From c3a5fba0283b59352537aa71947a4481009a54bb Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <yobibe@gmail.com>
Date: Mon, 19 Aug 2013 14:55:27 +0200
Subject: [PATCH] Adding iso14443b_crc_append()

---
 include/nfc/nfc.h      |  2 ++
 libnfc/iso14443-subr.c | 35 +++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/include/nfc/nfc.h b/include/nfc/nfc.h
index b34a005..44f92d9 100644
--- a/include/nfc/nfc.h
+++ b/include/nfc/nfc.h
@@ -135,6 +135,8 @@ NFC_EXPORT int nfc_device_set_property_bool(nfc_device *pnd, const nfc_property
 /* Misc. functions */
 NFC_EXPORT void iso14443a_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc);
 NFC_EXPORT void iso14443a_crc_append(uint8_t *pbtData, size_t szLen);
+NFC_EXPORT void iso14443b_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc);
+NFC_EXPORT void iso14443b_crc_append(uint8_t *pbtData, size_t szLen);
 NFC_EXPORT uint8_t *iso14443a_locate_historical_bytes(uint8_t *pbtAts, size_t szAts, size_t *pszTk);
 
 NFC_EXPORT void nfc_free(void *p);
diff --git a/libnfc/iso14443-subr.c b/libnfc/iso14443-subr.c
index 3f29bdf..27a1ba7 100644
--- a/libnfc/iso14443-subr.c
+++ b/libnfc/iso14443-subr.c
@@ -41,7 +41,7 @@
 
 
 /**
- * @brief CRC
+ * @brief CRC_A
  *
  */
 void
@@ -62,7 +62,7 @@ iso14443a_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc)
 }
 
 /**
- * @brief Append CRC
+ * @brief Append CRC_A
  *
  */
 void
@@ -71,6 +71,37 @@ iso14443a_crc_append(uint8_t *pbtData, size_t szLen)
   iso14443a_crc(pbtData, szLen, pbtData + szLen);
 }
 
+/**
+ * @brief CRC_B
+ *
+ */
+void
+iso14443b_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc)
+{
+  uint8_t  bt;
+  uint32_t wCrc = 0xFFFF;
+
+  do {
+    bt = *pbtData++;
+    bt = (bt ^ (uint8_t)(wCrc & 0x00FF));
+    bt = (bt ^ (bt << 4));
+    wCrc = (wCrc >> 8) ^ ((uint32_t) bt << 8) ^ ((uint32_t) bt << 3) ^ ((uint32_t) bt >> 4);
+  } while (--szLen);
+  wCrc = ~wCrc;
+  *pbtCrc++ = (uint8_t)(wCrc & 0xFF);
+  *pbtCrc = (uint8_t)((wCrc >> 8) & 0xFF);
+}
+
+/**
+ * @brief Append CRC_B
+ *
+ */
+void
+iso14443b_crc_append(uint8_t *pbtData, size_t szLen)
+{
+  iso14443b_crc(pbtData, szLen, pbtData + szLen);
+}
+
 /**
  * @brief Locate historical bytes
  * @see ISO/IEC 14443-4 (5.2.7 Historical bytes)