Logic for checksum of s19 file in stm8 stvp

[raja1]

Hello. I am trying to modify my s19 file which is generated for stm8 using stvd and cosmic c compiler.

Consider an S19 file which starts from 0x4000 address [EEPROM starting address]

The first two lines would be : 

S123400000000000000000000000000000000000000000000000000000000000000000009C
S123402000000000000000000000000000000000000000000000000000000000000000007C

I want to know what is the meaning of the first characters S123 and the last byte 9C/7C etc.

This is important for me to understand the logic to modify the s19 accordingly.  

[Tesla DeLorean]

You'd think it would be documented somewhere..

Perhaps look at srecords project

[Peter BENSCH · Accepted solution]

@raja1 You can also find the format described in Wikipedia.

Regards
/Peter

[raja1]

Thank you @Peter BENSCH ! This is what I was looking for. I was confused on how the checksum was being evaluated but it makes sense now.