From 47508ec70ea2c85cb1541b1c3a214439357ad735 Mon Sep 17 00:00:00 2001
From: Rob Austein <sra@hactrn.net>
Date: Tue, 29 Sep 2015 21:38:00 -0400
Subject: Attempting to optimize out the one-cycle delay didn't work,
 relatively low priority, so just disable the optimization for now.

---
 config/config.py       | 11 +++++++++--
 config/core_selector.v | 38 ++++++++++++++++++++++++++++----------
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/config/config.py b/config/config.py
index 1c5e5d0..0f3818f 100755
--- a/config/config.py
+++ b/config/config.py
@@ -112,7 +112,14 @@ def main():
         for core in cores:
             core.configure(cfg)
 
-        Core.need_one_cycle_delay = any(core.block_memory for core in cores)
+        if False:
+
+            # For some reason, attempting to optimize out the delay
+            # code entirely results in a non-working bitstream.  Don't
+            # know why, disabling the optimization works, so just do
+            # that for now.
+
+            Core.need_one_cycle_delay = any(core.block_memory for core in cores)
 
         args.verilog.write(createModule_template.format(
             addrs = "".join(core.createAddr()     for core in cores),
@@ -170,7 +177,7 @@ class Core(object):
     # Class variable recording whether we need a one-cycle delay to
     # compensate for block memories.
 
-    need_one_cycle_delay = False
+    need_one_cycle_delay = True
 
     def __init__(self, name):
         self.name = name
diff --git a/config/core_selector.v b/config/core_selector.v
index 0f60771..3c0a31f 100644
--- a/config/core_selector.v
+++ b/config/core_selector.v
@@ -62,6 +62,9 @@ module core_selector
       .error(error_board_regs)
       );
 
+   reg  [31: 0] read_data_board_regs_reg;
+   always @(posedge sys_clk)
+     read_data_board_regs_reg <= read_data_board_regs;
 
 
    //----------------------------------------------------------------
@@ -85,6 +88,9 @@ module core_selector
       .error(error_comm_regs)
       );
 
+   reg  [31: 0] read_data_comm_regs_reg;
+   always @(posedge sys_clk)
+     read_data_comm_regs_reg <= read_data_comm_regs;
 
 
    //----------------------------------------------------------------
@@ -108,6 +114,9 @@ module core_selector
       .error(error_sha256)
       );
 
+   reg  [31: 0] read_data_sha256_reg;
+   always @(posedge sys_clk)
+     read_data_sha256_reg <= read_data_sha256;
 
 
    //----------------------------------------------------------------
@@ -131,6 +140,9 @@ module core_selector
       .error(error_aes)
       );
 
+   reg  [31: 0] read_data_aes_reg;
+   always @(posedge sys_clk)
+     read_data_aes_reg <= read_data_aes;
 
 
    //----------------------------------------------------------------
@@ -158,6 +170,9 @@ module core_selector
       .debug(debug)
       );
 
+   reg  [31: 0] read_data_trng_reg;
+   always @(posedge sys_clk)
+     read_data_trng_reg <= read_data_trng;
 
 
    //----------------------------------------------------------------
@@ -180,6 +195,9 @@ module core_selector
       .read_data(read_data_modexp)
       );
 
+   reg  [31: 0] read_data_modexp_reg;
+   always @(posedge sys_clk)
+     read_data_modexp_reg <= read_data_modexp;
 
 
 
@@ -196,52 +214,52 @@ module core_selector
      case (addr_core_num)
        CORE_ADDR_BOARD_REGS:
          begin
-            sys_read_data_mux = read_data_board_regs;
+            sys_read_data_mux = read_data_board_regs_reg;
             sys_error_mux = error_board_regs;
          end
        CORE_ADDR_COMM_REGS:
          begin
-            sys_read_data_mux = read_data_comm_regs;
+            sys_read_data_mux = read_data_comm_regs_reg;
             sys_error_mux = error_comm_regs;
          end
        CORE_ADDR_SHA256:
          begin
-            sys_read_data_mux = read_data_sha256;
+            sys_read_data_mux = read_data_sha256_reg;
             sys_error_mux = error_sha256;
          end
        CORE_ADDR_AES:
          begin
-            sys_read_data_mux = read_data_aes;
+            sys_read_data_mux = read_data_aes_reg;
             sys_error_mux = error_aes;
          end
        CORE_ADDR_TRNG:
          begin
-            sys_read_data_mux = read_data_trng;
+            sys_read_data_mux = read_data_trng_reg;
             sys_error_mux = error_trng;
          end
        CORE_ADDR_AVALANCHE_ENTROPY:
          begin
-            sys_read_data_mux = read_data_trng;
+            sys_read_data_mux = read_data_trng_reg;
             sys_error_mux = error_trng;
          end
        CORE_ADDR_ROSC_ENTROPY:
          begin
-            sys_read_data_mux = read_data_trng;
+            sys_read_data_mux = read_data_trng_reg;
             sys_error_mux = error_trng;
          end
        CORE_ADDR_TRNG_MIXER:
          begin
-            sys_read_data_mux = read_data_trng;
+            sys_read_data_mux = read_data_trng_reg;
             sys_error_mux = error_trng;
          end
        CORE_ADDR_TRNG_CSPRNG:
          begin
-            sys_read_data_mux = read_data_trng;
+            sys_read_data_mux = read_data_trng_reg;
             sys_error_mux = error_trng;
          end
        CORE_ADDR_MODEXP:
          begin
-            sys_read_data_mux = read_data_modexp;
+            sys_read_data_mux = read_data_modexp_reg;
             sys_error_mux = 0;
          end
 
-- 
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