224 lines
11 KiB
Plaintext
224 lines
11 KiB
Plaintext
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''********************************************
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''* VGA 512x384 2-Color Bitmap Driver v1.0 *
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''* Author: Chip Gracey *
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''* Copyright (c) 2006 Parallax, Inc. *
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''* See end of file for terms of use. *
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''********************************************
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''
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'' This object generates a 512x384 pixel bitmap, signaled as 1024x768 VGA.
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'' Each pixel is one bit, so the entire bitmap requires 512 x 384 / 32 longs,
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'' or 6,144 longs (24KB). Color words comprised of two byte fields provide
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'' unique colors for every 32x32 pixel group. These color words require 512/32
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'' * 384/32 words, or 192 words. Pixel memory and color memory are arranged
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'' left-to-right then top-to-bottom.
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''
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'' A sync indicator signals each time the screen is drawn (you may ignore).
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''
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'' You must provide buffers for the colors, pixels, and sync. Once started,
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'' all interfacing is done via memory. To this object, all buffers are read-
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'' only, with the exception of the sync indicator which gets written with a
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'' non-0 value. You may freely write all buffers to affect screen appearance.
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''
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CON
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' 512x384 settings - signals as 1024 x 768 @ 67Hz
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hp = 512 'horizontal pixels
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vp = 384 'vertical pixels
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hf = 8 'horizontal front porch pixels
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hs = 48 'horizontal sync pixels
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hb = 88 'horizontal back porch pixels
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vf = 1 'vertical front porch lines
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vs = 3 'vertical sync lines
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vb = 28 'vertical back porch lines
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hn = 1 'horizontal normal sync state (0|1)
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vn = 1 'vertical normal sync state (0|1)
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pr = 35 'pixel rate in MHz at 80MHz system clock (5MHz granularity)
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' Tiles
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xtiles = hp / 32
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ytiles = vp / 32
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' H/V inactive states
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hv_inactive = (hn << 1 + vn) * $0101
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VAR long cog
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PUB start(BasePin, ColorPtr, PixelPtr, SyncPtr) : okay | i, j
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'' Start VGA driver - starts a COG
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'' returns false if no COG available
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''
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'' BasePin = VGA starting pin (0, 8, 16, 24, etc.)
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''
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'' ColorPtr = Pointer to 192 words which define the "0" and "1" colors for
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'' each 32x32 pixel group. The lower byte of each word contains
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'' the "0" bit RGB data while the upper byte of each word contains
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'' the "1" bit RGB data for the associated group. The RGB
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'' data in each byte is arranged as %RRGGBB00 (4 levels each).
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''
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'' color word example: %%0020_3300 = "0" = gold, "1" = blue
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''
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'' PixelPtr = Pointer to 6,144 longs containing pixels that make up the 512 x
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'' 384 pixel bitmap. Longs' LSBs appear left on the screen, while
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'' MSBs appear right. The longs are arranged in sequence from left-
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'' to-right, then top-to-bottom.
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''
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'' SyncPtr = Pointer to long which gets written with non-0 upon each screen
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'' refresh. May be used to time writes/scrolls, so that chopiness
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'' can be avoided. You must clear it each time if you want to see
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'' it re-trigger.
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'if driver is already running, stop it
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stop
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'implant pin settings and pointers, then launch COG
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reg_vcfg := $200000FF + (BasePin & %111000) << 6
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i := $FF << (BasePin & %011000)
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j := BasePin & %100000 == 0
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reg_dira := i & j
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reg_dirb := i & !j
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longmove(@color_base, @ColorPtr, 2)
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if (cog := cognew(@init, SyncPtr) + 1)
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return true
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PUB stop | i
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'' Stop VGA driver - frees a COG
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if cog
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cogstop(cog~ - 1)
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DAT
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'***********************************************
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'* Assembly language VGA 2-color bitmap driver *
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'***********************************************
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org 'set origin to $000 for start of program
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' Initialization code - init I/O
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init mov dira,reg_dira 'set pin directions
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mov dirb,reg_dirb
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movi ctra,#%00001_101 'enable PLL in ctra (VCO runs at 4x)
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movi frqa,#(pr / 5) << 3 'set pixel rate
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mov vcfg,reg_vcfg 'set video configuration
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' Main loop, display field and do invisible sync lines
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field mov color_ptr,color_base 'reset color pointer
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mov pixel_ptr,pixel_base 'reset pixel pointer
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mov y,#ytiles 'set y tiles
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:ytile mov yl,#32 'set y lines per tile
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:yline mov yx,#2 'set y expansion
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:yexpand mov x,#xtiles 'set x tiles
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mov vscl,vscl_pixel 'set pixel vscl
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:xtile rdword color,color_ptr 'get color word
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and color,colormask 'clear h/v bits
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or color,hv 'set h/v inactive states
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rdlong pixel,pixel_ptr 'get pixel long
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waitvid color,pixel 'pass colors and pixels to video
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add color_ptr,#2 'point to next color word
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add pixel_ptr,#4 'point to next pixel long
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djnz x,#:xtile 'another x tile?
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sub color_ptr,#xtiles * 2 'repoint to first colors in same line
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sub pixel_ptr,#xtiles * 4 'repoint to first pixels in same line
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mov x,#1 'do horizontal sync
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call #hsync
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djnz yx,#:yexpand 'y expand?
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add pixel_ptr,#xtiles * 4 'point to first pixels in next line
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djnz yl,#:yline 'another y line in same tile?
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add color_ptr,#xtiles * 2 'point to first colors in next tile
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djnz y,#:ytile 'another y tile?
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wrlong colormask,par 'visible done, write non-0 to sync
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mov x,#vf 'do vertical front porch lines
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call #blank
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mov x,#vs 'do vertical sync lines
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call #vsync
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mov x,#vb 'do vertical back porch lines
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call #vsync
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jmp #field 'field done, loop
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' Subroutine - do blank lines
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vsync xor hvsync,#$101 'flip vertical sync bits
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blank mov vscl,hvis 'do blank pixels
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waitvid hvsync,#0
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hsync mov vscl,#hf 'do horizontal front porch pixels
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waitvid hvsync,#0
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mov vscl,#hs 'do horizontal sync pixels
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waitvid hvsync,#1
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mov vscl,#hb 'do horizontal back porch pixels
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waitvid hvsync,#0
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djnz x,#blank 'another line?
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hsync_ret
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blank_ret
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vsync_ret ret
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' Data
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reg_dira long 0 'set at runtime
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reg_dirb long 0 'set at runtime
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reg_vcfg long 0 'set at runtime
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color_base long 0 'set at runtime (2 contiguous longs)
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pixel_base long 0 'set at runtime
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vscl_pixel long 1 << 12 + 32 '1 pixel per clock and 32 pixels per set
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colormask long $FCFC 'mask to isolate R,G,B bits from H,V
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hvis long hp 'visible pixels per scan line
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hv long hv_inactive '-H,-V states
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hvsync long hv_inactive ^ $200 '+/-H,-V states
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' Uninitialized data
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color_ptr res 1
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pixel_ptr res 1
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color res 1
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pixel res 1
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x res 1
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y res 1
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yl res 1
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yx res 1
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{{
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┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ TERMS OF USE: MIT License │
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├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
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│Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation │
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│files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, │
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│modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software│
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│is furnished to do so, subject to the following conditions: │
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│ │
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│The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.│
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│ │
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│THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE │
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│WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR │
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│COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │
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│ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
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└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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}}
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