wishbone/xwb_bus_fanout: now determines the number of peripheral select bits…

wishbone/xwb_bus_fanout: now determines the number of peripheral select bits from number of connected peripherals

wishbone/xwb_bus_fanout: now determines the number of peripheral select bits…
wishbone/xwb_bus_fanout: now determines the number of peripheral select bits from number of connected peripherals
601de57a · Tomasz Wlostowski · 2f4143b0 · 601de57a
Commit 601de57a authored Nov 02, 2011 by Tomasz Wlostowski
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xwb_bus_fanout.vhd modules/wishbone/wb_bus_fanout/xwb_bus_fanout.vhd +12 -1

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--- a/modules/wishbone/wb_bus_fanout/xwb_bus_fanout.vhd
+++ b/modules/wishbone/wb_bus_fanout/xwb_bus_fanout.vhd
@@ -27,7 +27,18 @@ end xwb_bus_fanout;

 architecture rtl of xwb_bus_fanout is

-  constant c_periph_addr_bits : integer := 3;
+  function f_log2_ceil(N : natural) return positive is
+  begin
+    if N <= 2 then
+      return 1;
+    elsif N mod 2 = 0 then
+      return 1 + f_log2_ceil(N/2);
+    else
+      return 1 + f_log2_ceil((N+1)/2);
+    end if;
+  end;
+  
+  constant c_periph_addr_bits : integer := f_log2_ceil(g_num_outputs);

  signal periph_addr     : std_logic_vector(c_periph_addr_bits - 1 downto 0);
  signal periph_addr_reg : std_logic_vector(c_periph_addr_bits - 1 downto 0);