the check sum is this the comments for simplification ...

time to try it

so wait

ghidra did unsigned substraction so .... local_70 is the string length, the expression length_70 - 5U is unsigned

this underflows to a huge number, which is >5, so the real condition is local_70 <5

so wait

the range is 5 to 10

as 6 or 7, 8, 9, 10 -5 are in range and true on the 5 < (local_70 -5U)

example 6-5 =1 and 1 is less than 5 ...

Give me a bit of time I am done with a and to go for the rest ....

Had to use a calculator

So for the string "abcde" the number is "734". Try it and it works

the value to find table[i] from 15 address

So this is the whole logic of the code revision engineered I will post the full writeup maybe tmrw.

Good night

I am happy today

By the way this is my first reverse engineered code.