Samsung S3F80JB - Manual (Page 151)

S3F80JB INSTRUCTION SET
6-23
BTJRF
— Bit Test, Jump Relative on False
BTJRF dst,src.b
Operation: If src(b) is a "0", then PC
← PC + dst
The specified bit within the source operand is tested. If it is a "0", the relative address is added to
the program counter and control passes to the statement whose address is now in the PC;
otherwise, the instruction following the BTJRF instruction is executed.
Flags: No flags are affected.
Format:
(Note 1)
Bytes Cycles Opcode
(Hex)
Addr Mode
dst src
opc src | b | 0 dst 3 10 37 RA rb
NOTE: In the second byte of the instruction format, the source address is four bits, the bit address 'b' is
three bits, and the LSB address value is one bit in length.
Example: Given: R1 = 07H:
BTJRF SKIP,R1.3
→
PC jumps to SKIP location
If working register R1 contains the value 07H (00000111B), the statement "BTJRF SKIP,R1.3"
tests bit 3. Because it is "0", the relative address is added to the PC and the PC jumps to the
memory location pointed to by the SKIP. (Remember that the memory location must be within the
allowed range of + 127 to – 128.)