#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include <cammy/sram.h>

static inline size_t _mapped_size(size_t size, size_t page_size) {
    return size + (page_size - (size % page_size));
}

cammy_sram *cammy_sram_open(const char *file) {
    cammy_sram *sram;
    struct stat st;

    if ((sram = malloc(sizeof(*sram))) == NULL) {
        goto error_malloc_sram;
    }

    if ((sram->fd = open(file, O_RDWR)) < 0) {
        goto error_open;
    }

    if (fstat(sram->fd, &st) < 0) {
        goto error_stat;
    }

    if (st.st_size < sizeof(cammy_sram_data)) {
        errno = EINVAL;

        goto error_invalid_file;
    }

    sram->size        = st.st_size;
    sram->page_size   = (size_t)sysconf(_SC_PAGESIZE); sram->mapped_size = _mapped_size(st.st_size, sram->page_size);

    if ((sram->data = mmap(NULL, sram->mapped_size,
            PROT_READ | PROT_WRITE, MAP_SHARED, sram->fd, 0)) == NULL) {
        goto error_mmap;
    }

    return sram;

error_mmap:
error_invalid_file:
error_stat:
    close(sram->fd);

error_open:
    free(sram);

error_malloc_sram:
    return NULL;
}

void cammy_sram_close(cammy_sram *sram) {
    munmap(sram->data, sram->mapped_size);
    close(sram->fd);
    free(sram);
}