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-rw-r--r--usrp2/timing/time_compare.v44
1 files changed, 7 insertions, 37 deletions
diff --git a/usrp2/timing/time_compare.v b/usrp2/timing/time_compare.v
index 54ea000d6..21607f51c 100644
--- a/usrp2/timing/time_compare.v
+++ b/usrp2/timing/time_compare.v
@@ -1,5 +1,5 @@
//
-// Copyright 2011 Ettus Research LLC
+// Copyright 2011-2012 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
@@ -16,49 +16,19 @@
//
-// Top 32 bits are integer seconds, bottom 32 are clock ticks within a second
+// 64 bits worth of ticks
module time_compare
(input [63:0] time_now,
input [63:0] trigger_time,
output now,
output early,
- output late,
+ output late,
output too_early);
-
- wire sec_match = (time_now[63:32] == trigger_time[63:32]);
- wire sec_late = (time_now[63:32] > trigger_time[63:32]);
- wire tick_match = (time_now[31:0] == trigger_time[31:0]);
- wire tick_late = (time_now[31:0] > trigger_time[31:0]);
-/*
- assign now = sec_match & tick_match;
- assign late = sec_late | (sec_match & tick_late);
- assign early = ~now & ~late;
-*/
+ assign now = time_now == trigger_time;
+ assign late = time_now > trigger_time;
+ assign early = ~now & ~late;
+ assign too_early = 0; //not implemented
- /*
- assign now = (time_now == trigger_time);
- assign late = (time_now > trigger_time);
- assign early = (time_now < trigger_time);
- */
-
- // Compare fewer bits instead of 64 to speed up logic
- // Unused bits are not significant
- // Top bit of seconds would put us in year 2038, long after
- // the warranty has run out :)
- // Top 5 bits of ticks are always zero for clocks less than 134MHz
- // "late" can drop bottom few bits of ticks, and just delay signaling
- // of late.
- // "now" cannot drop those bits, it needs to be exact.
-
- wire [57:0] short_now = {time_now[62:32],time_now[26:0]};
- wire [57:0] short_trig = {trigger_time[62:32],trigger_time[26:0]};
-
- assign now = (short_now == short_trig);
- assign late = (short_now[57:5] > short_trig[57:5]);
- assign early = (short_now < short_trig);
-
- assign too_early = (trigger_time[63:32] > (time_now[63:32] + 4)); // Don't wait too long
-
endmodule // time_compare