avcodec/vc2enc: Constify slices->main context pointers

Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/vc2enc.c

@@ -106,7 +106,7 @@ typedef struct Plane {
 typedef struct SliceArgs {
     PutBitContext pb;
     int cache[DIRAC_MAX_QUANT_INDEX];
-    struct VC2EncContext *ctx;
+    const struct VC2EncContext *ctx;
     int x;
     int y;
     int quant_idx;
@@ -116,7 +116,7 @@ typedef struct SliceArgs {
 } SliceArgs;
 
 typedef struct TransformArgs {
-    struct VC2EncContext *ctx;
+    const struct VC2EncContext *ctx;
     Plane *plane;
     const void *idata;
     ptrdiff_t istride;
@@ -527,8 +527,8 @@ static void encode_picture_start(VC2EncContext *s)
 #define QUANT(c, mul, add, shift) (((mul) * (c) + (add)) >> (shift))
 
 /* VC-2 13.5.5.2 - slice_band() */
-static void encode_subband(VC2EncContext *s, PutBitContext *pb, int sx, int sy,
-                           SubBand *b, int quant)
+static void encode_subband(const VC2EncContext *s, PutBitContext *pb,
+                           int sx, int sy, const SubBand *b, int quant)
 {
     int x, y;
 
@@ -558,7 +558,7 @@ static int count_hq_slice(SliceArgs *slice, int quant_idx)
     int x, y;
     uint8_t quants[MAX_DWT_LEVELS][4];
     int bits = 0, p, level, orientation;
-    VC2EncContext *s = slice->ctx;
+    const VC2EncContext *s = slice->ctx;
 
     if (slice->cache[quant_idx])
         return slice->cache[quant_idx];
@@ -576,7 +576,7 @@ static int count_hq_slice(SliceArgs *slice, int quant_idx)
         bits += 8;
         for (level = 0; level < s->wavelet_depth; level++) {
             for (orientation = !!level; orientation < 4; orientation++) {
-                SubBand *b = &s->plane[p].band[level][orientation];
+                const SubBand *b = &s->plane[p].band[level][orientation];
 
                 const int q_idx = quants[level][orientation];
                 const uint64_t q_m = ((uint64_t)s->qmagic_lut[q_idx][0]) << 2;
@@ -618,7 +618,7 @@ static int count_hq_slice(SliceArgs *slice, int quant_idx)
 static int rate_control(AVCodecContext *avctx, void *arg)
 {
     SliceArgs *slice_dat = arg;
-    VC2EncContext *s = slice_dat->ctx;
+    const VC2EncContext *s = slice_dat->ctx;
     const int top = slice_dat->bits_ceil;
     const int bottom = slice_dat->bits_floor;
     int quant_buf[2] = {-1, -1};
@@ -724,7 +724,7 @@ static int calc_slice_sizes(VC2EncContext *s)
 static int encode_hq_slice(AVCodecContext *avctx, void *arg)
 {
     SliceArgs *slice_dat = arg;
-    VC2EncContext *s = slice_dat->ctx;
+    const VC2EncContext *s = slice_dat->ctx;
     PutBitContext *pb = &slice_dat->pb;
     const int slice_x = slice_dat->x;
     const int slice_y = slice_dat->y;
@@ -839,7 +839,7 @@ static int encode_slices(VC2EncContext *s)
 static int dwt_plane(AVCodecContext *avctx, void *arg)
 {
     TransformArgs *transform_dat = arg;
-    VC2EncContext *s = transform_dat->ctx;
+    const VC2EncContext *s = transform_dat->ctx;
     const void *frame_data = transform_dat->idata;
     const ptrdiff_t linesize = transform_dat->istride;
     const int field = transform_dat->field;