From fe49ccd701b723addbba430721348f8ba7337a12 Mon Sep 17 00:00:00 2001
From: Romuald Conty <romuald@libnfc.org>
Date: Wed, 13 Apr 2011 16:39:58 +0000
Subject: [PATCH] Implement extended frame send/receive for PN532_UART driver.

---
 libnfc/chips/pn53x.c        | 41 +++++++++++++++++++++++++++++++++----
 libnfc/chips/pn53x.h        |  2 +-
 libnfc/drivers/pn532_uart.c | 17 ++++++++++++---
 3 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/libnfc/chips/pn53x.c b/libnfc/chips/pn53x.c
index 4e8c6da..ec524d7 100644
--- a/libnfc/chips/pn53x.c
+++ b/libnfc/chips/pn53x.c
@@ -358,8 +358,14 @@ pn53x_unwrap_frame (const byte_t * pbtFrame, const size_t szFrameBits, byte_t *
   }
 }
 
-void
-pn53x_build_frame(byte_t * pbtFrame, size_t * pszFrame, const byte_t * pbtData, const size_t szData)
+/**
+ * @brief Build a PN53x frame
+ * 
+ * @param pbtData payload (bytes array) of the frame, will become PD0, ..., PDn in PN53x frame
+ * @note The first byte of pbtData is the Command Code (CC)
+ */
+bool
+pn53x_build_frame (byte_t * pbtFrame, size_t * pszFrame, const byte_t * pbtData, const size_t szData)
 {
   if (szData <= PN53x_NORMAL_FRAME__DATA_MAX_LEN) {
     // LEN - Packet length = data length (len) + checksum (1) + end of stream marker (1)
@@ -382,10 +388,37 @@ pn53x_build_frame(byte_t * pbtFrame, size_t * pszFrame, const byte_t * pbtData,
     pbtFrame[szData + 7] = 0x00;
 
     (*pszFrame) = szData + PN53x_NORMAL_FRAME__OVERHEAD;
+  } else if (szData <= PN53x_EXTENDED_FRAME__DATA_MAX_LEN) {
+    // Extended frame marker
+    pbtFrame[3] = 0xff;
+    pbtFrame[4] = 0xff;
+    // LENm
+    pbtFrame[5] = (szData + 1) >> 8;
+    // LENl
+    pbtFrame[6] = (szData + 1) & 0xff;
+    // LCS
+    pbtFrame[7] = 256 - ((pbtFrame[5] + pbtFrame[6]) & 0xff);
+    // TFI
+    pbtFrame[8] = 0xD4;
+    // DATA - Copy the PN53X command into the packet buffer
+    memcpy (pbtFrame + 9, pbtData, szData);
+
+    // DCS - Calculate data payload checksum
+    byte_t btDCS = (256 - 0xD4);
+    for (size_t szPos = 0; szPos < szData; szPos++) {
+      btDCS -= pbtData[szPos];
+    }
+    pbtFrame[9 + szData] = btDCS;
+
+    // 0x00 - End of stream marker
+    pbtFrame[szData + 10] = 0x00;
+
+    (*pszFrame) = szData + PN53x_EXTENDED_FRAME__OVERHEAD;
   } else {
-    // FIXME: Build extended frame
-    abort();
+    ERR ("We can't send more than %d bytes in a raw (requested: %zd)", PN53x_EXTENDED_FRAME__DATA_MAX_LEN, szData);
+    return false;
   }
+  return true;
 }
 
 bool
diff --git a/libnfc/chips/pn53x.h b/libnfc/chips/pn53x.h
index 843927e..fbc35d0 100644
--- a/libnfc/chips/pn53x.h
+++ b/libnfc/chips/pn53x.h
@@ -329,6 +329,6 @@ bool	pn53x_TgInitAsTarget (nfc_device_t * pnd, pn53x_target_mode_t ptm,
 // Misc
 bool    pn53x_check_ack_frame (nfc_device_t * pnd, const byte_t * pbtRxFrame, const size_t szRxFrameLen);
 bool    pn53x_check_error_frame (nfc_device_t * pnd, const byte_t * pbtRxFrame, const size_t szRxFrameLen);
-void    pn53x_build_frame(byte_t * pbtFrame, size_t * pszFrame, const byte_t * pbtData, const size_t szData);
+bool    pn53x_build_frame (byte_t * pbtFrame, size_t * pszFrame, const byte_t * pbtData, const size_t szData);
 
 #endif // __NFC_CHIPS_PN53X_H__
diff --git a/libnfc/drivers/pn532_uart.c b/libnfc/drivers/pn532_uart.c
index a43ed93..190e885 100644
--- a/libnfc/drivers/pn532_uart.c
+++ b/libnfc/drivers/pn532_uart.c
@@ -202,7 +202,10 @@ pn532_uart_send (nfc_device_t * pnd, const byte_t * pbtData, const size_t szData
   CHIP_DATA (pnd)->ui8LastCommand = pbtData[0];
   size_t szFrame = 0;
 
-  pn53x_build_frame (abtFrame, &szFrame, pbtData, szData);
+  if (!pn53x_build_frame (abtFrame, &szFrame, pbtData, szData)) {
+    pnd->iLastError = DEINVAL;
+    return false;
+  }
 
   int res = uart_send (DRIVER_DATA(pnd)->port, abtFrame, szFrame);
   if (res != 0) {
@@ -271,8 +274,16 @@ pn532_uart_receive (nfc_device_t * pnd, byte_t * pbtData, const size_t szDataLen
     return -1;
   } else if ((0xff == abtRxBuf[3]) && (0xff == abtRxBuf[4])) {
     // Extended frame
-    // FIXME: Code this
-    abort ();
+    pnd->iLastError = uart_receive (DRIVER_DATA(pnd)->port, abtRxBuf, 3, 0);
+
+    // (abtRxBuf[0] << 8) + abtRxBuf[1] (LEN) include TFI + (CC+1)
+    len = (abtRxBuf[0] << 8) + abtRxBuf[1] - 2;
+    if (((abtRxBuf[0] + abtRxBuf[1] + abtRxBuf[2]) % 256) != 0) {
+      // TODO: Retry
+      ERR ("%s", "Length checksum mismatch");
+      pnd->iLastError = DEIO;
+      return -1;
+    }
   } else {
     // Normal frame
     if (256 != (abtRxBuf[3] + abtRxBuf[4])) {