/*
    * Copyright 2024 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty.channel.uring;
  
  import io.netty.util.internal.PlatformDependent;
  
  /**
   * <pre>{@code
   * struct iovec {
   *     void  *iov_base;    // Starting address
   *     size_t iov_len;     // Number of bytes to transfer
   * };
   * }</pre>
   */
  final class Iov {
  
      private Iov() { }
  
      static void write(long iovAddress, long bufferAddress, int length) {
          if (Native.SIZEOF_SIZE_T == 4) {
              PlatformDependent.putInt(iovAddress + Native.IOVEC_OFFSETOF_IOV_BASE, (int) bufferAddress);
              PlatformDependent.putInt(iovAddress + Native.IOVEC_OFFSETOF_IOV_LEN, length);
          } else {
              assert Native.SIZEOF_SIZE_T == 8;
              PlatformDependent.putLong(iovAddress + Native.IOVEC_OFFSETOF_IOV_BASE, bufferAddress);
              PlatformDependent.putLong(iovAddress + Native.IOVEC_OFFSETOF_IOV_LEN, length);
          }
      }
  
      static long readBufferAddress(long iovAddress) {
          if (Native.SIZEOF_SIZE_T == 4) {
              return PlatformDependent.getInt(iovAddress + Native.IOVEC_OFFSETOF_IOV_BASE);
          }
          assert Native.SIZEOF_SIZE_T == 8;
          return PlatformDependent.getLong(iovAddress + Native.IOVEC_OFFSETOF_IOV_BASE);
      }
  
      static int readBufferLength(long iovAddress) {
          if (Native.SIZEOF_SIZE_T == 4) {
              return PlatformDependent.getInt(iovAddress + Native.IOVEC_OFFSETOF_IOV_LEN);
          }
          assert Native.SIZEOF_SIZE_T == 8;
          return (int) PlatformDependent.getLong(iovAddress + Native.IOVEC_OFFSETOF_IOV_LEN);
      }
  
      static long sumSize(long iovAddress, int length) {
          long sum = 0;
          for (int i = 0; i < length; i++) {
              sum += readBufferLength(iovAddress);
              iovAddress += 2L * Native.SIZEOF_SIZE_T;
          }
          return sum;
      }
  }