div

Signed division

This instruction is defined by:

Encoding

Synopsis

Divide rs1 by rs2, and store the result in rd. The remainder is discarded.

Division by zero will put -1 into rd.

Division resulting in signed overflow (when most negative number is divided by -1) will put the most negative number into rd;

Access

Always

Decode Variables

Bits<5> rs2 = $encoding[24:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];

Execution

Pruned, XLEN == 64
Original

XReg src1 = X[rs1];
XReg src2 = X[rs2];
if (src2 == 0) {
  X[rd] = {XLEN{1'b1}};
} else if ((src1 == {1'b1, {63{1'b0}}}) && (src2 == {XLEN{1'b1}})) {
  X[rd] = {1'b1, {63{1'b0}}};
} else {
  X[rd] = $signed(src1) / $signed(src2);
}

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] = {XLEN{1'b1}};
} else if ((src1 == {1'b1, {XLEN - 1{1'b0}}}) && (src2 == {XLEN{1'b1}})) {
  X[rd] = {1'b1, {XLEN - 1{1'b0}}};
} else {
  X[rd] = $signed(src1) / $signed(src2);
}