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linux/arch/arm/include/asm/swab.h

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arm: introduce asm/swab.h Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 22:56:30 +00:00
/*
* arch/arm/include/asm/byteorder.h
*
* ARM Endian-ness. In little endian mode, the data bus is connected such
* that byte accesses appear as:
* 0 = d0...d7, 1 = d8...d15, 2 = d16...d23, 3 = d24...d31
* and word accesses (data or instruction) appear as:
* d0...d31
*
* When in big endian mode, byte accesses appear as:
* 0 = d24...d31, 1 = d16...d23, 2 = d8...d15, 3 = d0...d7
* and word accesses (data or instruction) appear as:
* d0...d31
*/
#ifndef __ASM_ARM_SWAB_H
#define __ASM_ARM_SWAB_H
UAPI: (Scripted) Disintegrate arch/arm/include/asm Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dave Jones <davej@redhat.com>
2012-10-12 12:05:52 +00:00
#include <uapi/asm/swab.h>
arm: introduce asm/swab.h Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 22:56:30 +00:00
UAPI: Split trivial #if defined(__KERNEL__) && X conditionals Split trivial #if defined(__KERNEL__) && X conditionals to make automated disintegration easier. Signed-off-by: David Howells <dhowells@redhat.com>
2011-12-13 15:07:49 +00:00
#if __LINUX_ARM_ARCH__ >= 6
ARM: 5772/1: Use REV and REV16 for byte swapping on ARMv6+ ARMv6 introduced the REV and REV16 instructions that reverse bytes in words and halfwords. Use them for the arch-specific implementation of the byte swapping helpers on ARMv6+. Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-10-25 15:55:33 +00:00
ARM: 7173/1: Add optimised swahb32() byteswap helper for v6 and above ARMv6 and later processors have the REV16 instruction, which swaps the bytes within each halfword of a register value. This is already used to implement swab16(), but since the native operation performaed by REV16 is actually swahb32(), this patch renames the existing swab16() helper accordingly and defines __arch_swab16() in terms of it. This allows calls to both swab16() and swahb32() to be optimised. The compiler's generated code might improve someday, but as of 4.5.2 the code generated for pure C implementing these 16-bit bytesswaps remains pessimal. swahb32() is useful for converting 32-bit Thumb instructions between integer and memory representation on BE8 platforms (among other uses). Signed-off-by: Dave Martin <dave.martin@linaro.org> Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-11-24 11:23:18 +00:00
static inline __attribute_const__ __u32 __arch_swahb32(__u32 x)
ARM: 5772/1: Use REV and REV16 for byte swapping on ARMv6+ ARMv6 introduced the REV and REV16 instructions that reverse bytes in words and halfwords. Use them for the arch-specific implementation of the byte swapping helpers on ARMv6+. Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-10-25 15:55:33 +00:00
{
__asm__ ("rev16 %0, %1" : "=r" (x) : "r" (x));
return x;
}
ARM: 7173/1: Add optimised swahb32() byteswap helper for v6 and above ARMv6 and later processors have the REV16 instruction, which swaps the bytes within each halfword of a register value. This is already used to implement swab16(), but since the native operation performaed by REV16 is actually swahb32(), this patch renames the existing swab16() helper accordingly and defines __arch_swab16() in terms of it. This allows calls to both swab16() and swahb32() to be optimised. The compiler's generated code might improve someday, but as of 4.5.2 the code generated for pure C implementing these 16-bit bytesswaps remains pessimal. swahb32() is useful for converting 32-bit Thumb instructions between integer and memory representation on BE8 platforms (among other uses). Signed-off-by: Dave Martin <dave.martin@linaro.org> Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-11-24 11:23:18 +00:00
#define __arch_swahb32 __arch_swahb32
#define __arch_swab16(x) ((__u16)__arch_swahb32(x))
ARM: 5772/1: Use REV and REV16 for byte swapping on ARMv6+ ARMv6 introduced the REV and REV16 instructions that reverse bytes in words and halfwords. Use them for the arch-specific implementation of the byte swapping helpers on ARMv6+. Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-10-25 15:55:33 +00:00
static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
{
__asm__ ("rev %0, %1" : "=r" (x) : "r" (x));
return x;
}
#define __arch_swab32 __arch_swab32
UAPI: Split trivial #if defined(__KERNEL__) && X conditionals Split trivial #if defined(__KERNEL__) && X conditionals to make automated disintegration easier. Signed-off-by: David Howells <dhowells@redhat.com>
2011-12-13 15:07:49 +00:00
#endif
#endif
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