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Beautified SBUS code

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- use “defines” for each constant.
- do not change the frame pointer while checking frame validity (improves readability).
This commit is contained in:
Raphael Coeffic 2015-07-29 08:47:58 +02:00
parent 0cfe5b6c76
commit d2ed8d9287
1 changed files with 26 additions and 14 deletions
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40
radio/src/sbus.cpp
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@ -36,13 +36,23 @@
#include "opentx.h" #include "opentx.h"
#define SBUS_FLAGS_IDX 23 #define SBUS_MIN_FRAME_SIZE 23
#define SBUS_MAX_FRAME_SIZE 28
#define SBUS_FRAMELOST_BIT 2 #define SBUS_FRAME_GAP_DELAY 1000 // 500uS
#define SBUS_FAILSAFE_BIT 3
#define SBUS_START_BYTE 0x0F
#define SBUS_FLAGS_IDX 23
#define SBUS_FRAMELOST_BIT 2
#define SBUS_FAILSAFE_BIT 3
#define SBUS_CH_BITS 11
#define SBUS_CH_MASK ((1<<SBUS_CH_BITS)-1)
#define SBUS_CH_CENTER 0x3E0
Fifo<32> sbusFifo; Fifo<32> sbusFifo;
uint8_t SbusFrame[28] ; uint8_t SbusFrame[SBUS_MAX_FRAME_SIZE];
uint16_t SbusTimer ; uint16_t SbusTimer ;
uint8_t SbusIndex = 0 ; uint8_t SbusIndex = 0 ;
@ -51,11 +61,11 @@ void processSbusFrame(uint8_t *sbus, int16_t *pulses, uint32_t size)
uint32_t inputbitsavailable = 0; uint32_t inputbitsavailable = 0;
uint32_t inputbits = 0; uint32_t inputbits = 0;
if (*sbus++ != 0x0F) { if (sbus[0] != SBUS_START_BYTE) {
return; // not a valid SBUS frame return; // not a valid SBUS frame
} }
if (size < 23) { if (size < SBUS_MIN_FRAME_SIZE) {
return; return;
} }
@ -64,20 +74,22 @@ void processSbusFrame(uint8_t *sbus, int16_t *pulses, uint32_t size)
return; // SBUS failsafe mode return; // SBUS failsafe mode
} }
// Skip start byte
sbus++;
for (uint32_t i=0; i<NUM_TRAINER; i++) { for (uint32_t i=0; i<NUM_TRAINER; i++) {
while (inputbitsavailable < 11) { while (inputbitsavailable < SBUS_CH_BITS) {
inputbits |= *sbus++ << inputbitsavailable; inputbits |= *sbus++ << inputbitsavailable;
inputbitsavailable += 8; inputbitsavailable += 8;
} }
*pulses++ = ((int32_t) (inputbits & 0x7FF) - 0x3E0) * 5 / 8; *pulses++ = ((int32_t) (inputbits & SBUS_CH_MASK) - SBUS_CH_CENTER) * 5 / 8;
inputbitsavailable -= 11; inputbitsavailable -= SBUS_CH_BITS;
inputbits >>= 11; inputbits >>= SBUS_CH_BITS;
} }
ppmInValid = PPM_IN_VALID_TIMEOUT; ppmInValid = PPM_IN_VALID_TIMEOUT;
} }
#define SBUS_DELAY 1000 // 500uS
void processSbusInput() void processSbusInput()
{ {
uint8_t rxchar; uint8_t rxchar;
@ -85,8 +97,8 @@ void processSbusInput()
while (sbusFifo.pop(rxchar)) { while (sbusFifo.pop(rxchar)) {
active = 1; active = 1;
SbusFrame[SbusIndex++] = rxchar; SbusFrame[SbusIndex++] = rxchar;
if (SbusIndex > 27) { if (SbusIndex > SBUS_MAX_FRAME_SIZE-1) {
SbusIndex = 27; SbusIndex = SBUS_MAX_FRAME_SIZE-1;
} }
} }
if (active) { if (active) {
@ -95,7 +107,7 @@ void processSbusInput()
} }
else { else {
if (SbusIndex) { if (SbusIndex) {
if ((uint16_t) (getTmr2MHz() - SbusTimer) > SBUS_DELAY) { if ((uint16_t) (getTmr2MHz() - SbusTimer) > SBUS_FRAME_GAP_DELAY) {
processSbusFrame(SbusFrame, g_ppmIns, SbusIndex); processSbusFrame(SbusFrame, g_ppmIns, SbusIndex);
SbusIndex = 0; SbusIndex = 0;
} }