cbmeeks/vga.spin

## vga.spin
''********************************************
''*  VGA 128x96 64-Color Bitmap Driver v1.0  *
''*  Author: Andy Schenk                     *
''*  See end of file for terms of use.       *
''********************************************
''*  based on Chip Gracey's 512x384 Bitmap driver
''
'' This object generates a 128x96 pixel bitmap, signaled as 1024x768 VGA.
'' Each pixel is one byte, so the entire bitmap requires 12 kbytes,
'' Pixel memory is arranged left-to-right then top-to-bottom.
''
'' A sync indicator signals each time the screen is drawn (you may ignore).
''
'' You must provide buffers for the pixels, and sync. Once started,
'' all interfacing is done via memory. To this object, all buffers are read-
'' only, with the exception of the sync indicator which gets written with a
'' non-0 value. You may freely write all buffers to affect screen appearance.
''

CON

    ' 128x96 settings - signals as 1024 x 768 @ 59Hz
    hp = 128      'horizontal pixels
    vp = 96       'vertical pixels
    hf = 8        'horizontal front porch pixels
    hs = 48       'horizontal sync pixels
    hb = 80       'horizontal back porch pixels
    vf = 1        'vertical front porch lines
    vs = 3        'vertical sync lines
    vb = 28       'vertical back porch lines
    hn = 1        'horizontal normal sync state (0|1)
    vn = 1        'vertical normal sync state (0|1)
    pr = 55       'pixel rate in MHz at 80MHz system clock (5MHz granularity)


    ' Tiles
    xtiles = hp / 4


    ' H/V inactive states
    hv_inactive = (hn << 1 + vn) * $01010101


VAR long cog

PUB start(BasePin, PixelPtr, SyncPtr) : okay

'' Start VGA driver - starts a COG
'' returns false if no COG available
''
''     BasePin = VGA starting pin (0, 8, 16, 24, etc.)
''
''    PixelPtr = Pointer to 12288 bytess containing colors that make up the
''               192 x 96 pixel bitmap. Only the upper 6 bits of a byte are
''               used to set one of 64 colors.
''               color byte examples: %%0020 = blue, %%3300 = gold
''
''     SyncPtr = Pointer to long which gets written with non-0 upon each screen
''               refresh. May be used to time writes/scrolls, so that chopiness
''               can be avoided. You must clear it each time if you want to see
''               it re-trigger.

    'if driver is already running, stop it
    stop

    'implant pin settings and pointers, then launch COG
    reg_vcfg := $300000FF + (BasePin & %111000) << 6
    reg_dira := $FF << (BasePin & %011000)
    pixel_base := PixelPtr

    if (cog := cognew(@init, SyncPtr) + 1)
        return true


PUB stop | i

    '' Stop VGA driver - frees a COG
    if cog
        cogstop(cog~ - 1)


DAT

'***********************************************
'* Assembly language VGA 2-color bitmap driver *
'***********************************************

                        org                             'set origin to $000 for start of program

' Initialization code - init I/O

init                    mov     dira, reg_dira           'set pin directions
                        mov     dirb, reg_dirb

                        movi    ctra, #%00001_101        'enable PLL in ctra (VCO runs at 4x)
                        movi    frqa, #(pr / 5) << 3     'set pixel rate

                        mov     vcfg, reg_vcfg           'set video configuration

' Main loop, display field and do invisible sync lines

field                   mov     pixel_ptr, pixel_base    'reset pixel pointer
                        mov     y, #vp                   'set y lines
:yline                  mov     yx, #8                   'set y expansion
:yexpand                mov     x, #xtiles               'set x tiles
                        mov     vscl, vscl_pixel         'set pixel vscl

:xtile                  rdlong  color, pixel_ptr         'get color word
                        and     color, colormask         'clear h/v bits
                        or      color, hv                'set h/v inactive states
                        waitvid color, #%%3210           'pass colors and pixels to video
                        add     pixel_ptr, #4            'point to next pixel long
                        djnz    x, #:xtile               'another x tile?

                        sub     pixel_ptr, #xtiles * 4   'repoint to first pixels in same line

                        mov     x, #1                    'do horizontal sync
                        call    #hsync

                        djnz    yx, #:yexpand            'y expand?

                        add     pixel_ptr, #xtiles * 4   'point to first pixels in next line
                        djnz    y, #:yline               'another y line?

                        wrlong   colormask, par          'visible done, write non-0 to sync

                        mov     x, #vf                   'do vertical front porch lines
                        call    #blank
                        mov     x, #vs                   'do vertical sync lines
                        call    #vsync
                        mov     x, #vb                   'do vertical back porch lines
                        call    #vsync

                        jmp     #field                  'field done, loop


' Subroutine - do blank lines

vsync                   xor     hvsync, #$101            'flip vertical sync bits

blank                   mov     vscl, hvis               'do blank pixels
                        waitvid hvsync, #0
hsync                   mov     vscl, #hf                'do horizontal front porch pixels
                        waitvid hvsync, #0
                        mov     vscl, #hs                'do horizontal sync pixels
                        waitvid hvsync, #1
                        mov     vscl, #hb                'do horizontal back porch pixels
                        waitvid hvsync, #0
                        djnz    x, #blank                'another line?
hsync_ret
blank_ret
vsync_ret               ret


' Data

reg_dira                long    0                       'set at runtime
reg_dirb                long    0                       'set at runtime
reg_vcfg                long    0                       'set at runtime

pixel_base              long    0                       'set at runtime

vscl_pixel              long    8 << 12 + 32            '8 clocks per pixel and 4 pixels per set
colormask               long    $FCFCFCFC               'mask to isolate R,G,B bits from H,V
hvis                    long    hp * 8                  'visible pixels per scan line
hv                      long    hv_inactive             '-H,-V states
hvsync                  long    hv_inactive ^ $200      '+/-H,-V states


' Uninitialized data

color_ptr               res     1
pixel_ptr               res     1
color                   res     1
pixel                   res     1
x                       res     1
y                       res     1
yl                      res     1
yx                      res     1
	''********************************************
	''* VGA 128x96 64-Color Bitmap Driver v1.0 *
	''* Author: Andy Schenk *
	''* See end of file for terms of use. *
	''********************************************
	''* based on Chip Gracey's 512x384 Bitmap driver
	''
	'' This object generates a 128x96 pixel bitmap, signaled as 1024x768 VGA.
	'' Each pixel is one byte, so the entire bitmap requires 12 kbytes,
	'' Pixel memory is arranged left-to-right then top-to-bottom.
	''
	'' A sync indicator signals each time the screen is drawn (you may ignore).
	''
	'' You must provide buffers for the pixels, and sync. Once started,
	'' all interfacing is done via memory. To this object, all buffers are read-
	'' only, with the exception of the sync indicator which gets written with a
	'' non-0 value. You may freely write all buffers to affect screen appearance.
	''

	CON

	' 128x96 settings - signals as 1024 x 768 @ 59Hz
	hp = 128 'horizontal pixels
	vp = 96 'vertical pixels
	hf = 8 'horizontal front porch pixels
	hs = 48 'horizontal sync pixels
	hb = 80 'horizontal back porch pixels
	vf = 1 'vertical front porch lines
	vs = 3 'vertical sync lines
	vb = 28 'vertical back porch lines
	hn = 1 'horizontal normal sync state (0\|1)
	vn = 1 'vertical normal sync state (0\|1)
	pr = 55 'pixel rate in MHz at 80MHz system clock (5MHz granularity)


	' Tiles
	xtiles = hp / 4


	' H/V inactive states
	hv_inactive = (hn << 1 + vn) * $01010101


	VAR long cog

	PUB start(BasePin, PixelPtr, SyncPtr) : okay

	'' Start VGA driver - starts a COG
	'' returns false if no COG available
	''
	'' BasePin = VGA starting pin (0, 8, 16, 24, etc.)
	''
	'' PixelPtr = Pointer to 12288 bytess containing colors that make up the
	'' 192 x 96 pixel bitmap. Only the upper 6 bits of a byte are
	'' used to set one of 64 colors.
	'' color byte examples: %%0020 = blue, %%3300 = gold
	''
	'' SyncPtr = Pointer to long which gets written with non-0 upon each screen
	'' refresh. May be used to time writes/scrolls, so that chopiness
	'' can be avoided. You must clear it each time if you want to see
	'' it re-trigger.

	'if driver is already running, stop it
	stop

	'implant pin settings and pointers, then launch COG
	reg_vcfg := $300000FF + (BasePin & %111000) << 6
	reg_dira := $FF << (BasePin & %011000)
	pixel_base := PixelPtr

	if (cog := cognew(@init, SyncPtr) + 1)
	return true


	PUB stop \| i

	'' Stop VGA driver - frees a COG
	if cog
	cogstop(cog~ - 1)


	DAT

	'***********************************************
	'* Assembly language VGA 2-color bitmap driver *
	'***********************************************

	org 'set origin to $000 for start of program

	' Initialization code - init I/O

	init mov dira, reg_dira 'set pin directions
	mov dirb, reg_dirb

	movi ctra, #%00001_101 'enable PLL in ctra (VCO runs at 4x)
	movi frqa, #(pr / 5) << 3 'set pixel rate

	mov vcfg, reg_vcfg 'set video configuration

	' Main loop, display field and do invisible sync lines

	field mov pixel_ptr, pixel_base 'reset pixel pointer
	mov y, #vp 'set y lines
	:yline mov yx, #8 'set y expansion
	:yexpand mov x, #xtiles 'set x tiles
	mov vscl, vscl_pixel 'set pixel vscl

	:xtile rdlong color, pixel_ptr 'get color word
	and color, colormask 'clear h/v bits
	or color, hv 'set h/v inactive states
	waitvid color, #%%3210 'pass colors and pixels to video
	add pixel_ptr, #4 'point to next pixel long
	djnz x, #:xtile 'another x tile?

	sub pixel_ptr, #xtiles * 4 'repoint to first pixels in same line

	mov x, #1 'do horizontal sync
	call #hsync

	djnz yx, #:yexpand 'y expand?

	add pixel_ptr, #xtiles * 4 'point to first pixels in next line
	djnz y, #:yline 'another y line?

	wrlong colormask, par 'visible done, write non-0 to sync

	mov x, #vf 'do vertical front porch lines
	call #blank
	mov x, #vs 'do vertical sync lines
	call #vsync
	mov x, #vb 'do vertical back porch lines
	call #vsync

	jmp #field 'field done, loop


	' Subroutine - do blank lines

	vsync xor hvsync, #$101 'flip vertical sync bits

	blank mov vscl, hvis 'do blank pixels
	waitvid hvsync, #0
	hsync mov vscl, #hf 'do horizontal front porch pixels
	waitvid hvsync, #0
	mov vscl, #hs 'do horizontal sync pixels
	waitvid hvsync, #1
	mov vscl, #hb 'do horizontal back porch pixels
	waitvid hvsync, #0
	djnz x, #blank 'another line?
	hsync_ret
	blank_ret
	vsync_ret ret


	' Data

	reg_dira long 0 'set at runtime
	reg_dirb long 0 'set at runtime
	reg_vcfg long 0 'set at runtime

	pixel_base long 0 'set at runtime

	vscl_pixel long 8 << 12 + 32 '8 clocks per pixel and 4 pixels per set
	colormask long $FCFCFCFC 'mask to isolate R,G,B bits from H,V
	hvis long hp * 8 'visible pixels per scan line
	hv long hv_inactive '-H,-V states
	hvsync long hv_inactive ^ $200 '+/-H,-V states


	' Uninitialized data

	color_ptr res 1
	pixel_ptr res 1
	color res 1
	pixel res 1
	x res 1
	y res 1
	yl res 1
	yx res 1