CRT mode seems to work. Finally.

Strangely enough non-CRT mode continues to work fine(!). One does not simply
add a feature without breaking something else. Very suspicious...

4 files changed, 132 insertions, 64 deletions

diff --git a/src/rtl/modexpa7_exponentiator.v b/src/rtl/modexpa7_exponentiator.v
index 93c8047..c50a881 100644
--- a/src/rtl/modexpa7_exponentiator.v
+++ b/src/rtl/modexpa7_exponentiator.v
@@ -456,109 +456,134 @@ module modexpa7_exponentiator #
 		// d_addr

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_CALC_1:	d_addr <= bit_cnt[OPERAND_ADDR_WIDTH+4:5];

+			FSM_STATE_EXP_CALC_1:		d_addr <= bit_cnt[OPERAND_ADDR_WIDTH+4:5];

 		endcase

 		//

 		// f_addr

 		//

 		case (fsm_next_state)

-			FSM_STATE_MUL_INIT_1: 	f_addr <= bram_addr_zero;

+			FSM_STATE_MUL_INIT_1: 		f_addr <= bram_addr_zero;

 			FSM_STATE_MUL_INIT_2,

 			FSM_STATE_MUL_INIT_3,

-			FSM_STATE_MUL_INIT_4:	f_addr <= !f_addr_done ? f_addr_next : f_addr;

+			FSM_STATE_MUL_INIT_4:		f_addr <= !f_addr_done ? f_addr_next : f_addr;

+			//

+			FSM_STATE_CRT_INIT_B_1: 	f_addr <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_B_2,

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4:		f_addr <= !f_addr_done ? f_addr_next : f_addr;

+			//

 		endcase

 		//

 		// r_addr

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_SAVE_3:	r_addr <= bram_addr_zero;

-			FSM_STATE_EXP_SAVE_4:	r_addr <= r_addr_next;

+			FSM_STATE_EXP_SAVE_3:		r_addr <= bram_addr_zero;

+			FSM_STATE_EXP_SAVE_4:		r_addr <= r_addr_next;

 		endcase

 		//

 		// p_addr_wr

 		//

 		case (fsm_next_state)

 			//

-			FSM_STATE_MUL_INIT_3:	p_addr_wr <= bram_addr_zero;

-			FSM_STATE_MUL_INIT_4:	p_addr_wr <= p_addr_wr_next;

+			FSM_STATE_MUL_INIT_3:		p_addr_wr <= bram_addr_zero;

+			FSM_STATE_MUL_INIT_4:		p_addr_wr <= p_addr_wr_next;

+			//

+			FSM_STATE_CRT_INIT_B_3:		p_addr_wr <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_B_4:		p_addr_wr <= p_addr_wr_next;

 			//

-			FSM_STATE_EXP_INIT_3:	p_addr_wr <= bram_addr_zero;

-			FSM_STATE_EXP_INIT_4:	p_addr_wr <= p_addr_wr_next;

+			FSM_STATE_EXP_INIT_3:		p_addr_wr <= bram_addr_zero;

+			FSM_STATE_EXP_INIT_4:		p_addr_wr <= p_addr_wr_next;

 			//

-			FSM_STATE_EXP_FILL_3:	p_addr_wr <= bram_addr_zero;

-			FSM_STATE_EXP_FILL_4:	p_addr_wr <= p_addr_wr_next;

+			FSM_STATE_EXP_FILL_3:		p_addr_wr <= bram_addr_zero;

+			FSM_STATE_EXP_FILL_4:		p_addr_wr <= p_addr_wr_next;

 		endcase

 		//

 		// t0_addr

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_LOAD_3:	t0_addr <= bram_addr_zero;

-			FSM_STATE_EXP_LOAD_4:	t0_addr <= t0_addr_next;

+			FSM_STATE_EXP_LOAD_3:		t0_addr <= bram_addr_zero;

+			FSM_STATE_EXP_LOAD_4:		t0_addr <= t0_addr_next;

 			//

-			FSM_STATE_EXP_FILL_1:	t0_addr <= bram_addr_zero;

+			FSM_STATE_EXP_FILL_1:		t0_addr <= bram_addr_zero;

 			FSM_STATE_EXP_FILL_2,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	t0_addr <= !t0_addr_done ? t0_addr_next : t0_addr;

+			FSM_STATE_EXP_FILL_4:		t0_addr <= !t0_addr_done ? t0_addr_next : t0_addr;

 		endcase		

 		//

 		// t1_addr

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_INIT_3:	t1_addr <= bram_addr_zero;

-			FSM_STATE_EXP_INIT_4:	t1_addr <= t1_addr_next;

+			FSM_STATE_EXP_INIT_3:		t1_addr <= bram_addr_zero;

+			FSM_STATE_EXP_INIT_4:		t1_addr <= t1_addr_next;

 			//

-			FSM_STATE_EXP_LOAD_1:	t1_addr <= bram_addr_zero;

+			FSM_STATE_EXP_LOAD_1:		t1_addr <= bram_addr_zero;

 			FSM_STATE_EXP_LOAD_2,

 			FSM_STATE_EXP_LOAD_3,

-			FSM_STATE_EXP_LOAD_4:	t1_addr <= !t1_addr_done ? t1_addr_next : t1_addr;

+			FSM_STATE_EXP_LOAD_4:		t1_addr <= !t1_addr_done ? t1_addr_next : t1_addr;

 			//

-			FSM_STATE_EXP_FILL_3:	t1_addr <= bram_addr_zero;

-			FSM_STATE_EXP_FILL_4:	t1_addr <= t1_addr_next;

+			FSM_STATE_EXP_FILL_3:		t1_addr <= bram_addr_zero;

+			FSM_STATE_EXP_FILL_4:		t1_addr <= t1_addr_next;

 			//

-			FSM_STATE_EXP_SAVE_1:	t1_addr <= bram_addr_zero;

+			FSM_STATE_EXP_SAVE_1:		t1_addr <= bram_addr_zero;

 			FSM_STATE_EXP_SAVE_2,

 			FSM_STATE_EXP_SAVE_3,

-			FSM_STATE_EXP_SAVE_4:	t1_addr <= !t1_addr_done ? t1_addr_next : t1_addr;

+			FSM_STATE_EXP_SAVE_4:		t1_addr <= !t1_addr_done ? t1_addr_next : t1_addr;

 		endcase

 		//

 		// t2_addr_wr

 		//

 		case (fsm_next_state)

 			//

-			FSM_STATE_MUL_INIT_3:	t2_addr_wr <= bram_addr_zero;

-			FSM_STATE_MUL_INIT_4:	t2_addr_wr <= t2_addr_wr_next;

+			FSM_STATE_MUL_INIT_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_MUL_INIT_4:		t2_addr_wr <= t2_addr_wr_next;

 			//

-			FSM_STATE_CRT_INIT_A_3:	t2_addr_wr <= bram_addr_zero;

-			FSM_STATE_CRT_INIT_A_4:	t2_addr_wr <= t2_addr_wr_next;

+			FSM_STATE_CRT_INIT_A_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_A_4:		t2_addr_wr <= t2_addr_wr_next;

 			//

-			FSM_STATE_EXP_INIT_3:	t2_addr_wr <= bram_addr_zero;

-			FSM_STATE_EXP_INIT_4:	t2_addr_wr <= t2_addr_wr_next;

+			FSM_STATE_CRT_INIT_B_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_B_4:		t2_addr_wr <= t2_addr_wr_next;

 			//

-			FSM_STATE_EXP_FILL_3:	t2_addr_wr <= bram_addr_zero;

-			FSM_STATE_EXP_FILL_4:	t2_addr_wr <= t2_addr_wr_next;

+			FSM_STATE_CRT_INIT_C_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_C_4:		t2_addr_wr <= t2_addr_wr_next;

+			//

+			FSM_STATE_EXP_INIT_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_EXP_INIT_4:		t2_addr_wr <= t2_addr_wr_next;

+			//

+			FSM_STATE_EXP_FILL_3:		t2_addr_wr <= bram_addr_zero;

+			FSM_STATE_EXP_FILL_4:		t2_addr_wr <= t2_addr_wr_next;

 		endcase		

 		//

 		// pp_addr_rd

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_FILL_1:	pp_addr_rd <= bram_addr_zero;

+			FSM_STATE_EXP_FILL_1:		pp_addr_rd <= bram_addr_zero;

 			FSM_STATE_EXP_FILL_2,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	pp_addr_rd <= !pp_addr_rd_done ? pp_addr_rd_next : pp_addr_rd;

+			FSM_STATE_EXP_FILL_4:		pp_addr_rd <= !pp_addr_rd_done ? pp_addr_rd_next : pp_addr_rd;

 		endcase

 		//

 		// tp_addr_rd

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_INIT_1: 	tp_addr_rd <= bram_addr_zero;

+			FSM_STATE_EXP_INIT_1: 		tp_addr_rd <= bram_addr_zero;

 			FSM_STATE_EXP_INIT_2,

 			FSM_STATE_EXP_INIT_3,

-			FSM_STATE_EXP_INIT_4:	tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

+			FSM_STATE_EXP_INIT_4:		tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

+			//

+			FSM_STATE_CRT_INIT_B_1: 	tp_addr_rd <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_B_2,

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4:		tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

 			//

-			FSM_STATE_EXP_FILL_1:	tp_addr_rd <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_C_1: 	tp_addr_rd <= bram_addr_zero;

+			FSM_STATE_CRT_INIT_C_2,

+			FSM_STATE_CRT_INIT_C_3,

+			FSM_STATE_CRT_INIT_C_4:		tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

+			//

+			FSM_STATE_EXP_FILL_1:		tp_addr_rd <= bram_addr_zero;

 			FSM_STATE_EXP_FILL_2,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

+			FSM_STATE_EXP_FILL_4:		tp_addr_rd <= !tp_addr_rd_done ? tp_addr_rd_next : tp_addr_rd;

 		endcase

 		//

 	end

@@ -573,8 +598,8 @@ module modexpa7_exponentiator #
 		//

 		case (fsm_next_state)

 			FSM_STATE_EXP_SAVE_3,

-			FSM_STATE_EXP_SAVE_4:	r_wren <= 1'b1;

-			default:						r_wren <= 1'b0;

+			FSM_STATE_EXP_SAVE_4:		r_wren <= 1'b1;

+			default:							r_wren <= 1'b0;

 		endcase

 		//

 		// p_wren

@@ -582,19 +607,21 @@ module modexpa7_exponentiator #
 		case (fsm_next_state)

 			FSM_STATE_MUL_INIT_3,

 			FSM_STATE_MUL_INIT_4,

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4,

 			FSM_STATE_EXP_INIT_3,

 			FSM_STATE_EXP_INIT_4,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	p_wren <= 1'b1;

-			default:						p_wren <= 1'b0;

+			FSM_STATE_EXP_FILL_4:		p_wren <= 1'b1;

+			default:							p_wren <= 1'b0;

 		endcase

 		//

 		// t0_wren

 		//

 		case (fsm_next_state)

 			FSM_STATE_EXP_LOAD_3,		

-			FSM_STATE_EXP_LOAD_4:	t0_wren <= 1'b1;

-			default:						t0_wren <= 1'b0;

+			FSM_STATE_EXP_LOAD_4:		t0_wren <= 1'b1;

+			default:							t0_wren <= 1'b0;

 		endcase

 		//

 		// t1_wren

@@ -603,8 +630,8 @@ module modexpa7_exponentiator #
 			FSM_STATE_EXP_INIT_3,		

 			FSM_STATE_EXP_INIT_4,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	t1_wren <= 1'b1;

-			default:						t1_wren <= 1'b0;

+			FSM_STATE_EXP_FILL_4:		t1_wren <= 1'b1;

+			default:							t1_wren <= 1'b0;

 		endcase

 		//

 		// t2_wren

@@ -614,11 +641,15 @@ module modexpa7_exponentiator #
 			FSM_STATE_MUL_INIT_4,

 			FSM_STATE_CRT_INIT_A_3,

 			FSM_STATE_CRT_INIT_A_4,

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4,

+			FSM_STATE_CRT_INIT_C_3,

+			FSM_STATE_CRT_INIT_C_4,

 			FSM_STATE_EXP_INIT_3,		

 			FSM_STATE_EXP_INIT_4,

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	t2_wren <= 1'b1;

-			default:						t2_wren <= 1'b0;

+			FSM_STATE_EXP_FILL_4:		t2_wren <= 1'b1;

+			default:							t2_wren <= 1'b0;

 		endcase

 		//

 	end

@@ -633,8 +664,8 @@ module modexpa7_exponentiator #
 		//

 		case (fsm_next_state)

 			FSM_STATE_EXP_SAVE_3,

-			FSM_STATE_EXP_SAVE_4:	r_data_in	<= t1_data_out;

-			default:						r_data_in	<= 32'dX;

+			FSM_STATE_EXP_SAVE_4:		r_data_in	<= t1_data_out;

+			default:							r_data_in	<= 32'dX;

 		endcase		

 		//

 		// p_data_in

@@ -642,34 +673,37 @@ module modexpa7_exponentiator #
 		case (fsm_next_state)

 			//

 			FSM_STATE_MUL_INIT_3,

-			FSM_STATE_MUL_INIT_4:	p_data_in	<= f_bram_out;

+			FSM_STATE_MUL_INIT_4:		p_data_in	<= f_bram_out;

+			//

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4:		p_data_in	<= f_bram_out;

 			//

 			FSM_STATE_EXP_INIT_3,

-			FSM_STATE_EXP_INIT_4:	p_data_in	<= tp_data_out;

+			FSM_STATE_EXP_INIT_4:		p_data_in	<= tp_data_out;

 			//

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	p_data_in	<= pp_data_out;

+			FSM_STATE_EXP_FILL_4:		p_data_in	<= pp_data_out;

 			//

-			default:						p_data_in	<= 32'dX;

+			default:							p_data_in	<= 32'dX;

 		endcase

 		//

 		// t0_data_in

 		//

 		case (fsm_next_state)

 			FSM_STATE_EXP_LOAD_3,

-			FSM_STATE_EXP_LOAD_4:	t0_data_in <= t1_data_out;

-			default:						t0_data_in <= 32'dX;

+			FSM_STATE_EXP_LOAD_4:		t0_data_in <= t1_data_out;

+			default:							t0_data_in <= 32'dX;

 		endcase		

 		//

 		// t1_data_in

 		//

 		case (fsm_next_state)

-			FSM_STATE_EXP_INIT_3:	t1_data_in <= 32'd1;

-			FSM_STATE_EXP_INIT_4:	t1_data_in <= 32'd0;

+			FSM_STATE_EXP_INIT_3:		t1_data_in <= 32'd1;

+			FSM_STATE_EXP_INIT_4:		t1_data_in <= 32'd0;

 			//

 			FSM_STATE_EXP_FILL_3,

-			FSM_STATE_EXP_FILL_4:	t1_data_in <= flag_update_r ? tp_data_out : t0_data_out;

-			default:						t1_data_in <= 32'dX;

+			FSM_STATE_EXP_FILL_4:		t1_data_in <= flag_update_r ? tp_data_out : t0_data_out;

+			default:							t1_data_in <= 32'dX;

 		endcase		

 		//

 		// t2_data_in

@@ -681,7 +715,12 @@ module modexpa7_exponentiator #
 			//

 			FSM_STATE_CRT_INIT_A_3,

 			FSM_STATE_CRT_INIT_A_4:		t2_data_in <= m_bram_out;

-

+			//

+			FSM_STATE_CRT_INIT_B_3,

+			FSM_STATE_CRT_INIT_B_4:		t2_data_in <= tp_data_out;

+			//

+			FSM_STATE_CRT_INIT_C_3,

+			FSM_STATE_CRT_INIT_C_4:		t2_data_in <= tp_data_out;

 			//

 			FSM_STATE_EXP_INIT_3:		t2_data_in <= 32'd1;

 			FSM_STATE_EXP_INIT_4:		t2_data_in <= 32'd0;

@@ -828,7 +867,29 @@ module modexpa7_exponentiator #
 			FSM_STATE_CRT_CALC_A_1:										fsm_next_state = FSM_STATE_CRT_CALC_A_2;

 			FSM_STATE_CRT_CALC_A_2:	if (mul_rdy_tp)				fsm_next_state = FSM_STATE_CRT_CALC_A_3;

 											else								fsm_next_state = FSM_STATE_CRT_CALC_A_2;

-			FSM_STATE_CRT_CALC_A_3:										fsm_next_state = FSM_STATE_EXP_INIT_1;

+			FSM_STATE_CRT_CALC_A_3:										fsm_next_state = FSM_STATE_CRT_INIT_B_1;

+			//

+			FSM_STATE_CRT_INIT_B_1:										fsm_next_state = FSM_STATE_CRT_INIT_B_2;

+			FSM_STATE_CRT_INIT_B_2:										fsm_next_state = FSM_STATE_CRT_INIT_B_3;

+			FSM_STATE_CRT_INIT_B_3:										fsm_next_state = FSM_STATE_CRT_INIT_B_4;

+			FSM_STATE_CRT_INIT_B_4:	if (t2_addr_wr_done)			fsm_next_state = FSM_STATE_CRT_CALC_B_1;

+											else								fsm_next_state = FSM_STATE_CRT_INIT_B_4;

+			//

+			FSM_STATE_CRT_CALC_B_1:										fsm_next_state = FSM_STATE_CRT_CALC_B_2;

+			FSM_STATE_CRT_CALC_B_2:	if (mul_rdy_tp)				fsm_next_state = FSM_STATE_CRT_CALC_B_3;

+											else								fsm_next_state = FSM_STATE_CRT_CALC_B_2;

+			FSM_STATE_CRT_CALC_B_3:										fsm_next_state = FSM_STATE_CRT_INIT_C_1;

+			//

+			FSM_STATE_CRT_INIT_C_1:										fsm_next_state = FSM_STATE_CRT_INIT_C_2;

+			FSM_STATE_CRT_INIT_C_2:										fsm_next_state = FSM_STATE_CRT_INIT_C_3;

+			FSM_STATE_CRT_INIT_C_3:										fsm_next_state = FSM_STATE_CRT_INIT_C_4;

+			FSM_STATE_CRT_INIT_C_4:	if (t2_addr_wr_done)			fsm_next_state = FSM_STATE_CRT_CALC_C_1;

+											else								fsm_next_state = FSM_STATE_CRT_INIT_C_4;

+			//

+			FSM_STATE_CRT_CALC_C_1:										fsm_next_state = FSM_STATE_CRT_CALC_C_2;

+			FSM_STATE_CRT_CALC_C_2:	if (mul_rdy_tp)				fsm_next_state = FSM_STATE_CRT_CALC_C_3;

+											else								fsm_next_state = FSM_STATE_CRT_CALC_C_2;

+			FSM_STATE_CRT_CALC_C_3:										fsm_next_state = FSM_STATE_EXP_INIT_1;

 			//

 			//

 			FSM_STATE_EXP_IDLE:		if (ena_trig)					fsm_next_state = crt ?

diff --git a/src/rtl/modexpa7_systolic_multiplier_array.v b/src/rtl/modexpa7_systolic_multiplier_array.v
index 3280010..9b2cd94 100644
--- a/src/rtl/modexpa7_systolic_multiplier_array.v
+++ b/src/rtl/modexpa7_systolic_multiplier_array.v
@@ -443,7 +443,7 @@ module modexpa7_systolic_multiplier_array #
 	always @(posedge clk)
 		//
 		if ((fsm_state == FSM_STATE_MULT_CRUNCH) && shreg_done_latency_dly)
-			p_data_in <= pe_p[0];
+			p_data_in <= crt ? pe_a_wide[31:0] : pe_p[0];
 

 		/*

 		 * Block Memory Address Control

@@ -457,7 +457,8 @@ module modexpa7_systolic_multiplier_array #
 		//

 		case (fsm_next_state)
 			FSM_STATE_MULT_START:	a_addr <= bram_addr_zero;
-			FSM_STATE_MULT_RELOAD:	crt ? //a_addr <= !a_addr_done ? a_addr_next : a_addr;
+			FSM_STATE_MULT_RELOAD:	if (crt)		a_addr <= !a_addr_done_crt ? a_addr_next : a_addr;

+											else			a_addr <= !a_addr_done     ? a_addr_next : a_addr;
 		endcase
 		//
 	end
diff --git a/src/rtl/modexpa7_top.v b/src/rtl/modexpa7_top.v
index 0c4eabe..ad101dd 100644
--- a/src/rtl/modexpa7_top.v
+++ b/src/rtl/modexpa7_top.v
@@ -35,7 +35,7 @@
 module modexpa7_top #
 	(
 		parameter OPERAND_ADDR_WIDTH		= 7,
-		parameter SYSTOLIC_ARRAY_POWER	= 4
+		parameter SYSTOLIC_ARRAY_POWER	= 1
 	)
 	(
 		input											clk,
@@ -47,6 +47,8 @@ module modexpa7_top #
 		input											next,
 		output										valid,
 
+		input											crt_mode,
+
 		input		[OPERAND_ADDR_WIDTH-1:0]	modulus_num_words,
 		input		[OPERAND_ADDR_WIDTH+4:0]	exponent_num_bits,
 
@@ -370,6 +372,8 @@ module modexpa7_top #
 		.ena						(exponent_ena),
 		.rdy						(exponent_rdy),
 		
+		.crt						(crt_mode),
+		
 		.m_bram_addr			(core_m_addr),
 		.d_bram_addr			(core_d_addr),
 		.f_bram_addr			(core_f_addr_rd),
diff --git a/src/rtl/modexpa7_wrapper.v b/src/rtl/modexpa7_wrapper.v
index 090ea8d..a4e2319 100644
--- a/src/rtl/modexpa7_wrapper.v
+++ b/src/rtl/modexpa7_wrapper.v
@@ -135,6 +135,8 @@ module modexpa7_wrapper #
 		
 		.next						(reg_control[CONTROL_NEXT_BIT]),
 		.valid					(reg_status[STATUS_VALID_BIT]),
+

+		.crt_mode				(reg_mode[MODE_CRT_BIT]),

 
 		.modulus_num_words	(modulus_num_words_core),
 		.exponent_num_bits	(exponent_num_bits_core),