How to calculate the checksum of the RSDP table

After dump the  ACPI table,we will need to verify if all of table is compliance with ACPI spec.we need to verify the checksum filed .

Here,I would write  about the checksum calculation for RSDP table.

First of all,we review the ACPI 6 spec and find the below description.                ‘ This includes only the first 20 bytes of this table, bytes 0 to 19, including the checksum field.These bytes must sum to zero ‘

Therefore, the checksum of RSDP  table depends on the structure bytes from 0 to 19.we can get these from RW utility.

52+53+44+20+50+54+52+20+(08+)49+4E+54+45+4C+20+02+74+D0+7C+7B=600

Because the checksum filed length is 1 byte, we comfirm the 1 byte of 0x600H is 0x00H.