; Seven Kingdoms: Ancient Adversaries
;
; Copyright 1997,1998 Enlight Software Ltd.
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program.  If not, see <http://www.gnu.org/licenses/>.
;

;Filename    : IB_TR.ASM
;Description : Blt a bitmap to the display surface buffer with color key transparency and color remapping handling


INCLUDE IMGFUN.inc
INCLUDE COLCODE.inc

.CODE

;-------- BEGIN OF FUNCTION IMBbltTransRemap ----------
;
; Put an non-compressed bitmap on image buffer.
; It handles color key transparency. The color key code is 255.
;
; T - Transparency key
; C - color remapping
;
; Syntax : IMBbltTransRemap( imageBuf, pitch, x, y, bitmapBuf, colorTable )
;
; char *imageBuf   - the pointer to the display surface buffer
; int  pitch        - pitch of the display surface buffer
; int  x,y         - where to put the image on the surface buffer
; char *bitmapPtr  - the pointer to the bitmap buffer
; char *colorTable - a 256-entry color remapping table
;
;-------------------------------------------------
;
; Format of the bitmap data :
;
; <short>  width
; <short>  height
; <char..> bitmap image
;
;-------------------------------------------------

		 PUBLIC    IMGbltTransRemap
IMGbltTransRemap PROC  	   imageBuf, pitch, x, y, bitmapPtr, colorTable
		 LOCAL	   bitmapWidth
		 STARTPROC

		MOV	EAX, imageBuf		; store the address of the image buffer to a variable
		MOV	image_buf, EAX

		;------ get the bitmap width and height -----;

		MOV     AX , DS
		MOV	ES , AX
		MOV     ESI, bitmapPtr

		XOR	EAX, EAX
		LODSW                            ; get bitmap width
		MOV     EBX, EAX

		LODSW                            ; get bitmap height
		MOV     ECX, EAX

		MOV	EDX, pitch	 ; EDX = lineDiff
		SUB	EDX, EBX		 ; lineDiff = pitch - bitmap_width

		MOV	bitmapWidth, EBX
		MOV	EBX, colorTable		 ; store it in register for fast access

		CLD                              ; clear direction flag for MOVSB

		;------- pixels copying loop --------;

		CALC_ADDR EDI, x, y, pitch              ; Get the offset to the image buffer address
@@moreLines:
		PUSH	ECX
		MOV     ECX, bitmapWidth	 ; ECX is the line pixel counter

		XOR	EAX, EAX		 ; clear EAX as it will be used below

		SHR 	ECX, 2
		JZ	SHORT @@nextScan

;-----------------------------------------------------------------------//
; The idea here is to not branch very often so we unroll the loop by four
; and try to not branch when a whole run of pixels is either transparent
; or not transparent.
;
; There are two loops. One loop is for a run of pixels equal to the
; transparent color, the other is for runs of pixels we need to store.
;
; When we detect a "bad" pixel we jump to the same position in the
; other loop.
;
; Here is the loop we will stay in as long as we encounter a "transparent"
; pixel in the source.
;-----------------------------------------------------------------------//

		align 	4
@@same:
		mov 	al, ds:[esi]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		jne 	short @@diff0
@@same0:
		mov 	al, ds:[esi+1]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		jne 	short @@diff1
@@same1:
		mov 	al, ds:[esi+2]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		jne 	short @@diff2
@@same2:
		mov 	al, ds:[esi+3]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		jne 	short @@diff3
@@same3:
		add 	edi,4
		add 	esi,4
		dec 	ecx
		jnz 	short @@same
		jz  	short @@nextScan

;-----------------------------------------------------------------------//
; Here is the loop we will stay in as long as
; we encounter a "non transparent" pixel in the source.
;-----------------------------------------------------------------------//

		align 	4
@@diff:
		mov 	al, ds:[esi]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		je 	short @@same0
@@diff0:
		POST_REMAP
		mov 	es:[edi], al
		mov 	al, ds:[esi+1]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		je 	short @@same1
@@diff1:
		POST_REMAP
		mov 	es:[edi+1], al
		mov 	al, ds:[esi+2]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		je 	short @@same2
@@diff2:
		POST_REMAP
		mov 	es:[edi+2], al
		mov 	al, ds:[esi+3]
		PRE_REMAP
		cmp 	al, TRANSPARENT_CODE
		je 	short @@same3
@@diff3:
		POST_REMAP
		mov 	es:[edi+3], al

		add 	edi,4
		add 	esi,4
		dec 	ecx
		jnz 	short @@diff
		jz  	short @@nextScan

;-----------------------------------------------------------------------//
; We are at the end of a scan, check for odd leftover pixels to do
; and go to the next scan.
;-----------------------------------------------------------------------//

		align 	4
@@nextScan:
		mov 	ecx,bitmapWidth        	; bitmap width
		and 	ecx,11b			; if its pixel count is an odd number
		jnz 	short @@oddStuff

;-----------------------------------------------------------------------//
; move on to the start of the next line
;-----------------------------------------------------------------------//

@@nextScan1:
		add 	edi, edx 		; edx = lineDiff

		pop	ecx
		dec	ecx
		jz	@@end
		jmp	@@moreLines

;-----------------------------------------------------------------------//
; If the width is not a multiple of 4 we will come here to clean up
; the last few pixels
;-----------------------------------------------------------------------//

@@oddStuff:
		inc 	ecx
@@oddLoop:
		dec 	ecx
		jz  	short @@nextScan1
		mov 	al, ds:[esi]
		inc 	esi
		PRE_REMAP
		inc 	edi
		cmp 	al, TRANSPARENT_CODE
		je  	short @@oddLoop
		POST_REMAP
		mov 	es:[edi-1], al
		jmp 	short @@oddLoop

@@end:          ENDPROC
IMGbltTransRemap  ENDP

;----------- END OF FUNCTION IMGbltTransRemap ----------


END