avcodec/mpegvideo_motion: Constify ff_mpv_motion

Also constify the corresponding code in mpegvideo.c that handles
lowres.
(Unfortunately, not everything that is const could be constified:
ref_picture could be made const uint8_t* const* if C allowed the
safe automatic conversion from uint8_t**; and pix_op, qpix_op
could be made to point to const function pointers, but C's handling
of const in pointers to arrays is broken.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

5 files changed, 37 insertions, 36 deletions

diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index 319934a114..1405176c06 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -916,12 +916,12 @@ void ff_mpv_common_end(MpegEncContext *s)
 
 
 static inline int hpel_motion_lowres(MpegEncContext *s,
-                                     uint8_t *dest, uint8_t *src,
+                                     uint8_t *dest, const uint8_t *src,
                                      int field_based, int field_select,
                                      int src_x, int src_y,
                                      int width, int height, ptrdiff_t stride,
                                      int h_edge_pos, int v_edge_pos,
-                                     int w, int h, h264_chroma_mc_func *pix_op,
+                                     int w, int h, const h264_chroma_mc_func *pix_op,
                                      int motion_x, int motion_y)
 {
     const int lowres   = s->avctx->lowres;
@@ -969,12 +969,12 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
                                                 int field_based,
                                                 int bottom_field,
                                                 int field_select,
-                                                uint8_t **ref_picture,
-                                                h264_chroma_mc_func *pix_op,
+                                                uint8_t *const *ref_picture,
+                                                const h264_chroma_mc_func *pix_op,
                                                 int motion_x, int motion_y,
                                                 int h, int mb_y)
 {
-    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
+    const uint8_t *ptr_y, *ptr_cb, *ptr_cr;
     int mx, my, src_x, src_y, uvsrc_x, uvsrc_y, sx, sy, uvsx, uvsy;
     ptrdiff_t uvlinesize, linesize;
     const int lowres     = s->avctx->lowres;
@@ -1103,8 +1103,8 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
 
 static inline void chroma_4mv_motion_lowres(MpegEncContext *s,
                                             uint8_t *dest_cb, uint8_t *dest_cr,
-                                            uint8_t **ref_picture,
-                                            h264_chroma_mc_func * pix_op,
+                                            uint8_t *const *ref_picture,
+                                            const h264_chroma_mc_func * pix_op,
                                             int mx, int my)
 {
     const int lowres     = s->avctx->lowres;
@@ -1115,7 +1115,7 @@ static inline void chroma_4mv_motion_lowres(MpegEncContext *s,
     const int v_edge_pos = s->v_edge_pos >> lowres + 1;
     int emu = 0, src_x, src_y, sx, sy;
     ptrdiff_t offset;
-    uint8_t *ptr;
+    const uint8_t *ptr;
 
     if (s->quarter_sample) {
         mx /= 2;
@@ -1172,8 +1172,8 @@ static inline void chroma_4mv_motion_lowres(MpegEncContext *s,
 static inline void MPV_motion_lowres(MpegEncContext *s,
                                      uint8_t *dest_y, uint8_t *dest_cb,
                                      uint8_t *dest_cr,
-                                     int dir, uint8_t **ref_picture,
-                                     h264_chroma_mc_func *pix_op)
+                                     int dir, uint8_t *const *ref_picture,
+                                     const h264_chroma_mc_func *pix_op)
 {
     int mx, my;
     int mb_x, mb_y, i;
@@ -1242,7 +1242,7 @@ static inline void MPV_motion_lowres(MpegEncContext *s,
         break;
     case MV_TYPE_16X8:
         for (i = 0; i < 2; i++) {
-            uint8_t **ref2picture;
+            uint8_t *const *ref2picture;
 
             if (s->picture_structure == s->field_select[dir][i] + 1 ||
                 s->pict_type == AV_PICTURE_TYPE_B || s->first_field) {
@@ -1492,7 +1492,7 @@ void mpv_reconstruct_mb_internal(MpegEncContext *s, int16_t block[12][64],
                 }
 
                 if(lowres_flag){
-                    h264_chroma_mc_func *op_pix = s->h264chroma.put_h264_chroma_pixels_tab;
+                    const h264_chroma_mc_func *op_pix = s->h264chroma.put_h264_chroma_pixels_tab;
 
                     if (s->mv_dir & MV_DIR_FORWARD) {
                         MPV_motion_lowres(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.f->data, op_pix);
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 195a2b3238..b1b2727535 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -586,7 +586,7 @@ void ff_init_block_index(MpegEncContext *s);
 void ff_mpv_motion(MpegEncContext *s,
                    uint8_t *dest_y, uint8_t *dest_cb,
                    uint8_t *dest_cr, int dir,
-                   uint8_t **ref_picture,
+                   uint8_t *const *ref_picture,
                    op_pixels_func (*pix_op)[4],
                    qpel_mc_func (*qpix_op)[16]);
 
diff --git a/libavcodec/mpegvideo_motion.c b/libavcodec/mpegvideo_motion.c
index 9a450b7c8e..fe3bfc4454 100644
--- a/libavcodec/mpegvideo_motion.c
+++ b/libavcodec/mpegvideo_motion.c
@@ -36,9 +36,9 @@
 
 static void gmc1_motion(MpegEncContext *s,
                         uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
-                        uint8_t **ref_picture)
+                        uint8_t *const *ref_picture)
 {
-    uint8_t *ptr;
+    const uint8_t *ptr;
     int src_x, src_y, motion_x, motion_y;
     ptrdiff_t offset, linesize, uvlinesize;
     int emu = 0;
@@ -133,9 +133,9 @@ static void gmc1_motion(MpegEncContext *s,
 
 static void gmc_motion(MpegEncContext *s,
                        uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
-                       uint8_t **ref_picture)
+                       uint8_t *const *ref_picture)
 {
-    uint8_t *ptr;
+    const uint8_t *ptr;
     int linesize, uvlinesize;
     const int a = s->sprite_warping_accuracy;
     int ox, oy;
@@ -232,7 +232,7 @@ void mpeg_motion_internal(MpegEncContext *s,
                           int field_based,
                           int bottom_field,
                           int field_select,
-                          uint8_t **ref_picture,
+                          uint8_t *const *ref_picture,
                           op_pixels_func (*pix_op)[4],
                           int motion_x,
                           int motion_y,
@@ -241,7 +241,7 @@ void mpeg_motion_internal(MpegEncContext *s,
                           int is_16x8,
                           int mb_y)
 {
-    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
+    const uint8_t *ptr_y, *ptr_cb, *ptr_cr;
     int dxy, uvdxy, mx, my, src_x, src_y,
         uvsrc_x, uvsrc_y, v_edge_pos, block_y_half;
     ptrdiff_t uvlinesize, linesize;
@@ -369,7 +369,7 @@ void mpeg_motion_internal(MpegEncContext *s,
 /* apply one mpeg motion vector to the three components */
 static void mpeg_motion(MpegEncContext *s,
                         uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
-                        int field_select, uint8_t **ref_picture,
+                        int field_select, uint8_t *const *ref_picture,
                         op_pixels_func (*pix_op)[4],
                         int motion_x, int motion_y, int h, int is_16x8, int mb_y)
 {
@@ -388,7 +388,7 @@ static void mpeg_motion(MpegEncContext *s,
 static void mpeg_motion_field(MpegEncContext *s, uint8_t *dest_y,
                               uint8_t *dest_cb, uint8_t *dest_cr,
                               int bottom_field, int field_select,
-                              uint8_t **ref_picture,
+                              uint8_t *const *ref_picture,
                               op_pixels_func (*pix_op)[4],
                               int motion_x, int motion_y, int h, int mb_y)
 {
@@ -489,12 +489,12 @@ static inline void qpel_motion(MpegEncContext *s,
                                uint8_t *dest_cb,
                                uint8_t *dest_cr,
                                int field_based, int bottom_field,
-                               int field_select, uint8_t **ref_picture,
+                               int field_select, uint8_t *const *ref_picture,
                                op_pixels_func (*pix_op)[4],
                                qpel_mc_func (*qpix_op)[16],
                                int motion_x, int motion_y, int h)
 {
-    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
+    const uint8_t *ptr_y, *ptr_cb, *ptr_cr;
     int dxy, uvdxy, mx, my, src_x, src_y, uvsrc_x, uvsrc_y, v_edge_pos;
     ptrdiff_t linesize, uvlinesize;
 
@@ -593,11 +593,11 @@ static inline void qpel_motion(MpegEncContext *s,
  */
 static void chroma_4mv_motion(MpegEncContext *s,
                               uint8_t *dest_cb, uint8_t *dest_cr,
-                              uint8_t **ref_picture,
+                              uint8_t *const *ref_picture,
                               op_pixels_func *pix_op,
                               int mx, int my)
 {
-    uint8_t *ptr;
+    const uint8_t *ptr;
     int src_x, src_y, dxy, emu = 0;
     ptrdiff_t offset;
 
@@ -643,7 +643,7 @@ static void chroma_4mv_motion(MpegEncContext *s,
     pix_op[dxy](dest_cr, ptr, s->uvlinesize, 8);
 }
 
-static inline void prefetch_motion(MpegEncContext *s, uint8_t **pix, int dir)
+static inline void prefetch_motion(MpegEncContext *s, uint8_t *const *pix, int dir)
 {
     /* fetch pixels for estimated mv 4 macroblocks ahead
      * optimized for 64byte cache lines */
@@ -661,11 +661,11 @@ static inline void apply_obmc(MpegEncContext *s,
                               uint8_t *dest_y,
                               uint8_t *dest_cb,
                               uint8_t *dest_cr,
-                              uint8_t **ref_picture,
+                              uint8_t *const *ref_picture,
                               op_pixels_func (*pix_op)[4])
 {
     LOCAL_ALIGNED_8(int16_t, mv_cache, [4], [4][2]);
-    Picture *cur_frame   = &s->current_picture;
+    const Picture *cur_frame = &s->current_picture;
     int mb_x = s->mb_x;
     int mb_y = s->mb_y;
     const int xy         = mb_x + mb_y * s->mb_stride;
@@ -749,7 +749,7 @@ static inline void apply_8x8(MpegEncContext *s,
                              uint8_t *dest_cb,
                              uint8_t *dest_cr,
                              int dir,
-                             uint8_t **ref_picture,
+                             uint8_t *const *ref_picture,
                              qpel_mc_func (*qpix_op)[16],
                              op_pixels_func (*pix_op)[4])
 {
@@ -757,7 +757,8 @@ static inline void apply_8x8(MpegEncContext *s,
     int i;
     int mb_x = s->mb_x;
     int mb_y = s->mb_y;
-    uint8_t *ptr, *dest;
+    uint8_t *dest;
+    const uint8_t *ptr;
 
     mx = 0;
     my = 0;
@@ -833,7 +834,7 @@ static av_always_inline void mpv_motion_internal(MpegEncContext *s,
                                                  uint8_t *dest_cb,
                                                  uint8_t *dest_cr,
                                                  int dir,
-                                                 uint8_t **ref_picture,
+                                                 uint8_t *const *ref_picture,
                                                  op_pixels_func (*pix_op)[4],
                                                  qpel_mc_func (*qpix_op)[16],
                                                  int is_mpeg12)
@@ -912,7 +913,7 @@ static av_always_inline void mpv_motion_internal(MpegEncContext *s,
     case MV_TYPE_16X8:
         if (CONFIG_SMALL || is_mpeg12) {
             for (i = 0; i < 2; i++) {
-                uint8_t **ref2picture;
+                uint8_t *const *ref2picture;
 
                 if ((s->picture_structure == s->field_select[dir][i] + 1 ||
                      s->pict_type == AV_PICTURE_TYPE_B || s->first_field) &&
@@ -974,7 +975,7 @@ static av_always_inline void mpv_motion_internal(MpegEncContext *s,
 void ff_mpv_motion(MpegEncContext *s,
                    uint8_t *dest_y, uint8_t *dest_cb,
                    uint8_t *dest_cr, int dir,
-                   uint8_t **ref_picture,
+                   uint8_t *const *ref_picture,
                    op_pixels_func (*pix_op)[4],
                    qpel_mc_func (*qpix_op)[16])
 {
diff --git a/libavcodec/wmv2.c b/libavcodec/wmv2.c
index 8d1d117dea..5fea009e12 100644
--- a/libavcodec/wmv2.c
+++ b/libavcodec/wmv2.c
@@ -49,11 +49,11 @@ av_cold void ff_wmv2_common_init(MpegEncContext *s)
 
 void ff_mspel_motion(MpegEncContext *s, uint8_t *dest_y,
                      uint8_t *dest_cb, uint8_t *dest_cr,
-                     uint8_t **ref_picture, op_pixels_func (*pix_op)[4],
+                     uint8_t *const *ref_picture, op_pixels_func (*pix_op)[4],
                      int motion_x, int motion_y, int h)
 {
     WMV2Context *const w = s->private_ctx;
-    uint8_t *ptr;
+    const uint8_t *ptr;
     int dxy, mx, my, src_x, src_y, v_edge_pos;
     ptrdiff_t offset, linesize, uvlinesize;
     int emu = 0;
diff --git a/libavcodec/wmv2.h b/libavcodec/wmv2.h
index cdd58cf011..e49b81cdfb 100644
--- a/libavcodec/wmv2.h
+++ b/libavcodec/wmv2.h
@@ -39,7 +39,7 @@ void ff_wmv2_common_init(MpegEncContext *s);
 
 void ff_mspel_motion(MpegEncContext *s,
                      uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
-                     uint8_t **ref_picture, op_pixels_func (*pix_op)[4],
+                     uint8_t *const *ref_picture, op_pixels_func (*pix_op)[4],
                      int motion_x, int motion_y, int h);