/*
 * Memory Pool implementation logic.
 */

#include "cache.h"
#include "mem-pool.h"

static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool, size_t block_alloc)
{
        struct mp_block *p;

        mem_pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
        p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
        p->next_block = mem_pool->mp_block;
        p->next_free = (char *)p->space;
        p->end = p->next_free + block_alloc;
        mem_pool->mp_block = p;

        return p;
}

void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
{
        struct mp_block *p;
        void *r;

        /* round up to a 'uintmax_t' alignment */
        if (len & (sizeof(uintmax_t) - 1))
                len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));

        for (p = mem_pool->mp_block; p; p = p->next_block)
                if (p->end - p->next_free >= len)
                        break;

        if (!p) {
                if (len >= (mem_pool->block_alloc / 2)) {
                        mem_pool->pool_alloc += len;
                        return xmalloc(len);
                }

                p = mem_pool_alloc_block(mem_pool, mem_pool->block_alloc);
        }

        r = p->next_free;
        p->next_free += len;
        return r;
}

void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
{
        size_t len = st_mult(count, size);
        void *r = mem_pool_alloc(mem_pool, len);
        memset(r, 0, len);
        return r;
}