z80:Opcodes:JR
From Learn @ Cemetech
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Relative jumps to the address. This means that it can only jump between 128 bytes ahead or behind. Can be conditional or unconditional. JR takes up one less byte than JP, but is also slower. Weigh the needs of the code at the time before choosing one over the other (speed vs. size).
Syntax
JP NN ;unconditional jump JP cond.,NN ;conditional jump
Allowed Instructions
;Constants JP NN ;no contition JR C,NN ;jumps if C is set JR NC,NN ;jumps if C is reset JR Z,NN ;jumps if Z is set JR NZ,NN ;jumps if Z is reset
Effects
All flags preserved.
Uses
T-States
cc is condition: NZ, Z, NC, C, PO, PE, P, M
| X | 12 |
| condition met | condition not met | |
| cc,X | 12 | 7 |
See Also
BIT,CALL,CP,CPD,CPDR,CPI,CPIR,DJNZ,JP
