Hi Albert, On Wed, Apr 17, 2013 at 12:23 PM, Albert ARIBAUD <albert.u.b...@aribaud.net> wrote: > Hi Simon -- and sorry for the dupe. > > On Wed, 17 Apr 2013 11:28:07 -0700, Simon Glass <s...@chromium.org> > wrote: > >> I tried using: >> >> #ifdef USE_HOSTCC >> crc = htobe32(crc); >> #else >> crc = cpu_to_be32(crc); >> #endif >> memcpy(output, &crc, sizeof(crc)); >> >> >> This is one instruction (4 bytes, 16%) smaller, but I suspect quite a >> lot slower due to the overhead of a very small memcpy(). >> >> 43e2c1d8: e28d1008 add r1, sp, #8 >> 43e2c1dc: e3a02004 mov r2, #4 >> 43e2c1e0: e6bf0f30 rev r0, r0 >> 43e2c1e4: e5210004 str r0, [r1, #-4]! >> 43e2c1e8: e1a00004 mov r0, r4 >> 43e2c1ec: eb001af7 bl 43e32dd0 <memcpy> > > How about replacing the memcpy with an explicit put_unaligned(), > similar to what was done in > > http://www.mail-archive.com/u-boot@lists.denx.de/msg109555.html > > with get_unaligned()? The code will be longer than above, but shorter > than the above plus the memcpy(), and faster too -- actually, I'm > surprised that the compiler does not unroll the memcpy() on its own, > considering the size argument is a constant.
Do you mean like this? #ifdef USE_HOSTCC crc = htobe32(crc); memcpy(output, &crc, sizeof(crc)); #else crc = cpu_to_be32(crc); put_unaligned(crc, (uint32_t *)output); #endif This produces the same code as my original patch. If this is acceptable then I will do that, although it doesn't really seem any better. Regards, Simon [and sorry for my dup] _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
