Fix potential undefined behavior in sin/cos

Author: dekutree64

src/common/foc_utils.cpp

@@ -10,7 +10,7 @@ __attribute__((weak)) float _sin(float a){
   // resulting precision compared to stdlib sine is 0.00006480 (RMS difference in range -PI,PI for 3217 steps)
   static uint16_t sine_array[65] = {0,804,1608,2411,3212,4011,4808,5602,6393,7180,7962,8740,9512,10279,11039,11793,12540,13279,14010,14733,15447,16151,16846,17531,18205,18868,19520,20160,20788,21403,22006,22595,23170,23732,24279,24812,25330,25833,26320,26791,27246,27684,28106,28511,28899,29269,29622,29957,30274,30572,30853,31114,31357,31581,31786,31972,32138,32286,32413,32522,32610,32679,32729,32758,32768};
   int32_t t1, t2;
-  unsigned int i = (unsigned int)(a * (64*4*256.0f/_2PI));
+  int i = (int)(a * (64*4*256.0f/_2PI));
   int frac = i & 0xff;
   i = (i >> 8) & 0xff;
   if (i < 64) {