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Add temperature compensation

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A new tempcomp directive can be used to specify a file for reading
current temperature, update interval and compensation coefficients. The
clock frequency corrections are applied in local module and are invisible
in upper layers. The measurements and corrections can be logged to
tempcomp.log file.
This commit is contained in:
Miroslav Lichvar
2010-04-12 17:07:57 +02:00
parent f12bc10917
commit c386d11765
10 changed files with 324 additions and 3 deletions
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43
local.c
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@@ -45,6 +45,9 @@
/* Variable to store the current frequency, in ppm */
static double current_freq_ppm;
/* Temperature compensation, in ppm */
static double temp_comp_ppm;
/* ================================================== */
/* Store the system dependent drivers */
@@ -152,6 +155,7 @@ LCL_Initialise(void)
/* This ought to be set from the system driver layer */
current_freq_ppm = 0.0;
temp_comp_ppm = 0.0;
calculate_sys_precision();
}
@@ -360,7 +364,16 @@ LCL_GetOffsetCorrection(struct timeval *raw, double *correction, double *err)
double
LCL_ReadAbsoluteFrequency(void)
{
return (*drv_read_freq)();
double freq;
freq = (*drv_read_freq)();
/* Undo temperature compensation */
if (temp_comp_ppm != 0.0) {
freq = (freq + temp_comp_ppm) / (1.0 - 1.0e-6 * temp_comp_ppm);
}
return freq;
}
/* ================================================== */
@@ -374,6 +387,11 @@ LCL_SetAbsoluteFrequency(double afreq_ppm)
struct timeval raw, cooked;
double dfreq;
/* Apply temperature compensation */
if (temp_comp_ppm != 0.0) {
afreq_ppm = afreq_ppm * (1.0 - 1.0e-6 * temp_comp_ppm) - temp_comp_ppm;
}
/* Call the system-specific driver for setting the frequency */
(*drv_set_freq)(afreq_ppm);
@@ -580,3 +598,26 @@ LCL_SetLeap(int leap)
}
/* ================================================== */
void
LCL_SetTempComp(double comp)
{
if (temp_comp_ppm == comp)
return;
/* Undo previous compensation */
current_freq_ppm = (current_freq_ppm + temp_comp_ppm) /
(1.0 - 1.0e-6 * temp_comp_ppm);
/* Apply new compensation */
current_freq_ppm = current_freq_ppm * (1.0 - 1.0e-6 * comp) - comp;
temp_comp_ppm = comp;
/* Call the system-specific driver for setting the frequency */
(*drv_set_freq)(current_freq_ppm);
return;
}
/* ================================================== */