From 95ece1f65d38a807ace68c18441693ac4137f126 Mon Sep 17 00:00:00 2001
From: wukong <wukong@longaeva>
Date: Tue, 13 Jan 2026 21:30:27 -0800
Subject: enabled alternate t0 based prediction of t_up; added prediction of t0
 baed on new t_meas value; merge t0 prediction with updated (measured) t0
 rather than t0_prev;

---
 ckt0.awk | 58 +++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 33 insertions(+), 25 deletions(-)

(limited to 'ckt0.awk')

diff --git a/ckt0.awk b/ckt0.awk
index 68dd358..35ff5ca 100644
--- a/ckt0.awk
+++ b/ckt0.awk
@@ -167,7 +167,7 @@ BEGIN {
     "uname" | getline uname
     close("uname")
 
-    # check ARGV for previous estimates
+    ## check ARGV for previous estimates
     if (ARGC) {
         ARGV[1] ? t_prev[1] = ARGV[1] : t_prev[1] = 0.0
         ARGV[2] ? t_prev[2] = ARGV[2] : t_prev[2] = ck_time(uname)
@@ -177,12 +177,12 @@ BEGIN {
         ARGV[6] ? t0_prev[2] = ARGV[6] : split(ck_boottime(uname), t0_prev)
     }
 
-    # check systime, check uptime, check systime again
+    ## check systime, check uptime, check systime again
     t_meas[1] = ck_time(uname)
     split(ck_uptime(), t_up_meas)
     t_meas[2] = ck_time(uname)
 
-    # convert to [val, unc] vector
+    ## convert to [val, unc] vector
     t_meas[2] -= t_meas[1]
     t_meas[1] += 0.5*t_meas[2]
     if ( t_meas[2] == 0.0 ) {
@@ -191,44 +191,52 @@ BEGIN {
     }
     t_meas_str = sigfig(t_meas[1], t_meas[2])
 
-    # estimate dt
+    ## estimate dt
     dt[1] = t_meas[1] - t_prev[1]
     dt[2] = t_meas[2] + t_prev[2]
 
-    # predict uptime based on dt, t_up(new) = t_up(old) + dt
+    ## predict uptime based on dt, t_up(new) = t_up(old) + dt
     t_up_est[1] = t_up_prev[1] + dt[1]
     t_up_est[2] = t_up_prev[2] + dt[2]
+
+    ## check for difference between dt and dt_up
     t_up_est[2] += sqrt((t_up_est[1] - t_up_prev[1] - dt[1])^2.0)
     t_up_prev[2] += sqrt((t_up_est[1] - t_up_prev[1] - dt[1])^2.0)
 
-    # alt. prediction based on t0
-    # t_up_alt[1] = t_meas[1] - t0_prev[1]
-    # t_up_alt[2] = t_meas[2] + t0_prev[2]
+    ## alt. t_up prediction based on t0_prev
+    t_up_alt[1] = t_meas[1] - t0_prev[1]
+    t_up_alt[2] = t_meas[2] + t0_prev[2]
+
+    ## dt_up_alt
+    dt_up_alt[1] = t_up_alt[1] - t_up_prev[1]
+    dt_up_alt[2] = t_up_alt[2] + t_up_prev[2]
 
-    # dt_up_alt
-    # dt_up_alt[1] = t_up_alt[1] - (t_prev[1] - t0_prev[1])
-    # dt_up_alt[2] = t_up_alt[2] + (t_prev[2] + t0_prev[2])
+    ## additional error terms
+    t_up_alt[2] += sqrt((dt_up_alt[1] - dt[1])^2.0)
+    t_up_alt[2] += sqrt((t_up_alt[1] - t_up_est[1])^2.0)
+    t_up_est[2] += sqrt((t_up_est[1] - t_up_alt[1])^2.0)
 
-    # merge alt. prediction
-    # t_up_alt[2] += sqrt((dt_up_alt[1] - dt[1])^2.0)
-    # t_up_alt[2] += sqrt((t_up_alt[1] - t_up_est[1])^2.0)
-    # t_up_est[2] += sqrt((t_up_est[1] - t_up_alt[1])^2.0)
+    ## merge alt. prediction
+    split(merge_meas(t_up_est[1], t_up_est[2], t_up_alt[1], t_up_alt[2]), t_up_est)
 
-    # split(merge_meas(t_up_est[1], t_up_est[2], t_up_alt[1], t_up_alt[2]), t_up_est)
-    # t_up_est[2] += (1.0E-3*rand())^2.0
+    ## predict boot time, t0
+    t0_est[1] = t_meas[1] - t_up_est[1]
+    t0_est[2] = t_meas[2] + t_up_est[2]
 
-    # merge predicted and measured uptimes
+    ## merge predicted and measured uptimes
     split(merge_meas(t_up_est[1], t_up_est[2], t_up_meas[1], t_up_meas[2]), t_up_est)
     t_up_est_str = sigfig(t_up_est[1], t_up_est[2])
 
-    # evaluate measured boot time, t0
-    t0_est[1] = t_meas[1] - t_up_est[1]
-    t0_est[2] = t_meas[2] + t_up_est[2]
-    t0_est[2] += sqrt((t0_est[1] - t0_prev[1])^2.0)
-    t0_prev[2] += sqrt((t0_est[1] - t0_prev[1])^2.0)
+    ## evaluate measured boot time, t0
+    t0_meas[1] = t_meas[1] - t_up_est[1]
+    t0_meas[2] = t_meas[2] + t_up_est[2]
+
+    ## additional error terms
+    t0_meas[2] += sqrt((t0_meas[1] - t0_est[1])^2.0)
+    t0_est[2] += sqrt((t0_meas[1] - t0_est[1])^2.0)
 
-    # merge previous and updated boot time, t0
-    split(merge_meas(t0_est[1], t0_est[2], t0_prev[1], t0_prev[2]), t0_est)
+    ## merge previous and updated boot time, t0
+    split(merge_meas(t0_meas[1], t0_meas[2], t0_est[1], t0_est[2]), t0_est)
 
     t0_est_str = sigfig(t0_est[1], t0_est[2])
 
-- 
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