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  1. #include <iostream>
  2. #include <vector>
  3. #include <cmath>
  4.  
  5. using namespace std;
  6. using Blob = vector<uint8_t>;
  7.  
  8. Blob toPrefix(Blob p) {
  9. 	Blob out(ceil(p.size() / 2.)); // Output is on 1 bit instead of 2 for each data
  10.  
  11. 	for ( int i = 0; i < p.size(); i++ ) {
  12.     	if ( (p[i] | 0x55) != 0xFF )
  13.     		throw std::domain_error("Can not convert to prefix with undefine bits"); 
  14.  
  15.     	uint8_t mask = 0x40;          // Mqsk for extracting bit a pos x               
  16.     	int shift = ( i % 2 ) ? 3 : 1; // For first uin8_t need to move shift bit to left
  17.     	                           // and to right for second uint8_t
  18.     							   // First : 0101 0000 - Second : 1111 0111
  19.     	                           // First : Bit pos 1 move to pos 0 - Second : Bit pos 1 move to pos 4
  20.  
  21.     	for ( int b = 1; b < 8; b += 2, mask >>= 2) { // for each bit of the uint8_t ( jump 1 of 2) and shift j mask
  22.     		out[i / 2] ^= (
  23.     						( i % 2 ) ? 
  24.     							( p[i] & mask ) >> shift  // Get bit pos l, move it to position by shifting of k
  25.     					  	  : ( p[i] & mask ) << shift
  26.     					  );
  27.  
  28.     		( i % 2 ) ? --shift : ++shift; // Next shift to do
  29.     	}
  30.     }
  31.  
  32.     return out;
  33. }
  34.  
  35. // http://stackoverflow.com/questions/29547628/convert-uint8-t-hex-value-to-binary
  36. void toBinary(uint8_t a) {
  37. 	int tmp = 0;
  38.     for(uint8_t i=0x80;i!=0;i>>=1) {
  39.     	if ( tmp++ % 4 == 0 ) 
  40.     		cout << " ";
  41.  
  42.         cout << ((a&i)?'1':'0');
  43.     }
  44. }
  45.  
  46. void toBinary(Blob p) {
  47. 	for (int i = 0; i < p.size(); i++ )
  48. 		toBinary(p[i]);
  49. }
  50.  
  51. int main() {
  52.  
  53. 	Blob p; // Test Blob	
  54. 	p.push_back(0xBA); // 1011 1010
  55.  
  56. 	Blob out(2 * p.size()); // ceil(p.size_ * 2. / 8.);
  57.  
  58.     cout << "Prefix with unknown value :" ;
  59.     toBinary(p);
  60. 	for ( int i = 0; i < p.size(); i++ ) {
  61.     	for ( int b = 0; b < 8; b++) {
  62.     		;
  63.     	}
  64. 	}
  65. 	cout << endl << "Output : ";
  66. 	toBinary(toPrefix(p));
  67.     cout << endl;
  68.  
  69.     exit(0);
  70. }
Success #stdin #stdout 0s 3416KB
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stdin
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Standard input is empty
stdout
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Prefix with unknown value : 1011 1010
Output :  0100 0000
https://ideone.com/8qeiZY
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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