rem
Signed 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 rs1 by rs2, and store the result in rd.
If the value in register rs2 is zero, write the 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);
}
XReg src1 = X[rs1];
XReg src2 = X[rs2];
if (src2 == 0) {
X[rd] = src1;
} else if ((src1 == {1'b1, {XLEN - 1{1'b0}}}) && (src2 == {XLEN{1'b1}})) {
X[rd] = 0;
} else {
X[rd] = $signed(src1) % $signed(src2);
}{
if extension("M") then {
let rs1_val = X(rs1);
let rs2_val = X(rs2);
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) = to_bits(sizeof(xlen), r);
RETIRE_SUCCESS
} else {
handle_illegal();
RETIRE_FAIL
}
}