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🐛 Perform sign extension after conversion and rounding #147

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🐛 Perform sign extension after conversion and rounding #147

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34 changes: 27 additions & 7 deletions src/fpnew_cast_multi.sv
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Original file line number Diff line number Diff line change
Expand Up @@ -510,14 +510,16 @@ module fpnew_cast_multi #(
logic [NUM_FORMATS-1:0] fmt_of_after_round;
logic [NUM_FORMATS-1:0] fmt_uf_after_round;

logic [NUM_INT_FORMATS-1:0][WIDTH-1:0] ifmt_pre_round_abs; // per format
logic [NUM_INT_FORMATS-1:0][WIDTH-1:0] ifmt_pre_round_abs; // per format
logic [NUM_INT_FORMATS-1:0][WIDTH-1:0] ifmt_rounded_signed_res; // per format
logic [NUM_INT_FORMATS-1:0] ifmt_of_after_round;

logic rounded_sign;
logic [WIDTH-1:0] rounded_abs; // absolute value of result after rounding
logic result_true_zero;

logic [WIDTH-1:0] rounded_int_res; // after possible inversion
logic [WIDTH-1:0] rounded_uint_res; // after possible inversion
logic [WIDTH-1:0] rounded_int_res; // sign-extended, after possible inversion
logic rounded_int_res_zero; // after rounding


Expand All @@ -536,15 +538,15 @@ module fpnew_cast_multi #(
end
end

// Sign-extend integer result
for (genvar ifmt = 0; ifmt < int'(NUM_INT_FORMATS); ifmt++) begin : gen_int_res_sign_ext
// Zero-extend integer result
for (genvar ifmt = 0; ifmt < int'(NUM_INT_FORMATS); ifmt++) begin : gen_int_res_zero_ext
// Set up some constants
localparam int unsigned INT_WIDTH = fpnew_pkg::int_width(fpnew_pkg::int_format_e'(ifmt));

if (IntFmtConfig[ifmt]) begin : active_format
always_comb begin : assemble_result
// sign-extend reusult
ifmt_pre_round_abs[ifmt] = '{default: final_int[INT_WIDTH-1]};
// zero-extend absolute value result
ifmt_pre_round_abs[ifmt] = '0;
ifmt_pre_round_abs[ifmt][INT_WIDTH-1:0] = final_int[INT_WIDTH-1:0];
end
end else begin : inactive_format
Expand Down Expand Up @@ -597,7 +599,25 @@ module fpnew_cast_multi #(
end

// Negative integer result needs to be brought into two's complement
assign rounded_int_res = rounded_sign ? unsigned'(-rounded_abs) : rounded_abs;
assign rounded_uint_res = rounded_sign ? unsigned'(-rounded_abs) : rounded_abs;

// Sign-extend integer result
for (genvar ifmt = 0; ifmt < int'(NUM_INT_FORMATS); ifmt++) begin : gen_int_res_sign_ext
// Set up some constants
localparam int unsigned INT_WIDTH = fpnew_pkg::int_width(fpnew_pkg::int_format_e'(ifmt));

if (IntFmtConfig[ifmt]) begin : active_format
always_comb begin : assemble_result
// zero-extend absolute value result
ifmt_rounded_signed_res[ifmt] = '{default: rounded_uint_res[INT_WIDTH-1]};
ifmt_rounded_signed_res[ifmt][INT_WIDTH-1:0] = rounded_uint_res[INT_WIDTH-1:0];
end
end else begin : inactive_format
assign ifmt_rounded_signed_res[ifmt] = '{default: fpnew_pkg::DONT_CARE};
end
end

assign rounded_int_res = ifmt_rounded_signed_res[int_fmt_q2];
assign rounded_int_res_zero = (rounded_int_res == '0);

// Detect integer overflows after rounding (only positives)
Expand Down