ALU
Opcodes
| Opcode | Action | Flags | Description |
|---|---|---|---|
ADD Rx,# | Rx <= Rx + Imm | Z, C | Rx is added to an Immediate 16 or 32 bit value with the result written back to Rx.The C Flag is set on carry (i.e. the register wraps from FFFFFFFF to 00000000).The Z flag is set if the result is zero |
SUB Rx,# | Rx <= Rx - Imm | Z, C | An immediate 16 or 32 bit value is subtracted from Rx and the result is written back to Rx.The C Flag is set if there is a borrow (i.e. wraps from00000000 to FFFFFFFF).The Z flag is set if the result is zero |
CMP Rx,# | Z and C <= Rx = Imm | Z, C | An immediate 16 or 32 bit value is subtracted from Rx, but only flags are updated. Rx is unmodified.The C Flag is set on borrow.The Z flag is set if the result is zero |
ADD Rx,Ry | Rx <= Rx + Ry | Z, C | Rx is added to Ry, and the result is written back into Rx.The C Flag is set on carry.The Z flag is set if the result is zero. |
SUB Rx,Ry | Rx <= Rx - Ry | Z, C | Ry is subtracted from Rx, and the result is written back to Rx.The C Flag is set on carry.The Z flag is set if the result is zero. |
CMP Rx,Ry | Z and C <= Rx = Ry | Z, C | Ry is subtracted from Rx, but only the flags are updated. Rx is unmodified.The C Flag is set on borrow.The Z flag is set if the result is zero. |
MUL Rx,Ry | Rx ← Rx * Ry | Z | Rx and Ry are multiplied together, with the result put into Rx.The Z flag is set if the result is zero. |
DIV Rx,Ry | Rx ← Rx / Ry Ry ← Rx % Ry | Z, C | This instruction performs two functions at once. Rx is divided by Ry, and the quotient is placed into Rx, and the remainder is placed into Ry.The Z flag is set if the quotient (Rx) is zero.The C flag is set if the remainder (Ry) is zero.If dividing by 0 is attempted, will generate an error. |
CLC | C ← 0 | C | Clears the Carry Flag |
SEC | C ← 1 | C | Sets the Carry Flag |
Notes
- Z Flag used for result is zero
- C Flag used for overflow on ALU