# AES GCM mode - what is ouput in that scheme?

I'm trying to understand that scheme:

https://xilinx.github.io/Vitis_Libraries/security/2019.2/guide_L1/internals/gcm.html

Here on page 11 it looks like GHASH gives only one value "Return $$Y_m$$":

https://web.cs.ucdavis.edu/~rogaway/ocb/gcm.pdf

After hashing several subsequent blocks. It make no sense to me. If I understand it well every GF128_mult(H) is one block of our output, right? So the stream is consisted of consequtive blocks GF128_mult(H). Am I right or it works in different way? From scheme above it looks like our result (all bits generated for the stream) are just "tag", which seem not to be true.

Or maybe this how it works? We convert all input blocks in one 128-bit tag? And send it as a ciphered message? Then to send every amount of data, we just need 128-bit block? I don't think it works that way, then it is not possible to decrypt it.

The ciphertext block $$k$$ is obtained by blockwise XOR of the output block $$k$$ with the plaintext block $$k$$ [happens in the middle layer of the diagram] for $$k=1,2,\ldots,\textrm{len}.$$ The ciphertexts are chained together using the GF128_mult mechanism to generate a single authentication tag at the end which is also transmitted.