c.beqz
Branch if Equal Zero
This instruction is defined by:
-
anyOf:
-
C, version >= 0
-
Zca, version >= 0
-
This instruction is included in the following profiles:
Synopsis
C.BEQZ performs conditional control transfers. The offset is sign-extended and added to the pc to form the branch target address. It can therefore target a ±256 B range. C.BEQZ takes the branch if the value in register rs1' is zero.
It expands to beq rs1, x0, offset.
Decode Variables
Bits<8> imm = {$encoding[12], $encoding[6:5], $encoding[2], $encoding[11:10], $encoding[4:3]};
Bits<3> rs1 = $encoding[9:7];Execution
-
IDL
-
Sail
if (implemented?(ExtensionName::C) && (CSR[misa].C == 1'b0)) {
raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
if (X[rs1] != 0) {
jump($pc + imm);
}{
let rs1_val = X(rs1);
let rs2_val = X(0);
let taken : bool = match op {
RISCV_BEQ => rs1_val == rs2_val,
RISCV_BNE => rs1_val != rs2_val,
RISCV_BLT => rs1_val <_s rs2_val,
RISCV_BGE => rs1_val >=_s rs2_val,
RISCV_BLTU => rs1_val <_u rs2_val,
RISCV_BGEU => rs1_val >=_u rs2_val
};
let t : xlenbits = PC + sign_extend(imm);
if taken then {
/* Extensions get the first checks on the prospective target address. */
match ext_control_check_pc(t) {
Ext_ControlAddr_Error(e) => {
ext_handle_control_check_error(e);
RETIRE_FAIL
},
Ext_ControlAddr_OK(target) => {
if bit_to_bool(target[1]) & not(extension("C")) then {
handle_mem_exception(target, E_Fetch_Addr_Align());
RETIRE_FAIL;
} else {
set_next_pc(target);
RETIRE_SUCCESS
}
}
}
} else RETIRE_SUCCESS
}