P5 EQU 0F8H
P7 EQU 0DBH


ORG 0


START:
   MOV A, #7FH
   LCALL TEST_ROW
   JNC NO_KEY
    LCALL FIND
    MOV P1, A
    SJMP START1
NO_KEY:
    MOV P1, #0
   SJMP START1

START1:
   MOV A, #7FH
   LCALL TEST_ROW
   JNC NO_KEY1
    LCALL FIND
    MOV P1, A
    SJMP START2
NO_KEY1:
    MOV P1, #0
   SJMP START2

START2:
   MOV A, #7FH
   LCALL TEST_ROW
   JNC NO_KEY2
    LCALL FIND
    MOV P1, A
    SJMP START3
NO_KEY2:
    MOV P1, #0
   SJMP START3

START3:
   MOV A, #7FH
   LCALL TEST_ROW
   JNC NO_KEY3
    LCALL FIND
    MOV P1, A
    SJMP START
NO_KEY3:
    MOV P1, #0
   SJMP START



;-------------------------------------------------
; SPRAWDZA CZY NACISNIETO KLAWISZ W DANYM WIERSZU A.7..4 - WIERSZ
;---------------------------------------------------
TEST_ROW:
    ANL A, #0F0H
    MOV B, A
    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, #12
    MOV R6, #12
    JZ END_FIND
LOOP_FIND:
    RRC A
    JC PRE
    INC  R7
    SJMP LOOP_FIND
PRE:
    MOV A, B
    SWAP A
LOOP_FIND2:
    RRC A
    JC END_FIND
    INC  R6
    SJMP LOOP_FIND2
END_FIND:
    MOV A, R6
    SWAP A
    ADD A, R7
    RET


END