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module top;
typedef struct packed {
byte a,b,c,d;
} byte4_t;
typedef union packed {
int x;
byte4_t y;
} w_t;
w_t w;
assign w.x = 'h42;
always_comb begin
assert(w.y.d == 8'h42);
end
typedef logic[4:0] reg_addr_t;
typedef logic[6:0] opcode_t;
typedef struct packed {
bit [6:0] func7;
reg_addr_t rs2;
reg_addr_t rs1;
bit [2:0] func3;
reg_addr_t rd;
opcode_t opcode;
} R_t;
typedef struct packed {
bit[11:0] imm;
reg_addr_t rs1;
bit[2:0] func3;
reg_addr_t rd;
opcode_t opcode;
} I_t;
typedef struct packed {
bit[19:0] imm;
reg_addr_t rd;
opcode_t opcode;
} U_t;
typedef union packed {
R_t r;
I_t i;
U_t u;
} instruction_t;
instruction_t ir1;
assign ir1 = 32'h0AA01EB7; // lui t4,0xAA01
always_comb begin
assert(ir1.u.opcode == 'h37);
assert(ir1.r.opcode == 'h37);
assert(ir1.u.rd == 'd29);
assert(ir1.r.rd == 'd29);
assert(ir1.u.imm == 'hAA01);
end
union packed {
int word;
struct packed {
byte a, b, c, d;
} byte4;
} u;
assign u.word = 'h42;
always_comb begin
assert(u.byte4.d == 'h42);
end
endmodule
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