sim: Parameterize chdr_word_t data type

This replaces chdr_word_t, which was a statically defined 64-bit data
type, with a paramaterizable data type that matches the defined CHDR_W.
Code that formerly referenced the chdr_word_t data type can now define
the data type for their desired CHDR_W and ITEM_W as follows:

  // Define the CHDR word and item/sample data types
  typedef ChdrData #(CHDR_W, ITEM_W)::chdr_word_t chdr_word_t;
  typedef ChdrData #(CHDR_W, ITEM_W)::item_t      item_t;

ITEM_W is optional when defining chdr_word_t if items are not
needed. Static methods in the ChdrData class also provide the ability to
convert between CHDR words and data items. For example:

  // Convert CHDR data buffer to a buffer of samples
  samples = ChdrData#(CHDR_W, ITEM_W)::chdr_to_item(data);


Original-commit: fc895feacb8dde3b02c9a4eccb4b4f4a654f2881

sim/rfnoc/PkgChdrData.sv

@@ -0,0 +1,155 @@
+//
+// Copyright 2020 Ettus Research, A National Instruments Company
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+//
+// Module: PkgChdrData
+//
+// Description: This package defines the data types used to represent CHDR
+// words and data samples in RFNoC as well as utilities for converting between
+// them.
+// 
+
+package PkgChdrData;
+
+  // Default value for ITEM_W needs to be 64 due to a bug in Vivado 2019.1.
+  class ChdrData #(int CHDR_W = 64, int ITEM_W = 64);
+
+    // CHDR bus word (CHDR_W bits)
+    typedef logic       [CHDR_W-1:0] chdr_word_t ;
+    typedef chdr_word_t              chdr_word_queue_t[$];
+
+    // The item/sample word type (user-defined width, a multiple of 8 bits)
+    typedef logic  [ITEM_W-1:0] item_t ;
+    typedef item_t              item_queue_t[$];
+
+
+    function new();
+      assert ((ITEM_W % 8 == 0) && (CHDR_W % ITEM_W == 0)) else begin
+        $fatal(1, "RfnocData::new: Invalid CHDR_W and/or ITEM_W");
+      end
+    endfunction
+
+
+    // Convert a queue of items to a queue of CHDR words
+    static function chdr_word_queue_t item_to_chdr(ref item_queue_t items);
+      int items_per_word = CHDR_W / ITEM_W;
+      int num_chdr_words = ((items.size() + items_per_word - 1) / items_per_word);
+      chdr_word_queue_t chdr_words;
+      chdr_word_t word;
+
+      for (int i = 0; i < num_chdr_words; i++) begin
+        for (int j = 0; j < items_per_word; j++) begin
+          word[j*ITEM_W +: ITEM_W] = items[i*items_per_word + j];
+        end
+        chdr_words.push_back(word);
+      end
+      return chdr_words;
+    endfunction : item_to_chdr
+
+
+    // Convert a queue of CHDR words to a queue of items. The optional
+    // num_bytes argument indicates how many bytes are in the item queue that
+    // you want to convert.
+    static function item_queue_t chdr_to_item(
+      ref   chdr_word_queue_t chdr_words, 
+      input int               num_bytes = -1
+    );
+      int items_per_word = CHDR_W / ITEM_W;
+      int bytes_left;
+      item_queue_t item_words;
+
+      if (num_bytes < 0) bytes_left = chdr_words.size() * (CHDR_W / 8);
+      else bytes_left = num_bytes;
+
+      foreach (chdr_words[i]) begin
+        for (int j = 0; j < items_per_word; j++) begin
+          if (bytes_left > 0) begin
+            item_words.push_back(chdr_words[i][j*ITEM_W +: ITEM_W]);
+            bytes_left -= (ITEM_W/8);
+          end
+        end
+      end
+
+      assert (bytes_left == 0) else begin
+        $warning("ChdrData::chdr_to_item: num_bytes is not a multiple of items");
+      end
+
+      return item_words;
+    endfunction : chdr_to_item
+
+
+    // Return a string representation of the contents of the CHDR queue
+    static function string chdr_string(
+      ref   chdr_word_queue_t chdr_words, 
+      input string            format = "%X"
+    );
+      string str = $sformatf("%0d-bit CHDR words (%0d words or %0d bytes):\n",
+        CHDR_W, chdr_words.size(), chdr_words.size() * (CHDR_W/8));
+      foreach (chdr_words[i]) begin
+        str = { str, $sformatf({"%5d> ", format, "\n"}, i, chdr_words[i]) };
+      end
+      return str;
+    endfunction : chdr_string
+
+
+    // Return a string representation of the contents of the item queue
+    static function string item_string(
+      ref   item_queue_t items,
+      input string       format = "%X"
+    );
+      string str = $sformatf("%0d-bit items (%0d items or %0d bytes)\n", 
+        ITEM_W, items.size(), items.size() * (ITEM_W/8));
+      foreach (items[i]) begin
+        str = { str, $sformatf({"%5d> ", format, "\n"}, i, items[i]) };
+      end
+      return str;
+    endfunction : item_string
+
+
+    // Display a string representation of the contents of a CHDR word queue
+    static function void print_chdr(
+      ref   chdr_word_queue_t chdr_words,
+      input string            format = "%X"
+    );
+      $display(chdr_string(chdr_words, format));
+    endfunction : print_chdr
+
+
+    // Display a string representation of the contents of an item queue
+    static function void print_item(
+      ref   item_queue_t items,
+      input string       format = "%X"
+    );
+      $display(item_string(items, format));
+    endfunction : print_item
+
+
+    // Check if the contents of two CHDR queues is equal
+    static function bit chdr_equal(
+      ref chdr_word_queue_t left, 
+      ref chdr_word_queue_t right
+    );
+      if (left.size() != right.size()) return 0;
+      for (int i = 0; i < left.size(); i++) begin
+        if (left[i] != right[i]) return 0;
+      end
+      return 1;
+    endfunction : chdr_equal
+
+
+    // Check if the contents of two item queues is equal
+    static function bit item_equal(
+      ref item_queue_t left,
+      ref item_queue_t right
+    );
+      if (left.size() != right.size()) return 0;
+      for (int i = 0; i < left.size(); i++) begin
+        if (left[i] != right[i]) return 0;
+      end
+      return 1;
+    endfunction : item_equal
+
+  endclass
+
+endpackage : PkgChdrData