Le 26/06/2015 14:17, Chris Pavlina a écrit : > On Fri, Jun 26, 2015 at 08:45:08AM +0200, jp charras wrote: >> I am *not* convinced by replacing >>> m_pos.x -= aYaxis_position; >>> NEGATE( m_pos.x ); >>> m_pos.x += aYaxis_position; >> >> by >>> m_pos.x = 2 * aYaxis_position - m_pos.x; >> >> When you read the last form, it is not clear this is a mirroring >> relative to the aYaxis_position X position. >> >> At least for me, it is not "a lot clearer...", this is quite the opposite. >> >> Perhaps a macro like MIRROR( m_pos.x, aYaxis_position ) >> is "a lot clearer..." > > Yup, that's fair. I still think that "m_pos.x = 2 *....." is clearer > than the original, but that's a matter of opinion, and I _do_ like > MIRROR(). That's even clearer still. Done - modified patch attached. > >> >> By the way, for me: >> "x = -x" looks better than "x *= -1" >> an should be faster to calculate. > > Also done. "x = -x" is more technically correct, so I can appreciate > that (and in the case of C++ objects, will call the correct operator - > unary negation instead of multiplication). > > To nitpick a bit, it's NOT faster to calculate. gcc compiles "x *= -1" > to a "negl" instruction just like "x = -x" even on the lowest > optimization setting; clang does not do this optimization on -O0 but > does it on all higher settings. (And even if they didn't perform this > optimization, the difference is _incredibly_ negligible compared to > everything else being done in the vicinity.) > > -- > Chris
Committed. Thanks. -- Jean-Pierre CHARRAS _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
