/**
 * Copyright (c) 2021 OceanBase
 * OceanBase CE is licensed under Mulan PubL v2.
 * You can use this software according to the terms and conditions of the Mulan PubL v2.
 * You may obtain a copy of Mulan PubL v2 at:
 *          http://license.coscl.org.cn/MulanPubL-2.0
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PubL v2 for more details.
 */

#ifndef EASY_LOCK_ATOMIC_H_
#define EASY_LOCK_ATOMIC_H_

#include "easy_define.h"
#include <stdint.h>
#include <sched.h>

EASY_CPP_START

#define easy_atomic_set(v, i) ((v) = (i))
typedef volatile int32_t easy_atomic32_t;

// 32bit
static __inline__ void easy_atomic32_add(easy_atomic32_t* v, int i)
{
  __sync_fetch_and_add(v, i);  // for x86 and arm
}
static __inline__ int32_t easy_atomic32_add_return(easy_atomic32_t* value, int32_t diff)
{
  return __sync_add_and_fetch(value, diff);  // for x86 and arm
}
static __inline__ void easy_atomic32_inc(easy_atomic32_t* v)
{
  __sync_add_and_fetch(v, 1);  // for x86 and arm
}
static __inline__ void easy_atomic32_dec(easy_atomic32_t* v)
{
  __sync_sub_and_fetch(v, 1);  // for x86 and arm
}

// 64bit
#if __WORDSIZE == 64
typedef volatile int64_t easy_atomic_t;
static __inline__ void easy_atomic_add(easy_atomic_t* v, int64_t i)
{
  __sync_fetch_and_add(v, i);  // for x86 and arm
}
static __inline__ int64_t easy_atomic_add_return(easy_atomic_t* value, int64_t i)
{
  return __sync_add_and_fetch(value, i);  // for x86 and arm
}
static __inline__ int64_t easy_atomic_cmp_set(easy_atomic_t* lock, int64_t old, int64_t set)
{
  return __sync_bool_compare_and_swap(lock, old, set);  // for x86 and arm
}
static __inline__ void easy_atomic_inc(easy_atomic_t* v)
{
  __sync_add_and_fetch(v, 1);  // for x86 and arm
}
static __inline__ void easy_atomic_dec(easy_atomic_t* v)
{
  __sync_sub_and_fetch(v, 1);  // for x86 and arm
}
#else
typedef volatile int32_t easy_atomic_t;
#define easy_atomic_add(v, i) easy_atomic32_add(v, i)
#define easy_atomic_add_return(v, diff) easy_atomic32_add_return(v, diff)
#define easy_atomic_inc(v) easy_atomic32_inc(v)
#define easy_atomic_dec(v) easy_atomic32_dec(v)
static __inline__ int32_t easy_atomic_cmp_set(easy_atomic_t* lock, int32_t old, int32_t set)
{
  return __sync_bool_compare_and_swap(lock, old, set);  // for x86 and arm
}
#endif

#define easy_trylock(lock) (*(lock) == 0 && easy_atomic_cmp_set(lock, 0, 1))
#define easy_unlock(lock) __atomic_store_n(lock, 0, __ATOMIC_SEQ_CST)
#define easy_spin_unlock easy_unlock
#define easy_mfence() __atomic_thread_fence(__ATOMIC_SEQ_CST)
static __inline__ void easy_spin_lock(easy_atomic_t* lock)
{
  int i, n;

  for (;;) {
    if (*lock == 0 && easy_atomic_cmp_set(lock, 0, 1)) {
      return;
    }

    for (n = 1; n < 1024; n <<= 1) {

      for (i = 0; i < n; i++) {
#if defined(__x86_64__)
        __asm__(".byte 0xf3, 0x90");
#elif defined(__aarch64__)
        __asm__("yield");  // for ARM
#elif defined(__sw_64__) || defined(__loongarch64)
  // These platforms currently do not natively support such operation
#else
#error arch unsupported
#endif
      }

      if (*lock == 0 && easy_atomic_cmp_set(lock, 0, 1)) {
        return;
      }
    }

    sched_yield();
  }
}

static __inline__ void easy_clear_bit(unsigned long nr, volatile void* addr)
{
  int8_t* m = ((int8_t*)addr) + (nr >> 3);
  *m &= (int8_t)(~(1 << (nr & 7)));
}
static __inline__ void easy_set_bit(unsigned long nr, volatile void* addr)
{
  int8_t* m = ((int8_t*)addr) + (nr >> 3);
  *m |= (int8_t)(1 << (nr & 7));
}

typedef struct easy_spinrwlock_t {
  easy_atomic_t ref_cnt;
  easy_atomic_t wait_write;
} easy_spinrwlock_t;
#define EASY_SPINRWLOCK_INITIALIZER \
  {                                 \
    0, 0                            \
  }
static __inline__ int easy_spinrwlock_rdlock(easy_spinrwlock_t* lock)
{
  int ret = EASY_OK;

  if (NULL == lock) {
    ret = EASY_ERROR;
  } else {
    int cond = 1;

    while (cond) {
      int loop = 1;

      do {
        easy_atomic_t oldv = lock->ref_cnt;

        if (0 <= oldv && 0 == lock->wait_write) {
          easy_atomic_t newv = oldv + 1;

          if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
            cond = 0;
            break;
          }
        }

#if defined(__x86_64__)
        asm("pause");
#elif defined(__aarch64__)
        asm("yield");      // for ARM
#elif defined(__sw_64__) || defined(__loongarch64)
  // These platforms currently do not natively support such operation
#else
#error arch unsupported
#endif
        loop <<= 1;
      } while (loop < 1024);

      sched_yield();
    }
  }

  return ret;
}
static __inline__ int easy_spinrwlock_wrlock(easy_spinrwlock_t* lock)
{
  int ret = EASY_OK;

  if (NULL == lock) {
    ret = EASY_ERROR;
  } else {
    int cond = 1;
    easy_atomic_inc(&lock->wait_write);

    while (cond) {
      int loop = 1;

      do {
        easy_atomic_t oldv = lock->ref_cnt;

        if (0 == oldv) {
          easy_atomic_t newv = -1;

          if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
            cond = 0;
            break;
          }
        }

#if defined(__x86_64__)
        asm("pause");
#elif defined(__aarch64__)
        asm("yield");      // for ARM
#elif defined(__sw_64__) || defined(__loongarch64)
  // These platforms currently do not natively support such operation
#else
#error arch unsupported
#endif

        loop <<= 1;
      } while (loop < 1024);

      sched_yield();
    }

    easy_atomic_dec(&lock->wait_write);
  }

  return ret;
}
static __inline__ int easy_spinrwlock_try_rdlock(easy_spinrwlock_t* lock)
{
  int ret = EASY_OK;

  if (NULL == lock) {
    ret = EASY_ERROR;
  } else {
    ret = EASY_AGAIN;
    easy_atomic_t oldv = lock->ref_cnt;

    if (0 <= oldv && 0 == lock->wait_write) {
      easy_atomic_t newv = oldv + 1;

      if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
        ret = EASY_OK;
      }
    }
  }

  return ret;
}
static __inline__ int easy_spinrwlock_try_wrlock(easy_spinrwlock_t* lock)
{
  int ret = EASY_OK;

  if (NULL == lock) {
    ret = EASY_ERROR;
  } else {
    ret = EASY_AGAIN;
    easy_atomic_t oldv = lock->ref_cnt;

    if (0 == oldv) {
      easy_atomic_t newv = -1;

      if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
        ret = EASY_OK;
      }
    }
  }

  return ret;
}
static __inline__ int easy_spinrwlock_unlock(easy_spinrwlock_t* lock)
{
  int ret = EASY_OK;

  if (NULL == lock) {
    ret = EASY_ERROR;
  } else {
    while (1) {
      easy_atomic_t oldv = lock->ref_cnt;

      if (-1 == oldv) {
        easy_atomic_t newv = 0;

        if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
          break;
        }
      } else if (0 < oldv) {
        easy_atomic_t newv = oldv - 1;

        if (easy_atomic_cmp_set(&lock->ref_cnt, oldv, newv)) {
          break;
        }
      } else {
        ret = EASY_ERROR;
        break;
      }
    }
  }

  return ret;
}

EASY_CPP_END

#endif