A2osX/DRV/DHGR.DRV.S.BLT.txt

PR#3
PREFIX /A2OSX.BUILD
LOMEM $A00
INC 1
AUTO 6
				.LIST OFF	
*--------------------------------------
* BitBlt
*  S.CB.X1 : SrcX1 in bitmap/mask
*  S.CB.Y1 : SrcY1
*  S.CB.X2 : SrcX2
*  S.CB.Y2 : SrcY2

*  S.CB.DestX : Destination X (screen)
*  S.CB.DestY : Destination Y (screen)

*  S.CB.SrcPtr : pointer to S.BM
*  S.CB.DstPtr : pointer to Save Buffer 
*--------------------------------------
BITBLT			>LDYA CB.CACHE+S.CB.SrcPtr
				>STYA ZPBMDataPtr

				ldy #S.BM-1

.1				lda (ZPBMDataPtr),y
				sta BM.Cache,y
				dey
				bpl .1
				
				lda ZPBMDataPtr
				clc
				adc #S.BM
				sta ZPBMDataPtr
				bcc .2
				
				inc ZPBMDataPtr+1
	
.2				>LDYA CB.Cache+S.CB.Y1
				ldx BM.Cache+S.BM.RowBytes
				
				jsr YAMultX
				
				pha
				tya
				clc
				adc ZPBMDataPtr
				sta ZPBMDataPtr
				pla
				pha
				adc ZPBMDataPtr+1
				sta ZPBMDataPtr+1
				
				tya
				adc BM.Cache+S.BM.MASK.OFS
				sta ZPBMMaskPtr
				pla 
				adc BM.Cache+S.BM.MASK.OFS+1
				sta ZPBMMaskPtr+1
				
				lda CB.Cache+S.CB.X1
				pha
				and #7
				sta BLT.BMBitOfs
				pla
				
				lsr CB.Cache+S.CB.X1+1
				ror
				lsr CB.Cache+S.CB.X1+1
				ror
				lsr CB.Cache+S.CB.X1+1
				ror
				
				pha
				clc
				adc ZPBMDataPtr
				sta ZPBMDataPtr
				bcc .3

				inc ZPBMDataPtr+1

.3				pla
				adc ZPBMMaskPtr
				sta ZPBMMaskPtr
				bcc .4
				
				inc ZPBMMaskPtr+1
				
.4				lda S.CB.X2
				sec
				sbc S.CB.X1
				sta BLT.DX
				
				lda S.CB.X2+1
				sbc S.CB.X1+1
				sta BLT.DX+1
				
				>LDYA S.CB.DestX
				jsr LBUF.SetBounds1YA
				stx BLT.SCRBitOfs
				
				lda S.CB.DestX
				clc
				adc BLT.DX
				tay
				lda S.CB.DestX+1
				adc BLT.DX+1
				jsr LBUF.SetBounds2YA
				
.5				lda BLT.BMBitOfs
				sta BLT.BMBitOfsL
				
.6				jsr BLT.Get7BMBits

				clc
				rts
*--------------------------------------
* BMD/BMM bits :
* 76543210 76543210
*    ^
*  BMBitOfsL (0->7)
* LBUF DATA/MASK Bits
* c6543210 c6543210
*      ^
*  SCRBitOfsL  (0->6)
*--------------------------------------
BLT.Get7BMBits	lda (ZPBMDataPtr)
				
				ldx BLT.BMBitOfsL
				beq BLT.Get7BMBits0		done! and no need to advance ZPBMDataPtr
				lsr						Range 0->127
				dex						Range 0->6
				beq BLT.Get7BMBits1		
				
				ldy Shift7.LO-1,x		X = 1->6
				sty ZPBMShiftPtr+1

				ldy Shift7.HI-1,x		X = 1->6
				sty ZPBMShiftPtr+1
				
				and Mask7BitsL,x		Get only needed bits
				tay
				
				lda (ZPBMShiftPtr),y
				pha
				
				inc ZPBMDataPtr			Next BM data byte
				bne .1
				inc ZPBMDataPtr+1
				
.1				lda (ZPBMDataPtr)
				and Mask7BitsH,x			
				tay
				
				pla
				
				ora (ZPBMShiftPtr),y
				
				dec BLT.BMBitOfsL		X = 1->6, ADD 7 MOD 8.....
				rts

BLT.Get7BMBits0	and #%01111111			Get only 7 needed bits
				ldx #7
				stx BLT.BMBitOfsL		Was 0, add 7 bits
				rts
				
BLT.Get7BMBits1	stz BLT.BMBitOfsL		Was 1, add 7 bits, MOD 8=0

				inc ZPBMDataPtr			go to next byte
				bne .1
				inc ZPBMDataPtr+1
				
.1				rts 					LSR did already 0xxxxxxx
*--------------------------------------
MAN
SAVE /A2OSX.SRC/DRV/DHGR.DRV.S.RECT
LOAD /A2OSX.SRC/DRV/DHGR.DRV.S
ASM