"Define a representation of the fb_fix_screeninfo structure."
CStruct subclass: #FixedScreenInfo
        declaration: #( (#id (#array #uChar 16))
	                (#smemStart #uLong)
			(#smemLen #uInt)
                        (#type #uInt)
                        (#typeAux #uInt)
                        (#visual #uInt)
                        (#xPanStep #uShort)
                        (#yPanStep #uShort)
                        (#yWrapStep #uShort)
                        (#lineLength #uInt)
                        (#mmioStart #uLong)
                        (#mmioLen #uInt)
                        (#accel #uInt)
                        (#reserved (#array #uShort 3)))
	classVariableNames: ''
	poolDictionaries: ''
	category: 'FrameBuffer Support'
!

"Define a representation of the fb_bitfield structure
 used by the fb_var_screeninfo structure."
CStruct subclass: #FbBitField
        declaration: #( (#offset #uInt)
	                (#length #uInt)
			(#msbRight #uInt))
	classVariableNames: ''
	poolDictionaries: ''
	category: 'FrameBuffer Support'
!

"Define a representation of the fb_var_screeninfo structure."
CStruct subclass: #VariableScreenInfo
        declaration: #( (#xRes #uInt)
                        (#yRes #uInt)
                        (#xResVirtual #uInt)
                        (#yResVirtual #uInt)
                        (#xOffset #uInt)
                        (#yOffset #uInt)
                        (#bitsPerPixel #uInt)
                        (#grayScale #uInt)
                        (#red #FbBitField)
                        (#green #FbBitField)
                        (#blue #FbBitField)
                        (#transp #FbBitField)
                        (#nonStd #uInt)
                        (#activate #uInt)
                        (#height #uInt)
                        (#width #uInt)
                        (#accelFlags #uInt)
                        (#pixClock #uInt)
                        (#leftMargin #uInt)
                        (#rightMargin #uInt)
                        (#upperMargin #uInt)
                        (#lowerMargin #uInt)
                        (#hSyncLen #uInt)
                        (#vSyncLen #uInt)
                        (#sync #uInt)
                        (#vMode #uInt)
                        (#reserved (#array #uInt 6)))
	classVariableNames: ''
	poolDictionaries: ''
	category: 'FrameBuffer Support'
!

"Declare Smalltalk access to the C functions."

SystemDictionary defineCFunc: 'openFrameBuffer'
    withSelectorArgs: 'openFrameBuffer: aString'
    returning: #int
    args: #(#string)
!

SystemDictionary defineCFunc: 'closeFrameBuffer'
    withSelectorArgs: 'closeFrameBuffer: anInteger'
    returning: #int
    args: #(#int)
!

SystemDictionary defineCFunc: 'fixedScreenInfo'
    withSelectorArgs: 'fixedScreenInfoFor: anInteger into: aFixedScreenInfo'
    returning: #int
    args: #(#int #cObject)
!

SystemDictionary defineCFunc: 'variableScreenInfo'
    withSelectorArgs:
      'variableScreenInfoFor: anInteger into: aVariableScreenInfo'
    returning: #int
    args: #(#int #cObject)
!

"Just for testing, add some global variables."
Smalltalk at: #Pstring put: nil!
Smalltalk at: #XRes put: nil!
Smalltalk at: #YRes put: nil!
Smalltalk at: #BitsPerPixel put: nil!
Smalltalk at: #ScreenSize put: nil!
Smalltalk at: #MyFB put: nil!
Smalltalk at: #MyFixedInfo put: nil!
Smalltalk at: #MyVariableInfo put: nil!
Smalltalk at: #FBTypes put: nil!
Smalltalk at: #FBVisuals put: nil!
"Decode of the framebuffer type."
FBTypes := #('packed pixels' 'non interleaved planes'
  'interleaved planes' 'text/attributes'
  'EGA/VGA planes')!
"Decode of the framebuffer visual."
FBVisuals := #('monochr 1=black 0=white' 'monochr 1=white 0=black'
  'true colour' 'pseudo colour' 'direct colour'
  'fixed pseudo colour')!

"Initialise the values of the structures.
 This is required as the C functions will put their results here."
MyFixedInfo := FixedScreenInfo new!
MyVariableInfo := VariableScreenInfo new!

"Call the functions and get the data."
MyFB := Smalltalk openFrameBuffer: '/dev/fb0'!
Smalltalk fixedScreenInfoFor: MyFB into: MyFixedInfo!
Smalltalk variableScreenInfoFor: MyFB into: MyVariableInfo!
Smalltalk closeFrameBuffer: MyFB!

"Display the information obtained.
 Note that the id is a C array so subscripts start at 0."
Transcript nextPutAll: 'ID: '!
0 to: 15 do: [ :i |
  (MyFixedInfo id at: i) >= $  and:
    [ (MyFixedInfo id at: i) <= $z and:
      [ Transcript nextPut: (MyFixedInfo id at: i) ] ] ]!
Transcript nextPutAll: ', len: ';
  nextPutAll: MyFixedInfo smemLen value printString; cr;
  nextPutAll: 'Framebuffer type ';
  nextPutAll: MyFixedInfo type value printString;
  nextPutAll: ': ';
  nextPutAll: (FBTypes at: MyFixedInfo type value + 1
                       ifAbsent: [ 'unknown' ]); cr;
  nextPutAll: 'Framebuffer visual ';
  nextPutAll: MyFixedInfo visual value printString;
  nextPutAll: ': ';
  nextPutAll: (FBVisuals at: MyFixedInfo visual value + 1
                         ifAbsent: [ 'unknown' ]); cr;
  nextPutAll: 'line len: ';
  nextPutAll: MyFixedInfo lineLength value printString;
  nextPutAll: ', accel: ';
  nextPutAll: MyFixedInfo accel value printString; cr;
  nextPutAll: 'xres: ';
  nextPutAll: MyVariableInfo xRes value printString;
  nextPutAll: ', yres: ';
  nextPutAll: MyVariableInfo yRes value printString;
  nextPutAll: ', xoff: ';
  nextPutAll: MyVariableInfo xOffset value printString;
  nextPutAll: ', yoff: ';
  nextPutAll: MyVariableInfo yOffset value printString; cr;
  nextPutAll: 'bits per pixel: ';
  nextPutAll: MyVariableInfo bitsPerPixel value printString; cr;
  nextPutAll: '       Offset  Length  MSBR'; cr;
  nextPutAll: 'red    '!
Pstring := MyVariableInfo red offset value printString!
1 to: (7 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring!
Pstring := MyVariableInfo red length value printString!
1 to: (8 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring;
  nextPutAll: '  ';
  nextPutAll: MyVariableInfo red msbRight value printString; cr;
  nextPutAll: 'green  '!
Pstring := MyVariableInfo green offset value printString!
1 to: (7 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring!
Pstring := MyVariableInfo green length value printString!
1 to: (8 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring;
  nextPutAll: '  ';
  nextPutAll: MyVariableInfo green msbRight value printString; cr;
  nextPutAll: 'blue   '!
Pstring := MyVariableInfo blue offset value printString!
1 to: (7 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring!
Pstring := MyVariableInfo blue length value printString!
1 to: (8 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring;
  nextPutAll: '  ';
  nextPutAll: MyVariableInfo blue msbRight value printString; cr;
  nextPutAll: 'transp '!
Pstring := MyVariableInfo transp offset value printString!
1 to: (7 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring!
Pstring := MyVariableInfo transp length value printString!
1 to: (8 - Pstring size) do: [ :i | Transcript nextPut: $  ]!
Transcript nextPutAll: Pstring;
  nextPutAll: '  ';
  nextPutAll: MyVariableInfo transp msbRight value printString; cr;
  nextPutAll: 'screen size: '!
XRes := MyVariableInfo xRes value!
YRes := MyVariableInfo yRes value!
BitsPerPixel := MyVariableInfo bitsPerPixel value!
ScreenSize := XRes * YRes * BitsPerPixel / 8!
Transcript nextPutAll: ScreenSize printString; cr
!