xpal.asm

视频游戏开发C语言源程序

;
; _x_set_rgb(unsigned char color, unsigned char R,unsigned char G,
;            unsigned char B)
;
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_set_rgb  proc
ARG  ColorIndex:byte,R:byte,G:byte,B:byte
		push bp		; Set up stack frame
		mov  bp,sp

		mov  al,[ColorIndex]
		mov  dx,DAC_WRITE_INDEX  ; Tell DAC what colour index to
		out  dx,al               ; write to
		mov  dx,DAC_DATA

		mov  al,[R]              ; Set the red component
		out  dx,al
		mov  al,[G]              ; Set the green component
		out  dx,al
		mov  al,[B]              ; Set the blue component
		out  dx,al
		pop  bp
		ret
_x_set_rgb endp


;----------------------------------------------------------------------
; Rotate annotated palette buffer entries
;
; x_rot_pal_struc(char far * pal, int direction)
;
; Direction : 0 = backward 1 = forward
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_rot_pal_struc  proc
ARG  PalBuff:dword,Direction:word
    push bp		; Set up stack frame
    mov	 bp,sp
    push ds
    push si
    push di

    cld
    lds	 si,dword ptr [PalBuff]  ; point ds:si to Palette buffer
    lodsw         ; al = colorst ot skip, ah = num colors

    xor  ch,ch    ; Set the number of palette entries to cycle in cx
    mov  cl,ah    ;

    jmp  short RotatePalEntry

_x_rot_pal_struc  endp



;----------------------------------------------------------------------
; Rotate raw palette buffer
;
; x_rot_pal_raw(char far * pal, int direction, int num_colrs)
;
; Direcction : 0 = backward 1 = forward
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_rot_pal_raw	proc
ARG  PalBuff:dword,Direction:word,NumColors:word
    push bp		; Set up stack frame
    mov	 bp,sp
    push ds
    push si
    push di

    cld
    mov	 cx,[NumColors]          ; Set the number of palette entries to cycle
    lds	 si,dword ptr [PalBuff]  ; point ds:si to Palette buffer

RotatePalEntry:


    mov	 ax,ds                ; copy ds to es
    mov	 es,ax

    dec  cx
    mov	 bx,cx                ; Multiply cx by 3
    shl	 bx,1
    add  cx,bx

    cmp  [Direction],0        ; are we going forward ?
    jne  @@forward            ; yes - jump (colors move one position back)

    std                       ; no - set reverse direction
    add  si,cx                ; set si to last byte in palette
    add  si,2

@@forward:
    mov	 ax,si                ; copy si to di
    mov	 di,ax

    lodsb                     ; load first color triplet into regs
    mov  dl,al
    lodsb
    mov  dh,al
    lodsb
    mov  bl,al

    rep	 movsb                ; move remaining triplets direction indicated
			      ; by direction flag

    mov  al,dl                ; write color triplet from regs to last position
    stosb
    mov  al,dh
    stosb
    mov  al,bl
    stosb

    pop	 di
    pop	 si
    pop	 ds
    pop	 bp
    ret
_x_rot_pal_raw  endp

;----------------------------------------------------------------------
; Copy palette making intensity adjustment
; x_cpcontrast_pal_struc(char far *src_pal, char far *dest_pal, unsigned char Intensity)
;
; WARNING: memory for the palette buffers must all be pre-allocated
;
; Written by Themie Gouthas
;----------------------------------------------------------------------
_x_cpcontrast_pal_struc	proc
ARG  PalSrcBuff:dword,PalDestBuff:dword,Intensity:byte
    push bp		; Set up stack frame
    mov	 bp,sp
    push ds
    push si
    push di

    cld
    mov  bh,0ffh
    sub  bh,[Intensity]
    and  bh,07fh            ; Palettes are 7 bit
    lds	 si,dword ptr [PalSrcBuff]  ; point ds:si to Source Palette buffer
    les	 di,dword ptr [PalDestBuff] ; point ds:si to Source Palette buffer
    lodsw			    ; al = colorst ot skip, ah = num color
    stosw

    xor  ch,ch    ; Set the number of palette entries to adjust
    mov  cl,ah    ;

    mov  dx,0     ; flag set to 0 if all output palette entries zero
@@MainLoop:
    lodsw
    sub  al,bh               ; adjust intensity and copy RED
    jns  @@DecrementOK_R
    xor  al,al
@@DecrementOK_R:
    sub  ah,bh               ; adjust intensity and copy GREEN
    jns  @@DecrementOK_G
    xor  ah,ah
@@DecrementOK_G:
    or   dx,ax
    or   dl,ah
    stosw
    lodsb
    sub  al,bh               ; adjust intensity and copy BLUE
    jns  @@DecrementOK_B
    xor  al,al
@@DecrementOK_B:
    or   dl,al
    stosb
    loop @@MainLoop

    mov  ax,dx
    pop  di
    pop	 si
    pop	 ds
    pop	 bp
    ret
_x_cpcontrast_pal_struc  endp



;----------------------------------------------------------------------
; Write DAC palette from annotated type buffer with specified intensity
; ie BYTE colours to skip, BYTE colours to set, r1,g1,b1,r1,g2,b2...rn,gn,bn
;
; x_put_contrast_pal_struc(char far * pal, unsigned char  intensity)
;
; Designed for fading in or out a palette without using an intermediate
; working palette buffer ! (Slow but memory efficient ... OK for small
; pal strucs}
;
; Written by Themie Gouthas
;----------------------------------------------------------------------

_x_put_contrast_pal_struc proc
ARG     CompPalBuff:dword,Intensity:byte
        push    bp      ;preserve caller's stack frame
	mov     bp,sp   ;point to local stack frame
	push    ds
	push    si
	push    di
	cld

	mov     bh,0ffh
	sub     bh,[Intensity]
	and     bh,07fh            ; Palettes are 7 bit
	mov     di,40              ; set the vsync check timer (Vsync
				   ; is tested for at each di'th entry to
				   ; prevent snow 40 is otimum for 10
				   ; MHz 286 or greater)
	lds     si,[CompPalBuff]   ; load the source compressed colour data
	lodsb			   ; get the colours to skip
	mov     bl,al

	lodsb			   ; get the count of colours to set
	mov     ah,0
	mov	cx,ax              ; use it as a loop counter
	or      cx,cx
	jz      @@Done

	WaitVsyncStart           ; Wait for vert sync to start

@@MainLoop:
        mov  al,bl
	mov  dx,DAC_WRITE_INDEX  ; Tell DAC what colour index to start
	out  dx,al               ; writing from
	inc  dx                  ; == mov  dx,DAC_DATA

	lodsb                    ; Load each colour component, modify for
	sub  al,bh               ; intensity and write to DAC H/Ware
	jns  @@DecrementOK_R
	xor  al,al
@@DecrementOK_R:
	out  dx,al

	lodsb
	sub  al,bh
	jns  @@DecrementOK_G
	xor  al,al
@@DecrementOK_G:
	out  dx,al

	lodsb
	sub  al,bh
	jns  @@DecrementOK_B
	xor  al,al
@@DecrementOK_B:
	out  dx,al

	inc  bl                  ; increment color index
	dec  di                  ; decrement vsync test flag
	js   @@test_vsync
	loop @@MainLoop
	jmp  short @@Done


@@test_vsync:
	mov     dx,INPUT_STATUS_0
	push    ax               ; save current colour index
@@Wait:
	in      al,dx            ; wait for vsync leading edge pulse
	test    al,08h
	jz      @@Wait

	pop     ax               ; restore current colour index
	mov     di,40            ; reset vsync test counter
	loop    @@MainLoop       ; loop for next colour index

@@Done:
	;sti
	pop  di
	pop  si
	pop  ds
	pop  bp
	ret

_x_put_contrast_pal_struc   endp


    end