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GPU/External Registers (edit)

Revision as of 21:25, 18 April 2018

146 bytes added ,  21:25, 18 April 2018
Documented some registers; removed the length column because it's unnecessary
Line 136: Line 136:     
== LCD Source Framebuffer Setup ==
 
== LCD Source Framebuffer Setup ==
 +
 +
All of these registers must be accessed with 32bit operations regardless of the registers' actual bit size.
 +
 
{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
 
! Offset
 
! Offset
−
! Length
   
! Name
 
! Name
 
! Comments
 
! Comments
 
|-
 
|-
 
| 0x00
 
| 0x00
−
| 4
+
| Pixel clock
−
| Pixel timer (not pixel clock)
+
| Higher values are slower, 12bits.
−
| Higher values are slower, min. 0x1C1, bitmask 0xFFF
+
 
 +
Setting this value too low will make the screen not be able to sync any pixels other than a single one from the wrong location. The lowest the screen can handle is 0x1C1, with rare glitching.
 
|-
 
|-
 
| 0x04
 
| 0x04
−
| 4
+
| HBlank timer(?)
−
| HDispStart(?)
+
| Seems to determine the horizontal blanking interval.
−
| Values 0xD1-0x1C1 inclusive are valid (except 2DS bottom screen)
+
 
−
min. 0xD1, bitmask 0xFFF
+
 
 +
Setting this to lower than <code>HTotal - HDisp</code> will make the screen not catch up with the scanlines, some will be skipped, some will be misaligned.
 +
 
 +
Setting this to higher than <code>HTotal - HDisp</code> will make the displayed image misaligned to the right.
 +
 
 +
Setting this to higher than <code>HTotal</code> seems to make the horizontal synchronization never happen.
 
|-
 
|-
 
| 0x08
 
| 0x08
−
| 4
   
| ?
 
| ?
 
| must be >= REG#0x00
 
| must be >= REG#0x00
 
|-
 
|-
 
| 0x0C
 
| 0x0C
−
| 4
   
| ?
 
| ?
 
| must be >= REG#0x08
 
| must be >= REG#0x08
 
|-
 
|-
 
| 0x10
 
| 0x10
−
| 4
+
| ???
−
| VAdjustGranule(?) or VBackPorch(?)
+
| Some sort of delay in signal, probably in the pixel clock
−
 
  −
or
  −
VAdjust(2DS bottom screen)
  −
 
  −
 
  −
Seems to offset pixels relative to someting
  −
 
  −
(last row of pixels blitted increases by this amount;
  −
 
  −
setting this to lower than 2 will kill the screen timing)
  −
| Finetune vertical pixel offset(blur screen), 0x1C2 max = half pixel
  −
 
  −
or (2DS)
  −
offset the bottom screen (0 to kill top screen, 0x1C2 max on bottom screen)
   
|-
 
|-
 
| 0x14
 
| 0x14
−
| 4
+
| HBlank length(?)
−
| HStartMin(?) (poor 2DS emulation)
+
| ??? Seems to offset the screen to the left if this value is high enough, but can glitch out the syncing on the bottom screen
−
| if this value is bigger than some value then it'll trim the first (value - this value) pixels from every line
  −
 
  −
default value is 0xCF
   
|-
 
|-
 
| 0x18
 
| 0x18
−
| 4
   
| ???
 
| ???
 
| should be < REG#0x10
 
| should be < REG#0x10
 
|-
 
|-
 
| 0x20
 
| 0x20
−
| 4
   
| HFrontPorch(?)
 
| HFrontPorch(?)
 
| ??? the screen gets vertically offset with wrap-around
 
| ??? the screen gets vertically offset with wrap-around
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|-
 
|-
 
| 0x24
 
| 0x24
−
| 4
   
| HSync timer?
 
| HSync timer?
 
|  
 
|  
 
|-
 
|-
 
| 0x28
 
| 0x28
−
| 4
   
| VDispStart(?) or VFrontPorch
 
| VDispStart(?) or VFrontPorch
 
|
 
|
 
|-
 
|-
 
| 0x30
 
| 0x30
−
| 4
   
| VTotal
 
| VTotal
 
| Total amount of vertical scanlines
 
| Total amount of vertical scanlines
 
|-
 
|-
 
| 0x34
 
| 0x34
−
| 4
   
| VDisp(?)
 
| VDisp(?)
 
| Total amonut of vertical scanlines displayed (only for top screen it seems like)
 
| Total amonut of vertical scanlines displayed (only for top screen it seems like)
 
|-
 
|-
 
| 0x44
 
| 0x44
−
| 4
   
| ???
 
| ???
 
| similar functionality to 0x10
 
| similar functionality to 0x10
 
|-
 
|-
 
| 0x4C
 
| 0x4C
−
| 4
   
| Overscan filler color
 
| Overscan filler color
 
|  
 
|  
 
|-
 
|-
 
| 0x50
 
| 0x50
−
| 4
   
| Horizontal position counter
 
| Horizontal position counter
 
| read-only
 
| read-only
 
|-
 
|-
 
| 0x54
 
| 0x54
−
| 4
   
| Horizontal scanline (HBlank) counter
 
| Horizontal scanline (HBlank) counter
 
| read-only
 
| read-only
 
|-
 
|-
 
| 0x5C
 
| 0x5C
−
| 4
   
| ???
 
| ???
 
| low u16: framebuffer width
 
| low u16: framebuffer width
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|-
 
|-
 
| 0x60
 
| 0x60
−
| 4
   
| ???
 
| ???
 
| low u16: timing data(?)
 
| low u16: timing data(?)
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|-
 
|-
 
| 0x64
 
| 0x64
−
| 4
   
| ???
 
| ???
 
| low u16: unknown
 
| low u16: unknown
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|-
 
|-
 
| 0x68
 
| 0x68
−
| 4
   
| Framebuffer A first address
 
| Framebuffer A first address
 
| For top screen, this is the left eye 3D framebuffer.
 
| For top screen, this is the left eye 3D framebuffer.
 
|-
 
|-
 
| 0x6C
 
| 0x6C
−
| 4
   
| Framebuffer A second address
 
| Framebuffer A second address
 
| For top screen, this is the left eye 3D framebuffer.
 
| For top screen, this is the left eye 3D framebuffer.
 
|-
 
|-
 
| 0x70
 
| 0x70
−
| 4
   
| Framebuffer format
 
| Framebuffer format
 
| Bit0-15: framebuffer format, bit16-31: unknown
 
| Bit0-15: framebuffer format, bit16-31: unknown
 
|-
 
|-
 
| 0x78
 
| 0x78
−
| 4
   
| Framebuffer select
 
| Framebuffer select
 
| Bit0: which framebuffer to display, bit1-7: unknown
 
| Bit0: which framebuffer to display, bit1-7: unknown
 
|-
 
|-
 
| 0x80
 
| 0x80
−
| 4
   
| Color lookup table index select
 
| Color lookup table index select
 
| 8bits, write-only
 
| 8bits, write-only
 
|-
 
|-
 
| 0x84
 
| 0x84
−
| 4
   
| Color lookup table indexed element
 
| Color lookup table indexed element
 
| Contains the value of the color lookup table indexed by the above register, 24bits, RGB8 (0x00BBGGRR)   
 
| Contains the value of the color lookup table indexed by the above register, 24bits, RGB8 (0x00BBGGRR)   
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|-
 
|-
 
| 0x90
 
| 0x90
−
| 4
   
| Framebuffer stride
 
| Framebuffer stride
 
| Distance in bytes between the start of two framebuffer rows (must be a multiple of 8).
 
| Distance in bytes between the start of two framebuffer rows (must be a multiple of 8).
 
|-
 
|-
 
| 0x94
 
| 0x94
−
| 4
   
| Framebuffer B first address
 
| Framebuffer B first address
 
| For top screen, this is the right eye 3D framebuffer. Unused for bottom screen.
 
| For top screen, this is the right eye 3D framebuffer. Unused for bottom screen.
 
|-
 
|-
 
| 0x98
 
| 0x98
−
| 4
   
| Framebuffer B second address
 
| Framebuffer B second address
 
| For top screen, this is the right eye 3D framebuffer. Unused for bottom screen.
 
| For top screen, this is the right eye 3D framebuffer. Unused for bottom screen.
MarcusD
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