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`include "core/uarch.sv"
`include "core/decode/isa.sv"
module core_alu
#(parameter W=16)
(
input alu_op op,
input logic[W - 1:0] a,
b,
input logic c_in,
output logic[W - 1:0] q,
output psr_flags nzcv,
output logic v_valid
);
logic c, v, c_add, c_sub, c_rsb, v_add, v_sub, v_rsb;
logic[W - 1:0] not_b, q_add, q_sub, q_rsb, q_and, q_bic, q_orr, q_xor;
assign not_b = ~b;
core_alu_add #(.W(W), .SUB(0)) op_add
(
.q(q_add),
.c(c_add),
.v(v_add),
.c_in(c_in && !op `FIELD_ALUOP_ADD_CMN && op `FIELD_ALUOP_ADD_NOTCMN_ADC),
.*
);
core_alu_add #(.W(W), .SUB(1)) op_sub
(
.q(q_sub),
.c(c_sub),
.v(v_sub),
.c_in(!c_in && op `FIELD_ALUOP_SUB_SBC),
.*
);
core_alu_add #(.W(W), .SUB(1)) op_rsb
(
.a(b),
.b(a),
.q(q_rsb),
.c(c_rsb),
.v(v_rsb),
.c_in(!c_in && op `FIELD_ALUOP_RSB_RSC),
.*
);
core_alu_and #(.W(W)) op_and
(
.q(q_and),
.*
);
core_alu_and #(.W(W)) op_bic
(
.b(not_b),
.q(q_bic),
.*
);
core_alu_orr #(.W(W)) op_orr
(
.q(q_orr),
.*
);
core_alu_xor #(.W(W)) op_xor
(
.q(q_xor),
.*
);
always_comb begin
unique case(op)
`ALU_ADD, `ALU_ADC, `ALU_CMN:
q = q_add;
`ALU_SUB, `ALU_SBC, `ALU_CMP:
q = q_sub;
`ALU_RSB, `ALU_RSC:
q = q_rsb;
`ALU_AND, `ALU_TST:
q = q_and;
`ALU_BIC:
q = q_bic;
`ALU_EOR, `ALU_TEQ:
q = q_xor;
`ALU_ORR:
q = q_orr;
`ALU_MOV:
q = b;
`ALU_MVN:
q = not_b;
endcase
v = 1'bx;
unique case(op)
`ALU_AND, `ALU_EOR, `ALU_TST, `ALU_TEQ, `ALU_ORR, `ALU_MOV, `ALU_BIC, `ALU_MVN:
c = c_in;
`ALU_ADD, `ALU_ADC, `ALU_CMN: begin
c = c_add;
v = v_add;
end
`ALU_SUB, `ALU_SBC, `ALU_CMP: begin
c = c_sub;
v = v_sub;
end
`ALU_RSB, `ALU_RSC: begin
c = c_rsb;
v = v_rsb;
end
endcase
unique case(op)
`ALU_AND, `ALU_EOR, `ALU_TST, `ALU_TEQ, `ALU_ORR, `ALU_MOV, `ALU_BIC, `ALU_MVN:
v_valid = 0;
`ALU_SUB, `ALU_RSB, `ALU_ADD, `ALU_ADC, `ALU_SBC, `ALU_RSC, `ALU_CMP, `ALU_CMN:
v_valid = 1;
endcase
end
assign nzcv = {q[W - 1], q == 0, c, v};
endmodule
|
