1 files changed, 25 insertions, 0 deletions
diff --git a/fmt_asn1length.c b/fmt_asn1length.c
new file mode 100644
index 0000000..3df929b
--- /dev/null
+++ b/fmt_asn1length.c
@@ -0,0 +1,25 @@
+#include "asn1.h"
+
+/* write int in least amount of bytes, return number of bytes */
+/* as used in ASN.1 length */
+size_t fmt_asn1length(char* dest,size_t l) {
+  /* encoding is either l%128 or (0x80+number of bytes,bytes) */
+  size_t needed=(sizeof l),i;
+  if (l<128) {
+    if (dest) *dest=l&0x7f;
+    return 1;
+  }
+  for (i=1; i<needed; ++i)
+    if (!(l>>(i*8)))
+      break;
+  if (dest) {
+    int j=i;
+    *dest=0x80+i; ++dest;
+    while (j) {
+      --j;
+      *dest=((l>>(j*8))&0xff);
+      ++dest;
+    }
+  }
+  return i+1;
+}