CP/M/CPM_CDROM.iso/simtel/sigm/vols000/vol043/pidmath.asm

Assembly Source File | 1984-04-29 | 4KB | 277 lines

MREV:    DB 33H ; 9/13/81 A. BENDER  ADD PIDGIN ENTRY POINTS
;MREV: DB 32H ;    06/08/79  R. CURTISS    FIX DMUL10  MOV D,H
;
;MREV: DB 31H ;    05/31/79  R. CURTISS    SIGNED OPERATIONS
;
;  DOUBLE SUBTRACT  (HL) = (HL) - (DE)
;
    ENTRY    ?ISUB
?ISUB:
DSUB:    MOV    A,L
    SUB    E    ; SUBTRACT LOW BYTE
    MOV    L,A
    MOV    A,H
    SBB    D    ; SUBTRACT HIGH BYTE WITH BORROW
    MOV    H,A
    RET
;
; ---------------------------------------- CMPEQ
; DOUBLE COMPARE (HL) - (DE)
;
;    IF HL = DE THEN Z=1
;
CMPEQ:    MOV    A,H
    CMP    D
    RNZ

    MOV    A,L
    CMP    E
    RET
;
;
;    IF HL < DE THEN CY=1  --  SIGNED
?CDEHL:
CMPLT:    MOV    A,H
    XRA    D
    MOV    A,H
    RLC        ; SET CY = SIGN OF HL
    RM        ; RETURN IF SIGNS DIFFERENT
;
;    IF HL < DE THEN CY=1  --  UNSIGNED
;
    ENTRY    ?CDEHL
UCMPLT:    MOV    A,H
    CMP    D
    RNZ

    MOV    A,L
    CMP    E
    RET
;
; ----------------------------------------- SPECIAL
;  SPECIAL MULTIPLY AND DIVIDE
;
;    HL = HL * 10  --  SIGNED
;
DMUL10:    MVI    B,0    ; MINUS SIGN COUNTER
    CALL    ICOMP    ; COMPLEMENT IF NECESSARY
    MOV    D,H
    MOV    E,L
    DAD    H
    DAD    H
    DAD    D
    DAD    H
    DCR    B
    RNZ        ; RETURN IF POSITIVE

    JMP    COMP    ; COMPLEMENT RESULT
;
;
;    HL = HL / 10  -- SIGNED
;
DDIV10:    MVI    B,0    ; MINUS SIGN COUNTER
    CALL    ICOMP
    PUSH    B
    CALL    UDIV10
    POP    B
    DCR    B
    RNZ        ; RETURN IF POSITIVE

    XCHG
    CALL    COMP
    XCHG
    JMP    COMP
;
;
;    HL = HL / 10  --  UNSIGNED
;    DE = HL MOD 10
;
UDIV10:    LXI    D,0
    LXI    B,05000H+12  ; B=10  C=LOOP COUNT
    JMP    UDV10B

UDV10A:    XCHG
    DAD    H    ; SHIFT DE LEFT 1 BIT
    XCHG
    DAD    H    ; SHIFT HL LEFT 1 BIT

UDV10B:    MOV    A,H
    SUB    B
    JC    UDV10C    ; JUMP IF CAN'T SUBTRACT 10

    MOV    H,A
    INR    E    ; SET LSB OF DE TO 1

UDV10C:    DCR    C    ; LOOP COUNT
    JNZ    UDV10A

    XCHG
    MOV    A,D
    RRC
    RRC
    RRC
    RRC
    ANI    0FH
    MOV    E,A    ; REMAINDER
    MVI    D,0
    RET
;
;
;    HL = HL / 4  --  UNSIGNED
;
UDIV4:    MOV    A,H
    DAD    H
    DAD    H
    DAD    H
    DAD    H
    DAD    H
    DAD    H
    MOV    L,H
    RRC
    RRC
    ANI    3FH
    MOV    H,A
    RET
;
; ------------------------------------------ NORMAL
;    NORMAL MULTIPLY AND DIVIDE
;
;    HL = HL * DE  --  SIGNED
;
    ENTRY    ?IMUL
?IMUL:
DMULT:    MVI    B,0    ; MINUS SIGN COUNTER
    XCHG
    CALL    ICOMP
    XCHG
    CALL    ICOMP
    PUSH    B    ; SAVE MINUS SIGN COUNTER
    CALL    UMULT
    POP    PSW    ; RECALL MINUS SIGN COUNTER
    ANI    1
    RZ        ; RETURN IF RESULT POSITIVE

    JMP    COMP
;
;
;  DOUBLE MULTIPLY  (HL) = (HL) * (DE)  --  UNSIGNED
;
UMULT:    MOV    B,H    ; MOVE MULTIPLICAND TO BC
    MOV    C,L
    LXI    H,0    ; INITIALIZE RESULT
    MVI    A,16    ; INITIALIZE LOOP COUNT
    ORA    A    ; CLEAR CARRY
    PUSH    PSW    ; SAVE COUNT AND ZERO CARRY
;
MLOOP:    MOV    A,D    ; GET MULTIPLIER BIT
    RLC
    JNC    OVER    ; JUMP IF BIT ZERO

    DAD    B

OVER:    POP    PSW    ; RECALL LOOP COUNT AND CLEAR CARRY
    DCR    A    ; DECREMENT LOOP COUNT
    RZ        ; RETURN IF COUNT ZERO

    PUSH    PSW    ; SAVE COUNT AND ZERO CARRY
    DAD    H    ; SHIFT RESULT LEFT
    XCHG
    DAD    H    ; SHIFT MULTIPLIER LEFT
    XCHG
    JMP    MLOOP
;
;
;    HL = HL / DE  --  SIGNED
;    DE = HL MOD DE
;
    ENTRY    ?IDIV
?IDIV:
DDIV:    MVI    B,0    ; MINUS SIGN COUNTER
    CALL    ICOMP
    XCHG
    CALL    ICOMP
    PUSH    B
    CALL    DIV80
    XCHG
    POP    PSW
    ANI    1
    RZ        ; RETURN IF RESULT POSITIVE

    XCHG
    CALL    COMP
    XCHG
    JMP    COMP
;
;
;  DOUBLE DIVIDE    (HL) = (HL) / (DE)
;
UDIV:    XCHG
    CALL    DIV80
    XCHG
    RET
;
;
DIV80:    SHLD    TEMP    ; SAVE DIVIDEND IN TEMPORARY
    LXI    H,BNUM    ; STORE
    MVI    M,17    ; BIT COUNT
    LXI    B,0    ; INITIALIZE RESULT
    PUSH    B    ; SAVE RESULT ON STACK
;
LOOP:    MOV    A,E    ; GET LOW DIVISOR BYTE
    RAL
    MOV    E,A    ; SHIFT DIVISOR LEFT ONE BIT
    MOV    A,D
    RAL
    MOV    D,A
    DCR    M    ; DECREMENT BIT COUNT
    POP    H    ; RESTORE TEMP RESULT
    RZ        ; RETURN IF COUNT ZERO

    MVI    A,0    ; ADD IN CARRY
    ACI    0
    DAD    H    ; SHIFT TEMP RESULT LEFT
    MOV    B,H    ; COPY HL TO AC
    ADD    L
    LHLD    TEMP    ; GET DIVIDEND
    SUB    L    ; SUBTRACT FROM
    MOV    C,A
    MOV    A,B
    SBB    H    ; TEMPORARY RESULT
    MOV    B,A
    PUSH    B    ; SAVE TEMP RESULT ON STACK
    JNC    SKIP    ; NO BORROW FROM SUBRRACT
;
    DAD    B    ; ADD DIVIDEND BACK IN
    XTHL        ; REPLACE TEMP RESULT ON STACK
;
SKIP:    LXI    H,BNUM    ; RESTORE HL
    CMC        ; COMPLEMENT CARRY
    JMP    LOOP
;
;
TEMP:    DS    2    ; FOR M   DIVIDE
BNUM:    DS    1    ; FOR DIVIDE
;
; ------------------------------------------- ICOMP, COMP
;  TWO'S COMPLEMENT ROUTINE FOR (HL)
;
ICOMP:    MOV    A,H    ; CHECK SIGN BIT
    ORA    A
    RP        ; RETURN IF POSITIVE

    INR    B    ; COUNT NEGATIVE
;
    ENTRY    ?ICOMP
?ICOMP:
COMP:    MOV    A,H
    CMA        ; COMPLEMENT HIGH BYTE
    MOV    H,A
    MOV    A,L
    CMA        ; COMPLEMENT LOW BYTE
    MOV    L,A
    INX    H    ; TWO'S COMPLEMENT
    RET
;
;
    END