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AR# 15841

5.1i XST - XST is not processing generics properly


Keywords: XST, VHDL, generic, incorrect, bad, wrong, logic

Urgency: Standard

General Description:
When an entity-level generic and a component-level generic have the same name (gen1), and another component-level generic is derived from the entity-level generic (gen2 = gen1/2), XST will derive the second component-level generic from the first component-level generic instead of deriving the second component-level generic form the entity-level generic.

For example:
entity generic_test is
generic (a : integer := 6);

-- Now, I define generics in a declared/instantiated comp:

component my_comp is
generic (a : integer;
b : integer);

u1 : my_comp generic map (a => 4, b => a/2);
-- "a" will be equal to 4, and "b" will be incorrectly equal to 2 (instead of 3).


To work around this problem, use different generic names in the component than you used in the entity.
AR# 15841
Date 10/20/2005
Status Archive
Type General Article