1 files changed, 79 insertions, 0 deletions
diff --git a/src/libstddjb/ip6_fmt.c b/src/libstddjb/ip6_fmt.c
new file mode 100644
index 0000000..afd8a21
--- /dev/null
+++ b/src/libstddjb/ip6_fmt.c
@@ -0,0 +1,79 @@
+/* ISC license. */
+
+#include <skalibs/diuint.h>
+#include <skalibs/fmtscan.h>
+
+#define px(c) ((j || (c)) ? (*s++ = fmtscan_asc(c), 1) : 0)
+
+static inline unsigned int xfmt16 (char *s, char const *key)
+{
+  register unsigned int j = 0 ;
+  j += px((unsigned char)key[0] >> 4) ;
+  j += px((unsigned char)key[0] & 15) ;
+  j += px((unsigned char)key[1] >> 4) ;
+  j += px((unsigned char)key[1] & 15) ;
+  return j ? j : (*s = '0', 1) ;
+}
+
+static inline unsigned int find_colcol (char const *key, unsigned int *pos)
+{
+  diuint z[4] = { DIUINT_ZERO, DIUINT_ZERO, DIUINT_ZERO, DIUINT_ZERO } ;
+  unsigned int j = 0 ;
+  unsigned int max = 0 ;
+  register int iszero = 0 ;
+  register unsigned int i = 0 ;
+  for ( ; i < 8 ; i++)
+  {
+    if (key[i<<1] || key[(i<<1)+1])
+    {
+      if (iszero)
+      {
+        iszero = 0 ;
+        z[j].right = i - z[j].left ;
+        if (z[j].right > max) max = z[j].right ;
+        j++ ;
+      }
+    }
+    else
+    {
+      if (!iszero)
+      {
+        iszero = 1 ;
+        z[j].left = i ;
+      }
+    }
+  }
+  if (iszero)
+  {
+    z[j].right = 8 - z[j].left ;
+    if (z[j].right > max) max = z[j].right ;
+    j++ ;
+  }
+
+  if (max >= 2)
+    for (i = 0 ; i < j ; i++) if (z[i].right == max) return (*pos = z[i].left, max) ;
+  return 0 ; 
+}
+
+unsigned int ip6_fmt (char *s, char const *ip6)
+{
+  unsigned int w = 0 ;
+  register unsigned int i = 0 ;
+  unsigned int pos = 8 ;
+  unsigned int len = find_colcol(ip6, &pos) ;
+  for (; i < 8 ; i++)
+  {
+    if (i == pos)
+    {
+      if (!i) s[w++] = ':' ;
+      s[w++] = ':' ;
+      i += len-1 ;
+    }
+    else
+    {
+      w += xfmt16(s + w, ip6 + (i<<1)) ;
+      if (i < 7) s[w++] = ':' ;
+    }
+  }
+  return w ;
+}