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AP_Airspeed: Commonize the CRC4 method

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This commit is contained in:
murata 2019-04-24 15:52:34 +09:00 committed by Tom Pittenger
parent 716cc26082
commit 295c343959
1 changed files with 2 additions and 21 deletions
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23
libraries/AP_Airspeed/AP_Airspeed_MS5525.cpp
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@ -26,6 +26,7 @@
#include <AP_HAL/I2CDevice.h> #include <AP_HAL/I2CDevice.h>
#include <AP_HAL/utility/sparse-endian.h> #include <AP_HAL/utility/sparse-endian.h>
#include <AP_Math/AP_Math.h> #include <AP_Math/AP_Math.h>
#include <AP_Math/crc.h>
extern const AP_HAL::HAL &hal; extern const AP_HAL::HAL &hal;
@ -113,27 +114,7 @@ bool AP_Airspeed_MS5525::init()
*/ */
uint16_t AP_Airspeed_MS5525::crc4_prom(void) uint16_t AP_Airspeed_MS5525::crc4_prom(void)
{ {
uint16_t n_rem = 0; return crc_crc4(prom);
uint8_t n_bit;
for (uint8_t cnt = 0; cnt < sizeof(prom); cnt++) {
/* uneven bytes */
if (cnt & 1) {
n_rem ^= (uint8_t)((prom[cnt >> 1]) & 0x00FF);
} else {
n_rem ^= (uint8_t)(prom[cnt >> 1] >> 8);
}
for (n_bit = 8; n_bit > 0; n_bit--) {
if (n_rem & 0x8000) {
n_rem = (n_rem << 1) ^ 0x3000;
} else {
n_rem = (n_rem << 1);
}
}
}
return (n_rem >> 12) & 0xF;
} }
bool AP_Airspeed_MS5525::read_prom(void) bool AP_Airspeed_MS5525::read_prom(void)