What is the instruction_data struct for program ED25519?

I'm trying to deserialize the ED25519 program, but the struct I derived does not tally with the bytes in the instruction data (buffer)https://github.com/solana-labs/solana/blob/master/sdk/src/ed25519_instruction.rsHas anyone deserialized the ix data before? or is there any bytes I'm missing?

pub struct ED25519Data {    padding: u8,    signature_offset: u16,             // offset to ed25519 signature of 64 bytes    signature_instruction_index: u16,  // instruction index to find signature    public_key_offset: u16,            // offset to public key of 32 bytes    public_key_instruction_index: u16, // instruction index to find public key    message_data_offset: u16,          // offset to start of message data    message_data_size: u16,            // size of message data    message_instruction_index: u16,   // index of instruction data to get message data    ix_data: ? }   

ix_data isn't a fixed parameter, it varies.. Thank you!