[FFmpeg-devel] [PATCH] elbg: remove VLAs

[Mans Rullgard]

---
 libavcodec/elbg.c |   38 +++++++++++++++++++++++---------------
 1 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/libavcodec/elbg.c b/libavcodec/elbg.c
index d6a4ce7..175d2c6 100644
--- a/libavcodec/elbg.c
+++ b/libavcodec/elbg.c
@@ -53,6 +53,7 @@ typedef struct{
     int *nearest_cb;
     int *points;
     AVLFG *rand_state;
+    int *scratchbuf;
 } elbg_data;
 
 static inline int distance_limited(int *a, int *b, int dim, int limit)
@@ -117,7 +118,8 @@ static int get_high_utility_cell(elbg_data *elbg)
 /**
  * Implementation of the simple LBG algorithm for just two codebooks
  */
-static int simple_lbg(int dim,
+static int simple_lbg(elbg_data *elbg,
+                      int dim,
                       int *centroid[3],
                       int newutility[3],
                       int *points,
@@ -125,10 +127,13 @@ static int simple_lbg(int dim,
 {
     int i, idx;
     int numpoints[2] = {0,0};
-    int newcentroid[2][dim];
+    int *newcentroid[2] = {
+        elbg->scratchbuf + 3*dim,
+        elbg->scratchbuf + 4*dim
+    };
     cell *tempcell;
 
-    memset(newcentroid, 0, sizeof(newcentroid));
+    memset(newcentroid[0], 0, 2 * dim * sizeof(*newcentroid[0]));
 
     newutility[0] =
     newutility[1] = 0;
@@ -158,8 +163,8 @@ static void get_new_centroids(elbg_data *elbg, int huc, int *newcentroid_i,
                               int *newcentroid_p)
 {
     cell *tempcell;
-    int min[elbg->dim];
-    int max[elbg->dim];
+    int *min = newcentroid_i;
+    int *max = newcentroid_p;
     int i;
 
     for (i=0; i< elbg->dim; i++) {
@@ -174,8 +179,10 @@ static void get_new_centroids(elbg_data *elbg, int huc, int *newcentroid_i,
         }
 
     for (i=0; i<elbg->dim; i++) {
-        newcentroid_i[i] = min[i] + (max[i] - min[i])/3;
-        newcentroid_p[i] = min[i] + (2*(max[i] - min[i]))/3;
+        int ni = min[i] + (max[i] - min[i])/3;
+        int np = min[i] + (2*(max[i] - min[i]))/3;
+        newcentroid_i[i] = ni;
+        newcentroid_p[i] = np;
     }
 }
 
@@ -248,14 +255,13 @@ static void try_shift_candidate(elbg_data *elbg, int idx[3])
 {
     int j, k, olderror=0, newerror, cont=0;
     int newutility[3];
-    int newcentroid[3][elbg->dim];
-    int *newcentroid_ptrs[3];
+    int *newcentroid[3] = {
+        elbg->scratchbuf,
+        elbg->scratchbuf + elbg->dim,
+        elbg->scratchbuf + 2*elbg->dim
+    };
     cell *tempcell;
 
-    newcentroid_ptrs[0] = newcentroid[0];
-    newcentroid_ptrs[1] = newcentroid[1];
-    newcentroid_ptrs[2] = newcentroid[2];
-
     for (j=0; j<3; j++)
         olderror += elbg->utility[idx[j]];
 
@@ -277,11 +283,11 @@ static void try_shift_candidate(elbg_data *elbg, int idx[3])
 
     newerror = newutility[2];
 
-    newerror += simple_lbg(elbg->dim, newcentroid_ptrs, newutility, elbg->points,
+    newerror += simple_lbg(elbg, elbg->dim, newcentroid, newutility, elbg->points,
                            elbg->cells[idx[1]]);
 
     if (olderror > newerror) {
-        shift_codebook(elbg, idx, newcentroid_ptrs);
+        shift_codebook(elbg, idx, newcentroid);
 
         elbg->error += newerror - olderror;
 
@@ -366,6 +372,7 @@ void ff_do_elbg(int *points, int dim, int numpoints, int *codebook,
     elbg->nearest_cb = closest_cb;
     elbg->points = points;
     elbg->utility_inc = av_malloc(numCB*sizeof(int));
+    elbg->scratchbuf = av_malloc(5*dim*sizeof(int));
 
     elbg->rand_state = rand_state;
 
@@ -425,4 +432,5 @@ void ff_do_elbg(int *points, int dim, int numpoints, int *codebook,
     av_free(list_buffer);
     av_free(elbg->cells);
     av_free(elbg->utility_inc);
+    av_free(elbg->scratchbuf);
 }
-- 
1.7.1