379_demos/lab9/bitwise.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>  // This gives us sized types
#include <stdbool.h>

#define NB_NODES 4

bool add_file(uint8_t* inodes, int file_size) {
    // We only have 7 bits for the file size, so it can't be bigger
    if (file_size > 0x7f || file_size < 0) {
        return false;
    }

    for (int i = 0; i < NB_NODES; i++) {
        bool is_taken = (inodes[i] & 0x8) > 0;

        if (!is_taken) {
            uint8_t size = file_size;
            inodes[i] = size | 0x80;  // Set highest bit + size
            return true;
        }
    }

    return false;
}

void printd_inodes(uint8_t* inodes) {
    printf("Debug: ");

    for (int i = 0; i < NB_NODES; i++) {
        printf("%02x", inodes[i]);

        if (i == NB_NODES - 1) {
            printf("\n");
        } else {
            printf(" ");
        }
    }
}

int main(void) {
    uint8_t* inodes = calloc(NB_NODES, sizeof(uint8_t));

    printd_inodes(inodes);

    add_file(inodes, 8);
    printd_inodes(inodes);

    add_file(inodes, 12);
    printd_inodes(inodes);

    add_file(inodes, 121);
    printd_inodes(inodes);

    add_file(inodes, 127);
    printd_inodes(inodes);

    FILE* f = fopen("bits.out", "wb");
    fwrite(inodes, sizeof(uint8_t), NB_NODES, f);
    fclose(f);

    free(inodes);
}