FlapJackApps/libdivecomputer
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Improved some code comments.

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This commit is contained in:
Jef Driesen 2007-12-03 13:56:22 +00:00
parent 4d4b0f141f
commit d265228b26
1 changed files with 13 additions and 13 deletions
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26
suunto_vyper.c
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@ -421,12 +421,12 @@ suunto_vyper_read_dive (vyper *device, unsigned char data[], unsigned int size,
rc = serial_read (device->port, header, 2); rc = serial_read (device->port, header, 2);
if (rc != 2 || memcmp (command, header, 1) != 0 || if (rc != 2 || memcmp (command, header, 1) != 0 ||
header[1] > SUUNTO_VYPER_PACKET_SIZE) { header[1] > SUUNTO_VYPER_PACKET_SIZE) {
// If no data is received at this point (a timeout occured), // If no data is received because a timeout occured, we assume
// we assume the last package was already received and the // the last package was already received and the transmission
// transmission should be finished. This is not 100% reliable, // can be finished. Unfortunately this is not 100% reliable,
// because there is always a small chance that more data will // because there is always a small chance that more data will
// arrive later (especially with a short timeout). But I'm not // arrive later (especially with a short timeout). But it works
// aware of a better method to detect the end of the transmission. // good enough in practice.
// Only for the very first package, we can be sure there was // Only for the very first package, we can be sure there was
// an error, because the DC always sends at least one package. // an error, because the DC always sends at least one package.
if (rc == 0 && npackages != 0) if (rc == 0 && npackages != 0)
@ -465,11 +465,10 @@ suunto_vyper_read_dive (vyper *device, unsigned char data[], unsigned int size,
return SUUNTO_VYPER_ERROR_MEMORY; return SUUNTO_VYPER_ERROR_MEMORY;
} }
// A null package (length zero) indicates the DC reached the end of // The DC sends a null package (a package with length zero) when it
// its internal ring buffer and the transmission should be aborted. // has reached the end of its internal ring buffer. From this point on,
// The remaining data of the current dive is overwritten with newer // the current dive has been overwritten with newer data. Therefore,
// data and thus not transmitted by the DC. Therefore, the data that // we discard the current (incomplete) dive and end the transmission.
// was already received is discarded.
if (len == 0) if (len == 0)
return 0; return 0;
@ -481,9 +480,10 @@ suunto_vyper_read_dive (vyper *device, unsigned char data[], unsigned int size,
break; break;
} }
// The DC traverses the internal ring buffer backwards while sending. // The DC traverses its internal ring buffer backwards. The most recent
// Therefore, we restore the original order before returning the // dive is send first (which allows you to download only the new dives),
// data to the application. // but also the contents of each dive is reversed. Therefore, we reverse
// the bytes again before returning them to the application.
suunto_vyper_reverse (data, nbytes); suunto_vyper_reverse (data, nbytes);
#ifndef NDEBUG #ifndef NDEBUG