gameoflife-appleii/gfx.asm
2016-10-23 01:15:58 +02:00

366 lines
8.8 KiB
NASM
Executable File

; Conway's Game of Life for Apple II
; Copyright (C) 2016 Christophe Meneboeuf <christophe@xtof.info>
;
; 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 3 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/>.
;
.include "apple2.inc"
.include "zeropage.inc"
.import pusha
.import popa
.import pushax
.import popax
.export _mode_text
.export _gfx_init
.export _gfx_fill
.export _gfx_pixel
.export _gfx_get_pixel
.export _gfx_refresh
.define FULLSCREEN #0
.define SPLIT #1
.define LOWRES #0
.define HIRES #1
.define PAGE_1 #1
.define PAGE_2 #2
.BSS
Page_Current: .byte 0
Page_Future: .byte 0
.DATA
;Pages are composed of lines. Here are their 1st pixel adress
Page1: .word $400, $480, $500, $580, $600, $680, $700, $780, $428, $4A8, $528, $5A8, $628, $6A8, $728, $7A8, $450, $4D0, $550, $5D0, $650, $6D0, $750, $7D0
Page2: .word $800, $880, $900, $980, $A00, $A80, $B00, $B80, $828, $8A8, $928, $9A8, $A28, $AA8, $B28, $BA8, $850, $8D0, $950, $9D0, $A50, $AD0, $B50, $BD0
.CODE
;will put the adress of the future page into ptr1
.macro GET_PAGE_FUTURE
.local get_page_future_page_1, get_page_future_page_2, get_page_future_end
LDA Page_Current
CMP PAGE_1
BEQ get_page_future_page_2
;storing the low and high bytes of the page address into ptr1
get_page_future_page_1:
LDA #<Page1
STA ptr1
LDA #>Page1
STA ptr1+1
CLC
BCC get_page_future_end
get_page_future_page_2:
LDA #<Page2
STA ptr1
LDA #>Page1
STA ptr1+1
get_page_future_end:
.endmacro
;**************************
;void __fastcall__ mode_text( void );
_mode_text:
LDA $C054 ;page 1
LDA $C051 ;text
RTS
;**************************
;void __fastcall__ gfx_init( uint8_t RES, uint8_t MODE )
; Switches to the desired res and mode.
; Always displays page 1
_gfx_init:
res: TAX
LDY #0
LDA (sp),Y
CMP LOWRES
BNE hires
lores: LDA $C056
CLC
BCC mode
hires: LDA $C057
mode: CPX FULLSCREEN
BNE split
fullscr:LDA $C052
CLC
BCC init_end
split: LDA $C053
init_end:
LDA $C054 ;page 1
LDA $C050 ;graphics
LDA PAGE_1
STA Page_Current
JSR popa ;the parameter on stack
RTS
;**************************
;void __fastcall__ gfx_fill( uint8_t color )
; Fills the screen with the given color
_gfx_fill:
; TODO SWITCH PAGES !!
;saving the context
;WARNING context us not saved properly: ptr+1 not saved!
TAX
LDA tmp1
JSR pusha
LDA ptr1
JSR pusha
LDA ptr2
JSR pusha
TXA
;duplicate nybble color
STA tmp1
ASL A
ASL A
ASL A
ASL A
ORA tmp1
STA tmp1
;select to page to write into
LDA Page_Current
CMP PAGE_1
BNE page_2
;storing the low and high bytes of the page address into ptr1
page_1: LDA #<Page1
STA ptr1
LDA #>Page1
STA ptr1+1
CLC
BCC fill
page_2: LDA #<Page2
STA ptr1
LDA #>Page1
STA ptr1+1
fill:
;iterating on X: the line number
for_lines:
;getting the 16 bit line adress and storing it in ptr2
TXA
ASL
TAY
LDA (ptr1),Y
STA ptr2
INY
LDA (ptr1),Y
STA ptr2+1
;iterating on Y to fill a line
LDY #0
fill_line:
LDA tmp1 ;reload the color
STA (ptr2),Y ;color the current pixel
INY ;next pixel
CPY #40 ;nb pixels per line
BNE fill_line
INX
CPX #20 ;nb lines
BNE for_lines
fill_end:
;displaying the page we filled
; TODO SWITCH PAGES !!
;restoring the context
JSR popa
STA ptr2
JSR popa
STA ptr1
JSR popa
STA tmp1
RTS
;**************************
;void __fastcall__ gfx_pixel( uint8_t color, uint8_t coord_x, uint8_t coord_y )
; Draws a pixel at the given coordinates on the Page_Future
_gfx_pixel:
;aliases
coord_y := tmp3
;saving the context
PHA
LDA tmp3
JSR pusha
LDA tmp2
JSR pusha
LDA tmp1
JSR pusha
LDA ptr1
LDX ptr1+1
JSR pushax
LDA ptr2
LDX ptr2+1
JSR pushax
PLA
STA coord_y ;coord_y
; Modify the color depending on the pixel's line parity
AND #1
BEQ even
odd: ; pixel is on an odd line
LDA #$0F ;To or with the other nybble when writting the pixel
STA tmp1
LDY #(1+7) ;there were 7 pushes to save registers
LDA (sp),Y ;color
ASL ;shift the color to put it on high nybble
ASL
ASL
ASL
CLC
BCC oddeven
even: ; pixel is on an even line
LDA #$F0 ;To or with the other nybble when writting the pixel
STA tmp1
LDY #(1+7) ;there were 7 pushes to save registers
LDA (sp),Y ;color
oddeven:
STA tmp2
; FIXME : switching to Page 2 does not work
; dont get the future page and work on page 1
;GET_PAGE_FUTURE
LDA #<Page1
STA ptr1
LDA #>Page1
STA ptr1+1
; get the line adress and store it in ptr2
LDA coord_y
LSR
ASL
TAY
LDA (ptr1),Y
STA ptr2
INY
LDA (ptr1),Y
STA ptr2+1
; get coord_x
LDY #7 ;there were 4 pushes to save registers
LDA (sp),Y
; draw
TAY
LDA (ptr2),Y ;a color may have been present on the other nybble
AND tmp1 ;clearing the pixel's nybble
ORA tmp2 ;adding the color to the pixel's nyyble
STA (ptr2),Y
;restoring the context
JSR popax
STA ptr2
STX ptr2+1
JSR popax
STA ptr1
STX ptr1+1
JSR popa
STA tmp1
JSR popa
STA tmp2
JSR popa
STA tmp3
JSR popa ;the 2 parameters on stack
JSR popa
RTS
;**************************
;uint8_t __fastcall__ gfx_get_pixel( uint8_t coord_x, uint8_t coord_y )
; Returns the pixel's color
_gfx_get_pixel:
TAX ; coord_y
;saving the context
LDA ptr1
JSR pusha
LDA ptr2
JSR pusha
; Page's address to ptr1
LDA #<Page1
STA ptr1
LDA #>Page1
STA ptr1+1
; Line's adress to ptr2
TXA
LSR
ASL
TAY
LDA (ptr1),Y
STA ptr2
INY
LDA (ptr1),Y
STA ptr2+1
; get coord_x
LDY #2 ;there were 4 pushes to save registers
LDA (sp),Y
TAY
TXA
AND #1 ; test line parity to read the correct nybble
BEQ even_2
odd_2: LDA (ptr2),Y
LSR ; color is in lo nybble
LSR
LSR
LSR
CLC
BCC end_2
even_2: LDA (ptr2),Y
AND #$0F ; color is in hi nybble
end_2: TAX
;restoring the context
JSR popa
STA ptr2
JSR popa
STA ptr1
JSR popa ;1st parameter
; return value
TXA
LDX #0
RTS
;**************************
;void __fastcall__ gfx_refresh( void )
; Updates the screen by displaying the Future Page which becomes Current
_gfx_refresh:
LDA Page_Current
CMP PAGE_1
BEQ switch_to_page_2
switch_to_page_1:
LDA $C054 ;page 1
LDA PAGE_1
CLC
BCC switch_to_page_end
switch_to_page_2:
LDA $C055 ;page 2
LDA PAGE_2
switch_to_page_end:
STA Page_Current
RTS