C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_100/112_01/ddoclib

Text File | 1985-08-19 | 3.6 KB | 281 lines

#asm
;
;   Library specially tailored for Diskdoc
;
;
;Fetch a single byte from the address in HL and
; sign extend into HL
CCGCHAR: MOV    A,M
CCSXT:    MOV    L,A
    RLC
    SBB    A
    MOV    H,A
    RET
;Fetch a full 16-bit integer from the address in HL
CCGINT: MOV    A,M
    INX    H
    MOV    H,M
    MOV    L,A
    RET
;Store a single byte from HL at the address in DE
CCPCHAR: MOV    A,L
    STAX    D
    RET
;Store a 16-bit integer in HL at the address in DE
CCPINT: MOV    A,L
    STAX    D
    INX    D
    MOV    A,H
    STAX    D
    RET
;Inclusive "or" HL and DE into HL
CCOR:    MOV    A,L
    ORA    E
    MOV    L,A
    MOV    A,H
    ORA    D
    MOV    H,A
    RET
;Exclusive "or" HL and DE into HL
CCXOR:    MOV    A,L
    XRA    E
    MOV    L,A
    MOV    A,H
    XRA    D
    MOV    H,A
    RET
;"And" HL and DE into HL
CCAND:    MOV    A,L
    ANA    E
    MOV    L,A
    MOV    A,H
    ANA    D
    MOV    H,A
    RET
;Test if HL = DE and set HL = 1 if true else 0
CCEQ:    CALL    CCCMP
    RZ
    DCX    H
    RET
;Test if DE ~= HL
CCNE:    CALL    CCCMP
    RNZ
    DCX    H
    RET
;Test if DE > HL (signed)
CCGT:    XCHG
    CALL    CCCMP
    RC
    DCX    H
    RET
;Test if DE <= HL (signed)
CCLE:    CALL    CCCMP
    RZ
    RC
    DCX    H
    RET
;Test if DE >= HL (signed)
CCGE:    CALL    CCCMP
    RNC
    DCX    H
    RET
;Test if DE < HL (signed)
CCLT:    CALL    CCCMP
    RC
    DCX    H
    RET
;Common routine to perform a signed compare
; of DE and HL
;This routine performs DE - HL and sets the conditions:
;    Carry reflects sign of difference (set means DE < HL)
;    Zero/non-zero set according to equality.
CCCMP:    MOV    A,E
    SUB    L
    MOV    E,A
    MOV    A,D
    SBB    H
    LXI    H,1    ;preset true condition
    JM    CCCMP1
    ORA    E    ;"OR" resets carry
    RET
CCCMP1: ORA    E
    STC        ;set carry to signal minus
    RET
;
;Test if DE >= HL (unsigned)
CCUGE:    CALL    CCUCMP
    RNC
    DCX    H
    RET
;
;Test if DE < HL (unsigned)
CCULT:    CALL    CCUCMP
    RC
    DCX    H
    RET
;
;Test if DE > HL (unsigned)
CCUGT:    XCHG
    CALL    CCUCMP
    RC
    DCX    H
    RET
;
;Test if DE <= HL (unsigned)
CCULE:    CALL    CCUCMP
    RZ
    RC
    DCX    H
    RET
;
;Common routine to perform unsigned compare
;carry set if DE < HL
;zero/nonzero set accordingly
CCUCMP: MOV    A,D
    CMP    H
    JNZ    $+5
    MOV    A,E
    CMP    L
    LXI    H,1
    RET
;
;Shift DE arithmetically right by HL and return in HL
CCASR:    XCHG
    MOV    A,H
    RAL
    MOV    A,H
    RAR
    MOV    H,A
    MOV    A,L
    RAR
    MOV    L,A
    DCR    E
    JNZ    CCASR+1
    RET
;Shift DE arithmetically left by HL and return in HL
CCASL:    XCHG
    DAD    H
    DCR    E
    JNZ    CCASL+1
    RET
;Subtract HL from DE and return in HL
CCSUB:    MOV    A,E
    SUB    L
    MOV    L,A
    MOV    A,D
    SBB    H
    MOV    H,A
    RET
;Form the two's complement of HL
CCNEG:    CALL    CCCOM
    INX    H
    RET
;Form the one's complement of HL
CCCOM:    MOV    A,H
    CMA
    MOV    H,A
    MOV    A,L
    CMA
    MOV    L,A
    RET
;Multiply DE by HL and return in HL
CCMULT: MOV    B,H
    MOV    C,L
    LXI    H,0
CCMULT1: MOV    A,C
    RRC
    JNC    $+4
    DAD    D
    XRA    A
    MOV    A,B
    RAR
    MOV    B,A
    MOV    A,C
    RAR
    MOV    C,A
    ORA    B
    RZ
    XRA    A
    MOV    A,E
    RAL
    MOV    E,A
    MOV    A,D
    RAL
    MOV    D,A
    ORA    E
    RZ
    JMP    CCMULT1
;Divide DE by HL and return quotient in HL, remainder in DE
CCDIV:    MOV    B,H
    MOV    C,L
    MOV    A,D
    XRA    B
    PUSH    PSW
    MOV    A,D
    ORA    A
    CM    CCDENEG
    MOV    A,B
    ORA    A
    CM    CCBCNEG
    MVI    A,16
    PUSH    PSW
    XCHG
    LXI    D,0
CCDIV1: DAD    H
    CALL    CCRDEL
    JZ    CCDIV2
    CALL    CCCMPBCDE
    JM    CCDIV2
    MOV    A,L
    ORI    1
    MOV    L,A
    MOV    A,E
    SUB    C
    MOV    E,A
    MOV    A,D
    SBB    B
    MOV    D,A
CCDIV2: POP    PSW
    DCR    A
    JZ    CCDIV3
    PUSH    PSW
    JMP    CCDIV1
CCDIV3: POP    PSW
    RP
    CALL    CCDENEG
    XCHG
    CALL    CCDENEG
    XCHG
    RET
CCDENEG: MOV    A,D
    CMA
    MOV    D,A
    MOV    A,E
    CMA
    MOV    E,A
    INX    D
    RET
CCBCNEG: MOV    A,B
    CMA
    MOV    B,A
    MOV    A,C
    CMA
    MOV    C,A
    INX    B
    RET
CCRDEL: MOV    A,E
    RAL
    MOV    E,A
    MOV    A,D
    RAL
    MOV    D,A
    ORA    E
    RET
CCCMPBCDE: MOV    A,E
    SUB    C
    MOV    A,D
    SBB    B
    RET
;
#endasm