C++读写内存的源代码 |21xrx.com

C++读写内存的源代码

2023-07-13 00:11:55 深夜i -- --

C++ 读写内存源代码

C++作为一门底层编程语言，可以直接读写内存，这对于需要高性能的程序非常有用。下面是C++读写内存的源代码。

读取内存：


// 读取一块内存
void* MemRead(const void* address, size_t size) {
  void* buffer = malloc(size);
  memcpy(buffer, address, size);
  return buffer;
}
// 读取一个未知大小的整数（注意字节序）
int ReadUnknownInt(const void* address) {
  uint8_t firstByte = *(uint8_t*)address;
  if (firstByte < 0x80)
    return firstByte;
  
  if (firstByte < 0xC0) {
    uint16_t value = (firstByte - 0x80) << 8;
    value |= *(uint8_t*)(address + 1);
    return value;
  }
  if (firstByte < 0xE0) {
    uint32_t value = (firstByte - 0xC0) << 24;
    value |= *(uint8_t*)(address + 1) << 16;
    value |= *(uint8_t*)(address + 2) << 8;
    value |= *(uint8_t*)(address + 3);
    return value;
  }
  if (firstByte < 0xF0) {
    uint64_t value = (firstByte - 0xE0ull) << 56;
    value |= (uint64_t)*(uint8_t*)(address + 1) << 48;
    value |= (uint64_t)*(uint8_t*)(address + 2) << 40;
    value |= (uint64_t)*(uint8_t*)(address + 3) << 32;
    value |= (uint64_t)*(uint8_t*)(address + 4) << 24;
    value |= (uint64_t)*(uint8_t*)(address + 5) << 16;
    value |= (uint64_t)*(uint8_t*)(address + 6) << 8;
    value |= (uint64_t)*(uint8_t*)(address + 7);
    return (int)value;
  }
  return 0;
}

写入内存：


// 将一块内存写入另一块内存
void MemWrite(void* destination, const void* source, size_t size) {
  memcpy(destination, source, size);
}
// 写入一个未知大小的整数（注意字节序）
void WriteUnknownInt(int value, void* address) {
  if (value >= -0x80 && value < 0x80) {
    *(uint8_t*)address = (uint8_t)value;
  } else if (value >= -0x4000 && value < 0x4000) {
    *(uint8_t*)address = 0x80 + (uint8_t)(value >> 8);
    *(uint8_t*)(address + 1) = (uint8_t)value;
  } else if (value >= -0x200000 && value < 0x200000) {
    *(uint8_t*)address = 0xC0 + (uint8_t)(value >> 24);
    *(uint8_t*)(address + 1) = (uint8_t)(value >> 16);
    *(uint8_t*)(address + 2) = (uint8_t)(value >> 8);
    *(uint8_t*)(address + 3) = (uint8_t)value;
  } else if (value >= -0x100000000ll && value < 0x100000000ll) {
    *(uint8_t*)address = 0xE0 + (uint8_t)(value >> 56);
    *(uint8_t*)(address + 1) = (uint8_t)(value >> 48);
    *(uint8_t*)(address + 2) = (uint8_t)(value >> 40);
    *(uint8_t*)(address + 3) = (uint8_t)(value >> 32);
    *(uint8_t*)(address + 4) = (uint8_t)(value >> 24);
    *(uint8_t*)(address + 5) = (uint8_t)(value >> 16);
    *(uint8_t*)(address + 6) = (uint8_t)(value >> 8);
    *(uint8_t*)(address + 7) = (uint8_t)value;
  }
}

这些函数可以帮助开发人员直接读写内存，如读取程序中某个变量的值，或将指定内存块中的数据写回磁盘。这些功能虽然强大，但也不宜滥用，因为读写内存实际上破坏了程序的内部状态，可能导致程序崩溃或运行不正常。因此，开发人员需要仔细地设计和测试代码，避免出现不可预测的错误。

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