Implement Functions To Encode, Decode Message PPM Image In C Assignment Solution

Instructions

Objective

Write a C assignment program to implement functions to encode, decode message ppm image.

Requirements and Specifications

For this assignments you will have at a minimal eight files:

1. driver.c – This is where main lives.
2. ppm.h – I will provide this file. It will contain the prototypes of the functions I implement. These functions deal specifically with a ppm file. It will also provide the definition of two structs.
   • One for the header
   • One for the pixels
3. ppm.c – This file is where I implemented the functions listed in the ppm.h file.
4. EncodeDecode.h – I will provide this file. It will contain additional prototypes of functions I needed to encode and decode a message in an image.
5. EncodeDecode.c – This file is where I implement the functions listed in EncodeDecode.h
6. utils.h – this provides the prototypes for two functions needed to check the number of command line arguments passed to the program. It also contains a function that check if the file pointers opened successfully.
7. utils.c – this file is where I implement the functions for utils.h
8. makefile
9. Each of your header files (.h) must have header guards. Points will be deducted if you do not provide header guards I also removed all of the #include statements, you will need to provide these.

Screenshots of output

Source Code

Driver.c

//************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #include #include #include "utils.h" #include "EncodeDecode.h" int main(int argc, char* argv[]) { checkArgs(argc, 2); FILE* in = fopen(argv[1], "r"); checkFile(in); FILE* out = fopen(argv[2], "w"); checkFile(out); /*This is my test message. It can be something different*/ char* msg = "I hope this works!"; encodeMsg(in, out, msg); FILE* dec = fopen(argv[2], "r"); checkFile(dec); decodeMsg(dec); fclose(in); fclose(out); fclose(dec); return EXIT_SUCCESS; }

EncodeDecode.h

/************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #ifndef ENCODEDECODE_H #define ENCODEDECODE_H #include #include #include "ppm.h" void removeDigit(pixel_t** , header_t ); void encodeMsg(FILE* in, FILE* out, char* msg); void charToBinary(char , int *); unsigned char binToCharacter(int*); void queue(int, int*, int*); void dec2bin(int*, int); void decodeMsg(FILE*); #endif /* ENCODEDECODE_H */ Ppm.c /************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #include #include #include #include "ppm.h" /* Parameters: f - FILE pointer to an input ppm file * Return: output - header_t that contains the ppm header * This function reads the PPM header information from the given file. */ header_t readHeader(FILE* f) { header_t header; // read the magic numbers fread(header.magicNum, 2, 1, f); // clear whitespace and comments ckws_comments(f); // read the width fscanf(f, "%d", &header.width); // clear whitespace and comments ckws_comments(f); // read the height fscanf(f, "%d", &header.height); // clear whitespace and comments ckws_comments(f); // read the max value fscanf(f, "%d", &header.maxVal); // read the last whitespace fgetc(f); return header; } /* Parameters: f - FILE pointer to an input ppm file * header - header_t that contains the ppm header * Return: output - pixel_t double pointer that contains the ppm * pixel information. * This function reads the PPM pixel information from the given file. * It allocates a 2D array to read the pixel data and returns it. */ pixel_t** readPixel(FILE* f, header_t header) { pixel_t** pixels; int i; int j; int bytes; char buffer[2]; // number of bytes per sample (r,g,b), 1 if < 256, 2 otherwise bytes = (header.maxVal < 256) ? 1 : 2; // allocate space for all row pointers pixels = (pixel_t**) malloc(header.height * sizeof(pixel_t*)); // go through all pixels rows for (i = 0; i < header.height; i++) { // allocate space for all pixels in the row pixels[i] = (pixel_t*) malloc(header.width * sizeof(pixel_t)); // go through all pixels in row for (j = 0; j < header.width; j++) { // read the red part fread(buffer, bytes, 1, f); // if maxvalue fits in 1 byte if (header.maxVal < 256) pixels[i][j].r = buffer[0]; // if maxvalue fits in 2 bytes, first byte is msb else pixels[i][j].r = (buffer[0] << 8) | buffer[1]; // read the green part fread(buffer, bytes, 1, f); // if maxvalue fits in 1 byte if (header.maxVal < 256) pixels[i][j].g = buffer[0]; // if maxvalue fits in 2 bytes, first byte is msb else pixels[i][j].g = (buffer[0] << 8) | buffer[1]; // read the blue part fread(buffer, bytes, 1, f); // if maxvalue fits in 1 byte if (header.maxVal < 256) pixels[i][j].b = buffer[0]; // if maxvalue fits in 2 bytes, first byte is msb else pixels[i][j].b = (buffer[0] << 8) | buffer[1]; } } return pixels; } /* Parameters: f - FILE pointer to an output ppm file * header - header_t that contains the ppm header * Return: output - none * This function writes the PPM header information into the given file. */ void writeHeader(FILE* f, header_t header) { // write the magic numbers fprintf(f, "%c%c\n", header.magicNum[0], header.magicNum[1]); // write the width x height fprintf(f, "%d %d\n", header.width, header.height); // write the max value and newline fprintf(f, "%d\n", header.maxVal); } /* Parameters: f - FILE pointer to an output ppm file * pixels - pixel_t double pointer that contains the ppm * pixel information. * header - header_t that contains the ppm header * Return: output - none * This function writes the PPM pixel information into the given file. */ void writePixels(FILE* f, pixel_t** pixels, header_t header) { int i; int j; int bytes; char buffer[2]; // number of bytes per sample (r,g,b), 1 if < 256, 2 otherwise bytes = (header.maxVal < 256) ? 1 : 2; // go through all pixels rows for (i = 0; i < header.height; i++) { // go through all pixels in row for (j = 0; j < header.width; j++) { // if maxvalue fits in 1 byte if (bytes == 1) buffer[0] = pixels[i][j].r; // if maxvalue fits in 2 bytes, first byte is msb else { buffer[0] = pixels[i][j].r >> 8; buffer[1] = pixels[i][j].r; } // write the red part fwrite(buffer, bytes, 1, f); // if maxvalue fits in 1 byte if (bytes == 1) buffer[0] = pixels[i][j].g; // if maxvalue fits in 2 bytes, first byte is msb else { buffer[0] = pixels[i][j].g >> 8; buffer[1] = pixels[i][j].g; } // write the green part fwrite(buffer, bytes, 1, f); // if maxvalue fits in 1 byte if (bytes == 1) buffer[0] = pixels[i][j].b; // if maxvalue fits in 2 bytes, first byte is msb else { buffer[0] = pixels[i][j].b >> 8; buffer[1] = pixels[i][j].b; } // write the blue part fwrite(buffer, bytes, 1, f); } } } /* Parameters: f - FILE pointer pointing to a ppm input file * Return: output - none * This function removes all the whitespace and comments found from * the current position. */ void ckws_comments (FILE *f) { int c; while (1) { // ignore all whitespace while (isspace(c = fgetc(f))); // if a comment if (c == '#') // read until newline while ((c = fgetc(f)) != '\n'); // if not a comment else { // undo the last read ungetc(c, f); // exit the loop to return break; } } } /* Parameters: pixels - pixel_t double pointer that contains the ppm * pixel information. * header - header_t that contains the ppm header * Return: output - none * This function frees all the allocated memory used by the pixel 2D array */ void freeMemory(pixel_t** pixels, header_t header) { int i; // go through all pixels rows for (i = 0; i < header.height; i++) // free space for all pixels free(pixels[i]); // free space for all rows free(pixels); }

Ppm.h

/************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #ifndef PPM_H #define PPM_H #include typedef struct { unsigned char r; unsigned char g; unsigned char b; }pixel_t; typedef struct { char magicNum[3]; int width; int height; int maxVal; }header_t; header_t readHeader(FILE*); pixel_t** readPixel(FILE*, header_t); void writeHeader(FILE*, header_t); void writePixels(FILE*, pixel_t**, header_t); void ckws_comments (FILE *); void freeMemory(pixel_t**, header_t); #endif /* PPM_H */

Utils.c

/************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #include #include #include "utils.h" /* Parameters: argc - number of command line arguments * n - required number of command line arguments * Return: output - none * This function verifies that the number of command line arguments * is at least the required n. If not, it exits with error. */ void checkArgs(int argc, int n) { // if not enough arguments, exit with error if (argc < n) { fprintf(stderr, "Error: Not enough command line arguments\n"); exit(EXIT_FAILURE); } } /* Parameters: f - FILE pointer pointing to a file that has been opened * Return: output - none * This function verifies that the file has been opened coorrectly. * If not, it exits with error. */ void checkFile(FILE* f) { // if file was not opened, exit with error if (f == NULL) { fprintf(stderr, "Error: Unable to open file\n"); exit(EXIT_FAILURE); } } Utils.h /************************* *Your names *CPSC 2310 F21 Section 00? *Your emails *************************/ #ifndef UTILS_H #define UTILS_H #include void checkArgs(int, int); void checkFile(FILE*); #endif /* UTILS_H */