單片機(jī)之匯編指令系統(tǒng)

控制轉(zhuǎn)移指令:

AJMP addr ;絕對(duì)跳轉(zhuǎn)指令

SJMP rel ;相對(duì)跳轉(zhuǎn)指令,(PC)+2+rel→PC

LJMP addr16 ;長(zhǎng)跳轉(zhuǎn)指令,addr16→PC

JMP @A+DPTR ;間接跳轉(zhuǎn)指令

JZ rel ;判零跳轉(zhuǎn)指令,(A)=1,則(PC)+2+rel→PC,若A!=0,則(PC)+2→PC

JNZ rel ;與上相反

CJNE A,direct,rel;比較不相等跳轉(zhuǎn)指令.執(zhí)行過程為:a.(A)=(direct),則(PC)+3→(PC),Cy=0

b.(A)>(direct),則(PC)+3+rel→(PC),Cy=0

c.(A)(direct),則(PC)+3+rel→(PC),Cy=1

DJNZ Rn,rel ;減一不為零跳轉(zhuǎn)指令 .執(zhí)行過錯(cuò)為 a.(PC)+2→PC. b.(Rn)-1→direct c.若Rn!=0,則(PC)+rel→PC;若direct=0,則程序往下執(zhí)行

ACALL addr ;短調(diào)用指令

LCALL addr ;長(zhǎng)調(diào)用指令

RET ;從子程序返回指令

RETI ;從中斷返回指令

NOP ;空操作指令

指令助記注釋:

ADDC ---Add with Carry Flag

SUBB ---Subtract With Borrow

INC ---- Increment

DEC-------Decrement

MUL----Multiply

DIV----Divide

DA----Decimal Adjust

MOV----move

MOVX----move external RAM

MOVC----move code

XCH----Exchange

XCHD----Exchange low-order Digit

ANL----and logical

ORL----or logical

XRL----exclusive-or logical

CLR----clear

CPL----complement logical

RL----rotate left

RR---rotate right

ACALL----absolute subroutine call

LCALL----long subroutine call

RET----return from subroutine

RETI----return from interrupt

AJUMP----absolute jump

LJMP----long jump

SJMP----short jump

JZ----jump if accumulator is zero

JNZ----jump if not zero

JC----jump if carray flag is set

JB----jump if direct bit not set

CJNE----compare jmp if not equal

DJNZ----decrement jump if zero

NOP----no operation