Date: Fri, 23 Aug 2013 00:23:55 +0100 From: Rafael Waldo Delgado Doblas <lord.rafa@...il.com> To: john-dev@...ts.openwall.com Subject: Re: Parallella: Litecoin mining Hello, 2013/8/22 Solar Designer <solar@...nwall.com> > It appears that you forgot (or failed?) to do this, and it never got > onto your "Priorities" lists (it should). > > Looking at "e-objdump -d epiphany-scrypt.elf", you actually have > ___udivsi3 and ___umodsi3 in there. These consume local memory space > and are pretty slow. > > (Actually, I am surprised gcc did not optimize the division by 6 into > multiplication by a constant needed to achieve division by 3, followed > by a right shift by 1.) > Sorry I forgot about it, but currently I don't understand. (x/6) = x * (1/6) = (x * (n/6)) / n, well I choose I nice power of 2 n the down division can be replaced by a m shift and the upper (n/6) can be computer and round it. for example if I say n = 16. (x/6) = (x * (16/6)) >> 4 ~ (x * 3) >> 4. I need to do a right shift by 1 how do you find the constant for right shift by 1 Regards, Rafael. Content of type "text/html" skipped
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