Thread: help me

In what context?

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Mats

So we are talking HDLC comms, yes?

The problem with bitstuffing in C is that the language is not "bit oriented". It makes life quite difficult.

I take it this is an assignment of some sort, so you really should post your code first, then we can help you "improve it".

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Mats

Does this code work for you? I don't see anything directly wrong, but I can't say for sure if it works for all cases or not.

Code:

pow(double(2),((max-1)-t))

is the same as

Code:

1 << ((max - 1)-t)

The latter doesn't use "math.h" and is much quicker.

Code:

    int data[2084];

Did you mean 2048? If you use constants, it would be much easier to avoid typos like this [not that it REALLY makes any difference in this case - but still].

Code:

 dataCount=dataCount-2;

Use:

Code:

 dataCount -= 2;

I just tried your code, typing in a few ~ characters [which is 01111110 in binary], and it didn't produce the same output as I input. It is hard to produce sequences that have more than 5 consecutive bits, since most such characters are unreachable from a normal keyboard.

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Mats

To turn your byte array into a bit array, try something like this

Code:

void writeBit ( unsigned char *array, int bitPosition, unsigned char bit ) {
  int bytePos = bitPosition / 8;        // or CHAR_BIT to be precise
  int bitPos = bitPosition % 8;
  unsigned char mask = ~(1 << bitPos);  // 11110111 with the 0 in the right place
  bit <<= bitPos;                       // the bit we want to set, in the right place, eg 00001000
  array[bytePos] &= mask;               // clear existing bit value
  array[bytePos] |= bit;                // set new bit value
}