From 7f2b300dde67dea5c82ff3849b3fae785bd37b41 Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <yobibe@gmail.com>
Date: Mon, 4 Apr 2011 22:23:38 +0000
Subject: [PATCH] support crc auto-handling in ...transceive_bytes_timed

---
 libnfc/chips/pn53x.c | 22 +++++++++++++---------
 libnfc/nfc.c         |  3 +--
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/libnfc/chips/pn53x.c b/libnfc/chips/pn53x.c
index ce28d2b..ef867a4 100644
--- a/libnfc/chips/pn53x.c
+++ b/libnfc/chips/pn53x.c
@@ -1195,15 +1195,14 @@ pn53x_initiator_transceive_bits_timed (nfc_device_t * pnd, const byte_t * pbtTx,
   unsigned int i;
   uint8_t sz;
 
-  // We can not just send bytes without parity while the PN53X expects we handled them
+  // Sorry, no arbitrary parity bits support for now
   if (!pnd->bPar)
     return false;
   // Sorry, no easy framing support
-  // TODO: to be changed once we'll provide easy framing support from libnfc itself...
   if (pnd->bEasyFraming)
     return false;
   // Sorry, no CRC support
-  // TODO: to be changed once we'll provide easy CRC support from libnfc itself...
+  // TODO but it probably doesn't make sense for (szTxBits % 8 != 0) ...
   if (pnd->bCrc)
     return false;
 
@@ -1293,10 +1292,6 @@ pn53x_initiator_transceive_bytes_timed (nfc_device_t * pnd, const byte_t * pbtTx
   // TODO: to be changed once we'll provide easy framing support from libnfc itself...
   if (pnd->bEasyFraming)
     return false;
-  // Sorry, no CRC support
-  // TODO: to be changed once we'll provide easy CRC support from libnfc itself...
-  if (pnd->bCrc)
-    return false;
 
   __pn53x_init_timer(pnd);
 
@@ -1321,8 +1316,17 @@ pn53x_initiator_transceive_bytes_timed (nfc_device_t * pnd, const byte_t * pbtTx
   }
 
   // Recv corrected timer value
-  *cycles = __pn53x_get_timer (pnd, pbtTx[szTx -1]);
-
+  if (pnd->bCrc) {
+    // We've to compute CRC ourselves to know last byte actually sent
+    uint8_t * pbtTxRaw;
+    pbtTxRaw = (uint8_t *) malloc(szTx+2);
+    memcpy (pbtTxRaw, pbtTx, szTx);
+    iso14443a_crc_append (pbtTxRaw, szTx);
+    *cycles = __pn53x_get_timer (pnd, pbtTxRaw[szTx +1]);
+    free(pbtTxRaw);
+  } else {
+    *cycles = __pn53x_get_timer (pnd, pbtTx[szTx -1]);
+  }
   return true;
 }
 
diff --git a/libnfc/nfc.c b/libnfc/nfc.c
index 95d31b8..b55e241 100644
--- a/libnfc/nfc.c
+++ b/libnfc/nfc.c
@@ -541,11 +541,10 @@ nfc_initiator_transceive_bits (nfc_device_t * pnd, const byte_t * pbtTx, const s
  *
  * This function is similar to nfc_initiator_transceive_bytes() with the following differences:
  * - A precise cycles counter will indicate the number of cycles between emission & reception of frames.
- * - It only supports mode with \a NDO_EASY_FRAMING option disabled and CRC must be handled manually.
+ * - It only supports mode with \a NDO_EASY_FRAMING option disabled.
  * - Overall communication with the host is heavier and slower.
  *
  * @warning The configuration option \a NDO_EASY_FRAMING must be set to \c false.
- * @warning The configuration option \a NDO_HANDLE_CRC must be set to \c false.
  * @warning The configuration option \a NDO_HANDLE_PARITY must be set to \c true (the default value).
  */
 bool