More const's and readability improvements

contrib/educational_decoder/harness.c

@@ -88,7 +88,7 @@ int main(int argc, char **argv) {
         decompressed_size = MAX_COMPRESSION_RATIO * input_size;
         fprintf(stderr, "WARNING: Compressed data does contain decompressed "
                         "size, going to assume the compression ratio is at "
-                        "most %d (decompressed size of at most %lld\n",
+                        "most %d (decompressed size of at most %zu)\n",
                 MAX_COMPRESSION_RATIO, decompressed_size);
     }
     output = malloc(decompressed_size);

contrib/educational_decoder/zstd_decompress.h

@@ -7,10 +7,10 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-size_t ZSTD_decompress(void *dst, size_t dst_len, const void *src,
-                       size_t src_len);
-size_t ZSTD_decompress_with_dict(void *dst, size_t dst_len, const void *src,
-                                 size_t src_len, const void *dict,
-                                 size_t dict_len);
-size_t ZSTD_get_decompressed_size(const void *src, size_t src_len);
+size_t ZSTD_decompress(void *const dst, const size_t dst_len,
+                       const void *const src, const size_t src_len);
+size_t ZSTD_decompress_with_dict(void *const dst, const size_t dst_len,
+                                 const void *const src, const size_t src_len,
+                                 const void *const dict, const size_t dict_len);
+size_t ZSTD_get_decompressed_size(const void *const src, const size_t src_len);