diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-07 11:56:29 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-07 11:56:29 -0800 |
commit | 52fefcec97c25b15887e6a9a885ca54e7f7c0928 (patch) | |
tree | 4898112a7fb30c20a9da3aefe9fdc7fdebda57a6 /arch/xtensa/include/asm/byteorder.h | |
parent | a0e280e0f33f6c859a235fb69a875ed8f3420388 (diff) | |
parent | 5fee325e7d2bcbebf1cb38b4ff3a7aa3744c43e3 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/czankel/xtensa-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/czankel/xtensa-2.6:
xtensa: Update platform files to reflect new location of the header files.
xtensa: switch to packed struct unaligned access implementation
xtensa: Add xt2000 support files.
xtensa: move headers files to arch/xtensa/include
xtensa: use the new byteorder headers
Diffstat (limited to 'arch/xtensa/include/asm/byteorder.h')
-rw-r--r-- | arch/xtensa/include/asm/byteorder.h | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/arch/xtensa/include/asm/byteorder.h b/arch/xtensa/include/asm/byteorder.h new file mode 100644 index 000000000000..07d10ad364d1 --- /dev/null +++ b/arch/xtensa/include/asm/byteorder.h @@ -0,0 +1,80 @@ +/* + * include/asm-xtensa/byteorder.h + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2001 - 2005 Tensilica Inc. + */ + +#ifndef _XTENSA_BYTEORDER_H +#define _XTENSA_BYTEORDER_H + +#include <asm/types.h> +#include <linux/compiler.h> + +#ifdef __XTENSA_EL__ +# define __LITTLE_ENDIAN +#elif defined(__XTENSA_EB__) +# define __BIG_ENDIAN +#else +# error processor byte order undefined! +#endif + +#define __SWAB_64_THRU_32__ + +static inline __attribute_const__ __u32 __arch_swab32(__u32 x) +{ + __u32 res; + /* instruction sequence from Xtensa ISA release 2/2000 */ + __asm__("ssai 8 \n\t" + "srli %0, %1, 16 \n\t" + "src %0, %0, %1 \n\t" + "src %0, %0, %0 \n\t" + "src %0, %1, %0 \n" + : "=&a" (res) + : "a" (x) + ); + return res; +} +#define __arch_swab32 __arch_swab32 + +static inline __attribute_const__ __u16 __arch_swab16(__u16 x) +{ + /* Given that 'short' values are signed (i.e., can be negative), + * we cannot assume that the upper 16-bits of the register are + * zero. We are careful to mask values after shifting. + */ + + /* There exists an anomaly between xt-gcc and xt-xcc. xt-gcc + * inserts an extui instruction after putting this function inline + * to ensure that it uses only the least-significant 16 bits of + * the result. xt-xcc doesn't use an extui, but assumes the + * __asm__ macro follows convention that the upper 16 bits of an + * 'unsigned short' result are still zero. This macro doesn't + * follow convention; indeed, it leaves garbage in the upport 16 + * bits of the register. + + * Declaring the temporary variables 'res' and 'tmp' to be 32-bit + * types while the return type of the function is a 16-bit type + * forces both compilers to insert exactly one extui instruction + * (or equivalent) to mask off the upper 16 bits. */ + + __u32 res; + __u32 tmp; + + __asm__("extui %1, %2, 8, 8\n\t" + "slli %0, %2, 8 \n\t" + "or %0, %0, %1 \n" + : "=&a" (res), "=&a" (tmp) + : "a" (x) + ); + + return res; +} +#define __arch_swab16 __arch_swab16 + +#include <linux/byteorder.h> + +#endif /* _XTENSA_BYTEORDER_H */ |