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Fix bug in carry_select_block

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This commit is contained in:
xenia 2024-01-12 23:08:18 +01:00
parent 1f53f7e90f
commit eb7cc73a80
2 changed files with 20 additions and 21 deletions
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11
simulation/test_alu.cpp
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@ -32,6 +32,17 @@ int main(int argc, char **argv) {
add_case.assert_eq("no Fzero", valu->Fzero, 0x0);
}
{
Tester add_case(&add_t, "0x5555+0x5555");
valu->op = 0b000;
valu->A = 0x5555;
valu->B = 0x5555;
valu->eval();
add_case.assert_eq("O == 0xaaaa", valu->O, 0xaaaa);
add_case.assert_eq("no overflow", valu->Fflow, 0x0);
add_case.assert_eq("no Fzero", valu->Fzero, 0x0);
}
{
Tester add_case(&add_t, "0xffffffff+0x1");
valu->op = 0b000;

30
verilog-src/alu/carry_select_block.v
View File

@ -10,30 +10,18 @@ module carry_select_block#(
// Case for Cin = 0
wire [N-1:0] O_C0;
wire Cout_C0;
begin
wire [N-1:1] carry;
fa fa0(A[0], B[0], 0, O_C0[0], carry[1]);
genvar i; for (i = 1; i <= N - 1; i = i + 1) begin
fa fai(A[i], B[i], carry[i], O_C0[i], carry[i+1]);
end
assign Cout_C0 = carry[N-1];
end
// Case for Cin = 1
wire [N-1:0] O_C1;
wire Cout_C1;
begin
wire [N-1:1] carry;
fa fa0(A[0], B[0], 1, O_C1[0], carry[1]);
genvar i; for (i = 1; i <= N - 1; i = i + 1) begin
fa fai(A[i], B[i], carry[i], O_C1[i], carry[i+1]);
end
assign Cout_C1 = carry[N-1];
wire [N:1] carry0;
wire [N:1] carry1;
fa fa00(A[0], B[0], 0, O_C0[0], carry0[1]);
fa fa10(A[0], B[0], 1, O_C1[0], carry1[1]);
genvar i; for (i = 1; i <= N - 1; i = i + 1) begin
fa fa0i(A[i], B[i], carry0[i], O_C0[i], carry0[i+1]);
fa fa1i(A[i], B[i], carry1[i], O_C1[i], carry1[i+1]);
end
assign O = Cin == 0 ? O_C0 : O_C1;
assign Cout = Cin == 0 ? Cout_C0 : Cout_C1;
assign Cout = Cin == 0 ? carry0[N] : carry1[N];
endmodule