From 9e9689d7b00ecdcc1c651f5e369e00a53d62df3c Mon Sep 17 00:00:00 2001
From: "Pavel V. Shatov (Meister)" <meisterpaul1@yandex.ru>
Date: Tue, 1 Oct 2019 15:05:11 +0300
Subject: Further work on the Montgomery modular multiplier. Can now to the
 "triangular" part of multiplication, i.e. compute the "magic" reduction
 coefficient Q = LSB(AB) * N_COEFF.

---
 rtl/dsp/dsp_array.v              |  42 +++-
 rtl/modexpng_mmm_fsm.vh          |  10 +
 rtl/modexpng_part_recombinator.v | 455 ++++++++++++++++++++++++++++-----------
 3 files changed, 377 insertions(+), 130 deletions(-)

(limited to 'rtl')

diff --git a/rtl/dsp/dsp_array.v b/rtl/dsp/dsp_array.v
index 178f87f..2a050d4 100644
--- a/rtl/dsp/dsp_array.v
+++ b/rtl/dsp/dsp_array.v
@@ -8,11 +8,11 @@ module dsp_array
     input             ce_p,
     input             ce_mode,
 
-    input  [8   -1:0] mode_z,
+    input  [9   -1:0] mode_z,
     
-    input  [4*18-1:0] a,
+    input  [5*18-1:0] a,
     input  [1*17-1:0] b,
-    output [8*47-1:0] p
+    output [9*47-1:0] p
 );
 
     `include "../modexpng_parameters_x8.vh"
@@ -37,7 +37,7 @@ module dsp_array
     genvar z;
     generate for (z=0; z<(NUM_MULTS/2); z=z+1)
         //
-        begin : DSP48E1
+        begin : gen_DSP48E1
             //        
             dsp_slice #
             (
@@ -64,7 +64,7 @@ module dsp_array
                 .opmode         ({1'b0, mode_z[2*z], 1'b0, 2'b01, 2'b01}),
                 .alumode        (4'b0000),
                 
-                .casc_a_in      ({17{1'b0}}),
+                .casc_a_in      ({18{1'b0}}),
                 .casc_b_in      ({17{1'b0}}),
                 
                 .casc_a_out     (casc_a[z]),
@@ -107,5 +107,37 @@ module dsp_array
         //
     endgenerate
 
+    dsp_slice #
+    (
+        .AB_INPUT("DIRECT"),
+        .B_REG(2)
+    )
+    dsp_aux
+    (
+        .clk            (clk),
+        
+        .ce_a1          (ce_a0),
+        .ce_b1          (ce_b0),
+        .ce_a2          (ce_a1),
+        .ce_b2          (ce_b1),
+        .ce_m           (ce_m),
+        .ce_p           (ce_p),
+        .ce_mode        (ce_mode),
+        
+        .a              (a[4*18+:18]),
+        .b              (b),
+        .p              (p[47*2*4+:47]),
+        
+        .inmode         (5'b00000),
+        .opmode         ({1'b0, mode_z[2*4], 1'b0, 2'b01, 2'b01}),
+        .alumode        (4'b0000),
+        
+        .casc_a_in      ({18{1'b0}}),
+        .casc_b_in      ({17{1'b0}}),
+        
+        .casc_a_out     (),
+        .casc_b_out     ()
+    );
+
 
 endmodule
diff --git a/rtl/modexpng_mmm_fsm.vh b/rtl/modexpng_mmm_fsm.vh
index c237a0b..2700a42 100644
--- a/rtl/modexpng_mmm_fsm.vh
+++ b/rtl/modexpng_mmm_fsm.vh
@@ -19,6 +19,16 @@ localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_SQUARE_COL_N_TRIG = 15;
 localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_SQUARE_COL_N_BUSY = 16;
     
 localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_SQUARE_HOLDOFF = 17;
+
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_0_INIT = 21;
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_0_TRIG = 22;
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_0_BUSY = 23;
+
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_N_INIT = 24;
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_N_TRIG = 25;
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_COL_N_BUSY = 26;
     
+localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_MULT_TRIANGLE_HOLDOFF = 27;
+
 localparam [FSM_STATE_WIDTH-1:0] FSM_STATE_STOP = 999;
     
\ No newline at end of file
diff --git a/rtl/modexpng_part_recombinator.v b/rtl/modexpng_part_recombinator.v
index db4774b..c51e7ef 100644
--- a/rtl/modexpng_part_recombinator.v
+++ b/rtl/modexpng_part_recombinator.v
@@ -7,7 +7,8 @@ module modexpng_part_recombinator
     dsp_x_ce_p, dsp_y_ce_p,
     ena_x,   ena_y,
     dsp_x_p, dsp_y_p,
-    col_index, col_index_last, slim_bram_xy_addr,
+    col_index, col_index_last,
+    slim_bram_xy_addr, slim_bram_xy_bank,
     fat_bram_xy_bank, fat_bram_xy_addr, fat_bram_x_dout, fat_bram_y_dout, fat_bram_xy_dout_valid
 );
 
@@ -28,11 +29,12 @@ module modexpng_part_recombinator
     input                        dsp_y_ce_p;
     input                        ena_x;
     input                        ena_y;
-    input  [8*47-1:0] dsp_x_p;
-    input  [8*47-1:0] dsp_y_p;
+    input  [9*47-1:0] dsp_x_p;
+    input  [9*47-1:0] dsp_y_p;
     input  [     4:0] col_index;
     input  [     4:0] col_index_last;
     input  [     7:0] slim_bram_xy_addr;
+    input  [     1:0] slim_bram_xy_bank;
 
     output [     2:0] fat_bram_xy_bank;
     output [     7:0] fat_bram_xy_addr;
@@ -44,18 +46,18 @@ module modexpng_part_recombinator
     //
     // Latches
     //
-    reg  [1*47-1:0] dsp_x_p_latch[0:7];
-    reg  [1*47-1:0] dsp_y_p_latch[0:7];
+    reg  [1*47-1:0] dsp_x_p_latch[0:8];
+    reg  [1*47-1:0] dsp_y_p_latch[0:8];
 
 
     //
     // Mapping
     //
-    wire [46:0] dsp_x_p_split[0:7];
-    wire [46:0] dsp_y_p_split[0:7];
+    wire [46:0] dsp_x_p_split[0:8];
+    wire [46:0] dsp_y_p_split[0:8];
     
     genvar z;
-    generate for (z=0; z<NUM_MULTS; z=z+1)
+    generate for (z=0; z<(NUM_MULTS+1); z=z+1)
         begin : gen_dsp_xy_p_split
             assign dsp_x_p_split[z] = dsp_x_p[47*z+:47];
             assign dsp_y_p_split[z] = dsp_y_p[47*z+:47];
@@ -83,6 +85,8 @@ module modexpng_part_recombinator
     // valid
     reg       x_valid_lsb = 1'b0;
     reg       y_valid_lsb = 1'b0;
+    reg       x_aux_lsb   = 1'b0;
+    reg       y_aux_lsb   = 1'b0;
     reg       x_valid_msb = 1'b0;
     reg       y_valid_msb = 1'b0;
     
@@ -106,6 +110,10 @@ module modexpng_part_recombinator
     reg       x_valid_latch_lsb = 1'b0;
     reg       y_valid_latch_lsb = 1'b0;
     
+    // aux - latch
+    reg       x_aux_latch_lsb = 1'b0;
+    reg       y_aux_latch_lsb = 1'b0;
+    
     // bitmap - latch
     reg [7:0] x_bitmap_latch_lsb = {8{1'b0}};
     reg [7:0] y_bitmap_latch_lsb = {8{1'b0}};
@@ -125,6 +133,7 @@ module modexpng_part_recombinator
     // 
     reg       xy_valid_lsb_adv[1:6];
     reg       xy_valid_msb_adv[1:6];
+    reg       xy_aux_lsb_adv[1:6];
     reg [7:0] xy_bitmap_lsb_adv[1:6];
     reg [7:0] xy_bitmap_msb_adv[1:6];
     reg [2:0] xy_index_lsb_adv[1:6];
@@ -132,11 +141,25 @@ module modexpng_part_recombinator
     reg       xy_purge_lsb_adv[1:6];
     reg       xy_purge_msb_adv[1:6];
     
-    
+    reg [1:0] rcmb_mode;
+       
+    always @(posedge clk)
+       //
+       if (ena_x && ena_y)
+           //
+           case (fsm_state_next)
+               FSM_STATE_MULT_SQUARE_COL_0_BUSY:       rcmb_mode <= 2'd1;
+               FSM_STATE_MULT_TRIANGLE_COL_0_BUSY:     rcmb_mode <= 2'd2;
+               //FSM_STATE_MULT_RECTANGLE_COL_0_BUSY:    rcmb_mode <= 2'd3;
+               default:                                rcmb_mode <= 2'd0;
+           endcase
+
+               
     integer i;
     initial for (i=1; i<6; i=i+1) begin
         xy_valid_lsb_adv[i] = 1'b0;
         xy_valid_msb_adv[i] = 1'b0;
+        xy_aux_lsb_adv[i] = 1'b0;
         xy_bitmap_lsb_adv[i] = {8{1'b0}};
         xy_bitmap_msb_adv[i] = {8{1'b0}};
         xy_index_lsb_adv[i] = 3'dX;
@@ -145,7 +168,7 @@ module modexpng_part_recombinator
         xy_purge_msb_adv[i] = 1'b0;
     end
     
-    function  [0:0] calc_square_valid_lsb;
+    function        calc_square_valid_lsb;
         input [4:0] col_index_value;
         input [4:0] col_index_last_value;
         input [7:0] slim_bram_xy_addr_value;
@@ -159,6 +182,40 @@ module modexpng_part_recombinator
         end
     endfunction
     
+    function        calc_triangle_valid_lsb;
+        input [4:0] col_index_value;
+        input [4:0] col_index_last_value;
+        input [7:0] slim_bram_xy_addr_value;
+        begin
+            //
+            if (slim_bram_xy_addr_value[7:3] == col_index_value)
+                calc_triangle_valid_lsb = 1'b1;
+            else
+                calc_triangle_valid_lsb = 1'b0;
+            //
+        end
+    endfunction
+
+    function        calc_triangle_aux_lsb;
+        input [4:0] col_index_value;
+        input [4:0] col_index_last_value;
+        input [7:0] slim_bram_xy_addr_value;
+        input [1:0] slim_bram_xy_bank_value;
+        begin
+            //
+            if (slim_bram_xy_bank_value == BANK_SLIM_N_COEFF_EXT)
+                calc_triangle_aux_lsb = 1'b1;
+            else
+                calc_triangle_aux_lsb = 1'b0;
+            //
+            //if (slim_bram_xy_addr_value[7:3] == col_index_value)
+                //calc_triangle_aux_lsb = 1'b1;
+            //else
+                //calc_triangle_aux_lsb = 1'b0;
+            //
+        end
+    endfunction
+    
     function  [7:0] calc_square_bitmap_lsb;
         input [4:0] col_index_value;
         input [4:0] col_index_last_value;
@@ -183,7 +240,32 @@ module modexpng_part_recombinator
             //
         end
     endfunction
-
+    
+    function  [7:0] calc_triangle_bitmap_lsb;
+           input [4:0] col_index_value;
+           input [4:0] col_index_last_value;
+           input [7:0] slim_bram_xy_addr_value;
+           begin
+               //
+               if (slim_bram_xy_addr_value[7:3] == col_index_value)
+                   //
+                   case (slim_bram_xy_addr_value[2:0])
+                       3'b000: calc_triangle_bitmap_lsb = 8'b00000001;
+                       3'b001: calc_triangle_bitmap_lsb = 8'b00000010;
+                       3'b010: calc_triangle_bitmap_lsb = 8'b00000100;
+                       3'b011: calc_triangle_bitmap_lsb = 8'b00001000;
+                       3'b100: calc_triangle_bitmap_lsb = 8'b00010000;
+                       3'b101: calc_triangle_bitmap_lsb = 8'b00100000;
+                       3'b110: calc_triangle_bitmap_lsb = 8'b01000000;
+                       3'b111: calc_triangle_bitmap_lsb = 8'b10000000;
+                   endcase
+                   //
+               else
+                   calc_triangle_bitmap_lsb = {8{1'b0}};
+               //
+           end
+       endfunction
+       
     function  [2:0] calc_square_index_lsb;
         input [4:0] col_index_value;
         input [4:0] col_index_last_value;
@@ -208,6 +290,31 @@ module modexpng_part_recombinator
             //
         end
     endfunction
+
+    function  [2:0] calc_triangle_index_lsb;
+        input [4:0] col_index_value;
+        input [4:0] col_index_last_value;
+        input [7:0] slim_bram_xy_addr_value;
+        begin
+            //
+            if (slim_bram_xy_addr_value[7:3] == col_index_value)
+                //
+                case (slim_bram_xy_addr_value[2:0])
+                    3'b000: calc_triangle_index_lsb = 3'd0;
+                    3'b001: calc_triangle_index_lsb = 3'd1;
+                    3'b010: calc_triangle_index_lsb = 3'd2;
+                    3'b011: calc_triangle_index_lsb = 3'd3;
+                    3'b100: calc_triangle_index_lsb = 3'd4;
+                    3'b101: calc_triangle_index_lsb = 3'd5;
+                    3'b110: calc_triangle_index_lsb = 3'd6;
+                    3'b111: calc_triangle_index_lsb = 3'd7;
+                endcase
+                //
+            else
+                calc_triangle_index_lsb = 3'dX;
+            //
+        end
+    endfunction
     
     function        calc_square_purge_lsb;
         input [4:0] col_index_value;
@@ -271,10 +378,10 @@ module modexpng_part_recombinator
 
     
     reg         recomb_lsb_ce = 1'b0;
+    reg         recomb_lsb_ce_aux;
     reg  [ 2:0] recomb_lsb_ce_purge = 3'b000;
-    wire        recomb_lsb_ce_combined = recomb_lsb_ce | recomb_lsb_ce_purge[0];
+    wire        recomb_lsb_ce_combined = recomb_lsb_ce | recomb_lsb_ce_aux | recomb_lsb_ce_purge[0];
     reg         recomb_lsb_clr;
-    reg         recomb_lsb_vld = 1'b0;
 
     reg  [46:0] recomb_lsb_din;
     wire [15:0] recomb_lsb_dout;
@@ -283,12 +390,7 @@ module modexpng_part_recombinator
     reg  [ 1:0] recomb_msb_ce_purge = 2'b00;
     wire        recomb_msb_ce_combined = recomb_msb_ce | recomb_msb_ce_purge[0];
     reg         recomb_msb_clr;
-    reg         recomb_msb_vld = 1'b0;
     
-    always @(posedge clk)
-        //
-        {recomb_msb_vld, recomb_lsb_vld} <= {recomb_msb_ce_combined, recomb_lsb_ce_combined};
-
     reg  [46:0] recomb_msb_din;
     wire [15:0] recomb_msb_dout;
     
@@ -313,6 +415,7 @@ module modexpng_part_recombinator
     always @(posedge clk) begin
         //
         recomb_lsb_ce <= x_valid_latch_lsb;
+        recomb_lsb_ce_aux <= x_aux_latch_lsb;
         recomb_msb_ce <= x_bitmap_latch_msb[0];
         //
         if (x_purge_latch_lsb)
@@ -342,6 +445,8 @@ module modexpng_part_recombinator
         //
         if (x_valid_latch_lsb)
             recomb_lsb_din <= dsp_x_p_latch[x_index_latch_lsb];
+        else if (x_aux_latch_lsb)
+            recomb_lsb_din <= dsp_x_p_latch[8];
         else
             recomb_lsb_din <= {47{1'b0}};
 
@@ -363,6 +468,7 @@ module modexpng_part_recombinator
             FSM_STATE_MULT_SQUARE_COL_N_BUSY: begin
                 //
                 xy_valid_lsb_adv [6] <= calc_square_valid_lsb (col_index, col_index_last, slim_bram_xy_addr);
+                xy_aux_lsb_adv   [6] <= 1'b0;
                 xy_bitmap_lsb_adv[6] <= calc_square_bitmap_lsb(col_index, col_index_last, slim_bram_xy_addr);
                 xy_index_lsb_adv [6] <= calc_square_index_lsb (col_index, col_index_last, slim_bram_xy_addr);
                 xy_purge_lsb_adv [6] <= calc_square_purge_lsb (col_index, col_index_last, slim_bram_xy_addr);
@@ -373,9 +479,27 @@ module modexpng_part_recombinator
                 //
             end
             //
+            FSM_STATE_MULT_TRIANGLE_COL_0_TRIG,
+            FSM_STATE_MULT_TRIANGLE_COL_N_TRIG,
+            FSM_STATE_MULT_TRIANGLE_COL_0_BUSY,
+            FSM_STATE_MULT_TRIANGLE_COL_N_BUSY: begin
+                //
+                xy_valid_lsb_adv [6] <= calc_triangle_valid_lsb (col_index, col_index_last, slim_bram_xy_addr); /// bank
+                xy_aux_lsb_adv   [6] <= calc_triangle_aux_lsb   (col_index, col_index_last, slim_bram_xy_addr, slim_bram_xy_bank);
+                xy_bitmap_lsb_adv[6] <= calc_triangle_bitmap_lsb(col_index, col_index_last, slim_bram_xy_addr); //! bank
+                xy_index_lsb_adv [6] <= calc_triangle_index_lsb (col_index, col_index_last, slim_bram_xy_addr); // ! bank!!!
+                xy_purge_lsb_adv [6] <= 1'b0;
+                //
+                xy_valid_msb_adv [6] <= 1'b0;
+                xy_bitmap_msb_adv[6] <= {8{1'b0}};
+                xy_purge_msb_adv [6] <= 1'b0;
+                //
+            end            
+            //
             default: begin
                 //
                 xy_valid_lsb_adv [6] <= 1'b0;
+                xy_aux_lsb_adv   [6] <= 1'b0;
                 xy_bitmap_lsb_adv[6] <= {8{1'b0}};
                 xy_index_lsb_adv [6] <= 3'dX;
                 xy_purge_lsb_adv [6] <= 1'b0;
@@ -392,11 +516,13 @@ module modexpng_part_recombinator
     always @(posedge clk) begin
         //
         {y_valid_lsb,  x_valid_lsb}  <= {2{xy_valid_lsb_adv [1]}};
+        {y_aux_lsb,    x_aux_lsb}    <= {2{xy_aux_lsb_adv   [1]}};
         {y_bitmap_lsb, x_bitmap_lsb} <= {2{xy_bitmap_lsb_adv[1]}};
         {y_index_lsb,  x_index_lsb}  <= {2{xy_index_lsb_adv [1]}};
         {y_purge_lsb,  x_purge_lsb}  <= {2{xy_purge_lsb_adv [1]}};
         //
         {y_valid_latch_lsb,  x_valid_latch_lsb}  <= {y_valid_lsb,  x_valid_lsb};
+        {y_aux_latch_lsb,    x_aux_latch_lsb}    <= {y_aux_lsb,    x_aux_lsb};
         {y_bitmap_latch_lsb, x_bitmap_latch_lsb} <= {y_bitmap_lsb, x_bitmap_lsb};
         {y_index_latch_lsb,  x_index_latch_lsb}  <= {y_index_lsb,  x_index_lsb};
         {y_purge_latch_lsb,  x_purge_latch_lsb}  <= {y_purge_lsb,  x_purge_lsb};
@@ -415,6 +541,7 @@ module modexpng_part_recombinator
         //
         for (i=1; i<6; i=i+1) begin
             xy_valid_lsb_adv [i] <= xy_valid_lsb_adv [i+1];
+            xy_aux_lsb_adv   [i] <= xy_aux_lsb_adv   [i+1];
             xy_bitmap_lsb_adv[i] <= xy_bitmap_lsb_adv[i+1];
             xy_index_lsb_adv [i] <= xy_index_lsb_adv [i+1];
             xy_purge_lsb_adv [i] <= xy_purge_lsb_adv [i+1];
@@ -436,7 +563,7 @@ module modexpng_part_recombinator
                 else
                     dsp_x_p_latch[i] <= {47{1'bX}};
             //
-        else if (dsp_x_ce_p_dly1)
+        else if (dsp_x_ce_p_dly1) begin
             //
             for (i=0; i<8; i=i+1)
                 //
@@ -444,6 +571,11 @@ module modexpng_part_recombinator
                     dsp_x_p_latch[i] <= dsp_x_p_split[i];
                 else if (x_valid_msb && x_bitmap_msb[i])
                     dsp_x_p_latch[i] <= dsp_x_p_split[i];
+            //
+            if (x_aux_lsb)
+                dsp_x_p_latch[8] <= dsp_x_p_split[8];
+            //
+        end
 
     reg recomb_x_lsb_dout_valid = 1'b0;
     reg recomb_x_msb_dout_valid = 1'b0;
@@ -493,12 +625,187 @@ module modexpng_part_recombinator
         else
             rdy_reg <= rdy_adv;
 
+            
+    task advance_recomb_msb_dout_delay;
+        input [15:0] dout;
+        input [ 7:0] cnt;
+        begin
+            recomb_msb_dout_delay_0 <= dout;
+            recomb_msb_dout_delay_1 <= recomb_msb_dout_delay_0;
+            recomb_msb_dout_delay_2 <= recomb_msb_dout_delay_1;
+            //
+            recomb_msb_cnt_delay_0 <= cnt;
+            recomb_msb_cnt_delay_1 <= recomb_msb_cnt_delay_0;
+            recomb_msb_cnt_delay_2 <= recomb_msb_cnt_delay_1;
+        end
+    endtask
+         
+    task shift_recomb_msb_dout_carry;
+        input [15:0] dout;
+        begin
+            recomb_msb_dout_carry_0 <= dout;
+            recomb_msb_dout_carry_1 <= recomb_msb_dout_carry_0;
+        end
+    endtask
+    
+    task _update_fat_bram_regs;
+        input [ 2:0] bank;
+        input [ 7:0] addr;
+        input [17:0] dout_x;
+        input [17:0] dout_y;
+        input        valid;
+        begin
+            fat_bram_xy_bank_reg       <= bank;
+            fat_bram_xy_addr_reg       <= addr;
+            fat_bram_x_dout_reg        <= dout_x;
+            fat_bram_y_dout_reg        <= dout_y;
+            fat_bram_xy_dout_valid_reg <= 1'b1;
+        end
+    endtask
+    
+            
+    task set_fat_bram_regs;
+        input [ 2:0] bank;
+        input [ 7:0] addr;
+        input [17:0] dout_x;
+        input [17:0] dout_y;
+        begin
+            _update_fat_bram_regs(bank, addr, dout_x, dout_y, 1'b1);
+        end
+    endtask
+    
+    task clear_fat_bram_regs;
+        begin
+            _update_fat_bram_regs(3'bXXX, 8'hXX, {18{1'bX}}, {18{1'bX}}, 1'b0);
+        end
+    endtask
+    
+    task _set_fat_bram_cnt_lsb;
+        input [7:0] cnt;
+        begin
+            fat_bram_xy_cnt_lsb <= cnt;
+        end
+    endtask
+    task _set_fat_bram_cnt_msb;
+        input [7:0] cnt;
+        begin
+            fat_bram_xy_cnt_msb <= cnt;
+        end
+    endtask    
+
+    task inc_fat_bram_cnt_lsb;
+        begin
+            _set_fat_bram_cnt_lsb(fat_bram_xy_cnt_lsb + 1'b1);
+        end
+    endtask
+    task inc_fat_bram_cnt_msb;
+        begin
+            _set_fat_bram_cnt_msb(fat_bram_xy_cnt_msb + 1'b1);
+        end
+    endtask
+    
+    task clr_fat_bram_cnt_lsb;
+        begin
+            _set_fat_bram_cnt_lsb(8'd0);
+        end
+    endtask
+    task clr_fat_bram_cnt_msb;
+        begin
+            _set_fat_bram_cnt_msb(8'd0);
+        end
+    endtask
+    
+    
+   
+    
+
+    wire [1:0] rcmb_xy_dout_valid = {recomb_x_msb_dout_valid, recomb_x_lsb_dout_valid}; 
+    
+    always @(posedge clk)
+        //
+        if (ena_x & ena_y) begin
+            clr_fat_bram_cnt_lsb();
+            clr_fat_bram_cnt_msb();
+        end else begin  // if not ready???
+            //
+            case (rcmb_mode)
+                2'd1: recombine_square();
+                2'd2: recombine_triangle();
+            endcase
+            //
+        end
+           
+    task recombine_square;
+        begin
+            //
+            case (rcmb_xy_dout_valid)
+                //
+                2'b01: inc_fat_bram_cnt_lsb(); 
+                2'b10: inc_fat_bram_cnt_msb();
+                2'b11: begin
+                    if (fat_bram_xy_cnt_lsb == index_last) clr_fat_bram_cnt_lsb();
+                    else                                   inc_fat_bram_cnt_lsb();
+                    inc_fat_bram_cnt_msb();
+                end
+                //
+            endcase            
+            //
+            case (rcmb_xy_dout_valid)
+                //
+                2'b00:  if (recomb_msb_cnt_delay_2 > 8'd0)      set_fat_bram_regs(BANK_FAT_ABH, recomb_msb_cnt_delay_2, {2'b00, recomb_msb_dout_delay_2}, {18{1'bX}});
+                        else                                    clear_fat_bram_regs();
+                2'b01:                                          set_fat_bram_regs(BANK_FAT_ABL,        fat_bram_xy_cnt_lsb, {2'b00, recomb_lsb_dout}, {18{1'bX}}); 
+                2'b10:  if (fat_bram_xy_cnt_msb < 8'd2)         clear_fat_bram_regs();                        
+                        else                                    set_fat_bram_regs(BANK_FAT_ABH, fat_bram_xy_cnt_msb, {2'b00, recomb_msb_dout}, {18{1'bX}});                        
+                2'b11:  if (fat_bram_xy_cnt_lsb < index_last)   set_fat_bram_regs(BANK_FAT_ABH, fat_bram_xy_cnt_lsb, {1'b0, {1'b0, recomb_lsb_dout} + {1'b0, recomb_msb_dout_carry_1}}, {18{1'bX}}); 
+                        else                                    set_fat_bram_regs(BANK_FAT_ABL, fat_bram_xy_cnt_lsb, {2'b00, recomb_lsb_dout}, {18{1'bX}});
+                //
+            endcase            
+            //
+            case (rcmb_xy_dout_valid)
+                //
+                2'b00:  if (recomb_msb_cnt_delay_2 > 8'd0)      advance_recomb_msb_dout_delay(16'hXXXX, 8'd0);
+                2'b10:  if (fat_bram_xy_cnt_msb < 8'd2)         shift_recomb_msb_dout_carry(recomb_msb_dout);
+                //
+                2'b11:  begin                                   advance_recomb_msb_dout_delay(recomb_msb_dout, fat_bram_xy_cnt_msb);
+                        if (fat_bram_xy_cnt_lsb < index_last)   shift_recomb_msb_dout_carry({16{1'bX}});
+                        end
+                //
+            endcase
+            //        
+        end
+        //
+    endtask
+    
+    
+    task recombine_triangle;
+        begin
+            //
+            case (rcmb_xy_dout_valid)
+                //
+                2'b01: begin                                  inc_fat_bram_cnt_lsb();
+                       if (fat_bram_xy_cnt_lsb == index_last) inc_fat_bram_cnt_msb();
+                end 
+                //
+            endcase            
+            //
+            case (rcmb_xy_dout_valid)
+                //
+                2'b00:  clear_fat_bram_regs();
+                2'b01:  if (fat_bram_xy_cnt_msb == 8'd0) set_fat_bram_regs(BANK_FAT_Q,     fat_bram_xy_cnt_lsb, {2'b00, recomb_lsb_dout}, {18{1'bX}}); 
+                        else                             set_fat_bram_regs(BANK_FAT_Q_EXT, fat_bram_xy_cnt_lsb, {2'b00, recomb_lsb_dout}, {18{1'bX}});
+                //
+            endcase
+            //        
+        end
+    endtask
+
+    
+    
     always @(posedge clk)
         //
         if (ena_x & ena_y) begin
             rdy_adv <= 1'b0;
-            fat_bram_xy_cnt_lsb <= 8'd0;
-            fat_bram_xy_cnt_msb <= 8'd0;
         end else begin
             //
             case ({recomb_x_msb_dout_valid, recomb_x_lsb_dout_valid})
@@ -509,115 +816,13 @@ module modexpng_part_recombinator
                         //
                         rdy_adv <= recomb_msb_cnt_delay_1 == 8'd0;
                         //
-                        recomb_msb_dout_delay_0 <= {18{1'bX}};
-                        recomb_msb_dout_delay_1 <= recomb_msb_dout_delay_0;
-                        recomb_msb_dout_delay_2 <= recomb_msb_dout_delay_1;
-                        //
-                        recomb_msb_cnt_delay_0 <= 8'd0;
-                        recomb_msb_cnt_delay_1 <= recomb_msb_cnt_delay_0;
-                        recomb_msb_cnt_delay_2 <= recomb_msb_cnt_delay_1;
-                        //
-                        fat_bram_xy_bank_reg        <= BANK_FAT_ABH;
-                        fat_bram_xy_addr_reg        <= recomb_msb_cnt_delay_2;
-                        fat_bram_x_dout_reg         <= recomb_msb_dout_delay_2;
-//                      fat_bram_y_dout_reg         <= {18{1'bX}};
-                        fat_bram_xy_dout_valid_reg  <= 1'b1;
-                        //
-                    end else begin
-                        //
-                        fat_bram_xy_bank_reg        <= 3'bXXX;
-                        fat_bram_xy_addr_reg        <= 8'hXX;
-                        fat_bram_x_dout_reg         <= {18{1'bX}};
-                        fat_bram_y_dout_reg         <= {18{1'bX}};
-                        fat_bram_xy_dout_valid_reg  <= 1'b0;
-                        //
-                    end
-                    //
-                end
-                //
-                2'b01: begin
-                    //
-                    fat_bram_xy_bank_reg        <= BANK_FAT_ABL;
-                    fat_bram_xy_addr_reg        <= fat_bram_xy_cnt_lsb;
-                    fat_bram_x_dout_reg         <= {2'b00, recomb_lsb_dout};
-//                  fat_bram_y_dout_reg
-                    fat_bram_xy_dout_valid_reg  <= 1'b1;
-                    //
-                    fat_bram_xy_cnt_lsb         <= fat_bram_xy_cnt_lsb + 1'b1; 
-                    //
-                end
-                //
-                2'b10: begin
-                    //
-                    if (fat_bram_xy_cnt_msb < 8'd2) begin
-                        //
-                        recomb_msb_dout_carry_0 <= recomb_msb_dout;
-                        recomb_msb_dout_carry_1 <= recomb_msb_dout_carry_0;
-                        //
-                        fat_bram_xy_bank_reg        <= 3'bXXX;
-                        fat_bram_xy_addr_reg        <= 8'hXX;
-                        fat_bram_x_dout_reg         <= {18{1'bX}};
-    //                  fat_bram_y_dout_reg
-                        fat_bram_xy_dout_valid_reg  <= 1'b0;
-                        //                        
-                    end else begin
-                        //
-                        fat_bram_xy_bank_reg        <= BANK_FAT_ABH;
-                        fat_bram_xy_addr_reg        <= fat_bram_xy_cnt_msb;
-                        fat_bram_x_dout_reg         <= {2'b00, recomb_msb_dout};
-    //                  fat_bram_y_dout_reg
-                        fat_bram_xy_dout_valid_reg  <= 1'b1;                        
-                        //
-                    end
-                    //
-                    fat_bram_xy_cnt_msb         <= fat_bram_xy_cnt_msb + 1'b1;
-                    //                
-                end
-                //
-                2'b11: begin
-                    //
-                    if (fat_bram_xy_cnt_lsb == index_last) begin
-                        //
-                        fat_bram_xy_bank_reg        <= BANK_FAT_ABL;
-                        fat_bram_xy_addr_reg        <= fat_bram_xy_cnt_lsb;
-                        fat_bram_x_dout_reg         <= {2'b00, recomb_lsb_dout};
-//                      fat_bram_y_dout_reg         <= {18{1'bX}};
-                        fat_bram_xy_dout_valid_reg  <= 1'b1;
-                        //
-                        fat_bram_xy_cnt_lsb         <= 8'd0;
-                        //
-                    end else begin
-                        //
-                        fat_bram_xy_bank_reg        <= BANK_FAT_ABH;
-                        fat_bram_xy_addr_reg        <= fat_bram_xy_cnt_lsb;
-                        fat_bram_x_dout_reg         <= {1'b0, {1'b0, recomb_lsb_dout} + {1'b0, recomb_msb_dout_carry_1}};
-//                      fat_bram_y_dout_reg         <= {18{1'bX}};
-                        fat_bram_xy_dout_valid_reg  <= 1'b1;
-                        //
-                        fat_bram_xy_cnt_lsb         <= fat_bram_xy_cnt_lsb + 1'b1;
-                        //
-                        recomb_msb_dout_carry_0 <= {16{1'bX}};
-                        recomb_msb_dout_carry_1 <= recomb_msb_dout_carry_0;                        
-                        //
                     end
                     //
-                    recomb_msb_dout_delay_0 <= recomb_msb_dout;
-                    recomb_msb_dout_delay_1 <= recomb_msb_dout_delay_0;
-                    recomb_msb_dout_delay_2 <= recomb_msb_dout_delay_1;
-                    //
-                    recomb_msb_cnt_delay_0 <= fat_bram_xy_cnt_msb;
-                    recomb_msb_cnt_delay_1 <= recomb_msb_cnt_delay_0;
-                    recomb_msb_cnt_delay_2 <= recomb_msb_cnt_delay_1;
-                    //
-                    fat_bram_xy_cnt_msb         <= fat_bram_xy_cnt_msb + 1'b1;
-                    //
                 end
-                //
             endcase
             //        
         end
-    
-    
-    
+
+
     
 endmodule
-- 
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