rfnoc: Add support for Split Stream RFNoC block

The split stream RFNoC block is an RFNoC block that takes in a single
CHDR stream and duplicates it, creating a number of output streams for
each input stream. Consult the split_stream_block_control class header
file for more details on block configuration and behavior, including how
property and action forwarding is handled by the block.

2 files changed, 110 insertions, 0 deletions

diff --git a/host/lib/rfnoc/CMakeLists.txt b/host/lib/rfnoc/CMakeLists.txt
index c095e86f9..d7c2006d2 100644
--- a/host/lib/rfnoc/CMakeLists.txt
+++ b/host/lib/rfnoc/CMakeLists.txt
@@ -49,6 +49,7 @@ LIBUHD_APPEND_SOURCES(
     ${CMAKE_CURRENT_SOURCE_DIR}/fosphor_block_control.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/null_block_control.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/radio_control_impl.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/split_stream_block_control.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/vector_iir_block_control.cpp
 )
 
diff --git a/host/lib/rfnoc/split_stream_block_control.cpp b/host/lib/rfnoc/split_stream_block_control.cpp
new file mode 100644
index 000000000..17485882a
--- /dev/null
+++ b/host/lib/rfnoc/split_stream_block_control.cpp
@@ -0,0 +1,109 @@
+//
+// Copyright 2019 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#include <uhd/convert.hpp>
+#include <uhd/exception.hpp>
+#include <uhd/rfnoc/defaults.hpp>
+#include <uhd/rfnoc/split_stream_block_control.hpp>
+#include <uhd/rfnoc/property.hpp>
+#include <uhd/rfnoc/registry.hpp>
+#include <string>
+
+using namespace uhd::rfnoc;
+
+
+class split_stream_block_control_impl : public split_stream_block_control
+{
+public:
+    RFNOC_BLOCK_CONSTRUCTOR(split_stream_block_control)
+    {
+        // Ensure that the block is configured correctly, i.e., that the
+        // number of output ports is an integer multiple of the number of
+        // input ports, and that there are at least two output branches.
+        const size_t num_input_ports  = get_num_input_ports();
+        const size_t num_output_ports = get_num_output_ports();
+        const size_t num_branches     = num_output_ports / num_input_ports;
+        UHD_ASSERT_THROW((num_output_ports % num_input_ports == 0) && (num_branches > 1));
+
+        //! Little helper to calculate the output port number given the branch
+        // (0..num_branches) and stream (0..num_input_ports()) numbers.
+        auto calculate_output_port = [num_input_ports, num_branches](
+                                         size_t branch, size_t stream) -> size_t {
+            UHD_ASSERT_THROW(branch < num_branches);
+            UHD_ASSERT_THROW(stream < num_input_ports);
+            return branch * num_input_ports + stream;
+        };
+
+        // Configure property propagation and action forwarding behavior for
+        // the split stream block.
+        set_prop_forwarding_policy(forwarding_policy_t::USE_MAP);
+        set_action_forwarding_policy(forwarding_policy_t::USE_MAP);
+
+        // Property propagation scheme (X --> Y means 'Properties received on
+        // X propagate to Y'):
+        //   Input stream S --> {output branch Bo, stream S} for all
+        //      S in streams and Bo in branches
+        //   Output branch Bo, stream S --> input stream S for all
+        //      S in streams and Bo in branches
+        //   Output branch Bo, stream S --> {output branch Bp, stream S}
+        //      for all S in stream and Bo, Bp in branches (Bo != Bp)
+        node_t::forwarding_map_t prop_fwd_map;
+        for (size_t stream = 0; stream < num_input_ports; stream++) {
+            std::vector<res_source_info> dest_ports;
+            for (size_t branch = 0; branch < num_branches; branch++) {
+                size_t output_port = calculate_output_port(branch, stream);
+                dest_ports.push_back({res_source_info::OUTPUT_EDGE, output_port});
+            }
+            // Input stream S --> {all output branches, stream S}
+            prop_fwd_map.insert({{res_source_info::INPUT_EDGE, stream}, dest_ports});
+
+            for (size_t branch_a = 0; branch_a < num_branches; branch_a++) {
+                size_t output_port_a = calculate_output_port(branch_a, stream);
+                // The first entry in the back propagation vector is
+                // output branch A, stream S --> input stream S
+                std::vector<res_source_info> dest_ports_back{
+                    {res_source_info::INPUT_EDGE, stream}};
+
+                for (size_t branch_b = 0; branch_b < num_branches; branch_b++) {
+                    if (branch_a == branch_b) {
+                        continue;
+                    }
+                    size_t output_port_b = calculate_output_port(branch_b, stream);
+                    // Add all output branches that are not the 'source'
+                    // output port
+                    dest_ports_back.push_back(
+                        {res_source_info::OUTPUT_EDGE, output_port_b});
+                }
+                prop_fwd_map.insert(
+                    {{res_source_info::OUTPUT_EDGE, output_port_a}, dest_ports_back});
+            }
+        }
+        set_prop_forwarding_map(prop_fwd_map);
+
+        // Action forwarding scheme (X --> Y means 'Actions received on
+        // X forward to Y'):
+        //   Input stream S --> {output branch Bo, stream S} for all
+        //      S in streams and Bo in branches
+        //   Output branch Bo, stream S --> input stream S for all
+        //      S in streams and Bo in branches
+        node_t::forwarding_map_t action_fwd_map;
+        for (size_t stream = 0; stream < num_input_ports; stream++) {
+            std::vector<res_source_info> dest_ports;
+            for (size_t branch = 0; branch < num_branches; branch++) {
+                size_t output_port = calculate_output_port(branch, stream);
+                dest_ports.push_back({res_source_info::OUTPUT_EDGE, output_port});
+
+                action_fwd_map.insert({{res_source_info::OUTPUT_EDGE, output_port},
+                    {{res_source_info::INPUT_EDGE, stream}}});
+            }
+            action_fwd_map.insert({{res_source_info::INPUT_EDGE, stream}, dest_ports});
+        }
+        set_action_forwarding_map(action_fwd_map);
+    }
+};
+
+UHD_RFNOC_BLOCK_REGISTER_DIRECT(
+    split_stream_block_control, SPLIT_STREAM_BLOCK, "SplitStream", CLOCK_KEY_GRAPH, "bus_clk")