext2_clear_bit_atomic(lock, nr, addr) \ - ({ \ - int ret; \ - spin_lock(lock); \ - ret = ext2_clear_bit((nr), (addr)); \ - spin_unlock(lock); \ - ret; \ - }) #define ext2_test_bit(nr, addr) test_le_bit((nr),(unsigned long*)addr) #define ext2_find_first_zero_bit(addr, size) \ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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