S3C84E5/C84E9/P84E9 INSTRUCTION SET
6-31
CPIJE — Compare, Increment, and Jump on Equal
CPIJE dst,src,RA
Operation: If dst–src = "0", PC ← PC + RA
Ir ← Ir + 1
The source operand is compared to (subtracted from) the destination operand. If the result is "0", the
relative address is added to the program counter and control passes to the statement whose
address is now in the program counter. Otherwise, the instruction immediately following the CPIJE
instruction is executed. In either case, the source pointer is incremented by one before the next
instruction is executed.
Flags: No flags are affected.
Format:
Bytes Cycles Opcode
(Hex) Addr Mode
dst src
opc src dst RA 3 12 C2 r Ir
Example: Given: R1 = 02H, R2 = 03H, and register 03H = 02H:
CPIJE R1,@R2,SKIP → R2 = 04H, PC jumps to SKIP location
In this example, the working register R1 contains the value 02H, the working register R2 the value
03H, and the register 03 contains 02H. The statement "CPIJE R1,@R2,SKIP" compares the @R2
value 02H (00000010B) to 02H (00000010B). Because the result of the comparison is equal, the
relative address is added to the PC and the PC then jumps to the memory location pointed to by
SKIP. The source register (R2) is incremented by one, leaving a value of 04H.
Remember that the memory location addressed by the CPIJE instruction must be within the allowed
range of + 127 to – 128.