lcl: Disentangle pointers to input data and decompression buffer

This is cleaner and avoids a cast plus a related const qualifier warning.

libavcodec/lcldec.c

@@ -162,10 +162,9 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
     LclDecContext * const c = avctx->priv_data;
-    unsigned char *encoded = (unsigned char *)buf;
     unsigned int pixel_ptr;
     int row, col;
-    unsigned char *outptr;
+    unsigned char *encoded, *outptr;
     uint8_t *y_out, *u_out, *v_out;
     unsigned int width = avctx->width; // Real image width
     unsigned int height = avctx->height; // Real image height
@@ -188,17 +187,17 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
         switch (c->compression) {
         case COMP_MSZH:
             if (c->flags & FLAG_MULTITHREAD) {
-                mthread_inlen = AV_RL32(encoded);
+                mthread_inlen = AV_RL32(buf);
                 mthread_inlen = FFMIN(mthread_inlen, len - 8);
-                mthread_outlen = AV_RL32(encoded+4);
+                mthread_outlen = AV_RL32(buf + 4);
                 mthread_outlen = FFMIN(mthread_outlen, c->decomp_size);
-                mszh_dlen = mszh_decomp(encoded + 8, mthread_inlen, c->decomp_buf, c->decomp_size);
+                mszh_dlen = mszh_decomp(buf + 8, mthread_inlen, c->decomp_buf, c->decomp_size);
                 if (mthread_outlen != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Mthread1 decoded size differs (%d != %d)\n",
                            mthread_outlen, mszh_dlen);
                     return AVERROR_INVALIDDATA;
                 }
-                mszh_dlen = mszh_decomp(encoded + 8 + mthread_inlen, len - 8 - mthread_inlen,
+                mszh_dlen = mszh_decomp(buf + 8 + mthread_inlen, len - 8 - mthread_inlen,
                                         c->decomp_buf + mthread_outlen, c->decomp_size - mthread_outlen);
                 if (mthread_outlen != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Mthread2 decoded size differs (%d != %d)\n",
@@ -208,7 +207,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
                 encoded = c->decomp_buf;
                 len = c->decomp_size;
             } else {
-                mszh_dlen = mszh_decomp(encoded, len, c->decomp_buf, c->decomp_size);
+                mszh_dlen = mszh_decomp(buf, len, c->decomp_buf, c->decomp_size);
                 if (c->decomp_size != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Decoded size differs (%d != %d)\n",
                            c->decomp_size, mszh_dlen);
@@ -254,23 +253,23 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
         if (c->compression == COMP_ZLIB_NORMAL && c->imgtype == IMGTYPE_RGB24 &&
             len == width * height * 3) {
             if (c->flags & FLAG_PNGFILTER) {
-                memcpy(c->decomp_buf, encoded, len);
+                memcpy(c->decomp_buf, buf, len);
                 encoded = c->decomp_buf;
             } else {
                 break;
             }
         } else if (c->flags & FLAG_MULTITHREAD) {
-            mthread_inlen = AV_RL32(encoded);
+            mthread_inlen = AV_RL32(buf);
             mthread_inlen = FFMIN(mthread_inlen, len - 8);
-            mthread_outlen = AV_RL32(encoded+4);
+            mthread_outlen = AV_RL32(buf + 4);
             mthread_outlen = FFMIN(mthread_outlen, c->decomp_size);
-            ret = zlib_decomp(avctx, encoded + 8, mthread_inlen, 0, mthread_outlen);
+            ret = zlib_decomp(avctx, buf + 8, mthread_inlen, 0, mthread_outlen);
             if (ret < 0) return ret;
-            ret = zlib_decomp(avctx, encoded + 8 + mthread_inlen, len - 8 - mthread_inlen,
+            ret = zlib_decomp(avctx, buf + 8 + mthread_inlen, len - 8 - mthread_inlen,
                               mthread_outlen, mthread_outlen);
             if (ret < 0) return ret;
         } else {
-            int ret = zlib_decomp(avctx, encoded, len, 0, c->decomp_size);
+            int ret = zlib_decomp(avctx, buf, len, 0, c->decomp_size);
             if (ret < 0) return ret;
         }
         encoded = c->decomp_buf;