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Acorn Arcade forums: Programming: Logic synthesis tools
 
  Logic synthesis tools
  adrianl (19:33 1/2/2008)
 
Adrian Lees Message #106283, posted by adrianl at 19:33, 1/2/2008
Member
Posts: 1637 		Barely programming (yet!) I know, but logic synth tools suck as much as compilers, despite the stupendous prices that EDA vendors charge for them.

Case in point.... someone (mistakenly/stupidly) wrote:

data_out = (data_in < 'h7F) ? data_in : 'h7F

and instead of spotting that in the case data_in == 'h7F, it doesn't matter which fork is chosen, and thus simplifying to:

data_out = (data_in < 'h80) ? data_in : 'h7F

which is a mere sprinkle of OR gates, it went ahead and built in effect:

data_out = (data_in > 'h7F || data_in == 'h7F) ? 'h7F : data_in;

ie. it explicitly included AND gates to check for the case data_in[6:0] == 'h7F. Rage I suppose I should be grateful that it didn't check the higher bits of data_in are zero too!
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Acorn Arcade forums: Programming: Logic synthesis tools