ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/cpm/walnut-creek-CDROM/CPM/PROGRAMS/LIST/EP-SRC.ARK/DRAW.MAC

Text File | 1988-05-21 | 4KB | 292 lines

    include BDS.LIB
    include EPDATA

;jumped to when cseq finds draw command
;causes a break
;purpose is to skip up page and draw all lines
draw::
    push    b
;check there was no page break
    lhld    vposition
    xchg
    lhld    tm
    inx    h
    call    albu
    jc    .drX
;now save current v. position to return to when done drawing
    lhld    skdots
    dad    d
    push    h
;search lines to find how far back up the page we have to go
    lxi    h,lilist-6
    mvi    a,NUMLINES
    push    psw
    lxi    b,0FFFFH
.dr1:    pop    psw
    dcr    a
    jm    .dr3
    push    psw

    lxi    d,6
    dad    d
    mov    e,m
    inx    h
    mov    d,m
    inx    h
    mov    a,d
    ora    e
    jz    .dr1
    push    h
    mov    h,b
    mov    l,c
    call    albu
    jnc    $+5
    mov    b,d
    mov    c,e
    pop    h
    jmp    .dr1
.dr3:
;BC is min v. pos in list, or FFFF if none
    mov    d,b
    mov    e,c
    inx    d
    mov    a,d
    ora    e
    jz    .drRET
    dcx    d
    lhld    vposition
    call    cmh
    dad    d
;HL now neg. skips we have to do
    shld    skdots

;Ready to start drawing at v. position after next paperup
; (a) For each pass: clear buffer, draw 8 dots for each line, sendit
; (b) skip down for next row, and if not past old v. position, go to (a)
.drLOOP:
    call    drrow
    call    drrow
    call    drrow

    lhld    skdots
    lxi    d,PICA-3
    dad    d
    shld    skdots
    xchg
    lhld    vposition
    dad    d

;cf old v. position on stack
    pop    d
    push    d
    call    albu
    jnc    .drLOOP

.drRET:
;return down to v. position when got the draw command
    lhld    vposition
    call    cmh
    pop    d
    dad    d
    shld    skdots

;last thing to do is zero out the lines to show that they have been drawn
.drX:
    lxi    d,NUMLINES*8
    lxi    h,lilist
.drXL:    mvi    m,0
    inx    h
    dcx    d
    mov    a,d
    ora    e
    jnz    .drXL
    pop    b
    ret

;clear buffer, draw 8 dots for each line, sendit
drrow:
    call    clrgbuf##
    mvi    a,NUMLINES
    lxi    h,lilist
.drrLOOP:
    push    psw
    push    h
;no draw if no line
    mov    a,m
    inx    h
    ora    m
    dcx    h
    cnz    dr8
    lxi    d,8
    pop    h
    dad    d
    pop    psw
    dcr    a
    jnz    .drrLOOP
    call    bumpgpt##
    jmp    sendit##

;draw 8 dots for the line at HL
dr8:    lxi    d,v0
    mvi    b,8
.dr8.1:
    mov    a,m
    stax    d
    inx    h
    inx    d
    dcr    b
    jnz    .dr8.1

;y-coordinate
    lhld    vposition
    xchg
    lhld    skdots
    dad    d
;the first dot
    mvi    a,80H
.dr8LOOP:
    push    psw
    push    h
    call    dr1
    pop    h
    inx    h
    inx    h
    inx    h
    pop    psw
    ora    a
    rar
    jnc    .dr8LOOP
    ret

;draw one dot in Acc at y=HL
dr1:    mov    c,a    ;to be passed to vdotset
    xchg
;DE = y
    lhld    v1
    call    albu    ;passed where line starts?
    rnc
    lhld    v0
    call    cmh
    dad    d
    mov    a,h    ;not yet to where line starts?
    ora    a
    rm

;no preadjust yet
    xra    a
    sta    _preadj
    call    adjfact

;v - v0
    push    h

    lhld    c1draw
    xchg
    lhld    c0draw
    push    h

    call    albu
    mvi    a,0
    jnc    $+5
    xchg
    inr    a

    sta    _nslflag

;HL is min(c0,c1)

    call    cmh
    dad    d
;save to figure num of dots
    shld    _hdiff
    call    adjfact
;HL is |c1 - c0|
    xchg
    pop    h
    xthl
;HL is v - v0 and c0 put back on stack
    call    usmul
;HL is |c1 - c0|*(v - v0)
    push    h

    lhld    v1
    xchg
    lhld    v0
    call    cmh
    dad    d
;HL is v1 - v0

;pause to figure delta-h
    push    h
    xchg
    lhld    _hdiff
    xchg
    call    usdiv
    shld    _hdiff
    pop    d

    pop    h
;add den.-1 to numerator
    dcx    d

;(check not div by 0)
    mov    a,d
    ora    a
    jp    $+5
    pop    d    ;clean stack and abort
    ret

    dad    d
    inx    d
;HL/DE
    xchg
    call    usdiv
;HL is ( |c1 - c0|*(v - v0) )/(v1 - v0)

;adjust by lost factor
    lda    _preadj
    mov    e,a
    call    shllbe

    lda    _nslflag
    ora    a
    jz    $+6
    call    cmh

    pop    d    ;(now stack clean)
    dad    d
;add min(c0,c1)

;(check bounds; OR in byte; set maxgpt up if less)
    xchg
    lda    _hdiff
    jmp    vvdotset##


adjfact:
    mov    a,h
    ora    a
    rz
    push    h
    lxi    h,_preadj
    inr    m
    pop    h
    inx    h    ;?
    mvi    e,1
    call    shlrbe
    jmp    adjfact



v0:    dw    0
c0draw:    dw    0
v1:    dw    0
c1draw:    dw    0

_nslflag:    db    0
_preadj:    db    0
_hdiff:        dw    0

    end