From 8903709b054a8dafe4e8c6d9a6444034d7aba36f Mon Sep 17 00:00:00 2001 From: Harvey Harrison Date: Wed, 7 Jan 2009 12:19:31 -0800 Subject: xtensa: introduce swab.h Fixes compile breakage as linux/byteorder.h was removed. Signed-off-by: Harvey Harrison Signed-off-by: Linus Torvalds --- arch/xtensa/include/asm/swab.h | 70 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 arch/xtensa/include/asm/swab.h (limited to 'arch/xtensa/include/asm/swab.h') diff --git a/arch/xtensa/include/asm/swab.h b/arch/xtensa/include/asm/swab.h new file mode 100644 index 00000000000..f50b697eb60 --- /dev/null +++ b/arch/xtensa/include/asm/swab.h @@ -0,0 +1,70 @@ +/* + * include/asm-xtensa/swab.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_SWAB_H +#define _XTENSA_SWAB_H + +#include +#include + +#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 + +#endif /* _XTENSA_SWAB_H */ -- cgit v1.2.3