[FFmpeg-cvslog] avcodec/vc1_block: Stop setting write-only block_last_index

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Fri Mar  7 02:06:40 2025 +0100| [1a564c1afff461a36f6ac0df178d87f105ed485f] | committer: Andreas Rheinhardt

avcodec/vc1_block: Stop setting write-only block_last_index

It is only used by the mpegvideo unquantize functions which
this decoder does not use at all.

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1a564c1afff461a36f6ac0df178d87f105ed485f
---

 libavcodec/vc1_block.c | 32 +++++++++-----------------------
 1 file changed, 9 insertions(+), 23 deletions(-)

diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index 8babbde38c..26adfbca1d 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -585,7 +585,6 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
     GetBitContext *gb = &v->s.gb;
     MpegEncContext *s = &v->s;
     int dc_pred_dir = 0; /* Direction of the DC prediction used */
-    int i;
     int16_t *dc_val;
     int16_t *ac_val, *ac_val2;
     int dcdiff, scale;
@@ -622,7 +621,6 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
     scale = v->pq * 2 + v->halfpq;
 
     //AC Decoding
-    i = !!coded;
 
     if (coded) {
         int last = 0, skip, value;
@@ -637,14 +635,14 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
         } else
             zz_table = v->zz_8x8[1];
 
-        while (!last) {
+        for (int i = 1; !last; ++i) {
             int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
             if (ret < 0)
                 return ret;
             i += skip;
             if (i > 63)
                 break;
-            block[zz_table[i++]] = value;
+            block[zz_table[i]] = value;
         }
 
         /* apply AC prediction if needed */
@@ -696,8 +694,6 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
             }
         }
     }
-    if (s->ac_pred) i = 63;
-    s->block_last_index[n] = i;
 
     return 0;
 }
@@ -716,7 +712,6 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
     GetBitContext *gb = &v->s.gb;
     MpegEncContext *s = &v->s;
     int dc_pred_dir = 0; /* Direction of the DC prediction used */
-    int i;
     int16_t *dc_val = NULL;
     int16_t *ac_val, *ac_val2;
     int dcdiff;
@@ -778,7 +773,6 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
     }
 
     //AC Decoding
-    i = 1;
 
     if (coded) {
         int last = 0, skip, value;
@@ -801,14 +795,14 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
                 zz_table = v->zzi_8x8;
         }
 
-        while (!last) {
+        for (int i = 1; !last; ++i) {
             int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
             if (ret < 0)
                 return ret;
             i += skip;
             if (i > 63)
                 break;
-            block[zz_table[i++]] = value;
+            block[zz_table[i]] = value;
         }
 
         /* apply AC prediction if needed */
@@ -880,8 +874,6 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
             }
         }
     }
-    if (use_pred) i = 63;
-    s->block_last_index[n] = i;
 
     return 0;
 }
@@ -900,7 +892,6 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
     GetBitContext *gb = &v->s.gb;
     MpegEncContext *s = &v->s;
     int dc_pred_dir = 0; /* Direction of the DC prediction used */
-    int i;
     int16_t *dc_val = NULL;
     int16_t *ac_val, *ac_val2;
     int dcdiff;
@@ -942,7 +933,6 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
     block[0] = dcdiff * s->y_dc_scale;
 
     //AC Decoding
-    i = 1;
 
     /* check if AC is needed at all and adjust direction if needed */
     if (!a_avail) dc_pred_dir = 1;
@@ -973,7 +963,7 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
         int last = 0, skip, value;
         int k;
 
-        while (!last) {
+        for (int i = 1; !last; ++i) {
             int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
             if (ret < 0)
                 return ret;
@@ -981,15 +971,15 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
             if (i > 63)
                 break;
             if (v->fcm == PROGRESSIVE)
-                block[v->zz_8x8[0][i++]] = value;
+                block[v->zz_8x8[0][i]] = value;
             else {
                 if (use_pred && (v->fcm == ILACE_FRAME)) {
                     if (!dc_pred_dir) // top
-                        block[v->zz_8x8[2][i++]] = value;
+                        block[v->zz_8x8[2][i]] = value;
                     else // left
-                        block[v->zz_8x8[3][i++]] = value;
+                        block[v->zz_8x8[3][i]] = value;
                 } else {
-                    block[v->zzi_8x8[i++]] = value;
+                    block[v->zzi_8x8[i]] = value;
                 }
             }
         }
@@ -1033,8 +1023,6 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
                 if (!v->pquantizer)
                     block[k] += (block[k] < 0) ? -quant : quant;
             }
-
-        if (use_pred) i = 63;
     } else { // no AC coeffs
         int k;
 
@@ -1082,10 +1070,8 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
                         block[k << v->top_blk_sh] += (block[k << v->top_blk_sh] < 0) ? -quant : quant;
                 }
             }
-            i = 63;
         }
     }
-    s->block_last_index[n] = i;
 
     return 0;
 }