Relative Address (Ra) Mode - Samsung S3F84B8 User Manual

S3F84B8_UM_REV 1.00

3.13 RELATIVE ADDRESS (RA) MODE

In Relative Address (RA) mode, a two's complement signed displacement between - 128 and + 127 is specified in
the instruction. The displacement value is then added to the current PC value. Its result is the address of next
instruction to be executed. Before this addition occurs, the PC contains the address of instruction immediately
following the current instruction.
Several program control instructions use the Relative Address mode to perform conditional jumps. The
instructions that support RA addressing are BTJRF, BTJRT, DJNZ, CPIJE, CPIJNE, and JR.
Current Instruction
Sample Instructions:
JR
Program Memory
Next OPCODE
Displacement
OPCODE
ULT,$+OFFSET ; Where OFFSET is a value in the range +127 to -128
Figure 3-13
Program Memory
Address Used
Current
PC Value
Signed
Displacement Value
Relative Addressing
3-13
3 ADDRESSING MODES
+