1 files changed, 24 insertions, 0 deletions
diff --git a/src/arithmetic_unit.v b/src/arithmetic_unit.v
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+++ b/src/arithmetic_unit.v
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+module arithmetic_unit #(
+  parameter N = 32
+)(
+  input [N-1:0] A, B,
+  input [1:0] OP, // 00: ADD, 01: SUB, 11: SLT
+  output [N-1:0] RESULT,
+  output OVERFLOW
+);
+
+wire [N-1:0] b, sum;
+wire cin, altb;
+
+assign b = OP[0] ? ~B : B;
+assign cin = OP[0];
+
+assign sum = A + b + cin;
+
+assign OVERFLOW = ~(A[N-1] ^ B[N-1] ^ OP[0]) & (A[N-1] ^ sum[N-1]);
+
+assign altb = OVERFLOW ^ sum[N-1];
+
+assign RESULT = OP[1] ? {{(N-1){1'b0}}, altb} : sum;
+
+endmodule