From 4601d0e77a740f8c059328b764ce4caa5304280c Mon Sep 17 00:00:00 2001
From: James Chambers <jameschambers2@gmail.com>
Date: Thu, 15 Mar 2018 13:45:21 -0400
Subject: [PATCH] mfu read block: retry block with bad CRC

---
 armsrc/mifarecmd.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/armsrc/mifarecmd.c b/armsrc/mifarecmd.c
index 3854b589..b3d14f72 100644
--- a/armsrc/mifarecmd.c
+++ b/armsrc/mifarecmd.c
@@ -310,6 +310,8 @@ void MifareUReadCard(uint8_t arg0, uint16_t arg1, uint8_t arg2, uint8_t *datain)
 		}
 	}
 
+	#define MFU_MAX_CRC_RETRIES 5
+	unsigned int retries = 0;
 	for (int i = 0; i < blocks; i++){
 		if ((i*4) + 4 >= CARD_MEMORY_SIZE) {
 			Dbprintf("Data exceeds buffer!!");
@@ -320,15 +322,22 @@ void MifareUReadCard(uint8_t arg0, uint16_t arg1, uint8_t arg2, uint8_t *datain)
 
 		if (len) {
 			if (MF_DBGLEVEL >= MF_DBG_ERROR) Dbprintf("Read block %d error",i);
-			// if no blocks read - error out
-			if (i==0){
-				OnError(2);
-				return;
+
+			if (retries >= MFU_MAX_CRC_RETRIES) {
+				// if no blocks read - error out
+				if (i==0) {
+					OnError(2);
+					return;
+				} else {
+					//stop at last successful read block and return what we got
+					break;
+				}
 			} else {
-				//stop at last successful read block and return what we got
-				break;
+				retries++;
+				i--;
 			}
 		} else {
+			retries = 0;
 			countblocks++;
 		}
 	}