add bitstream_hasnext function

diff --git a/src/bitstream.c b/src/bitstream.c
index 25867f6..259ec66 100644 (file)
--- a/src/bitstream.c
+++ b/src/bitstream.c
@@ -525,6 +525,16 @@ bitstream_length(bitstream_t *bs) {
     return bs->data_len;
 }
 
+unsigned long
+bitstream_hasnext(bitstream_t *bs, int byte_len, int bit_len) {
+    int byte_offset = bs->byte_offset + byte_len;
+    int bit_offset  = bs->bit_offset  + bit_len;
+    if (bs->data_len < (byte_offset + (bit_offset + 7) / 8)) {
+        return 0; // false
+    }
+    return 1; // true
+}
+
 /*
  * utility
  */

diff --git a/src/bitstream.h b/src/bitstream.h
index cd1e4d2..80e2f54 100644 (file)
--- a/src/bitstream.h
+++ b/src/bitstream.h
@@ -73,6 +73,9 @@ extern int bitstream_realloc(bitstream_t *bs);
 /* direct access */
 extern unsigned char *bitstream_buffer(bitstream_t *bs, unsigned long byte_offset);
 extern unsigned long bitstream_length(bitstream_t *bs);
+extern unsigned long bitstream_hasnext(bitstream_t *bs,
+                                      int byte_len, int bit_len);
+
 
 /* utility */