#if defined(_WIN32)
typedef void *HANDLE;
#else
#include <semaphore.h>
#endif

typedef struct ipc_sharedmemory_
{
    char*			name;
    unsigned char*	data;
    size_t			size;
#if defined(_WIN32)
    HANDLE			handle;
#else
    int				fd;
#endif
} ipc_sharedmemory;

typedef struct ipc_sharedsemaphore_
{
    char*			name;
#if defined(_WIN32)
    HANDLE			handle;
#else
    sem_t*			semaphore;
#endif
} ipc_sharedsemaphore;

#if defined(_WIN32)
#include <windows.h>
#else // !_WIN32
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#endif // !_WIN32

static char* ipc_strdup (char* src)
{
	int		i;
	int		len = 0;
    char*	dst = NULL;
    while (src[len]) len++;
#if !defined(_WIN32)
    len++;
#endif
    dst = (char*)malloc(len + 1);
    if (!dst) return NULL;
    dst[len] = 0;

#if defined(_WIN32)
    for (i = 0; i < len; i++)
        dst[i] = src[i];
#else
    dst[0] = '/';
    for (i = 0; i < len - 1; i++)
        dst[i + 1] = src[i];
#endif
    return dst;
}

void ipc_mem_init (ipc_sharedmemory* mem, char* name, size_t size)
{
    mem->name = ipc_strdup(name);

    mem->size = size;
    mem->data = NULL;
#if defined(_WIN32)
    mem->handle = 0;
#else
    mem->fd = -1;
#endif
}

unsigned char* ipc_mem_access (ipc_sharedmemory* mem)
{
    return mem->data;
}

void ipc_sem_init (ipc_sharedsemaphore* sem, char* name)
{
    sem->name = ipc_strdup(name);
#if defined(_WIN32)
    sem->handle = 0;
#else
    sem->semaphore = NULL;
#endif
}

#if defined(_WIN32)

int ipc_mem_open_existing (ipc_sharedmemory* mem)
{
    mem->handle = OpenFileMappingA(FILE_MAP_ALL_ACCESS, FALSE, mem->name);

    if (!mem->handle)
        return -1;

    mem->data = (unsigned char*)MapViewOfFile(mem->handle, FILE_MAP_ALL_ACCESS, 0, 0, mem->size);

    if (!mem->data)
        return -1;
    return 0;
}

int ipc_mem_create (ipc_sharedmemory* mem)
{
    mem->handle = CreateFileMappingA(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, (DWORD)mem->size, mem->name);

    if (!mem->handle)
        return -1;

    mem->data = (unsigned char*)MapViewOfFile(mem->handle, FILE_MAP_ALL_ACCESS, 0, 0, mem->size);

    if (!mem->data)
        return -1;

    return 0;
}

void ipc_mem_close (ipc_sharedmemory* mem)
{
    if (mem->data != NULL)
    {
        UnmapViewOfFile(mem->data);
        mem->data = NULL;
    }
    free(mem->name);
    mem->name = NULL;
    mem->size = 0;
}

int ipc_sem_create (ipc_sharedsemaphore* sem, int initialvalue)
{
    sem->handle = CreateSemaphoreA(NULL, initialvalue, 0x7fffffff, sem->name);
    if (!sem->handle)
        return -1;
    return 0;
}

void ipc_sem_close (ipc_sharedsemaphore* sem)
{
    CloseHandle(sem->handle);
    free(sem->name);
    sem->handle = 0;
}

void ipc_sem_increment (ipc_sharedsemaphore* sem)
{
    ReleaseSemaphore(sem->handle, 1, NULL);
}

void ipc_sem_decrement (ipc_sharedsemaphore* sem)
{
    WaitForSingleObject(sem->handle, INFINITE);
}

int ipc_sem_try_decrement (ipc_sharedsemaphore* sem)
{
    DWORD ret = WaitForSingleObject(sem->handle, 0);
    if (ret == WAIT_OBJECT_0)
        return 1;
    return 0;
}

#else // !defined(_WIN32)

int ipc_mem_open_existing (ipc_sharedmemory* mem)
{
    mem->fd = shm_open(mem->name, O_RDWR, 0755);
    if (mem->fd < 0)
        return -1;

    mem->data = (unsigned char *)mmap(NULL, mem->size, PROT_READ | PROT_WRITE, MAP_SHARED, mem->fd, 0);
    if (!mem->data)
        return -1;

    return 0;
}

int ipc_mem_create (ipc_sharedmemory* mem)
{
    int ret;
    ret = shm_unlink(mem->name);
    if (ret < 0 && errno != ENOENT)
        return -1;

    mem->fd = shm_open(mem->name, O_CREAT | O_RDWR, 0755);
    if (mem->fd < 0)
        return -1;

    ftruncate(mem->fd, mem->size);

    mem->data = (unsigned char *)mmap(NULL, mem->size, PROT_READ | PROT_WRITE, MAP_SHARED, mem->fd, 0);
    if (!mem->data)
        return -1;

    return 0;
}

void ipc_mem_close (ipc_sharedmemory* mem)
{
    if (mem->data != NULL)
    {
        munmap(mem->data, mem->size);
        close(mem->fd);
        shm_unlink(mem->name);
    }
    free(mem->name);
    mem->name = NULL;
    mem->size = 0;
}

int ipc_sem_create (ipc_sharedsemaphore* sem, int initialvalue)
{
    sem->semaphore = sem_open(sem->name, O_CREAT, 0700, initialvalue);
    if (sem->semaphore == SEM_FAILED)
        return -1;
    return 0;
}

void ipc_sem_close (ipc_sharedsemaphore* sem)
{
    sem_close(sem->semaphore);
    sem_unlink(sem->name);
    free(sem->name);
}

void ipc_sem_increment (ipc_sharedsemaphore* sem)
{
    sem_post(sem->semaphore);
}

void ipc_sem_decrement (ipc_sharedsemaphore* sem)
{
    sem_wait(sem->semaphore);
}

int ipc_sem_try_decrement(ipc_sharedsemaphore* sem)
{
    int res = sem_trywait(sem->semaphore);
    if (res == 0)
        return 1;
    return 0;
}

#endif // !_WIN32