[HELP] Convert BYTE

[XGLADEADOR]

Hi, how are you? i need help to convert a data type BYTE to binary and modify binary; or modify BYTE

for example I have:

BYTE convert=0x40

I want change the 4(four to A) and the 0(zero to 8)

So when finish I must have: converted: 0xA8

My idea:
Convert(40 Hex, 64 decimal, to binary: 01000000
take the first 4 bits(0100) and change for: 1010
take the last 4 bits(0000) and change for: 1000
So the modified byte is: 10101000 converted to hex: A8

Do you have some idea?

 

[GHOST107]

So what you want to get the high and low 4 bytes from a byte, and set other values, kinda does not have any sense, you can use bit-wise operators;

unsigned char byte = 0x40;
unsigned char low = 0x08
unsigned char high= 0x0A;
byte = ((high << 4)&0xF0) |( low &0x0F)

Or you could simply use:

unsigned char byte= 0xA8;

 

[Negata]

Yeah it doesn't really make any sense. Hard to say what the conversion is with just one arbitrary example. So.. why? Or more examples?

 

[XGLADEADOR]

I really need convert:

Natural HEX | Converted Hex
0 | 8
1 | 9
2 | 6
3 | 7
4 | A
5 | B
6 | 2
7 | 3
8 | 0
9 | 1
A | 4
B | 5
C | F
D | E
E | D
F | C

And as you know a byte must can contain 2 Hex and I need convert both byte on the "crypted/decrypted" byte

More examples:

E6 to D2
C8 to F0

 

[GHOST107]

You could create a shifting table, if you are sure this is the corrects results:

unsigned char shiftingTable[] = { 8, 9, 6, 7, A, B, 2, 3, 0, 1, 4, 5, F, E, D, C };
unsigned char low = convert &0x0F;
unsigned char high  = convert &0xF0 >> 4;
convert = ((shiftingTable[high] << 4 )& 0xF0) |( shiftingTable[low] & 0x0F);

 

[XGLADEADOR]

Thanks GHOST107 and Negata for reply.
GHOST107 dont work well, I ever get 0x88

 

[GHOST107]

unsigned char high = convert &0xF0 >> 4;
Change into:
unsigned char high = (convert & 0xF0) >> 4;

 

[XGLADEADOR]

Problem solved, thanks to much GHOST107