Very basic double-ended queue in C99

queue.c

//
// Created by jack on 03/02/25.
//

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

typedef struct Queue {
    int* allocation_start;
    int* start;
    int* end;
    int capacity;
} Queue;

Queue Queue_createQueue(int capacity);
void Queue_destroyQueue(const Queue* queue);

void Queue_push(Queue* queue, int value);
bool Queue_popBack(Queue* queue, int* output);
bool Queue_popFront(Queue* queue, int* output);

Queue Queue_createQueue(const int capacity) {
    int* start = (int*)malloc(sizeof(int) * capacity);

    Queue ret = {
        .allocation_start = start,
        .start = start,
        .end = start,
        .capacity = capacity,
    };
    return ret;
}

void Queue_destroyQueue(const Queue* queue) {
    free(queue->allocation_start);
}

void Queue_push(Queue* queue, const int value) {
    if (queue->end == (queue->allocation_start + queue->capacity)) {
        int currentLength = queue->end - queue->start;
        int newAllocSize = queue->capacity * 2;

        int* newAllocation = (int*)malloc(sizeof(int) * newAllocSize);
        memcpy(newAllocation, queue->start, sizeof(int) * currentLength);
        free(queue->allocation_start);

        queue->allocation_start = newAllocation;
        queue->start = queue->allocation_start;
        queue->end = queue->allocation_start + currentLength;
        queue->capacity *= newAllocSize;
    }

    *queue->end = value;
    queue->end++;
}

bool Queue_popBack(Queue *queue, int *output) {
    if (queue->end == queue->allocation_start + queue->capacity || queue->end == queue->start) {
        return false;
    }

    queue->end--;
    *output = *queue->end;

    return true;
}

bool Queue_popFront(Queue *queue, int *output) {
    if (queue->end == queue->allocation_start + queue->capacity || queue->start == queue->end) {
        return false;
    }

    *output = *queue->start;
    queue->start++;

    return true;
}