Fix more Coverity issues in the PHY lib

CID 369560 Missing unlock, in dft_fftw.c
CID 363710 Logically dead code, in resampler.c
CID 55097 Result is not floating point, in chest_test_dl.c
CID 351020 Result is not floating point, in chest_nbiot_test_dl.c

lib/src/phy/ch_estimation/test/chest_nbiot_test_dl.c

@@ -145,7 +145,7 @@ int main(int argc, char** argv)
     for (int n_port = 0; n_port < cell.base.nof_ports; n_port++) {
       srsran_vec_cf_zero(input, num_re);
       for (int i = 0; i < num_re; i++) {
-        input[i] = 0.5 - rand() / RAND_MAX + I * (0.5 - rand() / RAND_MAX);
+        input[i] = 0.5 - rand() / (float)RAND_MAX + I * (0.5 - rand() / (float)RAND_MAX);
       }
 
       srsran_vec_cf_zero(ce, num_re);

lib/src/phy/ch_estimation/test/chest_test_dl.c

@@ -137,7 +137,7 @@ int main(int argc, char** argv)
       for (uint32_t n_port = 0; n_port < cell.nof_ports; n_port++) {
         srsran_vec_cf_zero(input, num_re);
         for (i = 0; i < num_re; i++) {
-          input[i] = 0.5 - rand() / RAND_MAX + I * (0.5 - rand() / RAND_MAX);
+          input[i] = 0.5 - rand() / (float)RAND_MAX + I * (0.5 - rand() / (float)RAND_MAX);
         }
 
         srsran_vec_cf_zero(ce, num_re);

lib/src/phy/dft/dft_fftw.c

@@ -209,6 +209,7 @@ int srsran_dft_plan_guru_c(srsran_dft_plan_t* plan,
 
   plan->p = fftwf_plan_guru_dft(1, &iodim, 1, &howmany_dims, in_buffer, out_buffer, sign, FFTW_TYPE);
   if (!plan->p) {
+    pthread_mutex_unlock(&fft_mutex);
     return -1;
   }
   pthread_mutex_unlock(&fft_mutex);

lib/src/phy/resampling/resampler.c

@@ -234,31 +234,27 @@ static void resampler_fft_decimate(srsran_resampler_fft_t* q, const cf_t* input,
   while (count < nsamples) {
     uint32_t n = SRSRAN_MIN(q->window_sz, nsamples - count);
 
-    if (input) {
+    // Copy input samples
-      // Copy input samples
+    srsran_vec_cf_copy(q->in_buffer, &input[count], n);
-      srsran_vec_cf_copy(q->in_buffer, &input[count], n);
-
-      // Pad zeroes
-      srsran_vec_cf_zero(&q->in_buffer[n], q->fft.size - n);
 
-      // Execute FFT
+    // Pad zeroes
-      srsran_dft_run_guru_c(&q->fft);
+    srsran_vec_cf_zero(&q->in_buffer[n], q->fft.size - n);
 
-      // Apply filter
+    // Execute FFT
-      srsran_vec_prod_ccc(q->out_buffer, q->filter, q->out_buffer, q->fft.size);
+    srsran_dft_run_guru_c(&q->fft);
 
-      // Decimate
+    // Apply filter
-      srsran_vec_cf_copy(q->in_buffer, q->out_buffer, q->ifft.size);
+    srsran_vec_prod_ccc(q->out_buffer, q->filter, q->out_buffer, q->fft.size);
-      for (uint32_t i = 1; i < q->ratio; i++) {
-        srsran_vec_sum_ccc(&q->out_buffer[q->ifft.size * i], q->in_buffer, q->in_buffer, q->ifft.size);
-      }
 
-      // Execute iFFT
+    // Decimate
-      srsran_dft_run_guru_c(&q->ifft);
+    srsran_vec_cf_copy(q->in_buffer, q->out_buffer, q->ifft.size);
-    } else {
+    for (uint32_t i = 1; i < q->ratio; i++) {
-      srsran_vec_cf_zero(q->out_buffer, q->ifft.size);
+      srsran_vec_sum_ccc(&q->out_buffer[q->ifft.size * i], q->in_buffer, q->in_buffer, q->ifft.size);
     }
 
+    // Execute iFFT
+    srsran_dft_run_guru_c(&q->ifft);
+
     // Add previous state
     srsran_vec_sum_ccc(q->out_buffer, q->state, q->out_buffer, q->state_len);