remw
Signed 32-bit remainder
This instruction is defined by:
-
M, version >= 0
This instruction is included in the following profiles:
-
RVA20U64 (Mandatory)
-
RVA22U64 (Mandatory)
-
RVI20U32 (Optional)
-
RVI20U64 (Optional)
Synopsis
Calculate the remainder of signed division of the 32-bit values rs1 by rs2, and store the sign-extended result in rd.
If the value in register rs2 is zero, write the sign-extended 32-bit value in rs1 into rd;
If the result of the division overflows, write zero into rd;
Decode Variables
Bits<5> rs2 = $encoding[24:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];Execution
-
IDL
-
Sail
if (implemented?(ExtensionName::M) && (CSR[misa].M == 1'b0)) {
raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
Bits<32> src1 = X[rs1][31:0];
Bits<32> src2 = X[rs2][31:0];
if (src2 == 0) {
Bits<1> sign_bit = src1[31];
X[rd] = {{32{sign_bit}}, src1};
} else if ((src1 == {33'b1, 31'b0}) && (src2 == 32'b1)) {
X[rd] = 0;
} else {
Bits<32> result = $signed(src1) % $signed(src2);
Bits<1> sign_bit = result[31];
X[rd] = {{32{sign_bit}}, result};
}{
if extension("M") then {
let rs1_val = X(rs1)[31..0];
let rs2_val = X(rs2)[31..0];
let rs1_int : int = if s then signed(rs1_val) else unsigned(rs1_val);
let rs2_int : int = if s then signed(rs2_val) else unsigned(rs2_val);
let r : int = if rs2_int == 0 then rs1_int else rem_round_zero(rs1_int, rs2_int);
/* signed overflow case returns zero naturally as required due to -1 divisor */
X(rd) = sign_extend(to_bits(32, r));
RETIRE_SUCCESS
} else {
handle_illegal();
RETIRE_FAIL
}
}