You are right. Not a trick question - my mistake. Joep
Op dinsdag 6 september 2011 schreef Piers Goodhew ([email protected]) het volgende: > > > On Tuesday, 6 September 2011 00:51:54 UTC+10, Joep wrote: >> >> > rather than: >> > y = y & 63 -- or equivalent constant >> >> Check with y=180 (not sure if it is an intended difference though). > > Is that a trick question? I don't think they are different. > I got all unit-testy, the following Ruby script (which runs all the Jal if/thens unmodified*) says they produce the same value for all 8-bit numbers: > > #! /usr/bin/ruby > > SCREEN_MAX_Y = 63 > > SCREEN_ROWS = 64 > > def three_ifs_way(y) > > if y > 191 then > > y = y - 192 > > elsif y > 127 then > > y = y - 128 > > elsif y > SCREEN_MAX_Y then > > y = y - SCREEN_ROWS > > end > > return y > > end > > def one_AND_way(y) > > return y & 63 > > end > > #### main loop > > return_value = 0 > > for i in 0..255 > > if three_ifs_way(i) != one_AND_way(i) then > > puts "Bad! Methods differ for value #{i}" > > return_value += 1 > > end > > end > > exit return_value > > > * had to change "end if" to just "end" > > -- > You received this message because you are subscribed to the Google Groups "jallib" group. > To view this discussion on the web visit https://groups.google.com/d/msg/jallib/-/SUe3qf3xYfAJ. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to [email protected] <jallib%[email protected]>. > For more options, visit this group at http://groups.google.com/group/jallib?hl=en. > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
