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fpga: Fix sc16 to sc12 converter

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Re-wrote converter to remove clock cycle delay on i_tready when handling
residual output and fixed improper handling of tlast during residual
data processing.  Resolves some USB overflow issues when using sc12 data
type on B200 devices.

Signed-off-by: michael-west <michael.west@ettus.com>


Original-commit: 1fecf446e0358aa2b6a2d1f73a0daeac516435a0
This commit is contained in:
michael-west
2021-08-10 15:19:32 -05:00
committed by Aaron Rossetto
parent f3085587fd
commit 8332f5b161
1 changed files with 79 additions and 61 deletions
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lib/vita_200/chdr_16sc_to_12sc.v
+78 -60
View File
@@ -22,7 +22,7 @@ module chdr_16sc_to_12sc
input i_tvalid,
output i_tready,
// Output CHDR bus
output reg [63:0] o_tdata,
output [63:0] o_tdata,
output o_tlast,
output o_tvalid,
input o_tready,
@@ -46,17 +46,21 @@ module chdr_16sc_to_12sc
wire [16:0] round_q2;
wire [16:0] round_i2;
reg [63:0] curr_word;
// Pipeline register
reg [63:0] line_buff;
reg [63:0] buff;
reg buff_tvalid;
reg buff_tlast;
// CHDR has either 8 bytes of header or 16 if VITA time is included.
wire [15:0] chdr_header_lines = chdr_has_time? 16 : 8;
wire [15:0] chdr_header_bytes = chdr_has_time? 16 : 8;
// Calculate size of samples input in bytes by taking CHDR size filed and subtracting header length.
wire [15:0] sample_byte_count_in = i_tdata[47:32] - chdr_header_lines;
wire [15:0] sample_byte_count_in = i_tdata[47:32] - chdr_header_bytes;
// Calculate size of samples to be output by taking input size and scaling by 3/4
wire [15:0] sample_byte_count_out = (sample_byte_count_in*3) >> 2;
// Calculate size of output CHDR packet by adding back header size to new payload size.
wire [15:0] output_chdr_pkt_size = sample_byte_count_out + chdr_header_lines;
wire [15:0] output_chdr_pkt_size = sample_byte_count_out + chdr_header_bytes;
reg odd;
@@ -75,36 +79,64 @@ module chdr_16sc_to_12sc
localparam SAMPLE2 = 3'd3;
localparam SAMPLE3 = 3'd4;
localparam SAMPLE4 = 3'd5;
localparam RESIDUAL = 3'd6;
reg [2:0] state;
always @(posedge clk)
if (reset) begin
state <= HEADER;
line_buff <= 0;
buff <= 64'd0;
buff_tvalid <= 1'd0;
buff_tlast <= 1'd0;
end else begin
case(state)
//
// Process header
// Check for timestamp. Byte count conversion is done above.
// If there is residual data in the buffer, store the header and
// output the line in the buffer. If not, output the header.
//
HEADER: begin
if (i_tvalid & i_tready) begin
odd <= sample_byte_count_in [2];
// If the input packet had time, then add time to output packet
state <= (i_tdata[61])? TIME: SAMPLE1;
if (buff_tvalid) begin
buff <= curr_word;
buff_tvalid <= i_tvalid;
buff_tlast <= i_tlast;
end else begin
buff <= 64'd0;
buff_tvalid <= 1'd0;
buff_tlast <= 1'd0;
end
state <= i_tlast ? HEADER : (i_tdata[61]) ? TIME : SAMPLE1;
end else if (buff_tvalid & o_tready) begin
buff <= 64'd0;
buff_tvalid <= 1'd0;
buff_tlast <= 1'd0;
end
end
//
// Process time field
// If the header is in the buffer, output the header and
// store the timestamp. If not, output the timestamp.
//
TIME: begin
if (i_tvalid & i_tready) begin
// If we get a premature end of line go back to searching for start of new packet.
state <= (i_tlast) ? HEADER: SAMPLE1;
if (buff_tvalid) begin
buff <= curr_word;
buff_tvalid <= i_tvalid;
buff_tlast <= i_tlast;
end else begin
buff <= 64'd0;
buff_tvalid <= 1'd0;
buff_tlast <= 1'd0;
end
state <= i_tlast ? HEADER: SAMPLE1;
end
end
//
// There are 3 lines of output data for each 4 lines of input data.
// The 4 sample states below represent the 4 lines of input.
@@ -113,20 +145,17 @@ module chdr_16sc_to_12sc
// Process first line
// The 8 bytes are converted to 6 bytes, so there is not enough for an
// 8-byte output line. Store the data unless this is the last line in
// the packet.
// the packet. If the timestamp is in the buffer, output it.
//
SAMPLE1: begin
if (i_tvalid & i_tready) begin
if (i_tlast) begin
line_buff <= 0;
state <= HEADER;
end else begin
// Save data to buffer - no output
line_buff <= {q0,i0,q1,i1,16'd0};
state <= SAMPLE2;
end
buff <= curr_word;
buff_tvalid <= i_tlast;
buff_tlast <= i_tlast;
state <= i_tlast ? HEADER : SAMPLE2;
end
end
//
// Process second line
// Output a line comprised of the 6 bytes from the fist line and
@@ -134,10 +163,13 @@ module chdr_16sc_to_12sc
//
SAMPLE2: begin
if (i_tvalid & i_tready) begin
line_buff <= {i0[7:0],q1,i1,32'd0};
state <= i_tlast ? RESIDUAL : SAMPLE3;
buff <= {i0[7:0],q1,i1,32'd0};
buff_tvalid <= i_tlast;
buff_tlast <= i_tlast;
state <= i_tlast ? HEADER : SAMPLE3;
end
end
//
// Process third line
// Output line comprised of the 4 remaining bytes from the second line
@@ -146,13 +178,13 @@ module chdr_16sc_to_12sc
//
SAMPLE3: begin
if (i_tvalid & i_tready) begin
line_buff <= (i_tlast & odd) ? 0 : {q1[3:0],i1,48'd0};
if (i_tlast)
state <= odd ? HEADER : RESIDUAL;
else
state <= SAMPLE4;
buff <= {q1[3:0],i1,48'd0};
buff_tvalid <= i_tlast & ~odd;
buff_tlast <= i_tlast & ~odd;
state <= i_tlast ? HEADER : SAMPLE4;
end
end
//
// Process fourth line
// Output line comprised of the remaining 2 bytes from the third line
@@ -160,19 +192,13 @@ module chdr_16sc_to_12sc
//
SAMPLE4: begin
if (i_tvalid & i_tready) begin
line_buff <= 0;
buff <= 64'd0;
buff_tvalid <= 1'd0;
buff_tlast <= 1'd0;
state <= i_tlast ? HEADER : SAMPLE1;
end
end
//
// Pause input to output residual data in buffer
//
RESIDUAL: begin
if (o_tvalid & o_tready) begin
line_buff <= 0;
state <= HEADER;
end
end
//
// Should never get here.
//
@@ -196,32 +222,24 @@ module chdr_16sc_to_12sc
assign i1 = (round_i1[16:15] == 2'b01) ? 12'h3FF : ((round_i1[16:15] == 2'b10) ? 12'h800 : round_i1[15:4]);
//
// Mux Output data
// Mux for current word
//
always @(*)
case(state)
// Populate header with CHDR fields
HEADER: o_tdata = {i_tdata[63:48], output_chdr_pkt_size,
set_sid ? {i_tdata[15:0], new_sid_dst[15:0]}:i_tdata[31:0]};
// Add 64bit VITA time to packet
TIME: o_tdata = i_tdata;
// Only output if i_tlast in SAMPLE1 state
SAMPLE1: o_tdata = {q0,i0,q1, i1, 16'b0};
SAMPLE2: o_tdata = {line_buff[63:16], q0, i0[11:8]};
SAMPLE3: o_tdata = {line_buff[63:32], q0, i0,q1[11:4]};
SAMPLE4: o_tdata = {line_buff[63:48], q0, i0, q1, i1};
RESIDUAL: o_tdata = line_buff;
default : o_tdata = i_tdata;
endcase // case(state)
HEADER: curr_word <= {i_tdata[63:48], output_chdr_pkt_size, set_sid ?
{i_tdata[15:0], new_sid_dst[15:0]}:i_tdata[31:0]};
TIME: curr_word <= i_tdata;
SAMPLE1: curr_word <= {q0,i0,q1, i1, 16'b0};
SAMPLE2: curr_word <= {buff[63:16], q0, i0[11:8]};
SAMPLE3: curr_word <= {buff[63:32], q0, i0,q1[11:4]};
SAMPLE4: curr_word <= {buff[63:48], q0, i0, q1, i1};
endcase
assign o_tvalid = state == RESIDUAL || (i_tvalid &&
(state != SAMPLE1 || state == SAMPLE1 && i_tlast));
assign i_tready = (o_tready && state != RESIDUAL);
wire need_extra_line = state == SAMPLE1 || state == SAMPLE2 ||
(state == SAMPLE3 && ~odd);
assign o_tlast = state == RESIDUAL || (i_tlast & ~need_extra_line);
assign o_tdata = buff_tvalid ? buff : curr_word;
assign o_tvalid = (state == HEADER && buff_tvalid) || (i_tvalid &&
(state != SAMPLE1 || (state == SAMPLE1 && buff_tvalid)));
assign o_tlast = buff_tvalid ? buff_tlast : i_tlast && (state == HEADER ||
state == TIME || (state == SAMPLE3 && odd) || state == SAMPLE4);
assign i_tready = o_tready;
endmodule