NEC 78K/0 Series - Manual (Page 115)

CHAPTER 5 EXPLANATION OF INSTRUCTIONS
115 User's Manual U12326EJ4V0UM
Decrement and Branch if Not Zero
DBNZ
Conditional Loop (R1
≠
0)
[Instruction format] DBNZ dst, $addr16
[Operation] dst ← dst–1,
then PC ← PC+b+jdisp16 if dst R1 ≠
0
[Operand]
Mnemonic Operand(dst,$addr16) b(Number of bytes)
DBNZ B, $addr16 2
C, $addr16 2
saddr, $addr16 3
[Flag]
Z AC CY
[Description]
• One is subtracted from the destination operand (dst) contents specified by the 1st operand and the
subtraction result is stored in the destination operand (dst).
• If the subtraction result is not 0, data is branched to the address indicated with the 2nd operand ($addr16).
When the subtraction result is 0, no processing is carried out and the subsequent instruction is executed.
• The flag remains unchanged.
[Description example]
DBNZ B, $1215H; The B register contents are decremented. If the result is not 0, data is branched to 1215H
(with the start of this instruction set in the range of addresses 1194H to 1293H).