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-rw-r--r--src/rtl/montprod.v86
-rw-r--r--src/tb/tb_montprod.v2
2 files changed, 69 insertions, 19 deletions
diff --git a/src/rtl/montprod.v b/src/rtl/montprod.v
index fa7c438..7276b4b 100644
--- a/src/rtl/montprod.v
+++ b/src/rtl/montprod.v
@@ -132,7 +132,13 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
reg [(ADW - 1) : 0] word_index_reg;
reg [(ADW - 1) : 0] word_index_new;
+ reg word_index_we;
reg [(ADW - 1) : 0] word_index_prev_reg;
+ reg reset_word_index_lsw;
+ reg reset_word_index_msw;
+ reg inc_word_index;
+ reg dec_word_index;
+
reg [(ADW - 1) : 0] length_m1;
reg add_carry_in_sa_reg;
@@ -161,12 +167,13 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
wire shr_carry_out;
wire [(OPW - 1) : 0] shr_data_out;
- reg reset_word_index_lsw;
- reg reset_word_index_msw;
reg [(OPW - 1) : 0] sa_adder_data_in;
reg [(OPW - 1) : 0] muxed_s_mem_read_data;
+ // Temporary debug wires.
+ reg b_js;
+ reg pr_tt;
//----------------------------------------------------------------
@@ -253,13 +260,15 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
s_mem_we_reg <= s_mem_we_new;
s_mux_reg <= s_mux_new;
- word_index_reg <= word_index_new;
word_index_prev_reg <= word_index_reg;
shr_carry_in_reg <= shr_carry_in_new;
add_carry_in_sa_reg <= add_carry_in_sa_new;
add_carry_in_sm_reg <= add_carry_in_sm_new;
+ if (word_index_we)
+ word_index_reg <= word_index_new;
+
if (first_iteration_we)
first_iteration_reg <= first_iteration_new;
@@ -288,46 +297,74 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
//----------------------------------------------------------------
// prodcalc
+ //
+ // Logic to generate addresses and data selection
+ // for the OpA, OpM and Result memories.
//----------------------------------------------------------------
always @*
begin : prodcalc
opa_addr_reg = word_index_reg;
opb_addr_reg = b_word_index;
opm_addr_reg = word_index_reg;
- s_mem_addr = word_index_reg;
tmp_result_we = 1'b0;
-
result_addr_reg = word_index_prev_reg;
result_data_reg = s_mem_read_data;
-
if (montprod_ctrl_reg == CTRL_LOOP_ITER)
begin
opa_addr_reg = length_m1;
- s_mem_addr = length_m1;
end
if (montprod_ctrl_reg == CTRL_EMIT_S)
tmp_result_we = 1'b1;
+ end // prodcalc
+
+
+ //----------------------------------------------------------------
+ // word_index
+ //
+ // Logic that implements the word index used to drive
+ // addresses for operands.
+ //----------------------------------------------------------------
+ always @*
+ begin : word_index
+ word_index_new = {ADW{1'b0}};
+ word_index_we = 1'b0;
if (reset_word_index_lsw)
- word_index_new = length_m1;
+ begin
+ word_index_new = length_m1;
+ word_index_we = 1'b1;
+ end
- else if (reset_word_index_msw)
- word_index_new = {ADW{1'b0}};
+ if (reset_word_index_msw)
+ begin
+ word_index_new = {ADW{1'b0}};
+ word_index_we = 1'b1;
+ end
- else if (montprod_ctrl_reg == CTRL_CALC_SDIV2)
- word_index_new = word_index_reg + 1'b1;
+ if (inc_word_index)
+ begin
+ word_index_new = word_index_reg + 1'b1;
+ word_index_we = 1'b1;
+ end
- else
- word_index_new = word_index_reg - 1'b1;
- end // prodcalc
+ if (dec_word_index)
+ begin
+ word_index_new = word_index_reg - 1'b1;
+ word_index_we = 1'b1;
+ end
+ end // word_index
//----------------------------------------------------------------
// s_logic
+ //
+ // Logic to calculate S memory updates including address
+ // and write enable. This is where the main montprod
+ // calculation is performed.
//----------------------------------------------------------------
always @*
begin : s_logic
@@ -338,7 +375,7 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
add_carry_in_sm_new = 1'b0;
s_mem_new = {OPW{1'b0}};
s_mem_we_new = 1'b0;
-
+ s_mem_addr = word_index_reg;
case (montprod_ctrl_reg)
CTRL_INIT_S:
@@ -346,6 +383,11 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
s_mem_we_new = 1'b1;
end
+ CTRL_LOOP_ITER:
+ begin
+ s_mem_addr = length_m1;
+ end
+
CTRL_CALC_ADD:
begin
//s = (s + q*M + b*A) >>> 1;, if(b==1) S+= A. Takes (1..length) cycles.
@@ -461,6 +503,8 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
b_bit_index_we = 1'b0;
bq_we = 1'b0;
s_mux_new = SMUX_0;
+ dec_word_index = 1'b0;
+ inc_word_index = 1'b0;
reset_word_index_lsw = 1'b0;
reset_word_index_msw = 1'b0;
first_iteration_new = 1'b0;
@@ -485,6 +529,8 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
CTRL_INIT_S:
begin
+ dec_word_index = 1'b1;
+
if (word_index_reg == 0)
begin
loop_ctr_set = 1'b1;
@@ -519,7 +565,8 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
CTRL_CALC_ADD:
begin
- s_mux_new = SMUX_ADD;
+ s_mux_new = SMUX_ADD;
+ dec_word_index = 1'b1;
if (word_index_reg == 0)
begin
@@ -540,7 +587,8 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
CTRL_CALC_SDIV2:
begin
- s_mux_new = SMUX_SHR;
+ s_mux_new = SMUX_SHR;
+ inc_word_index = 1'b1;
if (word_index_reg == length_m1)
begin
@@ -571,6 +619,8 @@ module montprod #(parameter OPW = 32, parameter ADW = 8)
CTRL_EMIT_S:
begin
+ dec_word_index = 1'b1;
+
if (word_index_prev_reg == 0)
begin
ready_new = 1'b1;
diff --git a/src/tb/tb_montprod.v b/src/tb/tb_montprod.v
index 5e0a015..a162326 100644
--- a/src/tb/tb_montprod.v
+++ b/src/tb/tb_montprod.v
@@ -225,7 +225,7 @@ module tb_montprod();
begin : bq_debug
if (SHOW_BQ_DEBUG)
begin
- if (dut.montprod_ctrl_reg == dut.CTRL_L_CALC_SM)
+ if (dut.montprod_ctrl_reg == dut.CTRL_CALC_ADD)
$display("====================> B: %x Q: %x b_bit_index_reg: %x <=====================", dut.b_reg, dut.q_reg, dut.b_bit_index_reg);
end
end