Samsung S3F80JB manual Relative Address Mode RA, Relative Addressing

Models: S3F80JB

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S3F80JB

ADDRESSING MODES

 

 

RELATIVE ADDRESS MODE (RA)

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. The result is the address of the next instruction to be executed. Before this addition occurs, the PC contains the address of the 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.

Program Memory

Next OPCODE

Program Memory

Address Used

Displacement

Current Instruction

 

OPCODE

 

Current

PC Value +

Signed Displacement Value

Sample Instructions:

 

JR

ULT,$+OFFSET

; Where OFFSET is a value in the range +127 to -128

Figure 3-13. Relative Addressing

3-13

Page 66
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Samsung S3F80JB manual Relative Address Mode RA, Relative Addressing