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Cleanup cmp2lcu.v

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This commit is contained in:
Eddie Hung 2020-01-20 12:52:47 -08:00
parent 9b63700678
commit da880d5016
1 changed files with 16 additions and 16 deletions
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32
techlibs/common/cmp2lcu.v
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@ -17,18 +17,18 @@ input [B_WIDTH-1:0] B;
output [Y_WIDTH-1:0] Y; output [Y_WIDTH-1:0] Y;
parameter _TECHMAP_CELLTYPE_ = ""; parameter _TECHMAP_CELLTYPE_ = "";
localparam gt_width = `LUT_WIDTH/2; localparam cmp_width = `LUT_WIDTH/2;
generate generate
if (_TECHMAP_CELLTYPE_ == "" || (A_WIDTH <= gt_width || B_WIDTH <= gt_width)) if (_TECHMAP_CELLTYPE_ == "" || (A_WIDTH <= cmp_width || B_WIDTH <= cmp_width))
wire _TECHMAP_FAIL_ = 1; wire _TECHMAP_FAIL_ = 1;
else if (_TECHMAP_CELLTYPE_ == "$lt") begin else if (_TECHMAP_CELLTYPE_ == "$lt") begin
// Transform $lt into $gt by swapping A and B // Transform $lt into $gt by swapping A and B
$gt #(.A_SIGNED(B_SIGNED), .B_SIGNED(A_SIGNED), .A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(B), .B(A), .Y(Y)); $gt #(.A_SIGNED(B_SIGNED), .B_SIGNED(A_SIGNED), .A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(B), .B(A), .Y(Y));
end end
else if (_TECHMAP_CELLTYPE_ == "$le") begin else if (_TECHMAP_CELLTYPE_ == "$le") begin
// Transform $le into $ge by swapping A and B // Transform $le into $ge by swapping A and B
$ge #(.A_SIGNED(B_SIGNED), .B_SIGNED(A_SIGNED), .A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(B), .B(A), .Y(Y)); $ge #(.A_SIGNED(B_SIGNED), .B_SIGNED(A_SIGNED), .A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(B), .B(A), .Y(Y));
end end
else begin else begin
// Perform sign extension on A and B // Perform sign extension on A and B
@ -37,26 +37,26 @@ generate
wire [WIDTH-1:0] BB = {{(WIDTH-B_WIDTH){B_SIGNED ? B[B_WIDTH-1] : 1'b0}}, B}; wire [WIDTH-1:0] BB = {{(WIDTH-B_WIDTH){B_SIGNED ? B[B_WIDTH-1] : 1'b0}}, B};
// Compute width of $lcu/carry-chain cell // Compute width of $lcu/carry-chain cell
localparam lcu_width = (WIDTH+gt_width-1)/gt_width; localparam lcu_width = (WIDTH+cmp_width-1)/cmp_width;
wire [lcu_width-1:0] P, G, CO; wire [lcu_width-1:0] P, G, CO;
genvar i, j; genvar i, j;
integer j; integer j;
for (i = 0; i < WIDTH; i=i+gt_width) begin for (i = 0; i < WIDTH; i=i+cmp_width) begin
wire [gt_width-1:0] PP, GG; wire [cmp_width-1:0] PP, GG;
if (i < WIDTH-gt_width) begin if (i < WIDTH-cmp_width) begin
// Bit-wise equality (xnor) of sign-extended A and B // Bit-wise equality (xnor) of sign-extended A and B
assign PP = AA[i +: gt_width] ^~ BB[i +: gt_width]; assign PP = AA[i +: cmp_width] ^~ BB[i +: cmp_width];
// Priority "encoder" that checks A[i] == 1'b1 && B[i] == 1'b0 // Priority "encoder" that checks A[i] == 1'b1 && B[i] == 1'b0
// from MSB down, deferring to less significant bits if the // from MSB down, deferring to less significant bits if the
// MSBs are equal // MSBs are equal
assign GG[gt_width-1] = AA[i+gt_width-1] & ~BB[i+gt_width-1]; assign GG[cmp_width-1] = AA[i+cmp_width-1] & ~BB[i+cmp_width-1];
for (j = gt_width-2; j >= 0; j=j-1) for (j = cmp_width-2; j >= 0; j=j-1)
assign GG[j] = &PP[gt_width-1:j+1] & (AA[i+j] & ~BB[i+j]); assign GG[j] = &PP[cmp_width-1:j+1] & (AA[i+j] & ~BB[i+j]);
// Propagate only if all bits are equal // Propagate only if all bits are equal
// (inconclusive evidence to say A >= B) // (inconclusive evidence to say A >= B)
assign P[i/gt_width] = &PP; assign P[i/cmp_width] = &PP;
// Generate if any pairs call for it // Generate if any pairs call for it
assign G[i/gt_width] = |GG; assign G[i/cmp_width] = |GG;
end end
else begin else begin
assign PP = AA[WIDTH-1:i] ^~ BB[WIDTH-1:i]; assign PP = AA[WIDTH-1:i] ^~ BB[WIDTH-1:i];
@ -66,8 +66,8 @@ generate
assign GG[WIDTH-i-1] = AA[WIDTH-1] & ~BB[WIDTH-1]; assign GG[WIDTH-i-1] = AA[WIDTH-1] & ~BB[WIDTH-1];
for (j = WIDTH-i-2; j >= 0; j=j-1) for (j = WIDTH-i-2; j >= 0; j=j-1)
assign GG[j] = &PP[WIDTH-i-1:j+1] & (AA[i+j] & ~BB[i+j]); assign GG[j] = &PP[WIDTH-i-1:j+1] & (AA[i+j] & ~BB[i+j]);
assign P[i/gt_width] = &PP[WIDTH-i-1:0]; assign P[i/cmp_width] = &PP[WIDTH-i-1:0];
assign G[i/gt_width] = |GG[WIDTH-i-1:0]; assign G[i/cmp_width] = |GG[WIDTH-i-1:0];
end end
end end
// For $ge operation, start with the assumption that A and B are // For $ge operation, start with the assumption that A and B are