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Using "via_celltype" in $mul carry-save-acc implementation

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Clifford Wolf 2014-08-18 14:30:20 +02:00
parent 640d9fc551
commit a92a68ce52
1 changed files with 72 additions and 34 deletions
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106
techlibs/common/techmap.v
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@ -465,62 +465,98 @@ endmodule
// Multiply
// --------------------------------------------------------
module \$__arraymul (A, B, Y);
parameter WIDTH = 8;
module \$__acc_set (acc_new, value);
parameter WIDTH = 1;
output reg [2*WIDTH-1:0] acc_new;
input [WIDTH-1:0] value;
wire [1023:0] _TECHMAP_DO_ = "proc;;;";
integer k;
always @* begin
for (k = 0; k < WIDTH; k = k+1) begin
acc_new[2*k +: 2] = value[k];
end
end
endmodule
module \$__acc_add (acc_new, acc_old, value);
parameter WIDTH = 1;
output reg [2*WIDTH-1:0] acc_new;
input [2*WIDTH-1:0] acc_old;
input [WIDTH-1:0] value;
wire [1023:0] _TECHMAP_DO_ = "proc; simplemap; opt -purge";
integer k;
reg a, b, c;
always @* begin
for (k = 0; k < WIDTH; k = k+1) begin
a = acc_old[2*k];
b = k ? acc_old[2*k-1] : 1'b0;
c = value[k];
acc_new[2*k] = (a ^ b) ^ c;
acc_new[2*k+1] = (a & b) | ((a ^ b) & c);
end
end
endmodule
module \$__acc_get (value, acc);
parameter WIDTH = 1;
output reg [WIDTH-1:0] value;
input [2*WIDTH-1:0] acc;
wire [1023:0] _TECHMAP_DO_ = "proc;;;";
integer k;
always @* begin
// at the end of the multiplier chain the carry-save accumulator
// should also have propagated all carries. thus we just need to
// copy the even bits from the carry accumulator to the output.
for (k = 0; k < WIDTH; k = k+1) begin
value[k] = acc[2*k];
end
end
endmodule
module \$__acc_mul (A, B, Y);
parameter WIDTH = 1;
input [WIDTH-1:0] A, B;
output [WIDTH-1:0] Y;
wire [1023:0] _TECHMAP_DO_ = "proc;; opt";
wire [1023:0] _TECHMAP_DO_ = "proc;;";
integer i;
reg [WIDTH-1:0] x;
reg [2*WIDTH-1:0] y;
(* via_celltype = "\\$__acc_set acc_new" *)
(* via_celltype_defparam_WIDTH = WIDTH *)
function [2*WIDTH-1:0] acc_set;
input [WIDTH-1:0] value;
integer k;
begin
for (k = 0; k < WIDTH; k = k+1) begin
acc_set[2*k +: 2] = value[k];
end
end
endfunction
(* via_celltype = "\\$__acc_add acc_new" *)
(* via_celltype_defparam_WIDTH = WIDTH *)
function [2*WIDTH-1:0] acc_add;
input [2*WIDTH-1:0] old_acc;
input [2*WIDTH-1:0] acc_old;
input [WIDTH-1:0] value;
integer k;
reg a, b, c;
begin
for (k = 0; k < WIDTH; k = k+1) begin
a = old_acc[2*k];
b = k ? old_acc[2*k-1] : 1'b0;
c = value[k];
acc_add[2*k] = (a ^ b) ^ c;
acc_add[2*k+1] = (a & b) | ((a ^ b) & c);
end
end
endfunction
(* via_celltype = "\\$__acc_get value" *)
(* via_celltype_defparam_WIDTH = WIDTH *)
function [WIDTH-1:0] acc_get;
input [2*WIDTH-1:0] acc;
integer k;
begin
// at the end of the multiplier chain the carry-save accumulator
// should also have propagated all carries. thus we just need to
// copy the even bits from the carry accumulator to the output.
for (k = 0; k < WIDTH; k = k+1) begin
acc_get[k] = acc[2*k];
end
end
endfunction
always @* begin
x = B;
y = acc_set(A[0] ? x : 0);
y = acc_set(A[0] ? x : 1'b0);
for (i = 1; i < WIDTH; i = i+1) begin
x = {x[WIDTH-2:0], 1'b0};
y = acc_add(y, A[i] ? x : 0);
y = acc_add(y, A[i] ? x : 1'b0);
end
end
@ -538,13 +574,15 @@ module \$mul (A, B, Y);
input [B_WIDTH-1:0] B;
output [Y_WIDTH-1:0] Y;
wire [1023:0] _TECHMAP_DO_ = "RECURSION; CONSTMAP; opt -purge";
wire [Y_WIDTH-1:0] A_buf, B_buf;
\$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
\$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) B_conv (.A(B), .Y(B_buf));
\$__arraymul #(
\$__acc_mul #(
.WIDTH(Y_WIDTH)
) arraymul (
) _TECHMAP_REPLACE_ (
.A(A_buf),
.B(B_buf),
.Y(Y)