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More extensive overhaul of the PTP period output module to improve re…
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…source consumption and parallelize computation

Signed-off-by: Alex Forencich <alex@alexforencich.com>
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@alexforencich
alexforencich committed Jan 17, 2024
1 parent f313faf commit b4d09cb
Showing 1 changed file with 94 additions and 93 deletions.
187 changes: 94 additions & 93 deletions rtl/ptp_perout.v
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
/*
Copyright (c) 2019 Alex Forencich
Copyright (c) 2019-2024 Alex Forencich
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
Expand Down Expand Up @@ -77,15 +77,12 @@ module ptp_perout #
output wire output_pulse
);

localparam [2:0]
localparam [1:0]
STATE_IDLE = 3'd0,
STATE_UPDATE_RISE_1 = 3'd1,
STATE_UPDATE_RISE_2 = 3'd2,
STATE_UPDATE_FALL_1 = 3'd3,
STATE_UPDATE_FALL_2 = 3'd4,
STATE_WAIT_EDGE = 3'd5;
STATE_UPDATE_RISE = 3'd1,
STATE_UPDATE_FALL = 3'd2;

reg [2:0] state_reg = STATE_IDLE, state_next;
reg [1:0] state_reg = STATE_IDLE, state_next;

reg [47:0] time_s_reg = 0;
reg [30:0] time_ns_reg = 0;
Expand All @@ -95,9 +92,9 @@ reg [47:0] next_rise_s_reg = 0, next_rise_s_next;
reg [30:0] next_rise_ns_reg = 0, next_rise_ns_next;
reg [15:0] next_rise_fns_reg = 0, next_rise_fns_next;

reg [47:0] next_fall_s_reg = 0, next_fall_s_next;
reg [30:0] next_fall_ns_reg = 0, next_fall_ns_next;
reg [15:0] next_fall_fns_reg = 0, next_fall_fns_next;
reg [47:0] next_edge_s_reg = 0, next_edge_s_next;
reg [30:0] next_edge_ns_reg = 0, next_edge_ns_next;
reg [15:0] next_edge_fns_reg = 0, next_edge_fns_next;

reg [47:0] start_s_reg = OUT_START_S;
reg [30:0] start_ns_reg = OUT_START_NS;
Expand All @@ -116,6 +113,7 @@ reg [15:0] ts_96_fns_inc_reg = 0, ts_96_fns_inc_next;
reg [30:0] ts_96_ns_ovf_reg = 0, ts_96_ns_ovf_next;
reg [15:0] ts_96_fns_ovf_reg = 0, ts_96_fns_ovf_next;

reg restart_reg = 1'b1;
reg locked_reg = 1'b0, locked_next;
reg error_reg = 1'b0, error_next;
reg ffwd_reg = 1'b0, ffwd_next;
Expand All @@ -133,9 +131,9 @@ always @* begin
next_rise_ns_next = next_rise_ns_reg;
next_rise_fns_next = next_rise_fns_reg;

next_fall_s_next = next_fall_s_reg;
next_fall_ns_next = next_fall_ns_reg;
next_fall_fns_next = next_fall_fns_reg;
next_edge_s_next = next_edge_s_reg;
next_edge_ns_next = next_edge_ns_reg;
next_edge_fns_next = next_edge_fns_reg;

ts_96_ns_inc_next = ts_96_ns_inc_reg;
ts_96_fns_inc_next = ts_96_fns_inc_reg;
Expand All @@ -149,97 +147,97 @@ always @* begin
level_next = level_reg;
output_next = output_reg;

if (input_start_valid || input_period_valid || input_ts_step) begin
locked_next = 1'b0;
level_next = 1'b0;
output_next = 1'b0;
error_next = input_ts_step;
state_next = STATE_IDLE;
end else begin
case (state_reg)
STATE_IDLE: begin
// set next rise to start time
next_rise_s_next = start_s_reg;
next_rise_ns_next = start_ns_reg;
if (FNS_ENABLE) begin
next_rise_fns_next = start_fns_reg;
end
locked_next = 1'b0;
ffwd_next = 1'b1;
output_next = 1'b0;
level_next = 1'b0;
state_next = STATE_WAIT_EDGE;
end
STATE_UPDATE_RISE_1: begin
// set next rise time to next rise time plus period
case (state_reg)
STATE_IDLE: begin
if (ffwd_reg || level_reg) begin
// fast forward or falling edge, set up for next rising edge
// set next rise time to previous rise time plus period
{ts_96_ns_inc_next, ts_96_fns_inc_next} = {next_rise_ns_reg, next_rise_fns_reg} + {period_ns_reg, period_fns_reg};
{ts_96_ns_ovf_next, ts_96_fns_ovf_next} = {next_rise_ns_reg, next_rise_fns_reg} + {period_ns_reg, period_fns_reg} - {31'd1_000_000_000, 16'd0};
state_next = STATE_UPDATE_RISE_2;
end
STATE_UPDATE_RISE_2: begin
if (!ts_96_ns_ovf_reg[30]) begin
// if the overflow lookahead did not borrow, one second has elapsed
next_rise_s_next = next_rise_s_reg + period_s_reg + 1;
next_rise_ns_next = ts_96_ns_ovf_reg;
next_rise_fns_next = ts_96_fns_ovf_reg;
end else begin
// no increment seconds field
next_rise_s_next = next_rise_s_reg + period_s_reg;
next_rise_ns_next = ts_96_ns_inc_reg;
next_rise_fns_next = ts_96_fns_inc_reg;
end
state_next = STATE_WAIT_EDGE;
end
STATE_UPDATE_FALL_1: begin
// set next fall time to next rise time plus width
end else begin
// rising edge; set up for next falling edge
// set next fall time to previous rise time plus width
{ts_96_ns_inc_next, ts_96_fns_inc_next} = {next_rise_ns_reg, next_rise_fns_reg} + {width_ns_reg, width_fns_reg};
{ts_96_ns_ovf_next, ts_96_fns_ovf_next} = {next_rise_ns_reg, next_rise_fns_reg} + {width_ns_reg, width_fns_reg} - {31'd1_000_000_000, 16'd0};
state_next = STATE_UPDATE_FALL_2;
end
STATE_UPDATE_FALL_2: begin
if (!ts_96_ns_ovf_reg[30]) begin
// if the overflow lookahead did not borrow, one second has elapsed
next_fall_s_next = next_rise_s_reg + width_s_reg + 1;
next_fall_ns_next = ts_96_ns_ovf_reg;
next_fall_fns_next = ts_96_fns_ovf_reg;
end else begin
// no increment seconds field
next_fall_s_next = next_rise_s_reg + width_s_reg;
next_fall_ns_next = ts_96_ns_inc_reg;
next_fall_fns_next = ts_96_fns_inc_reg;
end
state_next = STATE_WAIT_EDGE;
end
STATE_WAIT_EDGE: begin
if ((!level_reg || ffwd_reg) && ((time_s_reg > next_rise_s_reg) || (time_s_reg == next_rise_s_reg && {time_ns_reg, time_fns_reg} > {next_rise_ns_reg, next_rise_fns_reg}))) begin
// rising edge
if (ffwd_reg) begin
output_next = 1'b0;
level_next = 1'b0;
state_next = STATE_UPDATE_RISE_1;
end else begin
locked_next = 1'b1;
error_next = 1'b0;
output_next = enable;
level_next = 1'b1;
state_next = STATE_UPDATE_FALL_1;
end
end else if (level_reg && ((time_s_reg > next_fall_s_reg) || (time_s_reg == next_fall_s_reg && {time_ns_reg, time_fns_reg} > {next_fall_ns_reg, next_fall_fns_reg}))) begin
// falling edge

// wait for edge
if ((time_s_reg > next_edge_s_reg) || (time_s_reg == next_edge_s_reg && {time_ns_reg, time_fns_reg} > {next_edge_ns_reg, next_edge_fns_reg})) begin
if (ffwd_reg || level_reg) begin
// fast forward or falling edge, set up for next rising edge
output_next = 1'b0;
level_next = 1'b0;
state_next = STATE_UPDATE_RISE_1;
state_next = STATE_UPDATE_RISE;
end else begin
ffwd_next = 1'b0;
state_next = STATE_WAIT_EDGE;
// rising edge; set up for next falling edge
locked_next = 1'b1;
error_next = 1'b0;
output_next = enable;
level_next = 1'b1;
state_next = STATE_UPDATE_FALL;
end
end else begin
ffwd_next = 1'b0;
state_next = STATE_IDLE;
end
endcase
end
STATE_UPDATE_RISE: begin
if (!ts_96_ns_ovf_reg[30]) begin
// if the overflow lookahead did not borrow, one second has elapsed
next_edge_s_next = next_rise_s_reg + period_s_reg + 1;
next_edge_ns_next = ts_96_ns_ovf_reg;
next_edge_fns_next = ts_96_fns_ovf_reg;
end else begin
// no increment seconds field
next_edge_s_next = next_rise_s_reg + period_s_reg;
next_edge_ns_next = ts_96_ns_inc_reg;
next_edge_fns_next = ts_96_fns_inc_reg;
end
next_rise_s_next = next_edge_s_next;
next_rise_ns_next = next_edge_ns_next;
next_rise_fns_next = next_edge_fns_next;
state_next = STATE_IDLE;
end
STATE_UPDATE_FALL: begin
if (!ts_96_ns_ovf_reg[30]) begin
// if the overflow lookahead did not borrow, one second has elapsed
next_edge_s_next = next_rise_s_reg + width_s_reg + 1;
next_edge_ns_next = ts_96_ns_ovf_reg;
next_edge_fns_next = ts_96_fns_ovf_reg;
end else begin
// no increment seconds field
next_edge_s_next = next_rise_s_reg + width_s_reg;
next_edge_ns_next = ts_96_ns_inc_reg;
next_edge_fns_next = ts_96_fns_inc_reg;
end
state_next = STATE_IDLE;
end
endcase

if (restart_reg || input_ts_step) begin
// set next rise and next edge to start time
next_rise_s_next = start_s_reg;
next_rise_ns_next = start_ns_reg;
if (FNS_ENABLE) begin
next_rise_fns_next = start_fns_reg;
end
next_edge_s_next = start_s_reg;
next_edge_ns_next = start_ns_reg;
if (FNS_ENABLE) begin
next_edge_fns_next = start_fns_reg;
end
locked_next = 1'b0;
ffwd_next = 1'b1;
output_next = 1'b0;
level_next = 1'b0;
error_next = input_ts_step;
state_next = STATE_IDLE;
end
end

always @(posedge clk) begin
state_reg <= state_next;
restart_reg <= 1'b0;

time_s_reg <= input_ts_96[95:48];
time_ns_reg <= input_ts_96[45:16];
Expand All @@ -253,6 +251,7 @@ always @(posedge clk) begin
if (FNS_ENABLE) begin
start_fns_reg <= input_start[15:0];
end
restart_reg <= 1'b1;
end

if (input_period_valid) begin
Expand All @@ -261,6 +260,7 @@ always @(posedge clk) begin
if (FNS_ENABLE) begin
period_fns_reg <= input_period[15:0];
end
restart_reg <= 1'b1;
end

if (input_width_valid) begin
Expand All @@ -277,10 +277,10 @@ always @(posedge clk) begin
next_rise_fns_reg <= next_rise_fns_next;
end

next_fall_s_reg <= next_fall_s_next;
next_fall_ns_reg <= next_fall_ns_next;
next_edge_s_reg <= next_edge_s_next;
next_edge_ns_reg <= next_edge_ns_next;
if (FNS_ENABLE) begin
next_fall_fns_reg <= next_fall_fns_next;
next_edge_fns_reg <= next_edge_fns_next;
end

ts_96_ns_inc_reg <= ts_96_ns_inc_next;
Expand Down Expand Up @@ -314,6 +314,7 @@ always @(posedge clk) begin
width_ns_reg <= OUT_WIDTH_NS;
width_fns_reg <= OUT_WIDTH_FNS;

restart_reg <= 1'b1;
locked_reg <= 1'b0;
error_reg <= 1'b0;
output_reg <= 1'b0;
Expand Down

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