From 255d2886bf7614d2513ef8fe1dd591b88d454dc5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Mon, 29 Jun 2015 15:57:35 +0200
Subject: Introduced the explicit exponent length improvement to baseline
before perfopt. Added testcases with operands > 1024 bits.
---
src/rtl/modexp_core.v | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
(limited to 'src/rtl')
diff --git a/src/rtl/modexp_core.v b/src/rtl/modexp_core.v
index b8c4403..6dd1570 100644
--- a/src/rtl/modexp_core.v
+++ b/src/rtl/modexp_core.v
@@ -236,6 +236,8 @@ module modexp_core(
reg residue_valid_int_validated;
wire [7 : 0] length_m1;
+ wire [7 : 0] modulus_length_m1;
+ wire [7 : 0] exponent_length_m1;
//----------------------------------------------------------------
@@ -244,7 +246,9 @@ module modexp_core(
assign ready = ready_reg;
assign cycles = {cycle_ctr_high_reg, cycle_ctr_low_reg};
- assign length_m1 = modulus_length - 8'h1;
+
+ assign modulus_length_m1 = modulus_length - 8'h1;
+ assign exponent_length_m1 = exponent_length - 8'h1;
//----------------------------------------------------------------
@@ -485,10 +489,10 @@ module modexp_core(
one_new = 32'h00000000;
b_one_new = 32'h00000000;
- if (montprod_opa_addr == length_m1)
+ if (montprod_opa_addr == modulus_length_m1)
one_new = 32'h00000001;
- if (montprod_opb_addr == length_m1)
+ if (montprod_opb_addr == modulus_length_m1)
b_one_new = 32'h00000001;
end
@@ -634,7 +638,7 @@ module modexp_core(
loop_counter_new = 13'b0;
loop_counter_we = 1'b0;
- if (loop_counter_reg == {length_m1, 5'b11111})
+ if (loop_counter_reg == {exponent_length_m1, 5'b11111})
last_iteration = 1'b1;
else
last_iteration = 1'b0;
@@ -668,7 +672,7 @@ module modexp_core(
begin : exponent_process
// Accessing new instead of reg - pick up update at
// CTRL_ITERATE_NEW to remove a pipeline stall.
- E_word_index = length_m1 - loop_counter_new[ 12 : 5 ];
+ E_word_index = exponent_length_m1 - loop_counter_new[ 12 : 5 ];
E_bit_index = loop_counter_reg[ 04 : 0 ];
--
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