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Revert "Improve FrSky's CRC lib"

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Konstantin Sharlaimov 2020-05-09 09:13:51 +02:00 • committed by GitHub
parent 4da9245588
commit c0a87cdcc2
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 9 additions and 15 deletions
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2
src/main/rx/fport.c
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@ -255,7 +255,7 @@ static uint8_t fportFrameStatus(rxRuntimeConfig_t *rxRuntimeConfig)
if (frameLength != bufferLength - 2) { if (frameLength != bufferLength - 2) {
reportFrameError(DEBUG_FPORT_ERROR_SIZE); reportFrameError(DEBUG_FPORT_ERROR_SIZE);
} else { } else {
if (!frskyCheckSumIsGood(&rxBuffer[rxBufferReadIndex].data[0], bufferLength)) { if (!frskyChecksumIsGood(&rxBuffer[rxBufferReadIndex].data[0], bufferLength)) {
reportFrameError(DEBUG_FPORT_ERROR_CHECKSUM); reportFrameError(DEBUG_FPORT_ERROR_CHECKSUM);
} else { } else {
fportFrame_t *frame = (fportFrame_t *)&rxBuffer[rxBufferReadIndex].data[1]; fportFrame_t *frame = (fportFrame_t *)&rxBuffer[rxBufferReadIndex].data[1];

17
src/main/rx/frsky_crc.c
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@ -26,29 +26,22 @@ FILE_COMPILE_FOR_SPEED
void frskyCheckSumStep(uint16_t *checksum, uint8_t byte) void frskyCheckSumStep(uint16_t *checksum, uint8_t byte)
{ {
*checksum += byte; *checksum += byte;
*checksum += (*checksum >> 8);
*checksum &= 0xFF;
} }
void frskyCheckSumFini(uint16_t *checksum) void frskyCheckSumFini(uint16_t *checksum)
{ {
while (*checksum > 0xFF) {
*checksum = (*checksum & 0xFF) + (*checksum >> 8);
}
*checksum = 0xFF - *checksum; *checksum = 0xFF - *checksum;
} }
uint8_t frskyCheckSum(uint8_t *data, uint8_t length) bool frskyChecksumIsGood(uint8_t *data, uint8_t length)
{ {
uint16_t checksum = 0; uint16_t checksum = 0;
for (unsigned i = 0; i < length; i++) { for (unsigned i = 0; i < length; i++) {
frskyCheckSumStep(&checksum, *data++); frskyCheckSumStep(&checksum, *data++);
} }
frskyCheckSumFini(&checksum);
return checksum; return checksum == FRSKY_CHECKSUM_GOOD_VALUE;
} }
bool frskyCheckSumIsGood(uint8_t *data, uint8_t length)
{
uint16_t checksum = frskyCheckSum(data, length);
return checksum == 0xFF;
}

5
src/main/rx/frsky_crc.h
View file

@ -18,7 +18,8 @@
#include <stdbool.h> #include <stdbool.h>
#include <stdint.h> #include <stdint.h>
uint8_t frskyCheckSum(uint8_t *data, uint8_t length); #define FRSKY_CHECKSUM_GOOD_VALUE 0xFF
bool frskyCheckSumIsGood(uint8_t *data, uint8_t length);
bool frskyChecksumIsGood(uint8_t *data, uint8_t length);
void frskyCheckSumStep(uint16_t *checksum, uint8_t byte); // Add byte to checksum void frskyCheckSumStep(uint16_t *checksum, uint8_t byte); // Add byte to checksum
void frskyCheckSumFini(uint16_t *checksum); // Finalize checksum void frskyCheckSumFini(uint16_t *checksum); // Finalize checksum