// We only use a custom allocator on linux (for now)
// The allocator we chose is 'dlmalloc' (doug lea's malloc).
// It's a good allocator for single-threaded programs.
// It needs to be configured by setting a bunch of defines.
//
#ifdef __linux__

// We need this to define dlmalloc, not malloc.
#define USE_DL_PREFIX 1

// We don't need mspaces.
#define ONLY_MSPACES 0
#define MSPACES 0

// We don't need mallinfo
#define NO_MALLINFO 1

// We don't need dlmalloc_inspect_all
#define MALLOC_INSPECT_ALL 0

// We don't need dlmalloc_stats.
#define NO_MALLOC_STATS 1

// Disable locking.  The entire engine is single-threaded.
#define USE_LOCKS 0

// For now, we'll let the allocator use mmap to get memory.
// It's not clear if this is going to be deterministic.
#define HAVE_MMAP 1

// One way to force determinism would be to emulate sbrk
// using mmap and mremap, always putting the heap at a fixed
// address.  For now, we're not doing that, we're just
// using mmap and relying on that being deterministic (we hope).
#define HAVE_MORECORE 0
#define MORECORE emulate_sbrk

// The properties of mmap under linux
#define MMAP_CLEARS 1
#define HAVE_MREMAP 1

// Don't generate random seeds, or time-based seeds.
#define USE_DEV_RANDOM 0
#define LACKS_TIME_H 1

#include "dlmalloc/dlmalloc.c"

#endif

int dlmalloc_hash() {
    void *blocks[15];
    int hash = 0;
    for (int i = 0; i < 15; i++) {
        void *blk = dlmalloc(1 << i);
        blocks[i] = blk;
        hash = (hash * 17) + (int)(intptr_t)(blk);
    }
    for (int i = 0; i < 15; i++) {
        free(blocks[i]);
    }
    return (hash & 0x7FFFFFFF) | (0x40000000);
}