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mul2dsp: Fix edge case where Y_WIDTH is less than B_WIDTH+`DSP_A_MAXWIDTH 

Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2019-07-16 16:44:40 +01:00
parent 7a75f5f3ac
commit 8da4c1ad82
1 changed files with 22 additions and 18 deletions
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38
techlibs/common/mul2dsp.v
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@ -80,19 +80,21 @@ module \$__mul_gen (A, B, Y);
localparam n = n_floored + (n_floored*`DSP_A_MAXWIDTH < A_WIDTH ? 1 : 0);
wire [`DSP_A_MAXWIDTH+B_WIDTH-1:0] partial [n-1:1];
wire [Y_WIDTH-1:0] partial_sum [n-2:0];
localparam int_yw = `MIN(Y_WIDTH, B_WIDTH+`DSP_A_MAXWIDTH);
\$__mul_gen #(
.A_SIGNED(A_SIGNED),
.B_SIGNED(B_SIGNED),
.A_WIDTH(`DSP_A_MAXWIDTH),
.B_WIDTH(B_WIDTH),
.Y_WIDTH(B_WIDTH+`DSP_A_MAXWIDTH)
.Y_WIDTH(int_yw)
) mul_slice_first (
.A(A[`DSP_A_MAXWIDTH-1:0]),
.B(B),
.Y(partial_sum[0][B_WIDTH+`DSP_A_MAXWIDTH-1:0])
.Y(partial_sum[0][int_yw-1:0])
);
assign partial_sum[0][Y_WIDTH-1:B_WIDTH+`DSP_A_MAXWIDTH]=0;
if (Y_WIDTH > int_yw)
assign partial_sum[0][Y_WIDTH-1:int_yw]=0;
for (i = 1; i < n-1; i=i+1) begin:slice
\$__mul_gen #(
@ -100,15 +102,15 @@ module \$__mul_gen (A, B, Y);
.B_SIGNED(B_SIGNED),
.A_WIDTH(`DSP_A_MAXWIDTH),
.B_WIDTH(B_WIDTH),
.Y_WIDTH(B_WIDTH+`DSP_A_MAXWIDTH)
.Y_WIDTH(int_yw)
) mul_slice (
.A(A[(i+1)*`DSP_A_MAXWIDTH-1:i*`DSP_A_MAXWIDTH]),
.B(B),
.Y(partial[i][B_WIDTH+`DSP_A_MAXWIDTH-1:0])
.Y(partial[i][int_yw-1:0])
);
//assign partial_sum[i] = (partial[i] << i*`DSP_A_MAXWIDTH) + partial_sum[i-1];
assign partial_sum[i] = {
partial[i][B_WIDTH+`DSP_A_MAXWIDTH-1:0]
partial[i][int_yw-1:0]
+ partial_sum[i-1][Y_WIDTH-1:(i*`DSP_A_MAXWIDTH)],
partial_sum[i-1][(i*`DSP_A_MAXWIDTH)-1:0]
};
@ -119,15 +121,15 @@ module \$__mul_gen (A, B, Y);
.B_SIGNED(B_SIGNED),
.A_WIDTH(A_WIDTH-(n-1)*`DSP_A_MAXWIDTH),
.B_WIDTH(B_WIDTH),
.Y_WIDTH(A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH),
.Y_WIDTH(`MIN(Y_WIDTH, A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH)),
) mul_slice_last (
.A(A[A_WIDTH-1:(n-1)*`DSP_A_MAXWIDTH]),
.B(B),
.Y(partial[n-1][A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH-1:0])
.Y(partial[n-1][`MIN(Y_WIDTH, A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH)-1:0])
);
//assign Y = (partial[n-1] << (n-1)*`DSP_A_MAXWIDTH) + partial_sum[n-2];
assign Y = {
partial[n-1][A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH:0]
partial[n-1][`MIN(Y_WIDTH, A_WIDTH-(n-1)*`DSP_A_MAXWIDTH+B_WIDTH):0]
+ partial_sum[n-2][Y_WIDTH-1:((n-1)*`DSP_A_MAXWIDTH)],
partial_sum[n-2][((n-1)*`DSP_A_MAXWIDTH)-1:0]
};
@ -137,18 +139,20 @@ module \$__mul_gen (A, B, Y);
localparam n = n_floored + (n_floored*`DSP_B_MAXWIDTH < B_WIDTH ? 1 : 0);
wire [A_WIDTH+`DSP_B_MAXWIDTH-1:0] partial [n-1:1];
wire [Y_WIDTH-1:0] partial_sum [n-2:0];
localparam int_yw = `MIN(Y_WIDTH, A_WIDTH+`DSP_B_MAXWIDTH);
\$__mul_gen #(
.A_SIGNED(A_SIGNED),
.B_SIGNED(B_SIGNED),
.A_WIDTH(A_WIDTH),
.B_WIDTH(`DSP_B_MAXWIDTH),
.Y_WIDTH(A_WIDTH+`DSP_B_MAXWIDTH)
.Y_WIDTH(int_yw)
) mul_first (
.A(A),
.B(B[`DSP_B_MAXWIDTH-1:0]),
.Y(partial_sum[0][A_WIDTH+`DSP_B_MAXWIDTH-1:0])
.Y(partial_sum[0][int_yw-1:0])
);
if (Y_WIDTH > int_yw)
assign partial_sum[0][Y_WIDTH-1:A_WIDTH+`DSP_B_MAXWIDTH]=0;
for (i = 1; i < n-1; i=i+1) begin:slice
@ -157,11 +161,11 @@ module \$__mul_gen (A, B, Y);
.B_SIGNED(B_SIGNED),
.A_WIDTH(A_WIDTH),
.B_WIDTH(`DSP_B_MAXWIDTH),
.Y_WIDTH(A_WIDTH+`DSP_B_MAXWIDTH)
.Y_WIDTH(int_yw)
) mul (
.A(A),
.B(B[(i+1)*`DSP_B_MAXWIDTH-1:i*`DSP_B_MAXWIDTH]),
.Y(partial[i][A_WIDTH+`DSP_B_MAXWIDTH-1:0])
.Y(partial[i][int_yw-1:0])
);
//assign partial_sum[i] = (partial[i] << i*`DSP_B_MAXWIDTH) + partial_sum[i-1];
// was:
@ -170,7 +174,7 @@ module \$__mul_gen (A, B, Y);
// partial[i][`DSP_B_MAXWIDTH-1:0] + partial_sum[i-1][A_WIDTH+(i*`DSP_B_MAXWIDTH)-1:A_WIDTH+((i-1)*`DSP_B_MAXWIDTH)],
// partial_sum[i-1][A_WIDTH+((i-1)*`DSP_B_MAXWIDTH):0]
assign partial_sum[i] = {
partial[i][A_WIDTH+`DSP_B_MAXWIDTH-1:0]
partial[i][int_yw-1:0]
+ partial_sum[i-1][Y_WIDTH-1:(i*`DSP_B_MAXWIDTH)],
partial_sum[i-1][(i*`DSP_B_MAXWIDTH)-1:0]
};
@ -181,11 +185,11 @@ module \$__mul_gen (A, B, Y);
.B_SIGNED(B_SIGNED),
.A_WIDTH(A_WIDTH),
.B_WIDTH(B_WIDTH-(n-1)*`DSP_B_MAXWIDTH),
.Y_WIDTH(A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH)
.Y_WIDTH(`MIN(Y_WIDTH, A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH))
) mul_last (
.A(A),
.B(B[B_WIDTH-1:(n-1)*`DSP_B_MAXWIDTH]),
.Y(partial[n-1][A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH-1:0])
.Y(partial[n-1][`MIN(Y_WIDTH, A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH)-1:0])
);
// AMD: this came comment out -- looks closer to right answer
//assign Y = (partial[n-1] << (n-1)*`DSP_B_MAXWIDTH) + partial_sum[n-2];
@ -195,7 +199,7 @@ module \$__mul_gen (A, B, Y);
// partial[n-1][`DSP_B_MAXWIDTH-1:0] + partial_sum[n-2][A_WIDTH+((n-1)*`DSP_B_MAXWIDTH)-1:A_WIDTH+((n-2)*`DSP_B_MAXWIDTH)],
// partial_sum[n-2][A_WIDTH+((n-2)*`DSP_B_MAXWIDTH):0]
assign Y = {
partial[n-1][A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH-1:0]
partial[n-1][`MIN(Y_WIDTH, A_WIDTH+B_WIDTH-(n-1)*`DSP_B_MAXWIDTH)-1:0]
+ partial_sum[n-2][Y_WIDTH-1:((n-1)*`DSP_B_MAXWIDTH)],
partial_sum[n-2][((n-1)*`DSP_B_MAXWIDTH)-1:0]
};