SendInput BlitzMax conversion.

BlitzMax Forums/BlitzMax Programming/SendInput BlitzMax conversion.

Thareh

(Posted 2010) [#1]

Hi!
I'm trying to use SendInput to generate some mouse and keyboard strokes.
I've had success with the mouse part of the function, but I can't get the keyboard part to work.
I'm thinking it has to do with the data types that BlizMax can't handle.

I've translated this:

typedef struct tagKEYBDINPUT {
    WORD wVk;
    WORD wScan;
    DWORD dwFlags;
    DWORD time;
    ULONG_PTR dwExtraInfo;
} KEYBDINPUT, *PKEYBDINPUT;

Into this:

Type KeyboardInput
	Field wVk:Byte
	Field wScan:Byte
	Field dwFlags:Int
	Field time:Int
	Field dwExtraInfo:Long Ptr
End Type

Is this correct?

_JIM	(Posted 2010) [#2]

I believe WORD is the equivalent of Short in bmax as the DWORD is a doubleword which is the size of an Int which is 4 bytes.

Thareh

(Posted 2010) [#3]

I think I found the problem!

Type TKBInput
	Field Class:Int		= 0
	Field wVk:Int		= 0
	Field wScan:Int 	= 0
	Field dwFlags:Int 	= 0
	Field Time:Int 		= 0
	Field dwExtraInfo:Long	= 0
End Type

Local KBInput:TKBInput = New TKBInput

Print SizeOf( KBInput.Class )
Print SizeOf( KBInput.wVk )
Print SizeOf( KBInput.wScan )
Print SizeOf( KBInput.dwFlags )
Print SizeOf( KBInput.Time )
Print SizeOf( KBInput.dwExtrainfo )

Print ""

Print SizeOf( KBInput )

If you add the fields sizes together manually, you get the right size.
But if you use SizeOf( KBInput ) you get 4 bytes more than you should?

Brucey

(Posted 2010) [#4]

But if you use SizeOf( KBInput ) you get 4 bytes more than you should

Either because of the 4 bytes for the type itself, or because dwExtraInfo is aligned to 8 bytes.

Brucey

(Posted 2010) [#5]

Anyway. Long is not LONG. LONG is Int.

Thareh

(Posted 2010) [#6]

What does aligned to 8 bytes mean?

Type TKBInput
	Field Class:Int		= 0
	Field wVk:Short		= 0
	Field wScan:Short 	= 0
	Field dwFlags:Int 	= 0
	Field Time:Int 		= 0
	Field dwExtraInfo:Long	= 0
End Type

Local KBInput:TKBInput = New TKBInput

Print SizeOf( KBInput.Class )
Print SizeOf( KBInput.wVk )
Print SizeOf( KBInput.wScan )
Print SizeOf( KBInput.dwFlags )
Print SizeOf( KBInput.Time )
Print SizeOf( KBInput.dwExtrainfo )

Print ""

Print SizeOf( KBInput )

If I change two of the fields to Shorts the SizeOf( KBInput ) goes down by 8 instead of 4?

Floyd

(Posted 2010) [#7]

Aligned to 8 bytes means padded with unused bytes, if necessary, so the address is a multiple of 8. Your first example with 5 Ints has 20 bytes before the last field. Thus 4 unused bytes are added to make this 24. The second example, with two Shorts, gives an offset of 16, already a multiple of 8, so no padding is needed.

I believe the size of word, dword and long are 2,4,4 so the corresponding BlitzMax datatypes would be Short, Int, Int. A BlitzMax Long is 8 bytes.

Thareh

(Posted 2010) [#8]

Oh okey :O :S
Is there any way to get the actual size then? The size without padding etc.

Floyd

(Posted 2010) [#9]

The actual size? That would be the size with padding.

In all cases I have checked BlitzMax uses the same padding/alignment as MinGW so this shouldn't be a problem.

The original struct doesn't have or need any padding. The data sizes are 2,2,4,4,4 and everything is already on a 2-byte or 4-byte boundary. If you changed the first DWORD to a WORD the size would not decrease by 2 bytes as you might expect since 2 bytes of padding would now be added in order to align the next DWORD.