/* common.h — project-wide types, attributes, and error codes.
 *
 * Pure C11. No allocation, no platform calls; safe to include everywhere.
 */
#ifndef NAUT_COMMON_H
#define NAUT_COMMON_H

#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdatomic.h>

/* --- sizes ------------------------------------------------------------- */
#define NAUT_CACHELINE 64u
#define NAUT_PAGE      4096u
/* BitTorrent wire block size (BEP-3). The fundamental transfer unit. */
#define NAUT_BLOCK     (16u * 1024u)

/* --- compiler attributes ----------------------------------------------- */
#define NAUT_LIKELY(x)      __builtin_expect(!!(x), 1)
#define NAUT_UNLIKELY(x)    __builtin_expect(!!(x), 0)
#define NAUT_INLINE         static inline __attribute__((always_inline))
#define NAUT_ALIGNED(n)     __attribute__((aligned(n)))
#define NAUT_CACHE_ALIGNED  __attribute__((aligned(NAUT_CACHELINE)))
#define NAUT_NORETURN       __attribute__((noreturn))
#define NAUT_UNUSED         __attribute__((unused))
#define NAUT_PACKED         __attribute__((packed))
#define NAUT_MUST_USE       __attribute__((warn_unused_result))
#define NAUT_PRINTF(fi, ai) __attribute__((format(printf, fi, ai)))

/* --- small helpers ----------------------------------------------------- */
#define NAUT_ARRAY_LEN(a)   (sizeof(a) / sizeof((a)[0]))
#define NAUT_MIN(a, b)      ((a) < (b) ? (a) : (b))
#define NAUT_MAX(a, b)      ((a) > (b) ? (a) : (b))
#define NAUT_ALIGN_UP(x, a)   (((uintptr_t)(x) + ((a) - 1)) & ~((uintptr_t)(a) - 1))
#define NAUT_ALIGN_DOWN(x, a) ((uintptr_t)(x) & ~((uintptr_t)(a) - 1))
#define NAUT_IS_POW2(x)     ((x) != 0 && (((x) & ((x) - 1)) == 0))
#define NAUT_CONTAINER_OF(ptr, type, member) \
    ((type *)((char *)(1 ? (ptr) : &((type *)0)->member) - offsetof(type, member)))

/* --- error codes ------------------------------------------------------- */
typedef int naut_err;
enum {
    NAUT_OK        = 0,
    NAUT_ERR_NOMEM = -1,
    NAUT_ERR_INVAL = -2,
    NAUT_ERR_IO    = -3,
    NAUT_ERR_AGAIN = -4,   /* would block / retry */
    NAUT_ERR_PROTO = -5,   /* protocol violation  */
    NAUT_ERR_RANGE = -6,
    NAUT_ERR_NOSYS = -7,   /* unsupported by kernel/build */
    NAUT_ERR_FULL  = -8,
    NAUT_ERR_EMPTY = -9,
    NAUT_ERR_NOTFOUND = -10,
    NAUT_ERR_EXIST    = -11,   /* already exists / data would overlap */
};

const char *naut_strerror(naut_err e);

#endif /* NAUT_COMMON_H */