From 44af8c908664f4e7c274a6fd0dabc422def2dd68 Mon Sep 17 00:00:00 2001
From: sellensr <sellensr@gmail.com>
Date: Tue, 16 Apr 2019 19:49:01 -0400
Subject: [PATCH 1/4] Index checksum explicitly on $ and *

parse() Improves slightly on https://github.com/adafruit/Adafruit_GPS/pull/86 by indexing on the position of the $ and the * in the string instead of the beginning and the end of the string.  Does not require sentence string have a particular termination, e.g. CRLF.
---
 Adafruit_GPS.cpp | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/Adafruit_GPS.cpp b/Adafruit_GPS.cpp
index c53aea4..4f0214a 100755
--- a/Adafruit_GPS.cpp
+++ b/Adafruit_GPS.cpp
@@ -57,14 +57,13 @@ boolean Adafruit_GPS::parse(char *nmea) {
   // do checksum check
 
   // first look if we even have one
-  size_t len = strlen(nmea);
-  if (nmea[len-5] == '*') {
-    uint16_t sum = parseHex(nmea[len-4]) * 16;
-    sum += parseHex(nmea[len-3]);
-
+  char *ast = strchr(nmea,'*');
+  if (ast != NULL) {
+    uint16_t sum = parseHex(*(ast+1)) * 16;
+    sum += parseHex(*(ast+2));
     // check checksum
-    for (uint8_t i=1; i < (len-5); i++) {
-      sum ^= nmea[i];
+    for (char *p = strchr(nmea,'$')+1; p < ast; p++) {
+      sum ^= *p;
     }
     if (sum != 0) {
       // bad checksum :(

From 653b565d2a35aaed2f382d1a611065d7bfa91fb8 Mon Sep 17 00:00:00 2001
From: Rick Sellens <sellensr@queensu.ca>
Date: Wed, 17 Apr 2019 12:13:17 -0400
Subject: [PATCH 2/4] Create .gitignore

---
 .gitignore | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 .gitignore

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9bea433
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+
+.DS_Store

From 4d064cb7963907920bc324e85e246677df590cca Mon Sep 17 00:00:00 2001
From: Rick Sellens <sellensr@queensu.ca>
Date: Wed, 17 Apr 2019 12:23:58 -0400
Subject: [PATCH 3/4] test parse string for $

---
 Adafruit_GPS.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Adafruit_GPS.cpp b/Adafruit_GPS.cpp
index 4f0214a..4f84a8a 100755
--- a/Adafruit_GPS.cpp
+++ b/Adafruit_GPS.cpp
@@ -62,12 +62,16 @@ boolean Adafruit_GPS::parse(char *nmea) {
     uint16_t sum = parseHex(*(ast+1)) * 16;
     sum += parseHex(*(ast+2));
     // check checksum
-    for (char *p = strchr(nmea,'$')+1; p < ast; p++) {
-      sum ^= *p;
-    }
-    if (sum != 0) {
-      // bad checksum :(
-      return false;
+    char *p = strchr(nmea,'$');
+    if(p == NULL) return false;
+    else{ 
+      for (char *p1 = p+1; p1 < ast; p1++) {
+        sum ^= *p1;
+      }
+      if (sum != 0) {
+        // bad checksum :(
+        return false;
+      }
     }
   } else {
   	return false;

From 2b06a9d0ef57207ad09fed24b6e06abc0ee1e264 Mon Sep 17 00:00:00 2001
From: Rick Sellens <sellensr@queensu.ca>
Date: Wed, 17 Apr 2019 12:31:59 -0400
Subject: [PATCH 4/4] Delete .gitignore

---
 .gitignore | 2 --
 1 file changed, 2 deletions(-)
 delete mode 100644 .gitignore

diff --git a/.gitignore b/.gitignore
deleted file mode 100644
index 9bea433..0000000
--- a/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-
-.DS_Store