1 files changed, 37 insertions, 0 deletions
diff --git a/lib/erl_interface/src/decode/decode_binary.c b/lib/erl_interface/src/decode/decode_binary.c
index 5b8d234984..0d28c67230 100644
--- a/lib/erl_interface/src/decode/decode_binary.c
+++ b/lib/erl_interface/src/decode/decode_binary.c
@@ -40,4 +40,41 @@ int ei_decode_binary(const char *buf, int *index, void *p, long *lenp)
   return 0; 
 }
 
+int ei_decode_bitstring(const char *buf, int *index,
+                        const char** pp,
+                        unsigned int* bitoffsp,
+                        size_t *nbitsp)
+{
+    const char *s = buf + *index;
+    const char *s0 = s;
+    unsigned char last_bits;
+    const unsigned char tag = get8(s);
+    size_t len = get32be(s);
+
+    switch(tag) {
+    case ERL_BINARY_EXT:
+        if (nbitsp)
+            *nbitsp = len * 8;
+        break;
+    case ERL_BIT_BINARY_EXT:
+        last_bits = get8(s);
+        if (((last_bits==0) != (len==0)) || last_bits > 8)
+            return -1;
+
+        if (nbitsp)
+            *nbitsp = (len == 0) ? 0 : ((len-1) * 8) + last_bits;
+        break;
+    default:
+        return -1;
+    }
+
+    if (pp)
+        *pp = s;
+    if (bitoffsp)
+        *bitoffsp = 0;
+
+    s += len;
+    *index += s-s0;
+    return 0;
+}