/*

 * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "runtime/sharedRuntime.hpp"

#include "utilities/copy.hpp"

// Copy bytes; larger units are filled atomically if everything is aligned.

void Copy::conjoint_memory_atomic(void* from, void* to, size_t size) {

  address src = (address) from;

  address dst = (address) to;

  uintptr_t bits = (uintptr_t) src | (uintptr_t) dst | (uintptr_t) size;

  // (Note:  We could improve performance by ignoring the low bits of size,

  // and putting a short cleanup loop after each bulk copy loop.

  // There are plenty of other ways to make this faster also,

  // and it's a slippery slope.  For now, let's keep this code simple

  // since the simplicity helps clarify the atomicity semantics of

  // this operation.  There are also CPU-specific assembly versions

  // which may or may not want to include such optimizations.)

  if (bits % sizeof(jlong) == 0) {

    Copy::conjoint_jlongs_atomic((jlong*) src, (jlong*) dst, size / sizeof(jlong));

  } else if (bits % sizeof(jint) == 0) {

    Copy::conjoint_jints_atomic((jint*) src, (jint*) dst, size / sizeof(jint));

  } else if (bits % sizeof(jshort) == 0) {

    Copy::conjoint_jshorts_atomic((jshort*) src, (jshort*) dst, size / sizeof(jshort));

  } else {

    // Not aligned, so no need to be atomic.

    Copy::conjoint_jbytes((void*) src, (void*) dst, size);

  }

}

class CopySwap : AllStatic {

public:

  /**

   * Copy and optionally byte swap elements

   *

   * <swap> - true if elements should be byte swapped

   *

   * @param src address of source

   * @param dst address of destination

   * @param byte_count number of bytes to copy

   * @param elem_size size of the elements to copy-swap

   */

  template<bool swap>

  static void conjoint_swap_if_needed(const void* src, void* dst, size_t byte_count, size_t elem_size) {

    assert(src != NULL, "address must not be NULL");

    assert(dst != NULL, "address must not be NULL");

    assert(elem_size == 2 || elem_size == 4 || elem_size == 8,

           "incorrect element size: " SIZE_FORMAT, elem_size);

           "byte_count " SIZE_FORMAT " must be multiple of element size " SIZE_FORMAT, byte_count, elem_size);

    address src_end = (address)src + byte_count;

    if (dst <= src || dst >= src_end) {

      do_conjoint_swap<RIGHT,swap>(src, dst, byte_count, elem_size);

    } else {

      do_conjoint_swap<LEFT,swap>(src, dst, byte_count, elem_size);

    }

  }

private:

  /**

   * Byte swap a 16-bit value

   */

  static uint16_t byte_swap(uint16_t x) {

    return (x << 8) | (x >> 8);

  }

  /**

   * Byte swap a 32-bit value

   */

  static uint32_t byte_swap(uint32_t x) {

    uint16_t lo = (uint16_t)x;

    uint16_t hi = (uint16_t)(x >> 16);

    return ((uint32_t)byte_swap(lo) << 16) | (uint32_t)byte_swap(hi);

  }

  /**

   * Byte swap a 64-bit value

   */

  static uint64_t byte_swap(uint64_t x) {

    uint32_t lo = (uint32_t)x;

    uint32_t hi = (uint32_t)(x >> 32);

    return ((uint64_t)byte_swap(lo) << 32) | (uint64_t)byte_swap(hi);

  }

  enum CopyDirection {

    RIGHT, // lower -> higher address

    LEFT   // higher -> lower address

  };

  /**

   * Copy and byte swap elements

   *

   * <T> - type of element to copy

   * <D> - copy direction

   * <is_src_aligned> - true if src argument is aligned to element size

   * <is_dst_aligned> - true if dst argument is aligned to element size

   *

   * @param src address of source

   * @param dst address of destination

   * @param byte_count number of bytes to copy

   */

  template <typename T, CopyDirection D, bool swap, bool is_src_aligned, bool is_dst_aligned>

  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {

    const char* cur_src;

    char* cur_dst;

    switch (D) {

    case RIGHT:

      cur_src = (const char*)src;

      cur_dst = (char*)dst;

      break;

    case LEFT:

      cur_src = (const char*)src + byte_count - sizeof(T);

      cur_dst = (char*)dst + byte_count - sizeof(T);

      break;

    }

    for (size_t i = 0; i < byte_count / sizeof(T); i++) {

      T tmp;

      if (is_src_aligned) {

        tmp = *(T*)cur_src;

      } else {

        memcpy(&tmp, cur_src, sizeof(T));

      }

      if (swap) {

        tmp = byte_swap(tmp);

      }

      if (is_dst_aligned) {

        *(T*)cur_dst = tmp;

      } else {

        memcpy(cur_dst, &tmp, sizeof(T));

      }

      switch (D) {

      case RIGHT:

        cur_src += sizeof(T);

        cur_dst += sizeof(T);

        break;

      case LEFT:

        cur_src -= sizeof(T);

        cur_dst -= sizeof(T);

        break;

      }

    }

  }

  /**

   * Copy and byte swap elements

   *

   * <T>    - type of element to copy

   * <D>    - copy direction

   * <swap> - true if elements should be byte swapped

   *

   * @param src address of source

   * @param dst address of destination

   * @param byte_count number of bytes to copy

   */

  template <typename T, CopyDirection direction, bool swap>

  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {

        do_conjoint_swap<T,direction,swap,true,true>(src, dst, byte_count);

      } else {

        do_conjoint_swap<T,direction,swap,true,false>(src, dst, byte_count);

      }

    } else {

        do_conjoint_swap<T,direction,swap,false,true>(src, dst, byte_count);

      } else {

        do_conjoint_swap<T,direction,swap,false,false>(src, dst, byte_count);

      }

    }

  }

  /**

   * Copy and byte swap elements

   *

   * <D>    - copy direction

   * <swap> - true if elements should be byte swapped

   *

   * @param src address of source

   * @param dst address of destination

   * @param byte_count number of bytes to copy

   * @param elem_size size of the elements to copy-swap

   */

  template <CopyDirection D, bool swap>

  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {

    switch (elem_size) {

    case 2: do_conjoint_swap<uint16_t,D,swap>(src, dst, byte_count); break;

    case 4: do_conjoint_swap<uint32_t,D,swap>(src, dst, byte_count); break;

    case 8: do_conjoint_swap<uint64_t,D,swap>(src, dst, byte_count); break;

    default: guarantee(false, "do_conjoint_swap: Invalid elem_size " SIZE_FORMAT "\n", elem_size);

    }

  }

};

void Copy::conjoint_copy(const void* src, void* dst, size_t byte_count, size_t elem_size) {

  CopySwap::conjoint_swap_if_needed<false>(src, dst, byte_count, elem_size);

}

void Copy::conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {

  CopySwap::conjoint_swap_if_needed<true>(src, dst, byte_count, elem_size);

}

// Fill bytes; larger units are filled atomically if everything is aligned.

void Copy::fill_to_memory_atomic(void* to, size_t size, jubyte value) {

  address dst = (address) to;

  uintptr_t bits = (uintptr_t) to | (uintptr_t) size;

  if (bits % sizeof(jlong) == 0) {

    jlong fill = (julong)( (jubyte)value ); // zero-extend

    if (fill != 0) {

      fill += fill << 8;

      fill += fill << 16;

      fill += fill << 32;

    }

    //Copy::fill_to_jlongs_atomic((jlong*) dst, size / sizeof(jlong));

    for (uintptr_t off = 0; off < size; off += sizeof(jlong)) {

      *(jlong*)(dst + off) = fill;

    }

  } else if (bits % sizeof(jint) == 0) {

    jint fill = (juint)( (jubyte)value ); // zero-extend

    if (fill != 0) {

      fill += fill << 8;

      fill += fill << 16;

    }

    //Copy::fill_to_jints_atomic((jint*) dst, size / sizeof(jint));

    for (uintptr_t off = 0; off < size; off += sizeof(jint)) {

      *(jint*)(dst + off) = fill;

    }

  } else if (bits % sizeof(jshort) == 0) {

    jshort fill = (jushort)( (jubyte)value ); // zero-extend

    fill += fill << 8;

    //Copy::fill_to_jshorts_atomic((jshort*) dst, size / sizeof(jshort));

    for (uintptr_t off = 0; off < size; off += sizeof(jshort)) {

      *(jshort*)(dst + off) = fill;

    }

  } else {

    // Not aligned, so no need to be atomic.

    Copy::fill_to_bytes(dst, size, value);

  }

}