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Altera_Forum
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10 years ago

Getting a comparator out of an ALM in arithmetic mode

So I am trying to get an adder/subtractor/comparator out of an ALM. According to the documentation I've seen, the ALM has a 4-input and 3-input LUT available before each full adder. There are two of ...
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Altera_Forum
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10 years ago

Just for reference, here are the control line settings:

a+b: r_nota=0, r_notb=0, r_cin=0, r_eq=0

a-b: r_nota=0, r_notb=1, r_cin=1, r_eq=0

b-a: r_nota=1, r_notb=0, r_cin=1, r_eq=0

a=b: r_nota=1, r_notb=0, r_cin=1, r_eq=1

a!=b: r_nota=0, r_notb=1, r_cin=0, r_eq=1

a>b: r_nota=0, r_notb=1, r_cin=0, r_eq=0

a>=b: r_nota=0, r_notb=1, r_cin=1, r_eq=0

a<b: r_nota=1, r_notb=0, r_cin=0, r_eq=0

a<=b: r_nota=1, r_notb=0, r_cin=1, r_eq=0