linux-stable/arch/mips/lib/bswapsi.c

#include <linux/module.h>

unsigned int __bswapsi2(unsigned int u)
{
	return (((u) & 0xff000000) >> 24) |
	       (((u) & 0x00ff0000) >>  8) |
	       (((u) & 0x0000ff00) <<  8) |
	       (((u) & 0x000000ff) << 24);
}

EXPORT_SYMBOL(__bswapsi2);
MIPS: Use ARCH_USE_BUILTIN_BSWAP. ARCH_USE_BUILTIN_BSWAP will use __builtin_bswap16(), __builtin_bswap32() and __builtin_bswap64() where available. This allows better instruction scheduling. On pre-R2 processors it will result in 32 bit and 64 bit swapping being performed in a call to a __bswapsi2() rsp. __bswapdi2() functions, so we add these, too. For a 4.2 kernel with GCC 4.9 this yields the following kernel sizes: text data bss dec hex filename 3996071 155804 88992 4240867 40b5e3 vmlinux ip22 baseline 3985687 159900 88992 4234579 409d53 vmlinux ip22 + bswap patch 6913157 378552 251024 7542733 7317cd vmlinux ip27 baseline 6878581 378552 251024 7508157 7290bd vmlinux ip27 + bswap patch 5773777 268752 187424 6229953 5f0fc1 vmlinux malta baseline 5773401 268752 187424 6229577 5f0e49 vmlinux malta + bswap patch Presumably the code size improvments yield better cache hit rate thus better performance compensating for the extra function call but this will still need to be benchmarked. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> 2015-09-29 10:19:48 +00:00			`#include <linux/module.h>`

			`unsigned int __bswapsi2(unsigned int u)`
			`{`
			`return (((u) & 0xff000000) >> 24) \|`
			`(((u) & 0x00ff0000) >> 8) \|`
			`(((u) & 0x0000ff00) << 8) \|`
			`(((u) & 0x000000ff) << 24);`
			`}`

			`EXPORT_SYMBOL(__bswapsi2);`