From: marshmellow42 <marshmellowrf@gmail.com>
Date: Tue, 21 Mar 2017 13:53:14 +0000 (-0400)
Subject: adjust ManchesterEncode
X-Git-Tag: v3.0.0~45^2
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/refs/pull/235/head

adjust ManchesterEncode

removed dead size check
added a max size of 2k input bits (4k out)
this shouldn't overload the array memory passed to it typically...
---

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 5a1007fb..8307a890 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -308,15 +308,17 @@ uint32_t manchesterEncode2Bytes(uint16_t datain) {
 
 //by marshmellow
 //encode binary data into binary manchester 
-//NOTE: BitStream must have double the size available in memory to do the swap
+//NOTE: BitStream must have triple the size of "size" available in memory to do the swap
 int ManchesterEncode(uint8_t *BitStream, size_t size) {
-	size_t modIdx=size, i=0;
-	if (size>modIdx) return -1;
+	//allow up to 4K out (means BitStream must be at least 2048+4096 to handle the swap)
+	size = (size>2048) ? 2048 : size;
+	size_t modIdx = size;
+	size_t i;
 	for (size_t idx=0; idx < size; idx++){
 		BitStream[idx+modIdx++] = BitStream[idx];
 		BitStream[idx+modIdx++] = BitStream[idx]^1;
 	}
-	for (; i<(size*2); i++){
+	for (i=0; i<(size*2); i++){
 		BitStream[i] = BitStream[i+size];
 	}
 	return i;