2011/12/30 Michael Haberler <mai...@mah.priv.at>: > > Am 30.12.2011 um 15:23 schrieb Viesturs Lācis: > >> 2011/12/30 Michael Haberler <mai...@mah.priv.at>: >>> use lut5: >>> >>> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Lut5 >>> http://www.linuxcnc.org/docs/devel/html/man/man9/lut5.9.html >>> >>> $ lut5 -n4 'i0 or i1 or i2 or i3' >>> # expression = i0 or i1 or i2 or i3 >>> #in: i4 i3 i2 i1 i0 out weight >>> # 0: 0 0 0 0 0 0 >>> # 1: 0 0 0 0 1 1 0x2 >>> # 2: 0 0 0 1 0 1 0x4 >>> # 3: 0 0 0 1 1 1 0x8 >>> # 4: 0 0 1 0 0 1 0x10 >>> # 5: 0 0 1 0 1 1 0x20 >>> # 6: 0 0 1 1 0 1 0x40 >>> # 7: 0 0 1 1 1 1 0x80 >>> # 8: 0 1 0 0 0 1 0x100 >>> # 9: 0 1 0 0 1 1 0x200 >>> #10: 0 1 0 1 0 1 0x400 >>> #11: 0 1 0 1 1 1 0x800 >>> #12: 0 1 1 0 0 1 0x1000 >>> #13: 0 1 1 0 1 1 0x2000 >>> #14: 0 1 1 1 0 1 0x4000 >>> #15: 0 1 1 1 1 1 0x8000 >>> # setp lut5.N.function 0xfffe >>> >> >> Michael, can You explain in simple language, how does the "weight" work? >> If I understand correctly, the look-up table should list all the >> possible combinations of inputs and specify output - 0 or 1 - for each >> case. But I do not get about the weight. > > 5 inputs have 2^5 combinations which can be represented in a 32bit int, which > is the function value > > The index access the 'table' is computed by giving the inputs a 'weight': > > FUNCTION(_) { > int shift = 0; > if(in_0) shift += 1; > if(in_1) shift += 2; > if(in_2) shift += 4; > if(in_3) shift += 8; > if(in_4) shift += 16; > > out = (function & (1<<shift)) != 0; > } > > see man lut5
I did look at both links You provided in Your first email. Do I understand correctly that the weight is function value for a particular input combination and it is needed to distinguish, which particular case of the look-up table is true at that particular moment? (This is not working for bit inputs and bit output, which only changes from 0 to 1) > > poor man's PAL, if you will - I think it's cool > Yes, it might be not only cool, but also very useful, but only if You know, how to use it. Once I was going through all the HAL component source files to get some understanding, what kind of things actually are there in EMC (pretty few names of HAL components are self-explanatory). I remember that lut was one of those "open-close" situations, because I did not understand anything... Viesturs ------------------------------------------------------------------------------ Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex infrastructure or vast IT resources to deliver seamless, secure access to virtual desktops. With this all-in-one solution, easily deploy virtual desktops for less than the cost of PCs and save 60% on VDI infrastructure costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
