258 lines
12 KiB
NASM
258 lines
12 KiB
NASM
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;;================================================================================================;;
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;;//// z80.asm //// (c) Nable, 2007-2008 /////////////////////////////////////////////////////////;;
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;;================================================================================================;;
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;; ;;
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;; This file is part of Common development libraries (Libs-Dev). ;;
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;; ;;
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;; Libs-Dev is free software: you can redistribute it and/or modify it under the terms of the GNU ;;
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;; Lesser General Public License as published by the Free Software Foundation, either version 2.1 ;;
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;; of the License, or (at your option) any later version. ;;
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;; ;;
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;; Libs-Dev is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without ;;
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;; even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ;;
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;; Lesser General Public License for more details. ;;
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;; ;;
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;; You should have received a copy of the GNU Lesser General Public License along with Libs-Dev. ;;
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;; If not, see <http://www.gnu.org/licenses/>. ;;
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;; ;;
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;;================================================================================================;;
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;; ;;
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;; References: ;;
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;; 1. ;;
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;; ;;
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;;================================================================================================;;
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include 'z80.inc'
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;;================================================================================================;;
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proc img.is.z80 _data, _length ;//////////////////////////////////////////////////////////////////;;
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;;------------------------------------------------------------------------------------------------;;
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;? Determine if raw data could be decoded (is in z80 screen format) ;;
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;;------------------------------------------------------------------------------------------------;;
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;> _data = raw data as read from file/stream ;;
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;> _length = data length ;;
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;;------------------------------------------------------------------------------------------------;;
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;< eax = false / true ;;
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;;================================================================================================;;
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xor eax,eax
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cmp [_length],6929
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setz al
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je @f
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cmp [_length],6912
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setz al
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@@:
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ret
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endp
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;;================================================================================================;;
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proc img.decode.z80 _data, _length ;//////////////////////////////////////////////////////////////;;
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;;------------------------------------------------------------------------------------------------;;
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;? Decode data into image if it contains correctly formed raw data in z80 screen format ;;
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;;------------------------------------------------------------------------------------------------;;
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;> _data = raw data as read from file/stream ;;
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;> _length = data length ;;
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;;------------------------------------------------------------------------------------------------;;
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;< eax = 0 (error) or pointer to image ;;
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;;================================================================================================;;
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;---------------------------------------------------------------------------------------------------
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;During the decoding:
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;bl - PixelLeft (this means how much pixels left to put in current string)
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;bh - CurrentString
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;High half of ebx - use DualStos (two frames per one pixel_write)
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;cl - PixelColorIndexInPalette
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;ch - BackgroundColorIndexInPalette
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;High half of ecx - blinking flag
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;edx - address of current attribute byte
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;---------------------------------------------------------------------------------------------------
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locals
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frame1 dd ?
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OffsetIn2ndFrame dd ?
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endl
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xor eax,eax
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pushad
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cld ;paranoia
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stdcall img.create,256,192,Image.bpp8
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test eax,eax
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jz img.decode.z80.locret ;test if allocation failed
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mov [frame1],eax
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mov esi,z80._._16color_palette
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mov ecx,16
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mov edi,[eax+Image.Palette]
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rep movsd ;write palette for the first frame
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mov esi,[_data]
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cmp [_length],6929
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jne @f
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add esi,17 ;in case of 6929 byte files we just skip the info in the begininning.
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@@:
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;---------------------------------------------------------------------------------------------------
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;At first we'll determine if there are any blinking pixels
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;if no - we'll produce statical single image
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mov ecx,768
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lea edx,[esi+6912-768];edx points to attribute area
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xor ebx,ebx ;begin from <0,0> (for further decoding)
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@@:
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test byte[edx+ecx-1],z80.BlinkFlag ;such addressing is a good optimisation
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;(as I hope), edx is unchanged
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jnz .decode_z80_with_blinking
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loop @b
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.decode_z80_without_blinking:
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jmp .decode_z80_main_stage
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.decode_z80_with_blinking:
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or ebx,0xFFFF0000 ;use DualStos
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mov ecx,eax ;eax still points to the first frame
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stdcall img.create,256,192,Image.bpp8
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test eax,eax
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jz img.decode.z80.failed
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mov [eax+Image.Previous],ecx
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mov [ecx+Image.Next],eax
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mov esi,z80._._16color_palette
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mov ecx,16
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mov edi,[eax+Image.Palette]
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rep movsd ;write palette for the second frame
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mov eax,[eax+Image.Data]
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mov [OffsetIn2ndFrame],eax
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;-------------------------------------------------------------------------------
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.decode_z80_main_stage:
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;2nd stage - convert z80 screen to 8bpp image with palette
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.decode_z80_main_stage_main_loop:
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test bl,7
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jnz .decode_z80_main_stage_put_now
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._z80_update_attributes:
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movsx ecx,byte[edx] ;note that BlinkFlag is the highest bit in attribute
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;byte, so ecx's highest bit is set automatically
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shl ecx,5
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shr cl,5
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and ch,0xF
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test ch,1000b
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jz @f
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or ecx,1000b ;it has the same size with 'or cl,1000b' but could be faster
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@@:
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inc edx
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lodsb
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mov ah,al
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.decode_z80_main_stage_put_now:
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shl ah,1
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;-------------------------------------------------------------------------------
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._z80_put_pixel:
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;In: CF - put pixel with color CL, !CF - pixel with color CH
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;High parts of ebx and ecx - as described above
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mov al,cl ;'mov' doesn't affect flags
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jc @f
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mov al,ch
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@@:
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stosb ;'stosb' doesn't affect flags
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test ebx,ebx
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jns @f
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test ecx,ecx
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jns .1
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mov al,ch
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.1:
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xchg [OffsetIn2ndFrame],edi
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stosb
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xchg [OffsetIn2ndFrame],edi
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@@:
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inc bl ;next pixel
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jz .decode_z80_main_stage_row_finished
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jmp .decode_z80_main_stage_main_loop
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;-------------------------------------------------------------------------------
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.decode_z80_main_stage_row_finished:
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cmp bh,191 ;is image finished?
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jb .decode_z80_main_stage_image_not_finished ;no.
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.decode_z80_finish:
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jmp .locret ;now really finished
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;-------------------------------------------------------------------------------
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;or not finished yet. Branch according to a row number (see documentation)
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.decode_z80_main_stage_next_third:
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sub bh,7
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sub edi,256*(8-1)
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jmp .decode_z80_main_stage_main_loop
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.decode_z80_main_stage_image_not_finished:
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;next row
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add bh,8 ;refer to documentation
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add edi,256*(8-1)
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;if finished row is 63 or 127 then we process next third of the image
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cmp bh,63+8
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je .decode_z80_main_stage_next_third
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cmp bh,127+8
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je .decode_z80_main_stage_next_third
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cmp bh,56+8 ;if finished row in [56;63) or [120;127) or [184;191)
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jb .decode_z80_main_stage_main_loop
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cmp bh,63+8
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jb .4
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cmp bh,120+8
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jb .decode_z80_main_stage_main_loop
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cmp bh,127+8
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jb .4
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cmp bh,184+8
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jb .decode_z80_main_stage_main_loop
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;note that if we are here then bh is < 191 (see label .2) but >= 184+8
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.4:
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;and if we here then bh is in [56;63) or [120;127) or [184;191)
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sub bh,(8+56-1)
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sub edi,256*(8+56-1)
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sub edx,z80.AttrString*8
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jmp .decode_z80_main_stage_main_loop
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img.decode.z80.locret:
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popad
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ret
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img.decode.z80.failed:
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stdcall img.destroy,[frame1]
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jmp img.decode.z80.locret
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endp
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;;================================================================================================;;
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proc img.encode.z80 _img, _p_length ;/////////////////////////////////////////////////////////////;;
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;;------------------------------------------------------------------------------------------------;;
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;? Encode image into raw data in z80 screen format ;;
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;;------------------------------------------------------------------------------------------------;;
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;> _img = pointer to image ;;
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;;------------------------------------------------------------------------------------------------;;
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;< eax = 0 (error) or pointer to encoded data ;;
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;< _p_length = encoded data length ;;
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;;================================================================================================;;
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xor eax, eax
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ret
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endp
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;;================================================================================================;;
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;;////////////////////////////////////////////////////////////////////////////////////////////////;;
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;;================================================================================================;;
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;! Below are private procs you should never call directly from your code ;;
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;;================================================================================================;;
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;;////////////////////////////////////////////////////////////////////////////////////////////////;;
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;;================================================================================================;;
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;;================================================================================================;;
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;;////////////////////////////////////////////////////////////////////////////////////////////////;;
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;;================================================================================================;;
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;! Below is private data you should never use directly from your code ;;
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;;================================================================================================;;
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;;////////////////////////////////////////////////////////////////////////////////////////////////;;
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;;================================================================================================;;
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z80._._16color_palette:
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dd 0 ; black
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dd 0x000000b0 ; blue
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dd 0x00b00000 ; red
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dd 0x00b000b0 ; magenta
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dd 0x0000b000 ; green
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dd 0x0000b0b0 ; cyan
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dd 0x00b0b000 ; yellow
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dd 0x00b0b0b0 ; gray
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dd 0 ; black
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dd 0x000000ff ; light blue
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dd 0x00ff0000 ; light red
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dd 0x00ff00ff ; light magenta
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dd 0x0000ff00 ; light green
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dd 0x0000ffff ; light cyan
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dd 0x00ffff00 ; light yellow
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dd 0x00ffffff ; white
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