space_game/src/controlscheme.c

#include "controlscheme.h"
#include <SDL2/SDL_scancode.h>
#include <sys/stat.h>

struct InputMap input_map;

#define INPUT_MAP_ID 83921864
#define INPUT_MAP_VERSION 0
#define CONTROLS_FNAME "controls.bin"


/*
 * Serialise controlscheme using simple (char *) cast. It is obviously not cross
 * platform but it doesnt need to be. Takes a very tentative approach to error
 * handling, if something is wrong it resets.
 *
 * There is no UI for setting controls yet. 
 *
 */

struct InputMap_Ser {
    unsigned int id;
    unsigned int ver;
    size_t size;
    struct InputMap input_map;
};

int load_controls(void); 

void get_input_map(void) {

    if (load_controls())  {
        return;
    }

    input_map.player_down = SDL_SCANCODE_S;
    input_map.player_up = SDL_SCANCODE_W;
    input_map.player_right = SDL_SCANCODE_D;
    input_map.player_left = SDL_SCANCODE_A;
    input_map.player_rope = SDL_SCANCODE_E;
    input_map.player_pull_rope = SDL_SCANCODE_Q;
    input_map.mute = SDL_SCANCODE_M;
    input_map.pause = SDL_SCANCODE_ESCAPE;
    input_map.quit = SDL_SCANCODE_Q;
    input_map.goto_level = SDL_SCANCODE_G;
    input_map.high_contrast_mode = SDL_SCANCODE_H;
    input_map.mouse_attach_rope_pull = SDL_BUTTON_LEFT;
    input_map.mouse_attach_rope = SDL_BUTTON_RIGHT;
}

struct Buffer {
    size_t len;
    char *data;
};

struct Buffer read_whole_file(char const *file_name) {
    struct stat sb;
    struct Buffer b = {};

    if (stat (file_name, & sb) != 0) {
        return b;
    }

    char *buffer = malloc(sb.st_size + 1);

    FILE *f = fopen(file_name, "r");
    size_t bytes_read = fread(buffer, sizeof (unsigned char), sb.st_size, f);
    if (bytes_read != sb.st_size) {
        fclose(f);
        free(buffer);
        return b;
    }

    fclose(f);

    b.data = buffer;
    b.len = bytes_read;
    return b;
}

int load_controls(void) {
    struct Buffer b = read_whole_file(CONTROLS_FNAME);

    if (b.len != sizeof (struct InputMap_Ser)) {
        return 0;
    }

    struct InputMap_Ser *im = (struct InputMap_Ser *)b.data;

    if (im->size != sizeof(struct InputMap_Ser))
        return 0;

    if (im->id != INPUT_MAP_ID)
        return 0;

    if (im->ver != INPUT_MAP_VERSION)
        return 0;

    memcpy(&input_map, &im->input_map, sizeof(struct InputMap));
    return 1;
}

void save_controls(void) {
    FILE *f = fopen(CONTROLS_FNAME, "w");

    struct InputMap_Ser im;
    im.id = INPUT_MAP_ID;
    im.ver = INPUT_MAP_VERSION;
    im.size = sizeof(struct InputMap_Ser);
    im.input_map = input_map;

    fwrite(&im, sizeof(unsigned char), sizeof(struct InputMap_Ser), f);
    fclose(f);
}