P5 EQU 0F8H
P7 EQU 0DBH


ORG 0


START:
   MOV A, #7FH
   LCALL TEST_ROW
   JNC NO_KEY
    LCALL FIND
    MOV P1, A
    SJMP START
NO_KEY:
    MOV P1, #0
   SJMP START



;-------------------------------------------------
; SPRAWDZA CZY NACISNIETO KLAWISZ W DANYM WIERSZU A.7..4 - WIERSZ
;---------------------------------------------------
TEST_ROW:
    ANL A, #0F0H
    ANL P5, #0FH
    ORL P5, A

    MOV A, P7
    CPL A
    ANL A, #0FH
    SETB C
    JNZ TEST_ROW_END
    CLR C

TEST_ROW_END:
    RET
;-------------------------------------------------
; ZNAJDUJE PIERWSZA JEDYNKE W AKUMULATORZE ZWRACA NR BITU WYSTAPIENIA
;---------------------------------------------------
FIND:
    MOV R7, #0FCH
    JZ END_FIND
LOOP_FIND:
    RRC A
    JC END_FIND
    INC  R7
    SJMP LOOP_FIND

END_FIND:
    MOV A, R7
    RET


END