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Fix transfer(buf, size) with LSBFIRST on Teensy 3.x
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@PaulStoffregen
PaulStoffregen committed May 31, 2017
1 parent a8af486 commit 22b7dbd
Showing 1 changed file with 21 additions and 12 deletions.
33 changes: 21 additions & 12 deletions SPI.cpp
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Expand Up @@ -328,11 +328,13 @@ uint8_t SPIClass::setCS(uint8_t pin)
}


void SPIClass::transfer(void *buf, size_t count) {
void SPIClass::transfer(void *buf, size_t count)
{
if (count == 0) return;
uint8_t *p_write = (uint8_t *)buf;
uint8_t *p_read = p_write;
size_t count_read = count;
bool lsbfirst = (SPI0_CTAR0 & SPI_CTAR_LSBFE) ? true : false;

// Lets clear the reader queue
SPI0_MCR = SPI_MCR_MSTR | SPI_MCR_CLR_RXF | SPI_MCR_PCSIS(0x1F);
Expand All @@ -349,10 +351,10 @@ void SPIClass::transfer(void *buf, size_t count) {
}

while (count > 0) {

// Push out the next byte;
uint16_t w = (*p_write++) << 8;
uint16_t w = (*p_write++) << 8;
w |= *p_write++;
if (lsbfirst) w = __builtin_bswap16(w);
if (count == 2)
KINETISK_SPI0.PUSHR = w | SPI_PUSHR_CTAS(1);
else
Expand All @@ -367,13 +369,13 @@ void SPIClass::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
}
}
} while ((sr & (15 << 12)) > (3 << 12));

}

// now lets wait for all of the read bytes to be returned...
Expand All @@ -385,6 +387,7 @@ void SPIClass::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
Expand Down Expand Up @@ -533,11 +536,13 @@ uint8_t SPI1Class::setCS(uint8_t pin)
return 0;
}

void SPI1Class::transfer(void *buf, size_t count) {
void SPI1Class::transfer(void *buf, size_t count)
{
if (count == 0) return;
uint8_t *p_write = (uint8_t *)buf;
uint8_t *p_read = p_write;
size_t count_read = count;
bool lsbfirst = (SPI1_CTAR0 & SPI_CTAR_LSBFE) ? true : false;

// Lets clear the reader queue
SPI1_MCR = SPI_MCR_MSTR | SPI_MCR_CLR_RXF | SPI_MCR_PCSIS(0x1F);
Expand All @@ -551,10 +556,10 @@ void SPI1Class::transfer(void *buf, size_t count) {
}

while (count > 0) {

// Push out the next byte;
uint16_t w = (*p_write++) << 8;
uint16_t w = (*p_write++) << 8;
w |= *p_write++;
if (lsbfirst) w = __builtin_bswap16(w);
KINETISK_SPI1.PUSHR = w | SPI_PUSHR_CTAS(1);
count -= 2; // how many bytes to output.
// Make sure queue is not full before pushing next byte out
Expand All @@ -566,13 +571,13 @@ void SPI1Class::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
}
}
} while ((sr & (15 << 12)) > (0 << 12)); // SPI1 and 2 only have 1 item queue

}

// now lets wait for all of the read bytes to be returned...
Expand All @@ -584,6 +589,7 @@ void SPI1Class::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
Expand Down Expand Up @@ -723,11 +729,13 @@ uint8_t SPI2Class::setCS(uint8_t pin)
return 0;
}

void SPI2Class::transfer(void *buf, size_t count) {
void SPI2Class::transfer(void *buf, size_t count)
{
if (count == 0) return;
uint8_t *p_write = (uint8_t *)buf;
uint8_t *p_read = p_write;
size_t count_read = count;
bool lsbfirst = (SPI2_CTAR0 & SPI_CTAR_LSBFE) ? true : false;

// Lets clear the reader queue
SPI2_MCR = SPI_MCR_MSTR | SPI_MCR_CLR_RXF | SPI_MCR_PCSIS(0x1F);
Expand All @@ -741,10 +749,10 @@ void SPI2Class::transfer(void *buf, size_t count) {
}

while (count > 0) {

// Push out the next byte;
uint16_t w = (*p_write++) << 8;
uint16_t w = (*p_write++) << 8;
w |= *p_write++;
if (lsbfirst) w = __builtin_bswap16(w);
KINETISK_SPI2.PUSHR = w | SPI_PUSHR_CTAS(1);
count -= 2; // how many bytes to output.
// Make sure queue is not full before pushing next byte out
Expand All @@ -756,13 +764,13 @@ void SPI2Class::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
}
}
} while ((sr & (15 << 12)) > (0 << 12)); // SPI2 and 2 only have 1 item queue

}

// now lets wait for all of the read bytes to be returned...
Expand All @@ -774,6 +782,7 @@ void SPI2Class::transfer(void *buf, size_t count) {
*p_read++ = w; // Read any pending RX bytes in
count_read--;
} else {
if (lsbfirst) w = __builtin_bswap16(w);
*p_read++ = w >> 8;
*p_read++ = (w & 0xff);
count_read -= 2;
Expand Down

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