/*
 *	BIRD Library
 *
 *	(c) 1998--2004 Martin Mares <mj@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#ifndef _BIRD_BIRDLIB_H_
#define _BIRD_BIRDLIB_H_

#include <stddef.h>

#include "sysdep/config.h"
#include "lib/alloca.h"
#include "lib/macro.h"

/* Ugly structure offset handling macros */

#define SAME_TYPE(a, b)	({ int _ = ((a) != (b)); !_; })
#define TYPE_CAST(from, to, what) ( SAME_TYPE(((from) NULL), (what)), ((to) (what)))

#ifdef offsetof
#define OFFSETOF offsetof
#else
#define OFFSETOF(s, i) ((size_t) &((s *)0)->i)
#endif

#define SKIP_BACK(s, i, p) ({ s *_ptr = ((s *)((char *)p - OFFSETOF(s, i))); SAME_TYPE(&_ptr->i, p); _ptr; })
#define BIRD_ALIGN(s, a) (((s)+a-1)&~(a-1))
#define CPU_STRUCT_ALIGN  (MAX_(_Alignof(void*), _Alignof(u64)))
#define BIRD_CPU_ALIGN(s) BIRD_ALIGN((s), CPU_STRUCT_ALIGN)

/* Structure item alignment macros */

#define PADDING_NAME(id)	_padding_##id
#define PADDING_(id, sz)	u8 PADDING_NAME(id)[sz]

#if CPU_POINTER_ALIGNMENT == 4
#define PADDING(id, n32, n64)	PADDING_(id, n32)
#elif CPU_POINTER_ALIGNMENT == 8
#define PADDING(id, n32, n64)	PADDING_(id, n64)
#else
#error "Strange CPU pointer alignment: " CPU_POINTER_ALIGNMENT
#endif

/* Utility macros */

#define MIN_(a,b) (((a)<(b))?(a):(b))
#define MAX_(a,b) (((a)>(b))?(a):(b))

#ifndef PARSER
#undef MIN
#undef MAX
#define MIN(a,b) MIN_(a,b)
#define MAX(a,b) MAX_(a,b)
#endif

#define ROUND_DOWN_POW2(a,b)  ((a) & ~((b)-1))
#define ROUND_UP_POW2(a,b)  (((a)+((b)-1)) & ~((b)-1))

#define U64(c) UINT64_C(c)
#define ABS(a)   ((a)>=0 ? (a) : -(a))
#define DELTA(a,b) (((a)>=(b))?(a)-(b):(b)-(a))
#define ARRAY_SIZE(a) (sizeof(a)/sizeof(*(a)))
#define BYTES(n) ((((uint) (n)) + 7) / 8)
#define CALL(fn, args...) ({ if (fn) fn(args); })
#define ADVANCE(w, r, l) ({ r -= (l); w += (l); })

static inline int uint_cmp(uint i1, uint i2)
{ return (int)(i1 > i2) - (int)(i1 < i2); }

static inline int u64_cmp(u64 i1, u64 i2)
{ return (int)(i1 > i2) - (int)(i1 < i2); }


/* Bitfield macros */

/* b is u32 array (or ptr), l is size of it in bits (multiple of 32), p is 0..(l-1) */
#define BIT32_VAL(p)		(((u32) 1) << ((p) % 32))
#define BIT32_TEST(b,p)		((b)[(p)/32] & BIT32_VAL(p))
#define BIT32_SET(b,p)		((b)[(p)/32] |= BIT32_VAL(p))
#define BIT32_CLR(b,p)		((b)[(p)/32] &= ~BIT32_VAL(p))
#define BIT32_ZERO(b,l)		memset((b), 0, (l)/8)

/* The same, but counting bits from MSB */
#define BIT32R_VAL(p)		((((u32) 1) << 31) >> ((p) % 32))
#define BIT32R_TEST(b,p)	((b)[(p)/32] & BIT32R_VAL(p))
#define BIT32R_SET(b,p)		((b)[(p)/32] |= BIT32R_VAL(p))
#define BIT32R_CLR(b,p)		((b)[(p)/32] &= ~BIT32R_VAL(p))
#define BIT32R_ZERO(b,l)	memset((b), 0, (l)/8)

/* Short Bitmask Constructor */
#define BIT32_ALL_HELPER(x)	(1 << (x)) |
#define BIT32_ALL(...)		(MACRO_FOREACH(BIT32_ALL_HELPER, __VA_ARGS__) 0)

#ifndef NULL
#define NULL ((void *) 0)
#endif

/* Macros for gcc attributes */

#define NORET __attribute__((noreturn))
#define USE_RESULT __atribute__((warn_unused_result))
#define UNUSED __attribute__((unused))
#define PACKED __attribute__((packed))
#define NONNULL(...) __attribute__((nonnull((__VA_ARGS__))))
#define CLEANUP(fun) __attribute__((cleanup(fun)))

#define STATIC_ASSERT(EXP) _Static_assert(EXP, #EXP)
#define STATIC_ASSERT_MSG(EXP,MSG) _Static_assert(EXP, MSG)

/* Microsecond time */

typedef s64 btime;
//typedef s64 bird_clock_t;

#define S_	* (btime) 1000000
#define MS_	* (btime) 1000
#define US_	* (btime) 1
#define TO_S	/1000000
#define TO_MS	/1000
#define TO_US	/1
#define TO_NS	* (btime) 1000

#ifndef PARSER
#define S	S_
#define MS	MS_
#define US	US_
#define NS	/1000
#endif

#define TIME_INFINITY ((s64) 0x7fffffffffffffff)


/* Rate limiting */

struct tbf {
  btime timestamp;			/* Last update */
  u64 count;				/* Available micro-tokens */
  u16 burst;				/* Max number of tokens */
  u16 rate;				/* Rate of replenishment (tokens / sec) */
  u32 drop;				/* Number of failed request since last successful */
};

/* Default TBF values for rate limiting log messages */
#define TBF_DEFAULT_LOG_LIMITS { .rate = 1, .burst = 5 }

int tbf_limit(struct tbf *f);


/* Logging and dying */

typedef struct buffer {
  byte *start;
  byte *pos;
  byte *end;
} buffer;

#define LOG_BUFFER_SIZE 2560

typedef struct log_buffer {
  struct buffer buf;
  byte *tm_pos;
  byte *msg_pos;
  int class;
  char block[LOG_BUFFER_SIZE];
} log_buffer;

#define STACK_BUFFER_INIT(buf,size)		\
  do {						\
    buf.start = alloca(size);			\
    buf.pos = buf.start;			\
    buf.end = buf.start + size;			\
  } while(0)

#define log log_msg
void log_prepare(log_buffer *buf, int class);
void log_commit(log_buffer *buf);
void log_msg(const char *msg, ...);
void log_rl(struct tbf *rl, const char *msg, ...);
void die(const char *msg, ...) NORET;
void bug(const char *msg, ...) NORET;

#define L_DEBUG "\001"			/* Debugging messages */
#define L_TRACE "\002"			/* Protocol tracing */
#define L_INFO "\003"			/* Informational messages */
#define L_REMOTE "\004"			/* Remote protocol errors */
#define L_WARN "\005"			/* Local warnings */
#define L_ERR "\006"			/* Local errors */
#define L_AUTH "\007"			/* Authorization failed etc. */
#define L_FATAL "\010"			/* Fatal errors */
#define L_BUG "\011"			/* BIRD bugs */

void debug(const char *msg, ...);	/* Printf to debug output */
void debug_safe(const char *msg);	/* Printf to debug output, async-safe */

/* Internal thread ID, useful for logging */
extern _Atomic uint max_thread_id;
extern _Thread_local uint this_thread_id;
#define THIS_THREAD_ID  (this_thread_id ?: (this_thread_id = atomic_fetch_add_explicit(&max_thread_id, 1, memory_order_acq_rel)))


/* Debugging */

#if defined(LOCAL_DEBUG) || defined(GLOBAL_DEBUG)
#define DBG(x, y...) debug(x, ##y)
#define DBGL(x, y...) debug(x "\n", ##y)
#elif defined(DEBUG_TO_LOG)
#define DBG(...) do { } while (0)
#define DBGL(...) log(L_DEBUG __VA_ARGS__)
#else
#define DBG(...) do { } while(0)
#define DBGL(...) do { } while (0)
#endif

#define ASSERT_DIE(x) do { if (!(x)) bug("Assertion '%s' failed at %s:%d", #x, __FILE__, __LINE__); } while(0)

#define EXPENSIVE_CHECK(x) /* intentionally left blank */

#ifdef DEBUGGING
#define ASSERT(x) ASSERT_DIE(x)
#define ASSUME(x) ASSERT_DIE(x)
#ifdef ENABLE_EXPENSIVE_CHECKS
#undef EXPENSIVE_CHECK
#define EXPENSIVE_CHECK(x) ASSERT_DIE(x)
#endif
#else
#define ASSERT(x) do { if (!(x)) log(L_BUG "Assertion '%s' failed at %s:%d", #x, __FILE__, __LINE__); } while(0)
#define ASSUME(x) /* intentionally left blank */
#endif


#ifdef DEBUGGING
asm(
    ".pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n"
    ".byte 1\n" /* Python */
    ".asciz \"bird-gdb.py\"\n"
    ".popsection\n"
   );
#endif


/* Pseudorandom numbers */

u32 random_u32(void);
void random_init(void);
void random_bytes(void *buf, size_t size);


/* Hashing */

/* Constant parameter for non-parametrized hashes */
#define HASH_PARAM 2902958171u

/* Precomputed powers of HASH_PARAM */
#define HASH_PARAM1 ((u64) HASH_PARAM)
#define HASH_PARAM2 (HASH_PARAM1 * HASH_PARAM)
#define HASH_PARAM3 (HASH_PARAM2 * HASH_PARAM)
#define HASH_PARAM4 (HASH_PARAM3 * HASH_PARAM)

/* Reduce intermediate 64-bit value to final 32-bit value */
static inline u32 hash_value(u64 a)
{ return ((u32) a) ^ ((u32) (a >> 32)); }

static inline u64 u32_hash0(u32 v, u32 p, u64 acc)
{ return (acc + v) * p; }

static inline u64 u64_hash0(u64 v, u32 p, u64 acc)
{ return u32_hash0(v >> 32, p, u32_hash0(v, p, acc)); }

static inline u32 u64_hash(u64 v)
{ return hash_value(u64_hash0(v, HASH_PARAM, 0)); }

#endif