| /** | |
| * Program: Simulate reverse xxd (to convert hex dump to binary RAW file) | |
| * Author: Abhishek Bhattacharya | |
| */ | |
| #include <bits/stdc++.h> | |
| using namespace std; | |
| unsigned int make_4_bit_binary(char &ch) { | |
| unsigned int hexval; | |
| if(ch >= '0' && ch <= '9') | |
| hexval = ch - '0'; | |
| else { | |
| hexval = ch - 'a' + 10; | |
| } | |
| return hexval & 0xff; | |
| } | |
| int main(int argc, char *argv[]) { | |
| if(argc >= 2 && string(argv[1]) == "--help") { | |
| cout << "HELP:" << endl | |
| << "\n<executable_file_name> [--help] hexdump_file_name binary_destination_file_name" << endl | |
| << "\nNOTE: The hexdump_file should be of a specific format. The right format is achieved using:" << endl | |
| << "\n$> xxd -p source_binary_file_name > hexdump_file_name\n" << endl; | |
| } else if(argc < 3) { | |
| cout << "ERROR: Too few arguments passed. Are you sure you passed the name of the FILEs?" << endl; | |
| return 0; | |
| } | |
| string buff; | |
| ifstream fin(argv[1]); | |
| ofstream fout(argv[2], ios::out|ios::binary); | |
| unsigned int out1, out2; | |
| char outc; | |
| if(fin.is_open() && fout.is_open()) { | |
| while(getline(fin, buff)) { | |
| for(size_t i = 0; i<buff.size(); i+=2) { | |
| // accumulate 8 bits of data | |
| // check if full 8 bits of data not available | |
| if(i == buff.size()-1) | |
| out2 = 0x00; | |
| else | |
| out2 = make_4_bit_binary(buff[i+1]); | |
| out1 = make_4_bit_binary(buff[i]); | |
| outc = (out1 << 4) + (out2 & 0x0f); | |
| // debug | |
| // cout << buff[i] << ((i == buff.size()-1) ? '0' : buff[i+1]) << " => " << out1 << " " << out2 << " -> " << outc << endl; | |
| // write binary 8-bit block | |
| fout.write(&outc, sizeof(outc)); | |
| } | |
| } | |
| // fin.close(); | |
| // fout.close(); | |
| } else | |
| cout << "ERROR: FILE " << argv[1] << " and/or " << argv[2] << " could not be opened. \ | |
| Check the files and try again." << endl; | |
| return 0; | |
| } |
A simple experiment to simulate the reverse effect of the xxd command. Converts a raw hexdump made with xxd back to a RAW binary file.
Compile as C++98 or above.
<executable_file_name> [--help] hexdump_file_name binary_destination_file_name
Example usage:
xxd -p sample.jpg test.hex
reverse_xxd test.hex sample_copy.jpg
Distributed under the MIT License.