diff --git a/pimd/pim_util.c b/pimd/pim_util.c
new file mode 100644
index 0000000..5bc8d07
--- /dev/null
+++ b/pimd/pim_util.c
@@ -0,0 +1,132 @@
+/*
+  PIM for Quagga
+  Copyright (C) 2008  Everton da Silva Marques
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+  
+  You should have received a copy of the GNU General Public License
+  along with this program; see the file COPYING; if not, write to the
+  Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+  MA 02110-1301 USA
+  
+  $QuaggaId: $Format:%an, %ai, %h$ $
+*/
+
+#include "pim_util.h"
+
+/*
+  RFC 3376: 4.1.7. QQIC (Querier's Query Interval Code)
+  
+  If QQIC < 128,  QQI = QQIC
+  If QQIC >= 128, QQI = (mant | 0x10) << (exp + 3)
+  
+  0 1 2 3 4 5 6 7
+  +-+-+-+-+-+-+-+-+
+  |1| exp | mant  |
+  +-+-+-+-+-+-+-+-+
+  
+  Since exp=0..7 then (exp+3)=3..10, then QQI has
+  one of the following bit patterns:
+  
+  exp=0: QQI = 0000.0000.1MMM.M000
+  exp=1: QQI = 0000.0001.MMMM.0000
+  ...
+  exp=6: QQI = 001M.MMM0.0000.0000
+  exp=7: QQI = 01MM.MM00.0000.0000
+  --------- ---------
+  0x4  0x0  0x0  0x0
+*/
+uint8_t igmp_msg_encode16to8(uint16_t value)
+{
+  uint8_t code;
+
+  if (value < 128) {
+    code = value;
+  }
+  else {
+    uint16_t mask = 0x4000;
+    uint8_t  exp;
+    uint16_t mant;
+    for (exp = 7; exp > 0; --exp) {
+      if (mask & value)
+	break;
+      mask >>= 1;
+    }
+    mant = 0x000F & (value >> (exp + 3));
+    code = ((uint8_t) 1 << 7) | ((uint8_t) exp << 4) | (uint8_t) mant;
+  }
+
+  return code;
+}
+
+/*
+  RFC 3376: 4.1.7. QQIC (Querier's Query Interval Code)
+  
+  If QQIC < 128,  QQI = QQIC
+  If QQIC >= 128, QQI = (mant | 0x10) << (exp + 3)
+  
+  0 1 2 3 4 5 6 7
+  +-+-+-+-+-+-+-+-+
+  |1| exp | mant  |
+  +-+-+-+-+-+-+-+-+
+*/
+uint16_t igmp_msg_decode8to16(uint8_t code)
+{
+  uint16_t value;
+
+  if (code < 128) {
+    value = code;
+  }
+  else {
+    uint16_t mant = (code & 0x0F);
+    uint8_t  exp  = (code & 0x70) >> 4;
+    value = (mant | 0x10) << (exp + 3);
+  }
+
+  return value;
+}
+
+#ifndef PIM_USE_QUAGGA_INET_CHECKSUM
+/*
+  RFC 3376: 4.1.2. Checksum
+
+  The Checksum is the 16-bit one's complement of the one's complement
+  sum of the whole IGMP message (the entire IP payload).  For
+  computing the checksum, the Checksum field is set to zero.  When
+  receiving packets, the checksum MUST be verified before processing a
+  packet.  [RFC-1071]
+*/
+uint16_t pim_inet_checksum(const char *buf, int size)
+{
+  const uint16_t *ptr;
+  uint32_t        sum;
+  uint16_t        checksum;
+
+  ptr = (const uint16_t *) buf;
+  sum = 0;
+  while (size > 1) {
+    sum += *ptr;
+    ++ptr;
+    size -= 2;
+  }
+
+  /* Add left-over byte, if any */
+  if (size > 0)
+    sum += (uint16_t) *(const uint8_t *) ptr;
+
+  /* Fold 32-bit sum to 16 bits */
+  sum = (sum & 0xffff) + (sum >> 16);
+
+  checksum = ~sum;
+
+  return checksum;
+}
+#endif /* PIM_USE_QUAGGA_INET_CHECKSUM */