@@ -212,7 +212,7 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

     double (*matrix)[3];

     double *h, *r;

-    int n = get_nb_points(points); // number of splines

+    const int n = get_nb_points(points); // number of splines

     if (n == 0) {

         for (i = 0; i < 256; i++)

@@ -247,9 +247,9 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

     /* right-side of the polynomials, will be modified to contains the solution */

     point = points;

     for (i = 1; i < n - 1; i++) {

-        double yp = point->y,

-               yc = point->next->y,

-               yn = point->next->next->y;

+        const double yp = point->y;

+        const double yc = point->next->y;

+        const double yn = point->next->next->y;

         r[i] = 6 * ((yn-yc)/h[i] - (yc-yp)/h[i-1]);

         point = point->next;

     }

@@ -268,8 +268,8 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

     /* tridiagonal solving of the linear system */

     for (i = 1; i < n; i++) {

-        double den = matrix[i][MD] - matrix[i][BD] * matrix[i-1][AD];

-        double k = den ? 1./den : 1.;

+        const double den = matrix[i][MD] - matrix[i][BD] * matrix[i-1][AD];

+        const double k = den ? 1./den : 1.;

         matrix[i][AD] *= k;

         r[i] = (r[i] - matrix[i][BD] * r[i - 1]) * k;

     }

@@ -286,24 +286,24 @@ static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *

     i = 0;

     av_assert0(point->next); // always at least 2 key points

     while (point->next) {

-        double yc = point->y;

-        double yn = point->next->y;

+        const double yc = point->y;

+        const double yn = point->next->y;

-        double a = yc;

-        double b = (yn-yc)/h[i] - h[i]*r[i]/2. - h[i]*(r[i+1]-r[i])/6.;

-        double c = r[i] / 2.;

-        double d = (r[i+1] - r[i]) / (6.*h[i]);

+        const double a = yc;

+        const double b = (yn-yc)/h[i] - h[i]*r[i]/2. - h[i]*(r[i+1]-r[i])/6.;

+        const double c = r[i] / 2.;

+        const double d = (r[i+1] - r[i]) / (6.*h[i]);

         int x;

-        int x_start = point->x       * 255;

-        int x_end   = point->next->x * 255;

+        const int x_start = point->x       * 255;

+        const int x_end   = point->next->x * 255;

         av_assert0(x_start >= 0 && x_start <= 255 &&

                    x_end   >= 0 && x_end   <= 255);

         for (x = x_start; x <= x_end; x++) {

-            double xx = (x - x_start) * 1/255.;

-            double yy = a + b*xx + c*xx*xx + d*xx*xx*xx;

+            const double xx = (x - x_start) * 1/255.;

+            const double yy = a + b*xx + c*xx*xx + d*xx*xx*xx;

             y[x] = av_clip_uint8(yy * 255);

             av_log(ctx, AV_LOG_DEBUG, "f(%f)=%f -> y[%d]=%d\n", xx, yy, x, y[x]);

         }

@@ -495,7 +495,7 @@ static av_cold int init(AVFilterContext *ctx)

     if (av_log_get_level() >= AV_LOG_VERBOSE) {

         for (i = 0; i < NB_COMP; i++) {

-            struct keypoint *point = comp_points[i];

+            const struct keypoint *point = comp_points[i];

             av_log(ctx, AV_LOG_VERBOSE, "#%d points:", i);

             while (point) {

                 av_log(ctx, AV_LOG_VERBOSE, " (%f;%f)", point->x, point->y);