USA Bestseller/USA BESTSELLER Vol 1-95 (Hepp-Computer)(1995).iso/e190/video.asm

Assembly Source File | 1995-02-20 | 5KB | 223 lines

.286

;;    Compact model

LOCALS

;; ----------------- UNINITIALIZED FAR DATA --------------------------

_FARBSS SEGMENT PARA PUBLIC 'FAR_BSS'
PUBLIC ram_buffer

    ram_buffer DB 64016 DUP (?)   ;; buffer for reading/writing to video

_FARBSS ENDS

;; --------------------------- CODE ----------------------------------

_TEXT SEGMENT PARA PUBLIC 'CODE'

PUBLIC _set_tweaked,_set_gmode,_fillbuf,_fillbuft

ASSUME CS:_TEXT

;; ------------------------------------------------------------------ ;;
;;    extern "C" void set_tweaked();
;; ------------------------------------------------------------------
;;    Setup tweaked mode 13h. (320x200x256 colors, with 4 pages)
;;    Code taken from Michael Abrash's Power Graphics Programming.
;; ------------------------------------------------------------------ ;;

_set_tweaked PROC

    push si di

    mov ax,13h  ;; Use BIOS to set to mode 13h (320x200x256 colors)
    int 10h

;;   Disable chain 4 mode

    mov dx,03c4h   ;; Sequencer Index
    mov al,4       ;; memory mode register
    out dx,al
    inc dx
    in al,dx
    and al,not 08h ;; turn off chain 4
    or al,04h      ;; turn off odd/even
    out dx,al

    mov dx,03ceh    ;; Graphics Controller Index
    mov al,5        ;; graphics mode register
    out dx,al
    inc dx
    in al,dx
    and al,not 010h ;; turn off odd/even
    out dx,al
    dec dx
    mov al,6        ;; miscellaneous register
    out dx,al
    inc dx
    in al,dx
    and al,not 02h  ;; turn off chain
    out dx,al

;; Change CRTC scanning from doubleword mode to byte mode,
;; allowing the CRTC to scan more than 64 K of video data

    mov dx,03d4h    ;; CRTC Index

    mov al,014h     ;; underline register
    out dx,al
    inc dx
    in al,dx
    and al,not 040h ;; turn off doubleword
    out dx,al
    dec dx
    mov al,017h     ;; mode control register
    out dx,al
    inc dx
    in al,dx
    or al,040h      ;; turn off byte mode bit, so memory is scanned
                    ;; for video data in a purely linear way, just
                    ;; as in modes 010h and 012h
    out dx,al

;;   Clear the video memory, 8 pixels at a time

    mov dx,03c4h  ;; Sequencer Register Index
    mov ax,0f02h
    out dx,ax     ;; Enable writes to all four planes
    mov ax,0a000h
    mov es,ax
    sub di,di
    sub ax,ax     ;; Clear to 0
    mov cx,8000h  ;; # of words in display memory
    rep stosw

    pop di si
    ret
_set_tweaked ENDP

;; ------------------------------------------------------------------ ;;
;;   extern "C" void set_gmode(int gmode);
;; ------------------------------------------------------------------
;;   Set graphics mode using BIOS
;; ------------------------------------------------------------------ ;;

_set_gmode PROC C
    ARG gmode:WORD

;; Save registers BIOS modifies
    push si
    push di

    mov ax,[gmode]
    xor ah,ah    ;; function:set video mode
    int 10h

    pop di
    pop si
    ret
_set_gmode ENDP

ASSUME ES:_FARBSS
;; ------------------------------------------------------------------ ;;
;;   extern "C" void fillbuf();
;; ------------------------------------------------------------------
;;   Pretend ram_buffer is set up in a non-planar form, and fill it
;;   with random color patterns. For use by mode 13h benchmarks.
;; ------------------------------------------------------------------ ;;

_fillbuf PROC
    push di
    mov ax,_FARBSS
    mov es,ax

    mov di,OFFSET ram_buffer
    mov ax,0101h    ;; blue
    mov cx,16000/2    ;; fill a quarter of screen (using WORDs)
    rep stosw

    mov ax,0404h    ;; red
    mov cx,16000/2    ;; next quarter
    rep stosw

    mov ax,0505h    ;; magenta
    mov cx,16000/2    ;; third quarter
    rep stosw

    mov ax,0202h    ;; green
    mov cx,16000/2    ;; last quarter
    rep stosw

    mov ax,0        ;; black
    mov cx,16/2        ;; fill up remaining 'extra' with black
    rep stosw

    pop di
    ret
_fillbuf ENDP

;; ------------------------------------------------------------------ ;;
;;   extern "C" void fillbuft();
;; ------------------------------------------------------------------
;;   Pretend ram_buffer is set up in a planar fashion, and fill it up
;;   with random color patterns. For use by Tweaked mode benchmarks.
;; ------------------------------------------------------------------ ;;

_fillbuft PROC
    push di
    mov ax,_FARBSS
    mov es,ax

    mov di,OFFSET ram_buffer    ;; start at plane 0, top quarter
    mov bx,4        ;; plane count
    mov ax,0202h    ;; green
@@PlaneDraw1:
    mov cx,4000/2    ;; one quarter
    rep stosw
    add di,12000    ;; next plane

    dec bx
    jnz @@PlaneDraw1

    mov di,OFFSET ram_buffer+4000    ;; start at plane 0, 2nd quarter
    mov bx,4
    mov ax,0505h    ;; magenta
@@PlaneDraw2:
    mov cx,4000/2    ;; one quarter
    rep stosw
    add di,12000    ;; next plane

    dec bx
    jnz @@PlaneDraw2

    mov di,OFFSET ram_buffer+8000    ;; start at plane 0, 3rd quarter
    mov bx,4
    mov ax,0404h    ;; red
@@PlaneDraw3:
    mov cx,4000/2    ;; one quarter
    rep stosw
    add di,12000    ;; next plane

    dec bx
    jnz @@PlaneDraw3

    mov di,OFFSET ram_buffer+12000    ;; start at plane 0, 4th quarter
    mov bx,4
    mov ax,0101h    ;; blue
@@PlaneDraw4:
    mov cx,4000/2    ;; one quarter
    rep stosw
    add di,12000    ;; next plane

    dec bx
    jnz @@PlaneDraw4

    pop di
    ret
_fillbuft ENDP

_TEXT ENDS

END