/**
* Write bytes to a flash page. Address must not cross a page boundary.
*
* Bits can only be set to zero, not from zero back to one again. In order to set bits to 1, use the erase command.
*
* Length must be smaller than the page size.
*
* This will wait for the flash to become ready before writing begins.
*
* Datasheet indicates typical programming time is 0.8ms for 256 bytes, 0.2ms for 64 bytes, 0.05ms for 16 bytes.
* (Although the maximum possible write time is noted as 5ms).
*
* If you want to write multiple buffers (whose sum of sizes is still not more than the page size) then you can
* break this operation up into one beginProgram call, one or more continueProgram calls, and one finishProgram call.
*/
void m25p16_pageProgram(uint32_t address, const uint8_t *data, int length)
{
m25p16_pageProgramBegin(address);
m25p16_pageProgramContinue(data, length);
m25p16_pageProgramFinish();
}
/**
* Write the given buffers to flash sequentially at the current tail address, advancing the tail address after
* each write.
*
* In synchronous mode, waits for the flash to become ready before writing so that every byte requested can be written.
*
* In asynchronous mode, if the flash is busy, then the write is aborted and the routine returns immediately.
* In this case the returned number of bytes written will be less than the total amount requested.
*
* Modifies the supplied buffer pointers and sizes to reflect how many bytes remain in each of them.
*
* bufferCount: the number of buffers provided
* buffers: an array of pointers to the beginning of buffers
* bufferSizes: an array of the sizes of those buffers
* sync: true if we should wait for the device to be idle before writes, otherwise if the device is busy the
* write will be aborted and this routine will return immediately.
*
* Returns the number of bytes written
*/
static uint32_t flashfsWriteBuffers(uint8_t const **buffers, uint32_t *bufferSizes, int bufferCount, bool sync)
{
uint32_t bytesTotal = 0;
int i;
for (i = 0; i < bufferCount; i++) {
bytesTotal += bufferSizes[i];
}
if (!sync && !m25p16_isReady()) {
return 0;
}
uint32_t bytesTotalRemaining = bytesTotal;
while (bytesTotalRemaining > 0) {
uint32_t bytesTotalThisIteration;
uint32_t bytesRemainThisIteration;
/*
* Each page needs to be saved in a separate program operation, so
* if we would cross a page boundary, only write up to the boundary in this iteration:
*/
if (tailAddress % M25P16_PAGESIZE + bytesTotalRemaining > M25P16_PAGESIZE) {
bytesTotalThisIteration = M25P16_PAGESIZE - tailAddress % M25P16_PAGESIZE;
} else {
bytesTotalThisIteration = bytesTotalRemaining;
}
// Are we at EOF already? Abort.
if (flashfsIsEOF()) {
// May as well throw away any buffered data
flashfsClearBuffer();
break;
}
m25p16_pageProgramBegin(tailAddress);
bytesRemainThisIteration = bytesTotalThisIteration;
for (i = 0; i < bufferCount; i++) {
if (bufferSizes[i] > 0) {
// Is buffer larger than our write limit? Write our limit out of it
if (bufferSizes[i] >= bytesRemainThisIteration) {
m25p16_pageProgramContinue(buffers[i], bytesRemainThisIteration);
buffers[i] += bytesRemainThisIteration;
bufferSizes[i] -= bytesRemainThisIteration;
bytesRemainThisIteration = 0;
break;
} else {
// We'll still have more to write after finishing this buffer off
m25p16_pageProgramContinue(buffers[i], bufferSizes[i]);
bytesRemainThisIteration -= bufferSizes[i];
buffers[i] += bufferSizes[i];
bufferSizes[i] = 0;
}
}
}
m25p16_pageProgramFinish();
bytesTotalRemaining -= bytesTotalThisIteration;
// Advance the cursor in the file system to match the bytes we wrote
flashfsSetTailAddress(tailAddress + bytesTotalThisIteration);
/*
* We'll have to wait for that write to complete before we can issue the next one, so if
* the user requested asynchronous writes, break now.
*/
if (!sync)
break;
}
return bytesTotal - bytesTotalRemaining;
}