From bedd2e7ccb1595c23e159eaa952ae1b0b5a3d2ad Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Sat, 15 Mar 2014 01:49:50 +0100
Subject: Lean and mean initial commit

Not much functionality yet
---
 scan_asn1tag.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 scan_asn1tag.c

(limited to 'scan_asn1tag.c')

diff --git a/scan_asn1tag.c b/scan_asn1tag.c
new file mode 100644
index 0000000..acf0c57
--- /dev/null
+++ b/scan_asn1tag.c
@@ -0,0 +1,17 @@
+#include "asn1.h"
+
+size_t scan_asn1tag(const char* src,const char* max,enum asn1_tagclass* tc,enum asn1_tagtype* tt,unsigned long* tag) {
+  if (max<=src) return 0;
+  *tc=(*src&0xC0);
+  *tt=(*src&0x20);
+/* The lower 5 bits are the tag, unless it's 0x1f, in which case the
+ * next bytes are the tag: always take the lower 7 bits; the last byte
+ * in the sequence is marked by a cleared high bit */
+  if ((*src & 0x1f) == 0x1f) {
+    size_t res=scan_asn1tagint(src+1,max,tag);
+    return res+!!res;	/* add 1 unless it's 0, then leave 0 */
+  } else {
+    *tag=*src&0x1f;
+    return 1;
+  }
+}
-- 
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