The SGMII Adaptation Module is described in the following files:
<project_dir>/<project_name>/<project_name>.srcs/sources1/ip/<component_name>/ synth/sgmii_adapt/
<component_name>_sgmii_adapt.v[hd]
<component_name>_clk_gen.v[hd]
<component_name>_johnson_cntr.v[hd]
<component_name>_tx_rate_adapt.v[hd]
<component_name>_rx_rate_adapt.v[hd]
The GMII of the core always operates at 125 MHz. The core does not differentiate between the three speeds of operation; it always effectively operates at 1 Gbps. However, at 100 Mbps, every data byte run through the core should be repeated 10 times to achieve the required bit rate; at 10 Mbps, each data byte run through the core should be repeated 100 times to achieve the required bit rate. Dealing with this repetition of bytes is the function of the SGMII adaptation module and its component blocks. The SGMII adaptation module and component blocks are described in detail in the Additional Client-Side SGMII Logic.