replace standards-wobbling variable-length-arrays with alloca()

diff --git a/libs/panners/vbap/vbap_speakers.cc b/libs/panners/vbap/vbap_speakers.cc
index 313fe7a5cd8d3e8ebeb1ab62e18ece7697f8a4e1..6b50e34d5a99804bd31b5d245ec30aabe984440f 100644 (file)
--- a/libs/panners/vbap/vbap_speakers.cc
+++ b/libs/panners/vbap/vbap_speakers.cc
@@ -34,6 +34,7 @@
 #include <cmath>
 #include <algorithm>
 #include <stdlib.h>
+#include <alloca.h>
 
 #include "pbd/cartesian.h"
 
@@ -115,10 +116,14 @@ VBAPSpeakers::choose_speaker_triplets(struct ls_triplet_chain **ls_triplets)
 
        int i,j,k,l,table_size;
        int n_speakers = _speakers.size ();
-       int connections[n_speakers][n_speakers];
-       float distance_table[((n_speakers * (n_speakers - 1)) / 2)];
-       int distance_table_i[((n_speakers * (n_speakers - 1)) / 2)];
-       int distance_table_j[((n_speakers * (n_speakers - 1)) / 2)];
+       /* variable length arrays arrived in C99, became optional in C11, and
+          are only planned for C++14. Use alloca which is functionally
+          identical (but uglier to read).
+       */
+       int** connections = (int**) alloca (sizeof (int) * n_speakers * n_speakers);
+       float* distance_table = (float *) alloca (sizeof (float) * ((n_speakers * (n_speakers - 1)) / 2));
+       int* distance_table_i = (int *) alloca (sizeof (int) * ((n_speakers * (n_speakers - 1)) / 2));
+       int* distance_table_j = (int *) alloca (sizeof (int) * ((n_speakers * (n_speakers - 1)) / 2));
        float distance;
        struct ls_triplet_chain *trip_ptr, *prev, *tmp_ptr;
 
@@ -527,9 +532,13 @@ VBAPSpeakers::choose_speaker_pairs (){
        */
        const int n_speakers = _speakers.size();
        const double AZIMUTH_DELTA_THRESHOLD_DEGREES = (180.0/M_PI) * (M_PI - 0.175);
-       int sorted_speakers[n_speakers];
-       bool exists[n_speakers];
-       double inverse_matrix[n_speakers][4];
+       /* variable length arrays arrived in C99, became optional in C11, and
+          are only planned for C++14. Use alloca which is functionally
+          identical (but uglier to read).
+       */
+       int* sorted_speakers = (int*) alloca (sizeof (int) * n_speakers);
+       bool* exists = (bool*) alloca (sizeof(bool) * n_speakers);
+       double** inverse_matrix = (double**) alloca (sizeof (double) * n_speakers * 4);
        int expected_pairs = 0;
        int pair;
        int speaker;