请帮忙确定一下

有一段英文，是求校验和的，如下：
The last byte in the 250-byte block represents a checksum value for the entire 250-byte block of data. The checksum value for each 250-byte block is determined by the binary addition of the first 249 bytes and the subsequent subtraction of the sum from AA(hex).

其校验和的求法是否如下所似，请帮忙确认一下。
BYTE   checksum = 0;
for ( int i=1; i<=249; i++)
{
    checksum += data; //data[251]为存放250个BYTE数据的数组
}
checksum = 0xAA - checksum;