gondwana.ecr.mu.oz.au/pub//Graphics.tar/Graphics/VOGLE.ZIP/VOGLE/DRIVERS/IBMPC/SIGMA_A.ASM

Assembly Source File | 2000-02-11 | 8KB | 482 lines

    TITLE    SIG_LINE - Line drawing routine.
    NAME    SIG_LINE
    PAGE    55,132


    COMMENT    $

    Name:        SIG_LINE

    Function:    Draw a line in 640x400 SIGMA graphics mode.

    Caller:        Microsoft C:

            void     sigline(x1, y1, x2, y2, n);
                int    x1, y1, x2, y2;    /* pixel co-ords */
                int    n;        /* pixel value */
        $



SIGMA_DATA    SEGMENT    WORD    PUBLIC    'DATA'
    color    dw    ?

row_table    label    word            ; define row table
    line_num = 0
    rept    100
        dw    line_num * 80
        dw    2000h + line_num * 80
        dw    4000h + line_num * 80
        dw    6000h + line_num * 80
        line_num = line_num + 1        ; next row
    endm

    negerr    dw    ?
    poserr    dw    ?
SIGMA_DATA    ENDS

extrn    __cur_color:word
extrn    _chartab:word
extrn    __fontsize:word

argbase    equ    2            ; 2 for large model, 0 for small
ARGx1    equ    [bp + argbase + 4]
ARGy1    equ    [bp + argbase + 6]
ARGx2    equ    [bp + argbase + 8]
ARGy2    equ    [bp + argbase + 10]
ARGcol    equ    [bp + argbase + 12]

inc_di    equ    47h
inc_cx    equ    41h
dec_di    equ    4fh
dec_cx    equ    49h
do_nop    equ    90h

public    _sig_line
public    _sigmachar
public    _sigmaclear
public    _sigma_set_colors

DGROUP    GROUP    SIGMA_DATA

SIGMA_TEXT    SEGMENT    byte public 'CODE'
        ASSUME    cs:SIGMA_TEXT, ds:DGROUP


_sig_line    proc    far
    push    bp
    mov    bp, sp
    push    di
    push    si
    push    bx
    push    cx
    push    dx

    mov    ax, ARGcol
    mov    color, ax
    mov    ax, 0b800h            ; display mem segment
    mov    es, ax                ; display mem segment

    mov    bx, inc_di * 256 + inc_cx    ; ystep + 1 in bh
                        ; xstep + 1 in bl
; | x2 - x1 |
    mov    cx, ARGx2            ; x2
    sub    cx, ARGx1            ; x1
    jge    pos_delta_x            ; jump if not negative
    mov    bl, dec_cx            ; cx = delta_x
    neg    cx

pos_delta_x:
; | y2 - y1 |
;    mov    bh, inc_di
    mov    dx, ARGy2            ; y2
    sub    dx, ARGy1            ; y1
    jge    pos_delta_y
    mov    bh, dec_di            ; ystep - 1
    neg    dx                ; | y2 - y1 |

pos_delta_y:                    ; dx = delta_y
; self modifying code
    mov    di, offset cs:positive
    mov    word ptr cs:[di], bx        ; self mod

; find long axis
    cmp    cx, dx                ; delta_x, delta_y
    jge    big_delta_x
    mov    bl, do_nop            ; if vert, no inc/dec so nop
    xchg    cx, dx                ; swap delta_x and delta_y
    jmp    short got_long_axis

big_delta_x:
    mov    bh, do_nop            ; if horiz, no inc/dec so nop

got_long_axis:
; self modifying code
    mov    di, offset cs:negative        ; location to modify
    mov    word ptr cs:[di], bx        ; make mod.
    shl    dx, 1                ; (delta_y * 2)
    mov    negerr, dx
    sub    dx, cx                ; (delta_y * 2) - delta_x
    mov    bx, dx                ; save initial value
    sub    dx, cx                ; (delta_y * 2) - (delta_x * 2)
    mov    poserr, dx
    mov    dx, 02DEh            ; plane select port

; adjust count
    mov    si, cx                ; si = length of long axis
    cmp    si, 0
    jne    not_0
    inc    si
not_0:
    mov    di, ARGy1            ; y
    mov    cx, ARGx1            ; x
    push    bp
    mov    bp, negerr

main_loop:
    push    di                ; save y
    push    cx                ; save x
    mov    ax, cx                ; x
    shl    di, 1                ; word table index
    mov    di, row_table[di]
    shr    ax, 1
    shr    ax, 1
    shr    ax, 1
    add    di, ax
    and    cl, 7
    mov    al, 10000000b            ; mask
    ror    al ,cl

    mov    cl, al                ; bitORmask
    mov    ch, al
    not    ch                ; bitANDmask

    xor    al, al
    out    dx, al                ; plane 0

    mov    ah, byte ptr color
    and    ah, 1
    jz    np1a
    or    es:[di], cl
    jmp    short np1b
np1a:
    and    es:[di], ch
np1b:
    mov    al, 1
    out    dx, al                ; plane 1

    mov    ah, byte ptr color
    and    ah, 2
    jz    np2a
    or    es:[di], cl
    jmp    short np2b
np2a:
    and    es:[di], ch
np2b:
    mov    al, 2
    out    dx, al                ; plane 2

    mov    ah, byte ptr color
    and    ah, 4
    jz    np3a
    or    es:[di], cl
    jmp    short np3b
np3a:
    and    es:[di], ch
np3b:
    mov    al, 3
    out    dx, al                ; plane 3

    mov    ah, byte ptr color
    and    ah, 8
    jz    np4a
    or    es:[di], cl
    jmp    short np4b
np4a:
    and    es:[di], ch
np4b:

    pop    cx
    pop    di

    cmp    bx, 0
    jge    positive

negative:
    inc    cx                ; update x
                        ; inc cx / dec cx / nop
                        ; update y
    inc    di                ; inc di / dec di / nop

    add    bx, bp                ; negerr

dec_long_axis:
    dec    si                ; dec count
    jge    main_loop
    jmp    short end_line            ; end of line

positive:
    inc    cx                ; update x
                        ; inc cx / dec cx
    inc    di                ; update y
                        ; inc di / dec di
    add    bx, poserr            ; (dx)
    dec    si                ; dec count
    jz    short end_line
    jmp    main_loop            ; not end of line

end_line:
    pop    bp
    pop    dx
    pop    cx
    pop    bx
    pop    si
    pop    di
    mov    sp, bp
    pop    bp
    ret
_sig_line    endp

;
;            void
;            sigmachar(c, x, y, col)
;                int    c;        /* character code */
;                int    x, y;        /* upper left pixel */
;                int    col        /* colour    */
;

ARGC        equ    word ptr [bp + argbase + 4]    ; stack frame addressing
ARGX        equ    word ptr [bp + argbase + 6]
ARGY        equ    word ptr [bp + argbase + 8]
ARGcol        equ             [bp + argbase + 10]

_sigmachar    proc    far

    push    bp        ; preserve caller registers
    mov    bp,sp
    push    di
    push    si
    push    ds

    mov    ax, ARGcol
    mov     color, ax

    mov    ax, 0b800h            ; display mem segment
    mov    es, ax                ; display mem segment

; calculate first pixel address

    mov    di,ARGY        ; di = y
    mov    cx,ARGX        ; aX = x
    mov    ax, cx
    sub    di,__fontsize    ; Make lower left the origin by
    shl    di, 1        ; Index into row table
    mov    di, row_table[di]
    shr    ax, 1
    shr    ax, 1
    shr    ax, 1
    add    di, ax
    and    cl, 7

; set up character definition table addressing

    mov    ch,byte ptr __fontsize
    cmp    ch,16
    je    big

    mov    ax,0f000h
    mov    ds,ax
    mov    ax,0fa6eh
    mov    si,ax

    jmp    cont1
big:
    mov    ax, SEG _chartab
    mov    ds, ax
    mov    si, OFFSET _chartab
cont1:
    mov    ax,ARGC
    mul    ch
    add    si,ax

; mask and set pixels in the video buffer


L20:
    xor    ax,ax
    lodsb            ; AX = bit pattern for next pixel row

    ror    ax, cl        ; rotate pixels into position
    mov    dx, ax        ; bitORmask
    mov    bx, ax
    not    bx        ; bitANDmask

    xor    al, al
    push    dx
    mov    dx, 02DEh
    out    dx, al        ; plane 0
    pop    dx

    mov    ah, byte ptr ARGcol
    and    ah, 1
    jz    np11a
    or    es:[di], dx
    jmp    short np11b
np11a:
    and    es:[di], bx
np11b:
    mov    al, 1
    push    dx
    mov    dx, 02DEh
    out    dx, al        ; plane 1
    pop    dx

    mov    ah, byte ptr ARGcol
    and    ah, 2
    jz    np22a
    or    es:[di], dx
    jmp    short np22b
np22a:
    and    es:[di], bx
np22b:
    mov    al, 2
    push    dx
    mov    dx, 02DEh
    out    dx, al        ; plane 2
    pop    dx

    mov    ah, byte ptr ARGcol
    and    ah, 4
    jz    np33a
    or    es:[di], dx
    jmp    short np33b
np33a:
    and    es:[di], bx
np33b:
    mov    al, 3
    push    dx
    mov    dx, 02DEh
    out    dx, al        ; plane 3
    pop    dx

    mov    ah, byte ptr ARGcol
    and    ah, 8
    jz    np44a
    or    es:[di], dx
    jmp    short np44b
np44a:
    and    es:[di], bx
np44b:

    add    di, 2000h
    jns    L22
    add    di, 80-8000h

L22:    dec    ch
    jnz    L20
Lexit:
    pop    ds        ; restore caller registers and return
    pop    si
    pop    di
    mov    sp,bp
    pop    bp
    ret

_sigmachar    endp

_sigmaclear    proc    far
    push    bp
    mov    bp, sp
    push    di
    push    si
    push    cx
    push    dx

    mov    ax, 0b800h            ; display mem segment
    mov    es, ax                ; display mem segment
    xor    di, di
        mov     cx, 04000h
    mov    dx, 02DEh

    mov    al, 0                ; plane 0
    out    dx, al
    mov    ah, byte ptr __cur_color
    and    ah, 1
    jz    n1
    mov    ax, 0FFFFh
    jmp    short    n2
n1:
    xor    ax, ax
n2:

        cld
        rep    stosw
    xor    di, di
        mov     cx, 04000h

    mov    al, 1                ; plane 1
    out    dx, al
    mov    ah, byte ptr __cur_color
    and    ah, 2
    jz    n3
    mov    ax, 0FFFFh
    jmp    short    n4
n3:
    xor    ax, ax
n4:
        rep stosw
    xor    di, di
        mov     cx, 04000h

    mov    al, 2                ; plane 2
    out    dx, al
    mov    ah, byte ptr __cur_color
    and    ah, 4
    jz    n5
    mov    ax, 0FFFFh
    jmp    short    n6
n5:
    xor    ax, ax
n6:
        rep stosw
    xor    di, di
        mov     cx, 04000h

    mov    al, 3                ; plane 2
    out    dx, al
    mov    ah, byte ptr __cur_color
    and    ah, 8
    jz    n7
    mov    ax, 0FFFFh
    jmp    short    n8
n7:
    xor    ax, ax
n8:
        rep stosw

        pop di
        pop si
        pop cx
        pop dx
    mov sp, bp
    pop bp
        ret
_sigmaclear endp

_sigma_set_colors    proc    far
         push    bp
         mov     bp, sp
         les     dx,[bp+argbase+4]
         mov    al,2
         mov    ah,16;

         int     10H
         pop     bp
         ret
_sigma_set_colors    endp

SIGMA_TEXT    ends

        end