[Cryptech-Commits] [core/math/modexp] 01/02: Adding write control of s_mem for first iteration and adding a new stage in priority mux.

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joachim at secworks.se pushed a commit to branch perfopt
in repository core/math/modexp.

commit bba9af35a9ed26870d7fcf16749cfcf7e6b38618
Author: Joachim Strömbergson <joachim at secworks.se>
Date:   Mon Jun 22 11:41:22 2015 +0200

    Adding write control of s_mem for first iteration and adding a new stage in priority mux.
---
 src/rtl/montprod.v | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/rtl/montprod.v b/src/rtl/montprod.v
index 4f4a9aa..00227d0 100644
--- a/src/rtl/montprod.v
+++ b/src/rtl/montprod.v
@@ -354,7 +354,7 @@ module montprod(
         CTRL_L_CALC_SA:
           begin
             //s = (s + q*M + b*A) >>> 1;, if(b==1) S+= A. Takes (1..length) cycles.
-            s_mem_we_new = b_reg | q_reg;
+            s_mem_we_new = b_reg | q_reg | first_iteration_reg;
           end
 
         CTRL_L_CALC_SDIV2:
@@ -392,8 +392,10 @@ module montprod(
 
             if (b_reg)
               s_mem_new = add_result_sa;
-            else
+            else if (q_reg)
               s_mem_new = add_result_sm;
+            else
+              s_mem_new = muxed_s_mem_read_data;
 
             add_carry_in_sa_new = add_carry_out_sa;
             add_carry_in_sm_new = add_carry_out_sm;