Merge pull request #10567 from tnguy19/optional-mask-size

ram: Optional mask size

Author: maliberty

src/ram/README.md

@@ -33,9 +33,10 @@ Standard cell libraries must be loaded before running this command.
 The module will create a new design, therefore a design should not be loaded before running the command.
 
 ```tcl
-generate_ram -mask_size bits
+generate_ram [-mask_size bits]
              -word_size bits
              -num_words words
+             [-column_mux_ratio ratio]
              [-read_ports count]
              [-storage_cell name]
              [-tristate_cell name]
@@ -55,9 +56,10 @@ generate_ram -mask_size bits
 
 | Switch Name | Description | 
 | ----- | ----- |
-| `-mask_size` | Determines the number of bits which are grouped together for masking during writes. For example, a mask size of `8` will enable each 8 bits of the word to be masked when writing (commonly known as byte masking). A mask size of `1` will enable each bit to be individually masked. The write enable signal for each port will be `(word_size / mask_size)` bits wide. The word size must be a multiple of the mask size. |
+| `-mask_size` | Determines the number of bits which are grouped together for masking during writes. For example, a mask size of `8` will enable each 8 bits of the word to be masked when writing (commonly known as byte masking). A mask size of `1` will enable each bit to be individually masked. The write enable signal for each port will be `(word_size / mask_size)` bits wide. The word size must be a multiple of the mask size. Default: equal to `-word_size`. |
 | `-word_size` | Size of each word in bits. |
 | `-num_words` | Number of words in the array. |
+| `-column_mux_ratio` | Number of words sharing a physical column. Must be `1`, `2`, or `4`. The number of words must be divisible by the column mux ratio. Default: `1` (no column muxing). |
 | `-read_ports` | Number of read ports for the array. Default: 1. |
 | `-storage_cell` | Name of the master to use for the storage device (i.e. a flip-flop). Must be positive-edge triggered. Default: auto-select from the loaded cell library. |
 | `-tristate_cell` | Name of the master to use for the tristate device (i.e. a tristate inverter). It is currently assumed that the device is inverting. Default: auto-select from the loaded cell library. |

src/ram/src/ram.tcl

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright (c) 2024-2025, The OpenROAD Authors
 
-sta::define_cmd_args "generate_ram_netlist" {-mask_size bits
+sta::define_cmd_args "generate_ram_netlist" {[-mask_size bits]
                                              -word_size bits
                                              -num_words words
                                              [-column_mux_ratio ratio]
@@ -23,18 +23,18 @@ proc generate_ram_netlist { args } {
     set column_mux_ratio $keys(-column_mux_ratio)
   }
 
-  if { [info exists keys(-mask_size)] } {
-    set mask_size $keys(-mask_size)
-  } else {
-    utl::error RAM 1 "The -mask_size argument must be specified."
-  }
-
   if { [info exists keys(-word_size)] } {
     set word_size $keys(-word_size)
   } else {
     utl::error RAM 2 "The -word_size argument must be specified."
   }
 
+  if { [info exists keys(-mask_size)] } {
+    set mask_size $keys(-mask_size)
+  } else {
+    set mask_size $word_size
+  }
+
   if { $word_size % $mask_size != 0 } {
     utl::error RAM 26 "The -word_size ($word_size) must be divisible by -mask_size ($mask_size)."
   }
@@ -93,7 +93,7 @@ proc generate_ram_netlist { args } {
     $tristate_cell $inv_cell $read_ports $use_latch $tapcell $max_tap_dist
 }
 
-sta::define_cmd_args "generate_ram" {-mask_size bits
+sta::define_cmd_args "generate_ram" {[-mask_size bits]
                                      -word_size bits
                                      -num_words words
                                      [-column_mux_ratio ratio]
@@ -129,10 +129,13 @@ proc generate_ram { args } {
   }
 
   set ram_netlist_args [list \
-    -mask_size $keys(-mask_size) \
     -word_size $keys(-word_size) \
     -num_words $keys(-num_words)]
 
+  if { [info exists keys(-mask_size)] } {
+    lappend ram_netlist_args -mask_size $keys(-mask_size)
+  }
+
   if { [info exists keys(-read_ports)] } {
     lappend ram_netlist_args -read_ports $keys(-read_ports)
   }