stalloc.c


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

static int nb_pools = 0;
static char ** mem_pools = 0;
static size_t * pools_size = 0;

#define POOL_SIZE 16384

static int create_pool() {
    nb_pools++;
    mem_pools = (char **) realloc(mem_pools, sizeof(char *) * nb_pools);
    pools_size = (size_t *) realloc(pools_size, sizeof(size_t) * nb_pools);
    mem_pools[nb_pools - 1] = malloc(POOL_SIZE);
    pools_size[nb_pools - 1] = 0;
    
    return nb_pools - 1;
}

static int search_pool(size_t s) {
    int i;
    
    // This algorithm could use a little bit more of cleverness, but... *shrug*
    // the whole purpose is to be used for small static strings, so...
    for (i = 0; i < nb_pools; i++) {
        if (s <= (POOL_SIZE - pools_size[i]))
            return i;
    }
    
    return -1;
}

void * st_alloc(size_t s) {
    int pool;
    
    if (s > POOL_SIZE)
        return malloc(s);
    
    pool = search_pool(s);
    if (pool < 0)
        pool = create_pool();
    
    pools_size[pool] += s;
    
    return mem_pools[pool] + pools_size[pool] - s;
}

char * st_strdup(const char * src) {
    int s = strlen(src) + 1;
    char * r = (char *) st_alloc(s);
    memcpy(r, src, s);
    
    return r;
}

void st_shutdown() {
    int i;
    
    for (i = 0; i < nb_pools; i++) {
        free(mem_pools[i]);
    }
    free(mem_pools);
    free(pools_size);
}