Propeller SPIN XGA driver

xga.spin

'VGA Driver by Lee Marshall

CON
  _clkmode = XINPUT + PLL16X
  _xinfreq = 4_000_000

VAR
  long bitmapbase[1536]
  byte cog
  
PUB Main

  cognew(@vgastart,@bitmapbase)
  

PUB Running : YesNo
  YesNo := cog

PUB Stop
  cogstop(cog~ -1)

 
DAT
        org
'Driver Start        
vgastart

                        rdlong bitmap_base,par          'store base address of bitmap
                        mov dira,IOdir                  
                        mov vcfg,videoconfig            'configure video generator
                        mov vscl,videoscale
                        mov frqa,frequencya             'set up counter module to produce internal 64 mhz signal, and start counter
                        mov ctra,countera

loop7                   mov currentline,vlines          'set currentline to 768
loop6                   call #whiteline                 'do a white line
                        djnz currentline,#loop6         'do this 768 times
                        call #vertical_sync             'do vertical sync
                        jmp #loop7                      'start again
                        

                        




whiteline                                               'produce a white line
                        mov tilecount,#32
                        
loop8                   waitvid vid_colors,vid_test     '32 horizontal pixelgroups of 32 pixels(1024 pixels)

                        djnz tilecount,#loop8
                        waitvid hsync_colors,hsync_pixels1                      'hsync
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3

                                                                                                                                
                        
whiteline_ret           ret



blankline                                               'produce a blank line
                        mov tilecount,#32
                        
loop1                   waitvid vid_colors,zero         '32 horizontal pixelgroups of 32 pixels(1024 pixels)

                        djnz tilecount,#loop1
                        waitvid hsync_colors,hsync_pixels1                      'hsync
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels2
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3
                        waitvid hsync_colors,hsync_pixels3

                                                                                                                                
                        
blankline_ret           ret







vsync_line
                        mov tilecount,#32
loop2                   waitvid vsync_colors,zero
                        djnz tilecount,#loop2
                        
                        waitvid vsync_colors,hsync_pixels1                      'hsync
                        waitvid vsync_colors,hsync_pixels2
                        waitvid vsync_colors,hsync_pixels2
                        waitvid vsync_colors,hsync_pixels2
                        waitvid vsync_colors,hsync_pixels2
                        waitvid vsync_colors,hsync_pixels3
                        waitvid vsync_colors,hsync_pixels3
                        waitvid vsync_colors,hsync_pixels3
                        waitvid vsync_colors,hsync_pixels3
                        waitvid vsync_colors,hsync_pixels3
                        
vsync_line_ret          ret




vertical_sync                                           'perform vsync

                        mov linecount,vfp               'front porch lines
loop3                   call #blankline
                        djnz linecount,#loop3
                        
                        mov linecount,vsync             'sync lines
loop4                   call #vsync_line
                        djnz linecount,#loop4

                        mov linecount,vbp               'back porch lines
loop5                   call #blankline
                        djnz linecount,#loop5                         

vertical_sync_ret       ret              
              
                            




bitmap_base   long       0                       'pointer to bitmap(1536 longs(6KBytes))
temp          long       0

IOdir         long      %00000000_11111111_0000000000000000

videoconfig   long      %0_01_0_0_0_000_00000000000_010_0_11111111
videoscale    long      %000000000000_00000001_000000100000

countera      long      %0_00001_110_00000000_000000_000_000000                 
frequencya    long      $2_000_0000

currentpixel  long      0
currentline   long      0
tilecount     long      0
linecount     long      0

hfp           long      24                      'horizontal details in pixels
hsync         long      136
hbp           long      160
hvid          long      1024

vfp           long      3                       'vertical details in lines                                                                                                             
vsync         long      6
vbp           long      29
zero          long      0

vlines        long      768

                                     
vsync_colors  long      %01010100_00000010      'color 0 : hsync 1, vsync 0     color 1 : hsync 0, vsync 0

hsync_colors  long      %00000001_01010111      'color 0 : hsync 1, vsync 1     color 1 : hsync 0, vsync 1

vid_colors    long      %11111111_01010111      'color 0 : syncs 1, rgb 000     color 1 : syncs 1, rgb 111




'                       hsync:
'                       requires:
'                       hsync_pixels1 (x1)
'                       hsync_pixels2 (x4)
'                       hsync_pixels3 (x5)
                       
hsync_pixels1 long      %11111111_000000000000000000000000                      'front porch, then beginning of sync pulse
hsync_pixels2 long      %11111111111111111111111111111111                       'rest of sync pulse
hsync_pixels3 long      %00000000000000000000000000000000                       'back porch

vid_test      long      %11111111111111111111111111111111

fit