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Break offset calculation out into a separate function 

This change will allow for a test program to verify that the offset
computation is valid.
pull/22/head
nirenjan 2020-06-09 14:43:59 -07:00
parent c9ffb415c8
commit 4d93df1d58
1 changed files with 44 additions and 52 deletions
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96
lib/libx52/x52_control.c
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@ -209,6 +209,45 @@ static int _x52_write_date(libx52_device *x52, uint32_t bit)
return rc;
}
int _x52_calculate_clock_offset(libx52_device *x52, libx52_clock_id clock, uint16_t h24)
{
int offset;
int negative;
offset = x52->timezone[clock] - x52->timezone[LIBX52_CLOCK_1];
/* Save the preliminary state, if negative, set the negative flag */
if (offset < 0) {
negative = 1;
offset = -offset;
} else {
negative = 0;
}
/* Because the packet format limits the offset from the base clock to
* a maximum of +/- 1023, we can only handle a maximum offset of 17
* hours from the base clock. Eg. Honolulu and Auckland at -1000 and
* +1200 respectively have a direct offset of +22 hours. A potentially
* greater issue is to take the two extreme timezones at -1200 and +1400
* for a difference of +26 hours. The safe bet is to check if the offset
* exceeds +/- 1023, and subtract 1440, which will convert the offset of
* +22 to -2 hours, or +26 to +4 hours.
*/
while (offset > 1023) {
offset -= 1440; // Subtract 24 hours
}
/* If offset is between 1024 and 1440, then we need to reverse the
* negative flag
*/
if (offset < 0) {
negative = !negative;
offset = -offset;
}
return (h24 << 15 | negative << 10 | (offset & 0x3FF));
}
static int _x52_write_time(libx52_device *x52, uint32_t bit)
{
uint16_t value = 0;
@ -218,72 +257,26 @@ static int _x52_write_time(libx52_device *x52, uint32_t bit)
switch (bit) {
case X52_BIT_MFD_TIME:
clock = LIBX52_CLOCK_1;
index = X52_TIME_CLOCK1;
break;
case X52_BIT_MFD_OFFS1:
clock = LIBX52_CLOCK_2;
index = X52_OFFS_CLOCK2;
break;
case X52_BIT_MFD_OFFS2:
clock = LIBX52_CLOCK_3;
index = X52_OFFS_CLOCK3;
break;
}
uint16_t h24 = !!(x52->time_format[clock]);
if (clock != LIBX52_CLOCK_1) {
int offset;
int negative;
offset = x52->timezone[clock] - x52->timezone[LIBX52_CLOCK_1];
/* Save the preliminary state, if negative, set the negative flag */
if (offset < 0) {
negative = 1;
offset = -offset;
} else {
negative = 0;
}
/* Because the packet format limits the offset from the base clock to
* a maximum of +/- 1023, we can only handle a maximum offset of 17
* hours from the base clock. Eg. Honolulu and Auckland at -1000 and
* +1200 respectively have a direct offset of +22 hours. A potentially
* greater issue is to take the two extreme timezones at -1200 and +1400
* for a difference of +26 hours. The safe bet is to check if the offset
* exceeds +/- 1023, and subtract 1440, which will convert the offset of
* +22 to -2 hours, or +26 to +4 hours.
*/
while (offset > 1023) {
offset -= 1440; // Subtract 24 hours
}
/* If offset is between 1024 and 1440, then we need to reverse the
* negative flag
*/
if (offset < 0) {
negative = !negative;
offset = -offset;
}
value = h24 << 15 |
negative << 10 |
(offset & 0x3FF);
}
switch (clock) {
case LIBX52_CLOCK_1:
index = X52_TIME_CLOCK1;
value = _x52_calculate_clock_offset(x52, clock, h24);
} else {
value = h24 << 15 |
(x52->time_hour & 0x7F) << 8 |
(x52->time_minute & 0xFF);
break;
case LIBX52_CLOCK_2:
index = X52_OFFS_CLOCK2;
break;
case LIBX52_CLOCK_3:
index = X52_OFFS_CLOCK3;
break;
}
return libx52_vendor_command(x52, index, value);
@ -329,7 +322,6 @@ int libx52_update(libx52_device *x52)
{
unsigned int i;
uint32_t update_mask;
uint16_t value;
int rc = LIBX52_SUCCESS;
x52_handler handler;