Instruction Manual

ADD_R (Add and Return)
The ADD_R instruction adds two numbers and performs a return-from-call
operation. The ADD_R instruction uses the implicit addressing mode. The
ADD_R instruction retrieves both TOS and NEXT from the data stack and adds
them together. TOS and NEXT are consumed, and the result is placed in TOS.
The operation modifies the Carry flag as result of the unsigned addition. The
return-from-call operation loads the instruction pointer (IP) with the return
address from the return stack.
The ADD_R instruction applies to Series 3100, 5000, and 6000 devices.
Syntax:
The ADD_R instruction requires no operands:
ADD_R
Table 12 describes the attributes of the ADD_R instruction.
Table 12. ADD_R Instruction
Instruction Hexadecimal
Opcode
Instruction
Size (Bytes)
CPU Cycles
Required
Affect on
Carry Flag
ADD_R 5C 1 7 Modified
Example:
The following example performs the operation 2+3 and performs the return-from-
call operation. The example assumes that the return stack contains the address
of the caller to which the ADD_R instruction returns.
pushs #2 ; (2, -, -)
pushs #3 ; (3, 2, -)
add_r ; (5, -, -)
The value of TOS after this code executes is 5 because 2+3 = 5. The value of the
Carry flag is modified (cleared) because the unsigned addition did not require an
extra carry bit. After completing the addition, the ADD_R instruction performs
the return-from-call operation.
66 Neuron Assembly Language Instruction Statements