CP/M/CPM_CDROM.iso/cpm/utils/asmutl/asmlib.lbr/SETLZB.AZM/SETLZB.ASM

Assembly Source File | 1991-06-25 | 5KB | 181 lines

;----------------------------------------------------------------
;        This is a module in the ASMLIB library
;
; Enable leading zero blanking on the next numeric output.
;
;            Written         R.C.H.     16/8/83
;            Last Update    R.C.H.       31/12/83
;
; Eliminate all self modifying code         R.C.H.   22/10/83
; Add ? to front of global subroutines         R.C.H.   31/12/83
;----------------------------------------------------------------
;
    name    'setlzb'
;
    public    lzb,blzb,clzb,nolzb
    public    ?lzpr1,?lzpr2,?lzpr3,?lzprint
    extrn    ?lzbchr,?blank,dispatch
    maclib    z80
;
; Leadng zero printing is done in the different modes by recoginzing the
; following codes. These are defined as follows.
;
; 00    No lzb, standard default
; 01    Standard leading zero blanking
; 02    Blank filled leading zero blanking
; 03    Character filled leading zero blanking
;
lzb:
    push    psw
    mvi    a,1            ; Select
lzb$common:
    sta    lzbtype            ; Save in the data byte for it
    pop    psw
    ret
;
;----------------------------------------------------------------
;       Enable blank filled LZB on next numeric output.
;----------------------------------------------------------------
;
blzb:
    push    psw
    mvi    a,2
    jr    lzb$common
;
;----------------------------------------------------------------
; Enable character fill leading zero blanking. Character in A
;----------------------------------------------------------------
;
clzb:
    push    psw
    sta    ?lzbchr            ; save the character to lzb fill with
    mvi    a,3            ; Character filled lzb code
    jr    lzb$common
;
;----------------------------------------------------------------
; Clear Leading Zero blanking
;----------------------------------------------------------------
;
nolzb:
    push    psw
    xra    a
    jr    lzb$common
;
;----------------------------------------------------------------
; This section is rather important since it is used by all numeric
; printing routines to leading zero print digits. All the routines
; for the different types of leading zero printing are contained
; herein. Also note that the LZ$PRINT label is called by all or
; most numeric prionting routines and uses the lzbtype byte to
; jump to the required printing routine.
;----------------------------------------------------------------
;
?lzprint:
    push    h            ; Deepest on the stack
    push    d
    push    psw
    lda    lzbtype            ; Load the destination
    mvi    d,0
    mov    e,a            ; Load the offset
    lxi    h,lz$table        ; Point to start of table
    dad    d
    dad    d            ; Index into the table
    mov    e,m
    inx    h
    mov    d,m            ; Now de -> the routine
    xchg                ; HL -> the address
    pop    psw
    pop    d
    xthl                ; Restore hl, stack -> address
    ret                ; Goto the table address
;
; The following table of routines is indexed into by the leading
; zero blanking type byte to get the address of the required routine
; to print the character in A.
;
lz$table:
    dw    dispatch
    dw    ?lzpr1        ; Standard lzb
    dw    ?lzpr2        ; Blank filled lzb
    dw    ?lzpr3        ; Character filled lzb
;
; The following three routines are pointed to by the above jump
; when it is modified by a call to one of the entries.
;
?lzpr1:    ; Standard leading zero suppression
    call    chk$blank        ; See if we are past LZB due to a digit
    cpi    '0'            ; is it a space ?
    rz
    jmp    dispatch        ; else print if not = 0
?lzpr2:    ; If it is = 0 then print a space
    call    chk$blank        ; See if we are past LZB due to a digit
    cpi    '0'
    jnz    dispatch        ; print it if > 0
    mvi    a,' '            ; else load a space
    jmp    dispatch
?lzpr3:    ; If the character = 0 then use the LZBCHR character to print
    call    chk$blank        ; See if we are past LZB due to a digit
    cpi    '0'            ; zero ?
    jnz    dispatch        ; print is > 0
    lda    ?lzbchr            ; else load the fill character
    jmp    dispatch
;
chk$blank:    ; Check the blank byte. If it is not 00 then we print the digit
    cpi    '0'            ; is the digit a zero ?
    jrnz    set$blank        ; Set the blank byte
; If the digit is a zero then detect if we MUST print it then
    lda    ?blank
    ora    a            ; if 00 the we do no need to
    jrnz    send$blank
    mvi    a,'0'
    ret                ; return and do what may
;
send$blank:    ; Here is jumped to when blank <> 0 so we must print it
    pop    psw            ; kill the return address
    mvi    a,'0'            ; load a zero
    jmp    dispatch        ; send the byte
;
set$blank:
    push    psw            ; save the digit
    mvi    a,0ffh
    sta    ?blank
    pop    psw
    ret                ; return to the caller, blank set
;
    dseg
lzbtype:
    db    00            ; Type of leading zero blanking
;
    end