From fb77c5e5b484ffd974de026244132f721c9aadaf Mon Sep 17 00:00:00 2001
From: Stanley Huang <stanleyhuangyc@gmail.com>
Date: Wed, 31 May 2017 20:39:45 +1000
Subject: Minor optimizations
---
libraries/TinyGPS/TinyGPS.cpp | 31 +++++++++++++++++++++++++++----
1 file changed, 27 insertions(+), 4 deletions(-)
diff --git a/libraries/TinyGPS/TinyGPS.cpp b/libraries/TinyGPS/TinyGPS.cpp
index 5a5b86b..c45ed19 100644
--- a/libraries/TinyGPS/TinyGPS.cpp
+++ b/libraries/TinyGPS/TinyGPS.cpp
@@ -66,7 +66,7 @@ bool TinyGPS::encode(char c)
switch(c)
{
case ',': // term terminators
- _parity ^= c;
+ _parity ^= ',';
case '\r':
case '\n':
case '*':
@@ -93,7 +93,7 @@ bool TinyGPS::encode(char c)
if (_term_offset < sizeof(_term) - 1)
_term[_term_offset++] = c;
if (!_is_checksum_term)
- _parity ^= c;
+ _parity ^= (byte)c;
return valid_sentence;
}
@@ -110,7 +110,7 @@ void TinyGPS::stats(unsigned long *chars, unsigned short *sentences, unsigned sh
//
// internal utilities
//
-int TinyGPS::from_hex(char a)
+byte TinyGPS::from_hex(char a)
{
if (a >= 'A' && a <= 'F')
return a - 'A' + 10;
@@ -120,6 +120,29 @@ int TinyGPS::from_hex(char a)
return a - '0';
}
+byte TinyGPS::hex2uint8(const char *p)
+{
+ byte c1 = *p;
+ byte c2 = *(p + 1);
+ if (c1 >= 'A' && c1 <= 'F')
+ c1 -= 7;
+ else if (c1 >= 'a' && c1 <= 'f')
+ c1 -= 39;
+ else if (c1 < '0' || c1 > '9')
+ return 0;
+
+ if (c2 == 0)
+ return (c1 & 0xf);
+ else if (c2 >= 'A' && c2 <= 'F')
+ c2 -= 7;
+ else if (c2 >= 'a' && c2 <= 'f')
+ c2 -= 39;
+ else if (c2 < '0' || c2 > '9')
+ return 0;
+
+ return c1 << 4 | (c2 & 0xf);
+}
+
unsigned long TinyGPS::parse_decimal()
{
char *p = _term;
@@ -165,7 +188,7 @@ bool TinyGPS::term_complete()
{
if (_is_checksum_term)
{
- byte checksum = 16 * from_hex(_term[0]) + from_hex(_term[1]);
+ byte checksum = hex2uint8(_term);
if (checksum == _parity)
{
if (_gps_data_good)
--
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