ram: condensed tapcell insertion, ram.tcl cleanup

Signed-off-by: braydenl9988 <[email protected]>

Author: braydenlouie

src/ram/include/ram/ram.h

@@ -86,6 +86,9 @@ class RamGen
 
   odb::dbBTerm* makeBTerm(const std::string& name, odb::dbIoType io_type);
 
+  std::unique_ptr<Layout> generateTapColumn(int word_count, 
+          int tapcell_col);
+
   std::unique_ptr<Cell> makeDecoder(const std::string& prefix,
                                     int num_word,
                                     int read_ports,

src/ram/src/ram.cpp

@@ -173,6 +173,22 @@ void RamGen::makeCellByte(Grid& ram_grid,
   ram_grid.addCell(std::move(sel_cell), (byte_number * 9) + 8);
 }
 
+std::unique_ptr<Layout> RamGen::generateTapColumn(const int word_count,
+        const int tapcell_col)
+{
+  auto tapcell_layout = std::make_unique<Layout>(odb::vertical);
+  for (int i = 0; i < word_count; ++i) {
+    auto tapcell_cell = std::make_unique<Cell>();
+    makeCellInst(tapcell_cell.get(),
+                 "tapcell",
+                 fmt::format("cell{}_{}", tapcell_col, i),
+                 tapcell_,
+                 {});
+    tapcell_layout->addCell(std::move(tapcell_cell));
+  }
+  return tapcell_layout;
+}
+
 std::unique_ptr<Cell> RamGen::makeDecoder(
     const std::string& prefix,
     const int num_word,
@@ -389,7 +405,6 @@ void RamGen::generate(const int bytes_per_word,
   clock_gate_cell_ = nullptr;
   buffer_cell_ = nullptr;
   findMasters();
-  max_tap_dist *= 10;
 
   auto chip = db_->getChip();
   if (!chip) {
@@ -551,35 +566,22 @@ void RamGen::generate(const int bytes_per_word,
   ram_grid.gridInit();
 
   if (tapcell_) {
+    // max tap distance specified is greater than the length of ram 
     if (ram_grid.getRowWidth() <= max_tap_dist) {
-      auto tapcell_layout = std::make_unique<Layout>(odb::vertical);
-      for (int i = 0; i < word_count; ++i) {
-        auto tapcell_cell = std::make_unique<Cell>();
-        makeCellInst(tapcell_cell.get(),
-                     "tapcell",
-                     fmt::format("cell_{}", i),
-                     tapcell_,
-                     {});
-        tapcell_layout->addCell(std::move(tapcell_cell));
-      }
+      auto tapcell_layout = generateTapColumn(word_count, 0);
       ram_grid.insertLayout(std::move(tapcell_layout), 0); 
     } else {
       int nearest_tap = 0;
+      int tapcell_count = 0;
+      // iterates through each of the columns 
       for (int col = 0; col < ram_grid.numLayouts(); ++col) {
-        if (nearest_tap >= max_tap_dist) {
-          auto tapcell_layout = std::make_unique<Layout>(odb::vertical);
-          for (int i = 0; i < word_count; ++i) {
-            auto tapcell_cell = std::make_unique<Cell>();
-            makeCellInst(tapcell_cell.get(),
-                         "tapcell",
-                         fmt::format("cell{}_{}", col, i),
-                         tapcell_,
-                         {});
-            tapcell_layout->addCell(std::move(tapcell_cell));
-          }
+        if (nearest_tap >= max_tap_dist) { 
+          //if the nearest_tap is too far, generate tap column
+          auto tapcell_layout = generateTapColumn(word_count, tapcell_count);
           ram_grid.insertLayout(std::move(tapcell_layout), col);
-          ++col;
+          ++col; // col adjustment after insertion
           nearest_tap = 0;
+          ++tapcell_count;
         } 
         nearest_tap += ram_grid.getLayoutWidth(col);
       }

src/ram/src/ram.tcl

@@ -52,10 +52,13 @@ proc generate_ram_netlist { args } {
   if { [info exists keys(-tapcell)] } {
     if { [info exists keys(-max_tap_dist)] } {
       set max_tap_dist $keys(-max_tap_dist)
+      set max_tap_dist [expr $max_tap_dist * 1000]
     } else {
       utl::error RAM 21 "The -max_tap_dist argument must be specified with tapcell."
     }
     set tapcell $keys(-tapcell)
+  } else {
+    utl::info RAM 22 "No tapcell is specified. The generated layout may not pass Design Rule Checks."
   }
 
   ram::generate_ram_netlist_cmd $bytes_per_word $word_count $storage_cell \

src/ram/test/make_8x8.tcl

@@ -20,7 +20,7 @@ generate_ram \
   -filler_cells {sky130_fd_sc_hd__fill_1 sky130_fd_sc_hd__fill_2 \
     sky130_fd_sc_hd__fill_4 sky130_fd_sc_hd__fill_8} \
   -tapcell sky130_fd_sc_hd__tap_1 \
-  -max_tap_dist 3000
+  -max_tap_dist 30
 
 set lef_file [make_result_file make_8x8.lef]
 write_abstract_lef $lef_file