ChaCha20 (without Poly1305) block counter

[Jerry Lui <jerrylui803@xxxxxxxxx>]

Hi,

I am trying to use ChaCha20 (without Poly1305)

From RFC 7539:

One of the inputs to ChaCha20 is:

"A 32-bit initial counter."

However I cannot find the function to set this. where should I input this?

Thanks,

Jerry