;;================================================================================================;;
;;//// z80.asm //// (c) Nable, 2007-2008 /////////////////////////////////////////////////////////;;
;;================================================================================================;;
;; ;;
;; This file is part of Common development libraries (Libs-Dev). ;;
;; ;;
;; Libs-Dev is free software: you can redistribute it and/or modify it under the terms of the GNU ;;
;; Lesser General Public License as published by the Free Software Foundation, either version 2.1 ;;
;; of the License, or (at your option) any later version. ;;
;; ;;
;; Libs-Dev 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 ;;
;; Lesser General Public License for more details. ;;
;; ;;
;; You should have received a copy of the GNU Lesser General Public License along with Libs-Dev. ;;
;; If not, see <http://www.gnu.org/licenses/>. ;;
;; ;;
;;================================================================================================;;
;; ;;
;; References: ;;
;; 1. ;;
;; ;;
;;================================================================================================;;
include 'z80.inc'
;;================================================================================================;;
proc img.is.z80 _data, _length ;//////////////////////////////////////////////////////////////////;;
;;------------------------------------------------------------------------------------------------;;
;? Determine if raw data could be decoded (is in z80 screen format) ;;
;;------------------------------------------------------------------------------------------------;;
;> _data = raw data as read from file/stream ;;
;> _length = data length ;;
;;------------------------------------------------------------------------------------------------;;
;< eax = false / true ;;
;;================================================================================================;;
xor eax,eax
cmp [_length],6929
setz al
je @f
cmp [_length],6912
setz al
@@:
ret
endp
;;================================================================================================;;
proc img.decode.z80 _data, _length, _options ;////////////////////////////////////////////////////;;
;;------------------------------------------------------------------------------------------------;;
;? Decode data into image if it contains correctly formed raw data in z80 screen format ;;
;;------------------------------------------------------------------------------------------------;;
;> _data = raw data as read from file/stream ;;
;> _length = data length ;;
;;------------------------------------------------------------------------------------------------;;
;< eax = 0 (error) or pointer to image ;;
;;================================================================================================;;
;---------------------------------------------------------------------------------------------------
;During the decoding:
;bl - PixelLeft (this means how much pixels left to put in current string)
;bh - CurrentString
;High half of ebx - use DualStos (two frames per one pixel_write)
;cl - PixelColorIndexInPalette
;ch - BackgroundColorIndexInPalette
;High half of ecx - blinking flag
;edx - address of current attribute byte
;---------------------------------------------------------------------------------------------------
locals
frame1 dd ?
OffsetIn2ndFrame dd ?
endl
xor eax,eax
pushad
cld ;paranoia
stdcall img.create,256,192,Image.bpp8i
test eax,eax
jz img.decode.z80.locret ;test if allocation failed
mov [frame1],eax
mov esi,z80._._16color_palette
mov ecx,16
mov edi,[eax+Image.Palette]
rep movsd ;write palette for the first frame
mov esi,[_data]
cmp [_length],6929
jne @f
add esi,17 ;in case of 6929 byte files we just skip the info in the begininning.
@@:
;---------------------------------------------------------------------------------------------------
;At first we'll determine if there are any blinking pixels
;if no - we'll produce statical single image
mov ecx,768
lea edx,[esi+6912-768];edx points to attribute area
xor ebx,ebx ;begin from <0,0> (for further decoding)
@@:
test byte[edx+ecx-1],z80.BlinkFlag ;such addressing is a good optimisation
;(as I hope), edx is unchanged
jnz .decode_z80_with_blinking
loop @b
.decode_z80_without_blinking:
jmp .decode_z80_main_stage
.decode_z80_with_blinking:
or ebx,0xFFFF0000 ;use DualStos
mov ecx,eax ;eax still points to the first frame
stdcall img.create,256,192,Image.bpp8i
test eax,eax
jz img.decode.z80.failed
mov [eax+Image.Previous],ecx
mov [ecx+Image.Next],eax
mov esi,z80._._16color_palette
mov ecx,16
mov edi,[eax+Image.Palette]
rep movsd ;write palette for the second frame
mov eax,[eax+Image.Data]
mov [OffsetIn2ndFrame],eax
;-------------------------------------------------------------------------------
.decode_z80_main_stage:
;2nd stage - convert z80 screen to 8bpp image with palette
.decode_z80_main_stage_main_loop:
test bl,7
jnz .decode_z80_main_stage_put_now
._z80_update_attributes:
movsx ecx,byte[edx] ;note that BlinkFlag is the highest bit in attribute
;byte, so ecx's highest bit is set automatically
shl ecx,5
shr cl,5
and ch,0xF
test ch,1000b
jz @f
or ecx,1000b ;it has the same size with 'or cl,1000b' but could be faster
@@:
inc edx
lodsb
mov ah,al
.decode_z80_main_stage_put_now:
shl ah,1
;-------------------------------------------------------------------------------
._z80_put_pixel:
;In: CF - put pixel with color CL, !CF - pixel with color CH
;High parts of ebx and ecx - as described above
mov al,cl ;'mov' doesn't affect flags
jc @f
mov al,ch
@@:
stosb ;'stosb' doesn't affect flags
test ebx,ebx
jns @f
test ecx,ecx
jns .1
mov al,ch
.1:
xchg [OffsetIn2ndFrame],edi
stosb
xchg [OffsetIn2ndFrame],edi
@@:
inc bl ;next pixel
jz .decode_z80_main_stage_row_finished
jmp .decode_z80_main_stage_main_loop
;-------------------------------------------------------------------------------
.decode_z80_main_stage_row_finished:
cmp bh,191 ;is image finished?
jb .decode_z80_main_stage_image_not_finished ;no.
.decode_z80_finish:
jmp .locret ;now really finished
;-------------------------------------------------------------------------------
;or not finished yet. Branch according to a row number (see documentation)
.decode_z80_main_stage_next_third:
sub bh,7
sub edi,256*(8-1)
jmp .decode_z80_main_stage_main_loop
.decode_z80_main_stage_image_not_finished:
;next row
add bh,8 ;refer to documentation
add edi,256*(8-1)
;if finished row is 63 or 127 then we process next third of the image
cmp bh,63+8
je .decode_z80_main_stage_next_third
cmp bh,127+8
je .decode_z80_main_stage_next_third
cmp bh,56+8 ;if finished row in [56;63) or [120;127) or [184;191)
jb .decode_z80_main_stage_main_loop
cmp bh,63+8
jb .4
cmp bh,120+8
jb .decode_z80_main_stage_main_loop
cmp bh,127+8
jb .4
cmp bh,184+8
jb .decode_z80_main_stage_main_loop
;note that if we are here then bh is < 191 (see label .2) but >= 184+8
.4:
;and if we here then bh is in [56;63) or [120;127) or [184;191)
sub bh,(8+56-1)
sub edi,256*(8+56-1)
sub edx,z80.AttrString*8
jmp .decode_z80_main_stage_main_loop
img.decode.z80.locret:
popad
ret
img.decode.z80.failed:
stdcall img.destroy,[frame1]
jmp img.decode.z80.locret
endp
;;================================================================================================;;
proc img.encode.z80 _img, _p_length, _options ;///////////////////////////////////////////////////;;
;;------------------------------------------------------------------------------------------------;;
;? Encode image into raw data in z80 screen format ;;
;;------------------------------------------------------------------------------------------------;;
;> _img = pointer to image ;;
;;------------------------------------------------------------------------------------------------;;
;< eax = 0 (error) or pointer to encoded data ;;
;< _p_length = encoded data length ;;
;;================================================================================================;;
xor eax, eax
ret
endp
;;================================================================================================;;
;;////////////////////////////////////////////////////////////////////////////////////////////////;;
;;================================================================================================;;
;! Below are private procs you should never call directly from your code ;;
;;================================================================================================;;
;;////////////////////////////////////////////////////////////////////////////////////////////////;;
;;================================================================================================;;
;;================================================================================================;;
;;////////////////////////////////////////////////////////////////////////////////////////////////;;
;;================================================================================================;;
;! Below is private data you should never use directly from your code ;;
;;================================================================================================;;
;;////////////////////////////////////////////////////////////////////////////////////////////////;;
;;================================================================================================;;
z80._._16color_palette:
dd 0 ; black
dd 0x000000b0 ; blue
dd 0x00b00000 ; red
dd 0x00b000b0 ; magenta
dd 0x0000b000 ; green
dd 0x0000b0b0 ; cyan
dd 0x00b0b000 ; yellow
dd 0x00b0b0b0 ; gray
dd 0 ; black
dd 0x000000ff ; light blue
dd 0x00ff0000 ; light red
dd 0x00ff00ff ; light magenta
dd 0x0000ff00 ; light green
dd 0x0000ffff ; light cyan
dd 0x00ffff00 ; light yellow
dd 0x00ffffff ; white