As shown in Figure 2, several backward streaming modules are connected via FIFOs to compute multiple wavefield time steps and corelate the image at the same time. The number of connected backward streaming modules are configured at compile time. The C++ implementation of 2D-RTM backward kernel can be found in L2/include/hw/rtm2d/rtmbackward.hpp.
Figure 49 Figure 2. 2D-RTM backward kernel