From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 9 Jan 2014 15:34:59 +0000 (+0100)
Subject: Fix frequency accumulation again
X-Git-Tag: 1.30-pre1~153
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=60d0fa299307076143da94d36deb7b908fa9bdb7;p=thirdparty%2Fchrony.git

Fix frequency accumulation again

This is a revert of commit 99d18abf updated for later changes. It seems
in that commit the calculation was changed to match the reversed dfreq
added in 1a7415a6, which itself was calculated incorrectly. Fix the
calculation of updated frequency and matching dfreq.
---

diff --git a/local.c b/local.c
index 8de198ed..e4be12b6 100644
--- a/local.c
+++ b/local.c
@@ -382,7 +382,7 @@ LCL_SetAbsoluteFrequency(double afreq_ppm)
   
   afreq_ppm = (*drv_set_freq)(afreq_ppm);
 
-  dfreq = (afreq_ppm - current_freq_ppm) / (1.0e6 + current_freq_ppm);
+  dfreq = (afreq_ppm - current_freq_ppm) / (1.0e6 - current_freq_ppm);
 
   LCL_ReadRawTime(&raw);
   LCL_CookTime(&raw, &cooked, NULL);
@@ -411,11 +411,11 @@ LCL_AccumulateDeltaFrequency(double dfreq)
    are handled in units of ppm, whereas the 'dfreq' argument is in
    terms of the gradient of the (offset) v (local time) function. */
 
-  current_freq_ppm = (1.0 + dfreq) * current_freq_ppm + 1.0e6 * dfreq;
+  current_freq_ppm = (1.0 - dfreq) * current_freq_ppm + 1.0e6 * dfreq;
 
   /* Call the system-specific driver for setting the frequency */
   current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
-  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 + old_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
 
   LCL_ReadRawTime(&raw);
   LCL_CookTime(&raw, &cooked, NULL);
@@ -508,14 +508,14 @@ LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)
   /* Work out new absolute frequency.  Note that absolute frequencies
    are handled in units of ppm, whereas the 'dfreq' argument is in
    terms of the gradient of the (offset) v (local time) function. */
-  current_freq_ppm = (1.0 + dfreq) * old_freq_ppm + 1.0e6 * dfreq;
+  current_freq_ppm = (1.0 - dfreq) * old_freq_ppm + 1.0e6 * dfreq;
 
   DEBUG_LOG(LOGF_Local, "old_freq=%.3fppm new_freq=%.3fppm offset=%.6fsec",
       old_freq_ppm, current_freq_ppm, doffset);
 
   /* Call the system-specific driver for setting the frequency */
   current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
-  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 + old_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
 
   (*drv_accrue_offset)(doffset, corr_rate);
 
diff --git a/rtc_linux.c b/rtc_linux.c
index fe52c336..3fcf2976 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -282,7 +282,7 @@ slew_samples
 
   if (coefs_valid) {
     coef_seconds_fast += doffset;
-    coef_gain_rate = (1.0 + dfreq) * (1.0 + coef_gain_rate) - 1.0;
+    coef_gain_rate = (1.0 - dfreq) * coef_gain_rate + dfreq;
   }
 
   DEBUG_LOG(LOGF_RtcLinux, "dfreq=%.8f doffset=%.6f old_fast=%.6f old_rate=%.3f new_fast=%.6f new_rate=%.3f",