Just out of curiosity...

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Socoder -> Blitz -> Just out of curiosity...
Tue, 20 Mar 2007, 10:57
Blitz3Dman	Is it possible to write individual bits (booleans) to files using B3D? If so how? -=-=- There are 10 kinds of people in this world - ( Insert 16 remarks about to what extent people know hex here )
Tue, 20 Mar 2007, 11:23
mike_g	I'm pretty sure you cant Intergers allocate 4 Bytes in Blitz. You could use an integer to hold up to 32 bool values using bit shifting if you really wanted to. \|edit\| If you are writing to files then you can write Bytes, but not individual bits. \|edit\|
Tue, 20 Mar 2007, 16:24
Jayenkai	Yeah, as Mike suggests, you can use a combination of bitshifting and bytes to do what you need. Or, use these handy GetBit and SetBit functions. quicky=OpenFile("your test file.txt") eight_bits=ReadByte(quicky) For n=1 To 8 TF$="True" chk=GetBit(eight_bits,n):If chk=0 Then TF$="False" DebugLog "Bit "+n+" = "+TF$ Next eight_bits=SetBit(eight_bits,4,True) eight_bits=SetBit(eight_bits,6,False) eight_bits=SetBit(eight_bits,8,True) DebugLog "---" For n=1 To 8 TF$="True" chk=GetBit(eight_bits,n):If chk=0 Then TF$="False" DebugLog "Bit "+n+" = "+TF$ Next SeekFile(quicky,0) WriteByte(quicky,eight_bits) CloseFile quicky Function GetBit(ByteInput,WhichBit) Return (((1 Shl (8-WhichBit)) And ByteInput) Shr (8-WhichBit)) End Function Function SetBit(ByteInput,WhichBit,Value) If Value=0 Then Return (255-(1 Shl (8-WhichBit))) And ByteInput If Value=1 Then Return (1 Shl (8-WhichBit)) Or ByteInput End Function --v -=-=- ''Load, Next List!''
Wed, 21 Mar 2007, 18:03
Blitz3Dman	Thanks, been wondering how I'd do something like that for a while. Did you write the code yourself or find it? -=-=- There are 10 kinds of people in this world - ( Insert 16 remarks about to what extent people know hex here )
Wed, 21 Mar 2007, 18:22
mike_g	If you learn how bit shifting works then coding something like that is pretty straight forward. Shl shifts a bit left doubling its decimal value. Shr shifts right halving the value. As an example: you can take a binary true state (1) and shift it left 7 times so it becomes 128. to get the value back shift right 7 times and you will be left with 1. You can also cancel out any higher bit values by using the term 'And'. For example: r1 = ((rgb1 Shr 16) And 255) --v This line of code shifts a 4 byte colour value right by 16 bits, then uses 'and' to ignore the high 8 bits reserved for Alpha information. This leaves you with the red component of the colour.
Thu, 22 Mar 2007, 05:07
Blitz3Dman	I still haven't really learned how to use Shr and Shl. Probably ought to learn I suppose. -=-=- There are 10 kinds of people in this world - ( Insert 16 remarks about to what extent people know hex here )