diff options
Diffstat (limited to 'tests/simple/rotate.v')
-rw-r--r-- | tests/simple/rotate.v | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/tests/simple/rotate.v b/tests/simple/rotate.v new file mode 100644 index 000000000..eb832e6f5 --- /dev/null +++ b/tests/simple/rotate.v @@ -0,0 +1,48 @@ + +// test case taken from amber23 verilog code +module a23_barrel_shift_fpga_rotate(i_in, direction, shift_amount, rot_prod); + +input [31:0] i_in; +input direction; +input [4:0] shift_amount; +output [31:0] rot_prod; + +// Generic rotate. Theoretical cost: 32x5 4-to-1 LUTs. +// Practically a bit higher due to high fanout of "direction". +generate +genvar i, j; + for (i = 0; i < 5; i = i + 1) + begin : netgen + wire [31:0] in; + reg [31:0] out; + for (j = 0; j < 32; j = j + 1) + begin : net + always @* + out[j] = in[j] & (~shift_amount[i] ^ direction) | + in[wrap(j, i)] & (shift_amount[i] ^ direction); + end + end + + // Order is reverted with respect to volatile shift_amount[0] + assign netgen[4].in = i_in; + for (i = 1; i < 5; i = i + 1) + begin : router + assign netgen[i-1].in = netgen[i].out; + end +endgenerate + +// Aliasing +assign rot_prod = netgen[0].out; + +function [4:0] wrap; +input integer pos; +input integer level; +integer out; +begin + out = pos - (1 << level); + wrap = out[4:0]; +end +endfunction + +endmodule + |