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Undef-related fixes in simlib $alu model

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This commit is contained in:
Clifford Wolf 2014-09-02 23:21:59 +02:00
parent f1869667ca
commit 635b922afe
1 changed files with 6 additions and 3 deletions
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9
techlibs/common/simlib.v
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@ -492,8 +492,11 @@ generate
end end
endgenerate endgenerate
// this is 'x' if Y and CO should be all 'x', and '0' otherwise
wire y_co_undef = ^{A, A, B, B, CI, CI, BI, BI};
assign X = AA ^ BB; assign X = AA ^ BB;
assign Y = AA + BB + CI; assign Y = (AA + BB + CI) ^ {Y_WIDTH{y_co_undef}};
function get_carry; function get_carry;
input a, b, c; input a, b, c;
@ -502,9 +505,9 @@ endfunction
genvar i; genvar i;
generate generate
assign CO[0] = get_carry(AA[0], BB[0], CI); assign CO[0] = get_carry(AA[0], BB[0], CI) ^ y_co_undef;
for (i = 1; i < Y_WIDTH; i = i+1) begin:BLOCK3 for (i = 1; i < Y_WIDTH; i = i+1) begin:BLOCK3
assign CO[i] = get_carry(AA[i], BB[i], CO[i-1]); assign CO[i] = get_carry(AA[i], BB[i], CO[i-1]) ^ y_co_undef;
end end
endgenerate endgenerate