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arduino API's SPI::transfer(void*, size) (optimized) #4925

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Merged
merged 6 commits into from
Jul 27, 2018
Merged

arduino API's SPI::transfer(void*, size) (optimized) #4925

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c85aa15
SPI::transfer(void*, size) (optimized)
d-a-v Jul 12, 2018
f190e04
spi: transfer(): fix checking size
d-a-v Jul 13, 2018
456c898
spi: transferBytes_: 32bits miso transfer
d-a-v Jul 13, 2018
67009fb
spi: transferBytes_: fix declaration
d-a-v Jul 13, 2018
e692175
spi: transferBytes: add comments, reduce diff
d-a-v Jul 13, 2018
1102f86
Merge branch 'master' into spitransfer
devyte Jul 27, 2018
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38 changes: 33 additions & 5 deletions libraries/SPI/SPI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -323,6 +323,25 @@ uint16_t SPIClass::transfer16(uint16_t data) {
return out.val;
}

void SPIClass::transfer(void *buf, uint16_t count) {
uint8_t *cbuf = reinterpret_cast<uint8_t*>(buf);

// cbuf may not be 32bits-aligned
for (; (((unsigned long)cbuf) & 3) && count; cbuf++, count--)
*cbuf = transfer(*cbuf);

// cbuf is now aligned
// count may not be a multiple of 4
uint16_t count4 = count & ~3;
transferBytes(cbuf, cbuf, count4);

// finish the last <4 bytes
cbuf += count4;
count -= count4;
for (; count; cbuf++, count--)
*cbuf = transfer(*cbuf);
}

void SPIClass::write(uint8_t data) {
while(SPI1CMD & SPIBUSY) {}
// reset to 8Bit mode
Expand Down Expand Up @@ -511,6 +530,14 @@ void SPIClass::transferBytes(const uint8_t * out, uint8_t * in, uint32_t size) {
}
}

/**
* Note:
* in and out need to be aligned to 32Bit
* or you get an Fatal exception (9)
* @param out uint8_t *
* @param in uint8_t *
* @param size uint8_t (max 64)
*/
void SPIClass::transferBytes_(const uint8_t * out, uint8_t * in, uint8_t size) {
while(SPI1CMD & SPIBUSY) {}
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I suggest an ASSERT() here checking the alignment of the inputs would be handy here and print a useful error when debugging was enabled...

// Set in/out Bits to transfer
Expand Down Expand Up @@ -539,12 +566,13 @@ void SPIClass::transferBytes_(const uint8_t * out, uint8_t * in, uint8_t size) {
while(SPI1CMD & SPIBUSY) {}

if(in) {
volatile uint8_t * fifoPtr8 = (volatile uint8_t *) &SPI1W0;
dataSize = size;
uint32_t * dataPtr = (uint32_t*) in;
fifoPtr = &SPI1W0;
dataSize = ((size + 3) / 4);
while(dataSize--) {
*in = *fifoPtr8;
in++;
fifoPtr8++;
*dataPtr = *fifoPtr;
dataPtr++;
fifoPtr++;
}
}
}
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1 change: 1 addition & 0 deletions libraries/SPI/SPI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ class SPIClass {
void beginTransaction(SPISettings settings);
uint8_t transfer(uint8_t data);
uint16_t transfer16(uint16_t data);
void transfer(void *buf, uint16_t count);
void write(uint8_t data);
void write16(uint16_t data);
void write16(uint16_t data, bool msb);
Expand Down