Circular Buffer Read

Code

#include <stdio.h>

typedef struct {
    int buffer[10];
    int head;           // Write pointer
    int tail;           // Read  pointer
    int count;          // Number of unread bytes
    int capacity;       // Always 10
} CircularBuffer;

#define MIN(A,B) ((A) < (B) ? (A) : (B))

void read_bytes(CircularBuffer *cb, int n) {
    // Cycles all bytes to be read
    for (int i = 0; i < n; i++) {
        // If i have values to print
        if (i < cb->count) {
            // Print value
            printf("%d", cb->buffer[(i + cb->tail) % cb->capacity]);
        }
        else {
            // Print missing value
            printf("NULL");
        }

        // Handle spacing
        if (i < n - 1) {
            printf(" ");
        }
    }

    printf("\n");

    // Update tail
    cb->tail = (cb->tail + MIN(n, cb->count)) % cb->capacity;

    printf("Tail: %d\n", cb->tail);
}

int main() {
    CircularBuffer cb = {
        .buffer = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100},
        .head = 3,
        .tail = 7,
        .count = 6,
        .capacity = 10
    };

    int n;
    scanf("%d", &n);
    read_bytes(&cb, n);

    return 0;
}

Solving Approach