Modified detailed routing to support different channel widths

Author: Brandon Heiner

doc/src/arch/reference.rst

@@ -754,8 +754,6 @@ Global Routing Information
 If global routing is to be performed, channels in different directions and in different parts of the FPGA can be set to different relative widths.
 This is specified in the content within the ``<chan_width_distr>`` tag.
 
-.. note:: If detailed routing is to be performed, all the channels in the FPGA must have the same width.
-
 .. arch:tag:: <x distr="{gaussian|uniform|pulse|delta}" peak="float" width=" float" xpeak=" float" dc=" float"/>
 
     :req_param distr: The channel width distribution function

vpr/src/base/CheckSetup.cpp

@@ -12,8 +12,7 @@ void CheckSetup(const t_packer_opts& PackerOpts,
                 const t_router_opts& RouterOpts,
                 const t_det_routing_arch& RoutingArch,
                 const std::vector<t_segment_inf>& Segments,
-                const t_timing_inf Timing,
-                const t_chan_width_dist Chans) {
+                const t_timing_inf Timing) {
     int i;
     int Tmp;
 
@@ -61,15 +60,6 @@ void CheckSetup(const t_packer_opts& PackerOpts,
         }
     }
 
-    if (DETAILED == RouterOpts.route_type) {
-        if ((Chans.chan_x_dist.type != UNIFORM)
-            || (Chans.chan_y_dist.type != UNIFORM)
-            || (Chans.chan_x_dist.peak != Chans.chan_y_dist.peak)) {
-            VPR_FATAL_ERROR(VPR_ERROR_OTHER,
-                            "Detailed routing currently only supported on FPGAs with all channels of equal width.\n");
-        }
-    }
-
     for (i = 0; i < (int)Segments.size(); ++i) {
         Tmp = Segments[i].arch_opin_switch;
         auto& device_ctx = g_vpr_ctx.device();

vpr/src/base/CheckSetup.h

@@ -7,7 +7,6 @@ void CheckSetup(const t_packer_opts& PackerOpts,
                 const t_router_opts& RouterOpts,
                 const t_det_routing_arch& RoutingArch,
                 const std::vector<t_segment_inf>& Segments,
-                const t_timing_inf Timing,
-                const t_chan_width_dist Chans);
+                const t_timing_inf Timing);
 
 #endif

vpr/src/base/place_and_route.cpp

@@ -37,6 +37,12 @@
 #include "timing_info.h"
 #include "tatum/echo_writer.hpp"
 
+/******************* Variables local to this module ************************/
+
+/* Used to pass directionality from the binary_search_place_and_route subroutine *
+ * to the init_chan subroutine.                                                  */
+static t_graph_type graph_directionality;
+
 /******************* Subroutines local to this module ************************/
 
 static float comp_width(t_chan* chan, float x, float separation);
@@ -87,8 +93,10 @@ int binary_search_place_and_route(const t_placer_opts& placer_opts_ref,
 
     if (router_opts.route_type == GLOBAL) {
         graph_type = GRAPH_GLOBAL;
+        graph_directionality = GRAPH_GLOBAL;
     } else {
         graph_type = (det_routing_arch->directionality == BI_DIRECTIONAL ? GRAPH_BIDIR : GRAPH_UNIDIR);
+        graph_directionality = (det_routing_arch->directionality == BI_DIRECTIONAL ? GRAPH_BIDIR : GRAPH_UNIDIR);
     }
 
     best_routing = alloc_saved_routing();
@@ -395,6 +403,7 @@ t_chan_width init_chan(int cfactor, t_chan_width_dist chan_width_dist) {
     t_chan_width chan_width;
     chan_width.x_list.resize(grid.height());
     chan_width.y_list.resize(grid.width());
+    int computed_width;
 
     if (grid.height() > 1) {
         int num_channels = grid.height() - 1;
@@ -403,7 +412,12 @@ t_chan_width init_chan(int cfactor, t_chan_width_dist chan_width_dist) {
 
         for (size_t i = 0; i < grid.height(); ++i) {
             float y = float(i) / num_channels;
-            chan_width.x_list[i] = (int)floor(cfactor * comp_width(&chan_x_dist, y, separation) + 0.5);
+            computed_width = (int)floor(cfactor * comp_width(&chan_x_dist, y, separation) + 0.5);
+            if ((GRAPH_BIDIR == graph_directionality) || computed_width % 2 == 0) {
+                chan_width.x_list[i] = computed_width;
+            } else {
+                chan_width.x_list[i] = computed_width - 1;
+            }
             chan_width.x_list[i] = std::max(chan_width.x_list[i], 1); //Minimum channel width 1
         }
     }
@@ -415,8 +429,12 @@ t_chan_width init_chan(int cfactor, t_chan_width_dist chan_width_dist) {
 
         for (size_t i = 0; i < grid.width(); ++i) { //-2 for no perim channels
             float x = float(i) / num_channels;
-
-            chan_width.y_list[i] = (int)floor(cfactor * comp_width(&chan_y_dist, x, separation) + 0.5);
+            computed_width = (int)floor(cfactor * comp_width(&chan_y_dist, x, separation) + 0.5);
+            if ((GRAPH_BIDIR == graph_directionality) || computed_width % 2 == 0) {
+                chan_width.y_list[i] = computed_width;
+            } else {
+                chan_width.y_list[i] = computed_width - 1;
+            }
             chan_width.y_list[i] = std::max(chan_width.y_list[i], 1); //Minimum channel width 1
         }
     }

vpr/src/base/vpr_api.cpp

@@ -301,8 +301,7 @@ void vpr_init_with_options(const t_options* options, t_vpr_setup* vpr_setup, t_a
     CheckSetup(vpr_setup->PackerOpts,
                vpr_setup->PlacerOpts,
                vpr_setup->RouterOpts,
-               vpr_setup->RoutingArch, vpr_setup->Segments, vpr_setup->Timing,
-               arch->Chans);
+               vpr_setup->RoutingArch, vpr_setup->Segments, vpr_setup->Timing);
 
     /* flush any messages to user still in stdout that hasn't gotten displayed */
     fflush(stdout);
@@ -1164,10 +1163,9 @@ void vpr_check_setup(const t_packer_opts& PackerOpts,
                      const t_router_opts& RouterOpts,
                      const t_det_routing_arch& RoutingArch,
                      const std::vector<t_segment_inf>& Segments,
-                     const t_timing_inf& Timing,
-                     const t_chan_width_dist& Chans) {
+                     const t_timing_inf& Timing) {
     CheckSetup(PackerOpts, PlacerOpts, RouterOpts, RoutingArch,
-               Segments, Timing, Chans);
+               Segments, Timing);
 }
 
 ///@brief Show current setup

vpr/src/base/vpr_api.h

@@ -174,8 +174,7 @@ void vpr_check_setup(const t_packer_opts& PackerOpts,
                      const t_router_opts& RouterOpts,
                      const t_det_routing_arch& RoutingArch,
                      const std::vector<t_segment_inf>& Segments,
-                     const t_timing_inf& Timing,
-                     const t_chan_width_dist& Chans);
+                     const t_timing_inf& Timing);
 
 ///@brief Show current setup
 void vpr_show_setup(const t_vpr_setup& vpr_setup);