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Reduce amount of wasted dataflash space upon power cycle 

This wasted overhead becomes important when using the Blackbox "pause"
switch and logging very few of your flights.
This commit is contained in:
Nicholas Sherlock 2015-09-11 14:15:43 +12:00
parent 7fe674a57d
commit 6c231e189b
1 changed files with 9 additions and 5 deletions
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14
src/main/io/flashfs.c
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@ -481,7 +481,7 @@ int flashfsIdentifyStartOfFreeSpace()
/* We can choose whatever power of 2 size we like, which determines how much wastage of free space we'll have
* at the end of the last written data. But smaller blocksizes will require more searching.
*/
FREE_BLOCK_SIZE = 65536,
FREE_BLOCK_SIZE = 2048,
/* We don't expect valid data to ever contain this many consecutive uint32_t's of all 1 bits: */
FREE_BLOCK_TEST_SIZE_INTS = 4, // i.e. 16 bytes
@ -493,16 +493,20 @@ int flashfsIdentifyStartOfFreeSpace()
uint32_t ints[FREE_BLOCK_TEST_SIZE_INTS];
} testBuffer;
int left = 0;
int right = flashfsGetSize() / FREE_BLOCK_SIZE;
int mid, result = right;
int left = 0; // Smallest block index in the search region
int right = flashfsGetSize() / FREE_BLOCK_SIZE; // One past the largest block index in the search region
int mid;
int result = right;
int i;
bool blockErased;
while (left < right) {
mid = (left + right) / 2;
m25p16_readBytes(mid * FREE_BLOCK_SIZE, testBuffer.bytes, FREE_BLOCK_TEST_SIZE_BYTES);
if (m25p16_readBytes(mid * FREE_BLOCK_SIZE, testBuffer.bytes, FREE_BLOCK_TEST_SIZE_BYTES) < FREE_BLOCK_TEST_SIZE_BYTES) {
// Unexpected timeout from flash, so bail early (reporting the device fuller than it really is)
break;
}
// Checking the buffer 4 bytes at a time like this is probably faster than byte-by-byte, but I didn't benchmark it :)
blockErased = true;