kolibrios-gitea/kernel/trunk/video/vesa20.inc

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                              ;;
;; Copyright (C) KolibriOS team 2004-2008. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
;;  VESA20.INC                                                  ;;
;;                                                              ;;
;;  Vesa 2.0 functions for MenuetOS                             ;;
;;                                                              ;;
;;  Copyright 2002 Ville Turjanmaa                              ;;
;;  Alexey, kgaz@crosswindws.net                                ;;
;;  - Voodoo compatible graphics                                ;;
;;  Juan M. Caravaca                                            ;;
;;  - Graphics optimimizations eg. drawline                     ;;
;;                                                              ;;
;;  See file COPYING for details                                ;;
;;                                                              ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision$


; If you're planning to write your own video driver I suggest
; you replace the VESA12.INC file and see those instructions.

;Screen_Max_X             equ     0xfe00
;Screen_Max_Y            equ     0xfe04
;BytesPerScanLine        equ     0xfe08
;LFBAddress              equ     0xfe80
;ScreenBPP               equ     0xfbf1
;WinMapAddress           equ     0x460000



;*************************************************
; getpixel
;
; in:
; eax = x coordinate
; ebx = y coordinate
;
; ret:
; ecx = 00 RR GG BB

getpixel:
     push    eax ebx edx edi
     call    dword [GETPIXEL]
     pop     edi edx ebx eax
     ret

Vesa20_getpixel24:
; eax = x
; ebx = y
     imul    ebx, [BytesPerScanLine]    ; ebx = y * y multiplier
     lea     edi, [eax+eax*2] ; edi = x*3
     add     edi, ebx         ; edi = x*3+(y*y multiplier)
     add     edi, [LFBAddress]    ; ebx = where pixel is in memory
     mov     ecx, [edi]
     and     ecx, 0xffffff
     ret

Vesa20_getpixel32:
     imul    ebx, [BytesPerScanLine]    ; ebx = y * y multiplier
     lea     edi, [ebx+eax*4] ; edi = x*4+(y*y multiplier)
     add     edi, [LFBAddress]    ; ebx = where pixel is in memory
     mov     ecx, [edi]
     and     ecx, 0xffffff
     ret

;*************************************************

virtual at esp
 putimg:
   .real_sx        dd ?
   .real_sy        dd ?
   .image_sx       dd ?
   .image_sy       dd ?
   .image_cx       dd ?
   .image_cy       dd ?
   .pti            dd ?
   .abs_cx         dd ?
   .abs_cy         dd ?
   .line_increment dd ?
   .winmap_newline dd ?
   .screen_newline dd ?
   .stack_data = 4*12
   .edi         dd      ?
   .esi         dd      ?
   .ebp         dd      ?
   .esp         dd      ?
   .ebx         dd      ?
   .edx         dd      ?
   .ecx         dd      ?
   .eax         dd      ?
   .ret_addr    dd      ?
   .arg_0       dd      ?
end virtual

align 16
; ebx = pointer
; ecx = size [x|y]
; edx = coordinates [x|y]
; ebp = pointer to 'get' function
; esi = pointer to 'init' function
; edi = parameter for 'get' function

vesa20_putimage:
     pushad
     call    [disable_mouse]
     sub     esp, putimg.stack_data
; save pointer to image
     mov     [putimg.pti], ebx
; unpack the size
     mov     eax, ecx
     and     ecx, 0xFFFF
     shr     eax, 16
     mov     [putimg.image_sx], eax
     mov     [putimg.image_sy], ecx
; unpack the coordinates
     mov     eax, edx
     and     edx, 0xFFFF
     shr     eax, 16
     mov     [putimg.image_cx], eax
     mov     [putimg.image_cy], edx
; calculate absolute (i.e. screen) coordinates
     mov     eax, [TASK_BASE]
     mov     ebx, [eax-twdw + WDATA.box.left]
     add     ebx, [putimg.image_cx]
     mov     [putimg.abs_cx], ebx
     mov     ebx, [eax-twdw + WDATA.box.top]
     add     ebx, [putimg.image_cy]
     mov     [putimg.abs_cy], ebx
; real_sx = MIN(wnd_sx-image_cx, image_sx);
     mov     ebx, [eax-twdw + WDATA.box.width] ; ebx = wnd_sx
; \begin{diamond}[20.08.2006]
; note that WDATA.box.width is one pixel less than real window x-size
     inc     ebx
; \end{diamond}[20.08.2006]
     sub     ebx, [putimg.image_cx]
     ja      @f
     add     esp, putimg.stack_data
     popad
     ret
@@:
     cmp     ebx, [putimg.image_sx]
     jbe     .end_x
     mov     ebx, [putimg.image_sx]
.end_x:
     mov     [putimg.real_sx], ebx
; init real_sy
     mov     ebx, [eax-twdw + WDATA.box.height] ; ebx = wnd_sy
; \begin{diamond}[20.08.2006]
     inc     ebx
; \end{diamond}[20.08.2006]
     sub     ebx, [putimg.image_cy]
     ja      @f
     add     esp, putimg.stack_data
     popad
     ret
@@:
     cmp     ebx, [putimg.image_sy]
     jbe     .end_y
     mov     ebx, [putimg.image_sy]
.end_y:
     mov     [putimg.real_sy], ebx
; line increment
     mov     eax, [putimg.image_sx]
     mov     ecx, [putimg.real_sx]
     sub     eax, ecx
;;     imul    eax, [putimg.source_bpp]
;     lea     eax, [eax + eax * 2]
     call    esi
     add     eax, [putimg.arg_0]
     mov     [putimg.line_increment], eax
; winmap new line increment
     mov     eax, [Screen_Max_X]
     inc     eax
     sub     eax, [putimg.real_sx]
     mov     [putimg.winmap_newline], eax
; screen new line increment
     mov     eax, [BytesPerScanLine]
     movzx   ebx, byte [ScreenBPP]
     shr     ebx, 3
     imul    ecx, ebx
     sub     eax, ecx
     mov     [putimg.screen_newline], eax
; pointer to image
     mov     esi, [putimg.pti]
; pointer to screen
     mov     edx, [putimg.abs_cy]
     imul    edx, [BytesPerScanLine]
     mov     eax, [putimg.abs_cx]
     movzx   ebx, byte [ScreenBPP]
     shr     ebx, 3
     imul    eax, ebx
     add     edx, eax
     add     edx, [LFBAddress]
; pointer to pixel map
     mov     eax, [putimg.abs_cy]
     imul    eax, [Screen_Max_X]
     add     eax, [putimg.abs_cy]
     add     eax, [putimg.abs_cx]
     add     eax, WinMapAddress
     xchg    eax, ebp
; get process number
     mov     ebx, [CURRENT_TASK]
     cmp     byte [ScreenBPP], 32
     je      put_image_end_32
;put_image_end_24:
     mov     edi, [putimg.real_sy]
align   4
.new_line:
     mov     ecx, [putimg.real_sx]
;     push    ebp edx
align   4
.new_x:
     push    [putimg.edi]
     mov     eax, [putimg.ebp+4]
     call    eax
     cmp     [ebp], bl
     jne     .skip
;     mov     eax, [esi]        ; eax = RRBBGGRR
     mov     [edx], ax
     shr     eax, 16
     mov     [edx+2], al
.skip:
;     add     esi, 3 ;[putimg.source_bpp]
     add     edx, 3
     inc     ebp
     dec     ecx
     jnz     .new_x
;     pop     edx ebp
     add     esi, [putimg.line_increment]
     add     edx, [putimg.screen_newline] ;[BytesPerScanLine]
     add     ebp, [putimg.winmap_newline] ;[Screen_Max_X]
;     inc     ebp
     cmp     [putimg.ebp], putimage_get1bpp
     jz      .correct
     cmp     [putimg.ebp], putimage_get2bpp
     jz      .correct
     cmp     [putimg.ebp], putimage_get4bpp
     jnz     @f
.correct:
     mov     eax, [putimg.edi]
     mov     byte [eax], 80h
@@:
     dec     edi
     jnz     .new_line
.finish:
     add     esp, putimg.stack_data
     popad
     ret

put_image_end_32:
     mov     edi, [putimg.real_sy]
align   4
.new_line:
     mov     ecx, [putimg.real_sx]
;     push    ebp edx
align   4
.new_x:
     push    [putimg.edi]
     mov     eax, [putimg.ebp+4]
     call    eax
     cmp     [ebp], bl
     jne     .skip
;     mov     eax, [esi]        ; ecx = RRBBGGRR
     mov     [edx], eax
.skip:
;     add     esi, [putimg.source_bpp]
     add     edx, 4
     inc     ebp
     dec     ecx
     jnz     .new_x
;     pop     edx ebp
     add     esi, [putimg.line_increment]
     add     edx, [putimg.screen_newline] ;[BytesPerScanLine]
     add     ebp, [putimg.winmap_newline] ;[Screen_Max_X]
;     inc     ebp
     cmp     [putimg.ebp], putimage_get1bpp
     jz      .correct
     cmp     [putimg.ebp], putimage_get2bpp
     jz      .correct
     cmp     [putimg.ebp], putimage_get4bpp
     jnz     @f
.correct:
     mov     eax, [putimg.edi]
     mov     byte [eax], 80h
@@:
     dec     edi
     jnz     .new_line
.finish:
     add     esp, putimg.stack_data
     popad
     call   VGA__putimage
     mov     [EGA_counter],1
     ret


;*************************************************
align 4
__sys_putpixel:

; eax = x coordinate
; ebx = y coordinate
; ecx = ?? RR GG BB    ; 0x01000000 negation
; edi = 0x00000001 force

;;;        mov  [novesachecksum], dword 0
     pushad
     test  edi,1                 ; force ?
     jnz   .forced
; not forced:
     push  ecx               ; save 24th bit in case negative pixel wanted
     call  checkpixel
     test  ecx,ecx
     pop   ecx
     jnz   .exit
.forced:
     cmp   [Screen_Max_X], eax
     jb    .exit
     cmp   [Screen_Max_Y], ebx
     jb    .exit
.ok:
; check if negation
     test  ecx,0x01000000
     jz    .noneg
     call  getpixel
     not   ecx
     mov   [esp+32-8],ecx
.noneg:
; OK to set pixel
     call  dword [PUTPIXEL]    ; call the real put_pixel function
.exit:
     popad
     ret

align 4
Vesa20_putpixel24:
; eax = x
; ebx = y
     imul    ebx, [BytesPerScanLine]     ; ebx = y * y multiplier
     lea     edi, [eax+eax*2]  ; edi = x*3
     mov     eax, [esp+32-8+4]
     add     edi, [LFBAddress]
     add     edi, ebx          ; ebx = where to put pixel in memory
     mov     [edi], ax
     shr     eax, 16
     mov     [edi+2], al
     ret


align 4
Vesa20_putpixel32:
; eax = x
; ebx = y
     imul    ebx, [BytesPerScanLine]     ; ebx = y * y multiplier
     lea     edi, [ebx+eax*4]  ; edi = x*4+(y*y multiplier)
     mov     eax, [esp+32-8+4] ; eax = color
     add     edi, [LFBAddress]     ; ebx = where to put pixel in memory
     mov     [edi], eax
     ret

;*************************************************

;align 4
calculate_edi:
     mov     edi, ebx
     imul    edi, [Screen_Max_X]
     add     edi, ebx
     add     edi, eax
     ret

;*************************************************

; DRAWLINE

align 4
__sys_draw_line:
;     inc   [mouse_pause]
     call    [disable_mouse]

; draw a line
; eax = HIWORD = x1
;       LOWORD = x2
; ebx = HIWORD = y1
;       LOWORD = y2
; ecx = color
; edi = force ?
        pusha

dl_x1 equ esp+20
dl_y1 equ esp+16
dl_x2 equ esp+12
dl_y2 equ esp+8
dl_dx equ esp+4
dl_dy equ esp+0

     xor     edx, edx      ; clear edx
     xor     esi, esi      ; unpack arguments
     xor     ebp, ebp
     mov     si, ax        ; esi = x2
     mov     bp, bx        ; ebp = y2
     shr     eax, 16       ; eax = x1
     shr     ebx, 16       ; ebx = y1
     push    eax           ; save x1
     push    ebx           ; save y1
     push    esi           ; save x2
     push    ebp           ; save y2
; checking x-axis...
     sub     esi, eax      ; esi = x2-x1
     push    esi           ; save y2-y1
     jl      .x2lx1        ; is x2 less than x1 ?
     jg      .no_vline     ; x1 > x2 ?
     mov     edx, ebp      ; else (if x1=x2)
     call    vline
     push    edx    ; necessary to rightly restore stack frame at .exit
     jmp     .exit
.x2lx1:
     neg     esi            ; get esi absolute value
.no_vline:
; checking y-axis...
     sub     ebp, ebx       ; ebp = y2-y1
     push    ebp            ; save y2-y1
     jl      .y2ly1         ; is y2 less than y1 ?
     jg      .no_hline      ; y1 > y2 ?
     mov     edx, [dl_x2]   ; else (if y1=y2)
     call    hline
     jmp     .exit

.y2ly1:
     neg     ebp            ; get ebp absolute value
.no_hline:
     cmp     ebp, esi
     jle     .x_rules       ; |y2-y1| < |x2-x1|  ?
     cmp     [dl_y2], ebx   ; make sure y1 is at the begining
     jge     .no_reverse1
     neg     dword [dl_dx]
     mov     edx, [dl_x2]
     mov     [dl_x2], eax
     mov     [dl_x1], edx
     mov     edx, [dl_y2]
     mov     [dl_y2], ebx
     mov     [dl_y1], edx
.no_reverse1:
     mov     eax, [dl_dx]
     cdq                    ; extend eax sing to edx
     shl     eax, 16        ; using 16bit fix-point maths
     idiv    ebp            ; eax = ((x2-x1)*65536)/(y2-y1)
     mov     edx, ebp       ; edx = counter (number of pixels to draw)
     mov     ebp, 1 *65536  ; <<16   ; ebp = dy = 1.0
     mov     esi, eax       ; esi = dx
     jmp     .y_rules

.x_rules:
     cmp     [dl_x2], eax    ; make sure x1 is at the begining
     jge     .no_reverse2
     neg     dword [dl_dy]
     mov     edx, [dl_x2]
     mov     [dl_x2], eax
     mov     [dl_x1], edx
     mov     edx, [dl_y2]
     mov     [dl_y2], ebx
     mov     [dl_y1], edx
.no_reverse2:
     xor     edx, edx
     mov     eax, [dl_dy]
     cdq                    ; extend eax sing to edx
     shl     eax, 16        ; using 16bit fix-point maths
     idiv    esi            ; eax = ((y2-y1)*65536)/(x2-x1)
     mov     edx, esi       ; edx = counter (number of pixels to draw)
     mov     esi, 1 *65536  ;<< 16   ; esi = dx = 1.0
     mov     ebp, eax       ; ebp = dy
.y_rules:
     mov     eax, [dl_x1]
     mov     ebx, [dl_y1]
     shl     eax, 16
     shl     ebx, 16
align 4
.draw:
     push    eax ebx
     shr     eax, 16
     shr     ebx, 16
     call    [putpixel]
     pop     ebx eax
     add     ebx, ebp        ; y = y+dy
     add     eax, esi        ; x = x+dx
     dec     edx
     jnz     .draw
; force last drawn pixel to be at (x2,y2)
     mov     eax, [dl_x2]
     mov     ebx, [dl_y2]
     call    [putpixel]
.exit:
     add     esp, 6*4
     popa
;     dec   [mouse_pause]
     call   [draw_pointer]
     ret


hline:
; draw an horizontal line
; eax = x1
; edx = x2
; ebx = y
; ecx = color
; edi = force ?
     push    eax edx
     cmp     edx, eax      ; make sure x2 is above x1
     jge     @f
     xchg    eax, edx
align   4
@@:
     call    [putpixel]
     inc     eax
     cmp     eax, edx
     jle     @b
     pop     edx eax
     ret


vline:
; draw a vertical line
; eax = x
; ebx = y1
; edx = y2
; ecx = color
; edi = force ?
     push    ebx edx
     cmp     edx, ebx      ; make sure y2 is above y1
     jge     @f
     xchg    ebx, edx
align   4
@@:
     call    [putpixel]
     inc     ebx
     cmp     ebx, edx
     jle     @b
     pop     edx ebx
     ret


;*************************************************


virtual at esp
drbar:
     .bar_sx       dd ?
     .bar_sy       dd ?
     .bar_cx       dd ?
     .bar_cy       dd ?
     .abs_cx       dd ?
     .abs_cy       dd ?
     .real_sx      dd ?
     .real_sy      dd ?
     .color        dd ?
     .line_inc_scr dd ?
     .line_inc_map dd ?
     .stack_data = 4*11
end virtual

align 4
; eax   cx
; ebx   cy
; ecx   xe
; edx   ye
; edi   color
vesa20_drawbar:
     pushad
     call    [disable_mouse]
     sub     esp, drbar.stack_data
     mov     [drbar.color], edi
     sub     edx, ebx
     jle     .exit          ;// mike.dld, 2005-01-29
     sub     ecx, eax
     jle     .exit          ;// mike.dld, 2005-01-29
     mov     [drbar.bar_sy], edx
     mov     [drbar.bar_sx], ecx
     mov     [drbar.bar_cx], eax
     mov     [drbar.bar_cy], ebx
     mov     edi, [TASK_BASE]
     add     eax, [edi-twdw + WDATA.box.left] ; win_cx
     add     ebx, [edi-twdw + WDATA.box.top] ; win_cy
     mov     [drbar.abs_cx], eax
     mov     [drbar.abs_cy], ebx
; real_sx = MIN(wnd_sx-bar_cx, bar_sx);
     mov     ebx, [edi-twdw + WDATA.box.width] ; ebx = wnd_sx
; \begin{diamond}[20.08.2006]
; note that WDATA.box.width is one pixel less than real window x-size
     inc     ebx
; \end{diamond}[20.08.2006]
     sub     ebx, [drbar.bar_cx]
     ja      @f
.exit:                       ;// mike.dld, 2005-01-29
     add     esp, drbar.stack_data
     popad
     xor     eax, eax
     inc     eax
     ret
@@:
     cmp     ebx, [drbar.bar_sx]
     jbe     .end_x
     mov     ebx, [drbar.bar_sx]
.end_x:
     mov     [drbar.real_sx], ebx
; real_sy = MIN(wnd_sy-bar_cy, bar_sy);
     mov     ebx, [edi-twdw + WDATA.box.height] ; ebx = wnd_sy
; \begin{diamond}[20.08.2006]
     inc     ebx
; \end{diamond}
     sub     ebx, [drbar.bar_cy]
     ja      @f
     add     esp, drbar.stack_data
     popad
     xor     eax, eax
     inc     eax
     ret
@@:
     cmp     ebx, [drbar.bar_sy]
     jbe     .end_y
     mov     ebx, [drbar.bar_sy]
.end_y:
     mov     [drbar.real_sy], ebx
; line_inc_map
     mov     eax, [Screen_Max_X]
     sub     eax, [drbar.real_sx]
     inc     eax
     mov     [drbar.line_inc_map], eax
; line_inc_scr
     mov     eax, [drbar.real_sx]
     movzx   ebx, byte [ScreenBPP]
     shr     ebx, 3
     imul    eax, ebx
     neg     eax
     add     eax, [BytesPerScanLine]
     mov     [drbar.line_inc_scr], eax
; pointer to screen
     mov     edx, [drbar.abs_cy]
     imul    edx, [BytesPerScanLine]
     mov     eax, [drbar.abs_cx]
;     movzx   ebx, byte [ScreenBPP]
;     shr     ebx, 3
     imul    eax, ebx
     add     edx, eax
     add     edx, [LFBAddress]
; pointer to pixel map
     mov     eax, [drbar.abs_cy]
     imul    eax, [Screen_Max_X]
     add     eax, [drbar.abs_cy]
     add     eax, [drbar.abs_cx]
     add     eax, WinMapAddress
     xchg    eax, ebp
; get process number
     mov     ebx, [CURRENT_TASK]
     cmp     byte [ScreenBPP], 24
     jne     draw_bar_end_32
draw_bar_end_24:
     mov     eax, [drbar.color]    ;; BBGGRR00
     mov     bh, al                ;; bh  = BB
     shr     eax, 8                ;; eax = RRGG
; eax - color high   RRGG
; bl - process num
; bh - color low    BB
; ecx - temp
; edx - pointer to screen
; esi - counter
; edi - counter
     mov     esi, [drbar.real_sy]
align   4
.new_y:
     mov     edi, [drbar.real_sx]
align   4
.new_x:
     cmp     byte [ebp], bl
     jne     .skip
     mov     [edx], bh
     mov     [edx + 1], ax
.skip:
; add pixel
     add     edx, 3
     inc     ebp
     dec     edi
     jnz     .new_x
; add line
     add     edx, [drbar.line_inc_scr]
     add     ebp, [drbar.line_inc_map]
; <Ivan 15.10.04> drawing gradient bars
     test    eax, 0x00800000
     jz      @f
     test    bh, bh
     jz      @f
     dec     bh
@@:
; </Ivan 15.10.04>
     dec     esi
     jnz     .new_y
     add     esp, drbar.stack_data
     popad
     xor     eax, eax
     ret

draw_bar_end_32:
     mov     eax, [drbar.color]    ;; BBGGRR00
     mov     esi, [drbar.real_sy]
align   4
.new_y:
     mov     edi, [drbar.real_sx]
align   4
.new_x:
     cmp     byte [ebp], bl
     jne     .skip
     mov     [edx], eax
.skip:
; add pixel
     add     edx, 4
     inc     ebp
     dec     edi
     jnz     .new_x
; add line
     add     edx, [drbar.line_inc_scr]
     add     ebp, [drbar.line_inc_map]
; <Ivan 15.10.04> drawing gradient bars
     test    eax, 0x80000000
     jz      @f
     test    al, al
     jz      @f
     dec     al
@@:
; </Ivan 15.10.04>
     dec     esi
     jnz     .new_y
     add     esp, drbar.stack_data
     popad
     call    VGA_draw_bar
     xor     eax, eax
     mov     [EGA_counter],1
     ret

;voodoodbcplimit:

; ebp:=(y+Ywin)*(ScreenXSize+1)+(x+Xwin)+AddrBuffer


;     pusha

;     xor edx,edx
;     mov eax,ebp
;     mov ebx,[Screen_Max_X] ; Screen_X_size
;     inc ebx   ; +1
;     sub eax,WinMapAddress ; -AddrBuffer
;     div ebx ;
;     mov ebx,eax ; ebx:=Y
;     mov eax,edx ; eax:=X
;     call cplimit

;     test ecx,ecx
;     jne  dbcpl12
;     popa
;     clc
;     ret
;   dbcpl12:
;     popa
;     stc
;     ret




;dbcplimit:

;        pusha

;        xor  edx,edx
;        mov  ebx,[Screen_Max_X]
;        inc  ebx
;        sub  eax,WinMapAddress
;        div  ebx
;        mov  ebx,eax
;        mov  eax,edx
;        call cplimit

;        test ecx,ecx
;        jne  dbcpl1
;        popa
;        clc
;        ret
;     dbcpl1:
;        popa
;        stc
;        ret


vesa20_drawbackground_tiled:
        call    [disable_mouse]
        pushad
; External loop for all y from start to end
        mov     ebx, [draw_data+32+RECT.top]    ; y start
dp2:
        mov     ebp, [draw_data+32+RECT.left]   ; x start
; 1) Calculate pointers in WinMapAddress (does pixel belong to OS thread?) [ebp]
;                       and LFB data (output for our function) [edi]
        mov     eax, [BytesPerScanLine]
        mul     ebx
        xchg    ebp, eax
        add     ebp, eax
        add     ebp, eax
        add     ebp, eax
        cmp     [ScreenBPP], byte 24    ; 24 or 32 bpp ? - x size
        jz      @f
        add     ebp, eax
@@:
        add     ebp, [LFBAddress]
; ebp:=Y*BytesPerScanLine+X*BytesPerPixel+AddrLFB
        call    calculate_edi
        xchg    edi, ebp
; Now eax=x, ebx=y, edi->output, ebp=offset in WinMapAddress
; 2) Calculate offset in background memory block
        push    eax
        xor     edx, edx
        mov     eax, ebx
        div     dword [BgrDataHeight]   ; edx := y mod BgrDataHeight
        pop     eax
        push    eax
        mov     ecx, [BgrDataWidth]
        mov     esi, edx
        imul    esi, ecx                ; esi := (y mod BgrDataHeight) * BgrDataWidth
        xor     edx, edx
        div     ecx             ; edx := x mod BgrDataWidth
        sub     ecx, edx
        add     esi, edx        ; esi := (y mod BgrDataHeight)*BgrDataWidth + (x mod BgrDataWidth)
        pop     eax
        lea     esi, [esi*3]
        add     esi, [img_background]
        xor     edx, edx
        inc     edx
; 3) Loop through redraw rectangle and copy background data
; Registers meaning:
; eax = x, ebx = y (screen coordinates)
; ecx = deltax - number of pixels left in current tile block
; edx = 1
; esi -> bgr memory, edi -> output
; ebp = offset in WinMapAddress
dp3:
        cmp     [ebp+WinMapAddress], dl
        jnz     nbgp
        movsb
        movsb
        movsb
        jmp     @f
nbgp:
        add     esi, 3
        add     edi, 3
@@:
        cmp     [ScreenBPP], byte 25    ; 24 or 32 bpp?
        sbb     edi, -1         ; +1 for 32 bpp
; I do not use 'inc eax' because this is slightly slower then 'add eax,1'
        add     ebp, edx
        add     eax, edx
        cmp     eax, [draw_data+32+RECT.right]
        ja      dp4
        sub     ecx, edx
        jnz     dp3
; next tile block on x-axis
        mov     ecx, [BgrDataWidth]
        sub     esi, ecx
        sub     esi, ecx
        sub     esi, ecx
        jmp     dp3
dp4:
; next scan line
        inc     ebx
        cmp     ebx, [draw_data+32+RECT.bottom]
        jbe     dp2
        popad
        mov     [EGA_counter], 1
        call    VGA_drawbackground
        ret

; ----------


vesa20_drawbackground_stretch:
        call    [disable_mouse]
        pushad
; Helper variables
; calculate 2^32*(BgrDataWidth-1) mod (ScreenWidth-1)
        mov     eax, [BgrDataWidth]
        dec     eax
        xor     edx, edx
        div     dword [Screen_Max_X]
        push    eax     ; high
        xor     eax, eax
        div     dword [Screen_Max_X]
        push    eax     ; low
; the same for height
        mov     eax, [BgrDataHeight]
        dec     eax
        xor     edx, edx
        div     dword [Screen_Max_Y]
        push    eax     ; high
        xor     eax, eax
        div     dword [Screen_Max_Y]
        push    eax     ; low
; External loop for all y from start to end
        mov     ebx, [draw_data+32+RECT.top]    ; y start
        mov     ebp, [draw_data+32+RECT.left]   ; x start
; 1) Calculate pointers in WinMapAddress (does pixel belong to OS thread?) [ebp]
;                       and LFB data (output for our function) [edi]
        mov     eax, [BytesPerScanLine]
        mul     ebx
        xchg    ebp, eax
        add     ebp, eax
        add     ebp, eax
        add     ebp, eax
        cmp     [ScreenBPP], byte 24    ; 24 or 32 bpp ? - x size
        jz      @f
        add     ebp, eax
@@:
        add     ebp, [LFBAddress]
; ebp:=Y*BytesPerScanLine+X*BytesPerPixel+AddrLFB
        call    calculate_edi
        xchg    edi, ebp
; Now eax=x, ebx=y, edi->output, ebp=offset in WinMapAddress
        push    ebx
        push    eax
; 2) Calculate offset in background memory block
        mov     eax, ebx
        imul    ebx, dword [esp+12]
        mul     dword [esp+8]
        add     edx, ebx        ; edx:eax = y * 2^32*(BgrDataHeight-1)/(ScreenHeight-1)
        mov     esi, edx
        imul    esi, [BgrDataWidth]
        push    edx
        push    eax
        mov     eax, [esp+8]
        mul     dword [esp+28]
        push    eax
        mov     eax, [esp+12]
        mul     dword [esp+28]
        add     [esp], edx
        pop     edx             ; edx:eax = x * 2^32*(BgrDataWidth-1)/(ScreenWidth-1)
        add     esi, edx
        lea     esi, [esi*3]
        add     esi, [img_background]
        push    eax
        push    edx
        push    esi
; 3) Smooth horizontal
bgr_resmooth0:
        mov     ecx, [esp+8]
        mov     edx, [esp+4]
        mov     esi, [esp]
        push    edi
        mov     edi, bgr_cur_line
        call    smooth_line
bgr_resmooth1:
        mov     eax, [esp+16+4]
        inc     eax
        cmp     eax, [BgrDataHeight]
        jae     bgr.no2nd
        mov     ecx, [esp+8+4]
        mov     edx, [esp+4+4]
        mov     esi, [esp+4]
        add     esi, [BgrDataWidth]
        add     esi, [BgrDataWidth]
        add     esi, [BgrDataWidth]
        mov     edi, bgr_next_line
        call    smooth_line
bgr.no2nd:
        pop     edi
sdp3:
        xor     esi, esi
        mov     ecx, [esp+12]
; 4) Loop through redraw rectangle and copy background data
; Registers meaning:
; esi = offset in current line, edi -> output
; ebp = offset in WinMapAddress
; dword [esp] = offset in bgr data
; qword [esp+4] = x * 2^32 * (BgrDataWidth-1) / (ScreenWidth-1)
; qword [esp+12] = y * 2^32 * (BgrDataHeight-1) / (ScreenHeight-1)
; dword [esp+20] = x
; dword [esp+24] = y
; precalculated constants:
; qword [esp+28] = 2^32*(BgrDataHeight-1)/(ScreenHeight-1)
; qword [esp+36] = 2^32*(BgrDataWidth-1)/(ScreenWidth-1)
sdp3a:
        cmp     [ebp+WinMapAddress], byte 1
        jnz     snbgp
        mov     eax, [bgr_cur_line+esi]
        test    ecx, ecx
        jz      .novert
        mov     ebx, [bgr_next_line+esi]
        call    [overlapping_of_points_ptr]
.novert:
        mov     [edi], ax
        shr     eax, 16
        mov     [edi+2], al
snbgp:
        cmp     [ScreenBPP], byte 25
        sbb     edi, -4
        add     ebp, 1
        mov     eax, [esp+20]
        add     eax, 1
        mov     [esp+20], eax
        add     esi, 4
        cmp     eax, [draw_data+32+RECT.right]
        jbe     sdp3a
sdp4:
; next y
        mov     ebx, [esp+24]
        add     ebx, 1
        mov     [esp+24], ebx
        cmp     ebx, [draw_data+32+RECT.bottom]
        ja      sdpdone
; advance edi, ebp to next scan line
        sub     eax, [draw_data+32+RECT.left]
        sub     ebp, eax
        add     ebp, [Screen_Max_X]
        add     ebp, 1
        sub     edi, eax
        sub     edi, eax
        sub     edi, eax
        cmp     [ScreenBPP], byte 24
        jz      @f
        sub     edi, eax
@@:
        add     edi, [BytesPerScanLine]
; restore ecx,edx; advance esi to next background line
        mov     eax, [esp+28]
        mov     ebx, [esp+32]
        add     [esp+12], eax
        mov     eax, [esp+16]
        adc     [esp+16], ebx
        sub     eax, [esp+16]
        mov     ebx, eax
        lea     eax, [eax*3]
        imul    eax, [BgrDataWidth]
        sub     [esp], eax
        mov     eax, [draw_data+32+RECT.left]
        mov     [esp+20], eax
        test    ebx, ebx
        jz      sdp3
        cmp     ebx, -1
        jnz     bgr_resmooth0
        push    edi
        mov     esi, bgr_next_line
        mov     edi, bgr_cur_line
        mov     ecx, [Screen_Max_X]
        inc     ecx
        rep     movsd
        jmp     bgr_resmooth1
sdpdone:
        add     esp, 44
        popad
        mov     [EGA_counter],1
        call    VGA_drawbackground
        ret

uglobal
align 4
bgr_cur_line    rd      1280    ; maximum width of screen
bgr_next_line   rd      1280
endg

smooth_line:
        mov     al, [esi+2]
        shl     eax, 16
        mov     ax, [esi]
        test    ecx, ecx
        jz      @f
        mov     ebx, [esi+2]
        shr     ebx, 8
        call    [overlapping_of_points_ptr]
@@:
        stosd
        mov     eax, [esp+20+8]
        add     eax, 1
        mov     [esp+20+8], eax
        cmp     eax, [draw_data+32+RECT.right]
        ja      @f
        add     ecx, [esp+36+8]
        mov     eax, edx
        adc     edx, [esp+40+8]
        sub     eax, edx
        lea     eax, [eax*3]
        sub     esi, eax
        jmp     smooth_line
@@:
        mov     eax, [draw_data+32+RECT.left]
        mov     [esp+20+8], eax
        ret

align 16
overlapping_of_points:
if 0
; this version of procedure works, but is slower than next version
        push    ecx edx
        mov     edx, eax
        push    esi
        shr     ecx, 24
        mov     esi, ecx
        mov     ecx, ebx
        movzx   ebx, dl
        movzx   eax, cl
        sub     eax, ebx
        movzx   ebx, dh
        imul    eax, esi
        add     dl, ah
        movzx   eax, ch
        sub     eax, ebx
        imul    eax, esi
        add     dh, ah
        ror     ecx, 16
        ror     edx, 16
        movzx   eax, cl
        movzx   ebx, dl
        sub     eax, ebx
        imul    eax, esi
        pop     esi
        add     dl, ah
        mov     eax, edx
        pop     edx
        ror     eax, 16
        pop     ecx
        ret
else
        push    ecx edx
        mov     edx, eax
        push    esi
        shr     ecx, 26
        mov     esi, ecx
        mov     ecx, ebx
        shl     esi, 9
        movzx   ebx, dl
        movzx   eax, cl
        sub     eax, ebx
        movzx   ebx, dh
        add     dl, [BgrAuxTable+(eax+0x100)+esi]
        movzx   eax, ch
        sub     eax, ebx
        add     dh, [BgrAuxTable+(eax+0x100)+esi]
        ror     ecx, 16
        ror     edx, 16
        movzx   eax, cl
        movzx   ebx, dl
        sub     eax, ebx
        add     dl, [BgrAuxTable+(eax+0x100)+esi]
        pop     esi
        mov     eax, edx
        pop     edx
        ror     eax, 16
        pop     ecx
        ret
end if

iglobal
align 4
overlapping_of_points_ptr       dd      overlapping_of_points
endg

init_background:
        mov     edi, BgrAuxTable
        xor     edx, edx
.loop2:
        mov     eax, edx
        shl     eax, 8
        neg     eax
        mov     ecx, 0x200
.loop1:
        mov     byte [edi], ah
        inc     edi
        add     eax, edx
        loop    .loop1
        add     dl, 4
        jnz     .loop2
        test    byte [cpu_caps+(CAPS_MMX/8)], 1 shl (CAPS_MMX mod 8)
        jz      @f
        mov     [overlapping_of_points_ptr], overlapping_of_points_mmx
@@:
        ret

align 16
overlapping_of_points_mmx:
        movd    mm0, eax
        movd    mm4, eax
        movd    mm1, ebx
        pxor    mm2, mm2
        punpcklbw mm0, mm2
        punpcklbw mm1, mm2
        psubw   mm1, mm0
        movd    mm3, ecx
        psrld   mm3, 24
        packuswb mm3, mm3
        packuswb mm3, mm3
        pmullw  mm1, mm3
        psrlw   mm1, 8
        packuswb mm1, mm2
        paddb   mm4, mm1
        movd    eax, mm4
        ret