Texconv.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>

char inputname[13];
char outputname[13];
char inname[13];
char outname[13];
uint8_t* far buffer;
uint16_t filesize = 0;
int width;
int height;
int checksum1;
int checksum2;
int running = 1;

void load_file(char* inname)
{
    FILE* file_ptr;
    char c;
    uint16_t i=0;
    int j=0;
    int lines=1;

    printf("Loading file %s...\n", inname);

    file_ptr = fopen(inname, "rb");

    //check that the file actually exists
    if (file_ptr == NULL)
    {
        printf("Unable to open file: %s\n", inname);
        printf("Please check the file actually exists\n");
        exit(EXIT_FAILURE);
        // exit will terminate the program here, nothing further will happen
    }

    fseek(file_ptr, 0, SEEK_SET);
    fread(&checksum1, 2, 1, file_ptr); //check for BMP file header
    fseek(file_ptr, 28, SEEK_SET);
    fread(&checksum2, 1, 1, file_ptr); // check bit depth

    //if file header or bit depth is wrong, then exit
    if (checksum1 != 19778 || checksum2 != 8)
    {
        printf("Fatal error: %s is not a valid 8-bit bitmap!\n", inname);
        printf("This program will now exit.\n");
        exit(EXIT_FAILURE);
        // exit will terminate the program here, nothing further will happen
    }

    fseek(file_ptr, 18, SEEK_SET);
    fread(&width, 2, 1, file_ptr);
    printf("Checking file width... %dpx\n", width);
    fseek(file_ptr, 22, SEEK_SET);
    fread(&height, 2, 1, file_ptr);
    printf("Checking file height... %dpx\n", height);
    printf("Checking file dimensions complete!\n");

    filesize = width * height;
    printf("Total file size: %u bytes\n", filesize);
    printf("\n");

    printf("Allocating memory...");
    buffer = (uint8_t far*)malloc(filesize);
    printf("\n");

    printf("Starting to read first line...\n");
    fseek(file_ptr, -width, SEEK_END);
    c = fgetc(file_ptr);

    while (i < filesize)
    {
        buffer[j] = c;
        i++;
        if (i % width == 0)
        {
            lines++;
            fseek(file_ptr, (-width*lines), SEEK_END);
        }
        c = fgetc(file_ptr);
        j++;
    }

    printf("\n%u bytes read!\n", i);
    printf("\nFile read successfully!\n");
    fclose(file_ptr);
    printf("\n");
}

void save_file(char* outname, uint8_t* source_data, uint16_t data_size)
{
    FILE* file_ptr;
    file_ptr = fopen(outname, "wb+");
    fseek(file_ptr, 0, SEEK_SET);
    fwrite(source_data, 1, data_size, file_ptr);
    fclose(file_ptr);
}

void menu()
{
    char response;

    // take in the file input name
    printf("Enter file to convert (without file extension):\n");
    scanf("%s", inputname);
    sprintf(inname, "%s.bmp", inputname);

    // load file into buffer
    load_file(inname);

    // take in the file output name
    printf("Enter output name (without file extension)\n");
    printf("or write 'same' to save with the BMP name:\n");
    scanf("%s", outputname);

    if (strcmp ("same", outputname) == 0)
        sprintf(outname, "%s.7UP", inputname);

    else
        sprintf(outname, "%s.7UP", outputname);

    printf("Writing file: %s\n", outname);

    // save file to 7UP format
    save_file(outname, buffer, filesize);

    printf("BMP successfully converted into %s!\n", outname);

    //clear memory
    inputname [0] = '\0';
    outputname [0] = '\0';
    inname [0] = '\0';
    outname [0] = '\0';
    farfree(buffer);

    // ask if user wants to convert another file, or quit
    printf("Y to convert another file, or N to quit.\n");
    scanf (" %c", &response);
    if (response == 'y' || response == 'Y')
        running = 1;

    else if (response == 'n' || response == 'N')
        running = 0;
}

int main()
{
    while (running == 1)
        menu();
    return 0;
}