diff --git a/src/anlogicBitParser.cpp b/src/anlogicBitParser.cpp
index df9cc4f..771169c 100644
--- a/src/anlogicBitParser.cpp
+++ b/src/anlogicBitParser.cpp
@@ -107,11 +107,11 @@ int AnlogicBitParser::parse()
 
 	_bit_data.clear();
 	for (auto it = blocks.begin(); it != blocks.end(); it++) {
-		for (size_t pos = 0; pos < it->size(); pos++) {
+		for (size_t xpos = 0; xpos < it->size(); xpos++) {
 			if (_reverseOrder == true)
-				_bit_data += reverseByte(((*it)[pos]));
+				_bit_data += reverseByte(((*it)[xpos]));
 			else
-				_bit_data += ((*it)[pos]);
+				_bit_data += ((*it)[xpos]);
 		}
 	}
 	_bit_length = _bit_data.size() * 8;
diff --git a/src/bitparser.cpp b/src/bitparser.cpp
index 65299a7..ebfbe38 100644
--- a/src/bitparser.cpp
+++ b/src/bitparser.cpp
@@ -38,7 +38,7 @@ int BitParser::parseHeader()
 	int pos_data = 0;
 	int ret = 1;
 	short length;
-	string tmp(64, ' ');
+	string tmp;
 	int pos, prev_pos;
 
 	/* Field 1 : misc header */
diff --git a/src/ch552_jtag.cpp b/src/ch552_jtag.cpp
index 99d8a3b..0d051c1 100644
--- a/src/ch552_jtag.cpp
+++ b/src/ch552_jtag.cpp
@@ -30,7 +30,8 @@ using namespace std;
 #endif
 
 CH552_jtag::CH552_jtag(const cable_t &cable,
-			string dev, const string &serial, uint32_t clkHZ, uint8_t verbose):
+			const string &dev, const string &serial, uint32_t clkHZ,
+			uint8_t verbose):
 			FTDIpp_MPSSE(cable, dev, serial, clkHZ, verbose), _to_read(0)
 {
 	init_internal(cable.config);
diff --git a/src/ch552_jtag.hpp b/src/ch552_jtag.hpp
index 6c04f21..bdcc2bd 100644
--- a/src/ch552_jtag.hpp
+++ b/src/ch552_jtag.hpp
@@ -23,7 +23,7 @@
 
 class CH552_jtag : public JtagInterface, private FTDIpp_MPSSE {
  public:
-	CH552_jtag(const cable_t &cable, std::string dev,
+	CH552_jtag(const cable_t &cable, const std::string &dev,
 		const std::string &serial, uint32_t clkHZ, uint8_t verbose = false);
 	virtual ~CH552_jtag();
 
diff --git a/src/display.cpp b/src/display.cpp
index cca69a3..ae0f164 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -20,7 +20,7 @@
 #define KCYN  "\x1B[36m"
 #define KWHT  "\x1B[37m"
 
-void printError(std::string err, bool eol)
+void printError(const std::string &err, bool eol)
 {
 	if (isatty(STDERR_FILENO))
 		std::cerr << KRED << err << "\e[0m";
@@ -31,7 +31,7 @@ void printError(std::string err, bool eol)
 		std::cerr << std::endl;
 }
 
-void printWarn(std::string warn, bool eol)
+void printWarn(const std::string &warn, bool eol)
 {
 	if (isatty(STDOUT_FILENO))
 		std::cout << KYEL << warn << "\e[0m" << std::flush;
@@ -42,7 +42,7 @@ void printWarn(std::string warn, bool eol)
 		std::cout << std::endl;
 }
 
-void printInfo(std::string info, bool eol)
+void printInfo(const std::string &info, bool eol)
 {
 	if (isatty(STDOUT_FILENO))
 		std::cout << KBLUL << info << "\e[0m" << std::flush;
@@ -53,7 +53,7 @@ void printInfo(std::string info, bool eol)
 		std::cout << std::endl;
 }
 
-void printSuccess(std::string success, bool eol)
+void printSuccess(const std::string &success, bool eol)
 {
 	if (isatty(STDOUT_FILENO))
 		std::cout << KGRN << success << "\e[0m" << std::flush;
diff --git a/src/display.hpp b/src/display.hpp
index 8b57f70..2551642 100644
--- a/src/display.hpp
+++ b/src/display.hpp
@@ -9,9 +9,9 @@
 #include <iostream>
 #include <string>
 
-void printError(std::string err, bool eol = true);
-void printWarn(std::string warn, bool eol = true);
-void printInfo(std::string info, bool eol = true);
-void printSuccess(std::string success, bool eol = true);
+void printError(const std::string &err, bool eol = true);
+void printWarn(const std::string &warn, bool eol = true);
+void printInfo(const std::string &info, bool eol = true);
+void printSuccess(const std::string &success, bool eol = true);
 
 #endif  // DISPLAY_HPP_
diff --git a/src/feaparser.cpp b/src/feaparser.cpp
index 56ea6bf..b11377a 100644
--- a/src/feaparser.cpp
+++ b/src/feaparser.cpp
@@ -65,7 +65,7 @@
 
 using namespace std;
 
-FeaParser::FeaParser(string filename, bool verbose):
+FeaParser::FeaParser(const string &filename, bool verbose):
 	ConfigBitstreamParser(filename, ConfigBitstreamParser::BIN_MODE, verbose),
 	_feabits(0), _has_feabits(false)
 {
diff --git a/src/feaparser.hpp b/src/feaparser.hpp
index 14d3cd4..4dcc7a2 100644
--- a/src/feaparser.hpp
+++ b/src/feaparser.hpp
@@ -17,7 +17,7 @@
 
 class FeaParser: public ConfigBitstreamParser {
 	public:
-		FeaParser(std::string filename, bool verbose = false);
+		FeaParser(const std::string &filename, bool verbose = false);
 		int parse() override;
 		void displayHeader() override;
 
diff --git a/src/ftdiJtagBitbang.cpp b/src/ftdiJtagBitbang.cpp
index 2e93f2b..1eeea66 100644
--- a/src/ftdiJtagBitbang.cpp
+++ b/src/ftdiJtagBitbang.cpp
@@ -31,8 +31,8 @@ using namespace std;
 #endif
 
 FtdiJtagBitBang::FtdiJtagBitBang(const cable_t &cable,
-			const jtag_pins_conf_t *pin_conf, string dev, const std::string &serial,
-			uint32_t clkHZ, uint8_t verbose):
+			const jtag_pins_conf_t *pin_conf, const string &dev,
+			const std::string &serial, uint32_t clkHZ, uint8_t verbose):
 			FTDIpp_MPSSE(cable, dev, serial, clkHZ, verbose), _bitmode(0),
 			_curr_tms(0), _rx_size(0)
 {
diff --git a/src/ftdiJtagBitbang.hpp b/src/ftdiJtagBitbang.hpp
index 1b7623a..4252d08 100644
--- a/src/ftdiJtagBitbang.hpp
+++ b/src/ftdiJtagBitbang.hpp
@@ -24,8 +24,8 @@
 class FtdiJtagBitBang : public JtagInterface, private FTDIpp_MPSSE {
  public:
 	FtdiJtagBitBang(const cable_t &cable,
-		const jtag_pins_conf_t *pin_conf, std::string dev, const std::string &serial,
-		uint32_t clkHZ, uint8_t verbose = 0);
+		const jtag_pins_conf_t *pin_conf, const std::string &dev,
+		const std::string &serial, uint32_t clkHZ, uint8_t verbose = 0);
 	virtual ~FtdiJtagBitBang();
 
 	int setClkFreq(uint32_t clkHZ) override;
diff --git a/src/ftdiJtagMPSSE.cpp b/src/ftdiJtagMPSSE.cpp
index 213fe78..91bd205 100644
--- a/src/ftdiJtagMPSSE.cpp
+++ b/src/ftdiJtagMPSSE.cpp
@@ -31,7 +31,7 @@ using namespace std;
 #endif
 
 FtdiJtagMPSSE::FtdiJtagMPSSE(const cable_t &cable,
-			string dev, const string &serial, uint32_t clkHZ,
+			const string &dev, const string &serial, uint32_t clkHZ,
 			bool invert_read_edge, int8_t verbose):
 			FTDIpp_MPSSE(cable, dev, serial, clkHZ, verbose), _ch552WA(false),
 			_write_mode(MPSSE_WRITE_NEG),  // always write on neg edge
diff --git a/src/ftdiJtagMPSSE.hpp b/src/ftdiJtagMPSSE.hpp
index 2a59c68..d1e3038 100644
--- a/src/ftdiJtagMPSSE.hpp
+++ b/src/ftdiJtagMPSSE.hpp
@@ -23,7 +23,7 @@
 
 class FtdiJtagMPSSE : public JtagInterface, public FTDIpp_MPSSE {
  public:
-	FtdiJtagMPSSE(const cable_t &cable, std::string dev,
+	FtdiJtagMPSSE(const cable_t &cable, const std::string &dev,
 		const std::string &serial, uint32_t clkHZ, bool invert_read_edge,
 		int8_t verbose = 0);
 	virtual ~FtdiJtagMPSSE();
diff --git a/src/jedParser.cpp b/src/jedParser.cpp
index c3f19eb..01ace0e 100644
--- a/src/jedParser.cpp
+++ b/src/jedParser.cpp
@@ -31,7 +31,7 @@
 
 using namespace std;
 
-JedParser::JedParser(string filename, bool verbose):
+JedParser::JedParser(const string &filename, bool verbose):
 	ConfigBitstreamParser(filename, ConfigBitstreamParser::BIN_MODE, verbose),
 	_fuse_count(0), _pin_count(0), _max_vect_test(0),
 	_featuresRow(0), _feabits(0), _has_feabits(false), _checksum(0),
@@ -168,7 +168,7 @@ void JedParser::displayHeader()
 	printf("Fuse Count : %d\n", _fuse_count);
 
 	for (size_t i = 0; i < _data_list.size(); i++) {
-		printf("area[%zd] %4d %4d ", i, _data_list[i].offset, _data_list[i].len);
+		printf("area[%zu] %4d %4d ", i, _data_list[i].offset, _data_list[i].len);
 		printf("%zu ", _data_list[i].data.size());
 		for (size_t ii = 0; ii < _data_list[i].data.size(); ii++)
 			for (size_t iii = 0; iii < _data_list[i].data[ii].size(); iii++)
diff --git a/src/jedParser.hpp b/src/jedParser.hpp
index 02c89dd..eb36cb7 100644
--- a/src/jedParser.hpp
+++ b/src/jedParser.hpp
@@ -25,7 +25,7 @@ class JedParser: public ConfigBitstreamParser {
 		};
 
 	public:
-		JedParser(std::string filename, bool verbose = false);
+		JedParser(const std::string &filename, bool verbose = false);
 		int parse() override;
 		void displayHeader() override;
 
diff --git a/src/jetsonNanoJtagBitbang.cpp b/src/jetsonNanoJtagBitbang.cpp
index 3965908..e5935d9 100644
--- a/src/jetsonNanoJtagBitbang.cpp
+++ b/src/jetsonNanoJtagBitbang.cpp
@@ -215,6 +215,9 @@ int JetsonNanoJtagBitbang::writeTMS(uint8_t *tms_buf, uint32_t len,
 {
 	int tms;
 
+	if (len == 0) // nothing -> stop
+		return len;
+
 	for (uint32_t i = 0; i < len; i++) {
 		tms = ((tms_buf[i >> 3] & (1 << (i & 7))) ? 1 : 0);
 
diff --git a/src/jtag.cpp b/src/jtag.cpp
index cc9358b..e02f9e3 100644
--- a/src/jtag.cpp
+++ b/src/jtag.cpp
@@ -70,7 +70,8 @@ using namespace std;
  *           - envoyer le dernier avec 0x4B ou 0x6B
  */
 
-Jtag::Jtag(const cable_t &cable, const jtag_pins_conf_t *pin_conf, string dev,
+Jtag::Jtag(const cable_t &cable, const jtag_pins_conf_t *pin_conf,
+			const string &dev,
 			const string &serial, uint32_t clkHZ, int8_t verbose,
 			const string &ip_adr, int port,
 			const bool invert_read_edge, const string &firmware_path):
diff --git a/src/jtag.hpp b/src/jtag.hpp
index a1b4a42..a5518ae 100644
--- a/src/jtag.hpp
+++ b/src/jtag.hpp
@@ -16,7 +16,8 @@
 
 class Jtag {
  public:
-	Jtag(const cable_t &cable, const jtag_pins_conf_t *pin_conf, std::string dev,
+	Jtag(const cable_t &cable, const jtag_pins_conf_t *pin_conf,
+		const std::string &dev,
 		const std::string &serial, uint32_t clkHZ, int8_t verbose,
 		const std::string &ip_adr, int port,
 		const bool invert_read_edge = false,
diff --git a/src/lattice.cpp b/src/lattice.cpp
index f77f148..66dae8b 100644
--- a/src/lattice.cpp
+++ b/src/lattice.cpp
@@ -883,7 +883,7 @@ bool Lattice::wr_rd(uint8_t cmd,
 	uint8_t xfer_rx[kXferLen];
 	memset(xfer_tx, 0, kXferLen);
 	int i;
-	if (tx) {
+	if (tx != NULL && tx_len > 0) {
 		for (i = 0; i < tx_len; i++)
 			xfer_tx[i] = tx[i];
 	}
diff --git a/src/libgpiodJtagBitbang.cpp b/src/libgpiodJtagBitbang.cpp
index fef2442..5583d3d 100644
--- a/src/libgpiodJtagBitbang.cpp
+++ b/src/libgpiodJtagBitbang.cpp
@@ -175,6 +175,9 @@ int LibgpiodJtagBitbang::writeTMS(uint8_t *tms_buf, uint32_t len,
 {
 	int tms;
 
+	if (len == 0) // nothing -> stop
+		return len;
+
 	for (uint32_t i = 0; i < len; i++) {
 		tms = ((tms_buf[i >> 3] & (1 << (i & 7))) ? 1 : 0);
 
diff --git a/src/pofParser.cpp b/src/pofParser.cpp
index e7be4cf..1eccf27 100644
--- a/src/pofParser.cpp
+++ b/src/pofParser.cpp
@@ -139,7 +139,7 @@ uint32_t POFParser::parseSection(uint16_t flag, uint32_t pos, uint32_t size)
 					_bit_data.begin());
 			_bit_length = size * 8;
 			if (_verbose)
-				printf("size %u %lu\n", size, _bit_data.size());
+				printf("size %u %zu\n", size, _bit_data.size());
 			break;
 		case 0x1a:  // flash sections
 					// 12Bytes ?
diff --git a/src/progressBar.cpp b/src/progressBar.cpp
index 4eda4a5..6df4878 100644
--- a/src/progressBar.cpp
+++ b/src/progressBar.cpp
@@ -10,12 +10,13 @@
 #include "progressBar.hpp"
 #include "display.hpp"
 
-ProgressBar::ProgressBar(std::string mess, int maxValue, int progressLen,
-		bool quiet): _mess(mess), _maxValue(maxValue),
-		_progressLen(progressLen), _quiet(quiet), _first(true)
+ProgressBar::ProgressBar(const std::string &mess, int maxValue,
+		int progressLen, bool quiet): _mess(mess), _maxValue(maxValue),
+		_progressLen(progressLen), last_time(std::chrono::system_clock::now()),
+		_quiet(quiet), _first(true)
 {
-	last_time = std::chrono::system_clock::now();
 }
+
 void ProgressBar::display(int value, char force)
 {
 	if (_quiet) {
diff --git a/src/progressBar.hpp b/src/progressBar.hpp
index cbd21da..7a14f81 100644
--- a/src/progressBar.hpp
+++ b/src/progressBar.hpp
@@ -10,7 +10,7 @@
 
 class ProgressBar {
 	public:
-		ProgressBar(std::string mess, int maxValue, int progressLen,
+		ProgressBar(const std::string &mess, int maxValue, int progressLen,
 				bool quiet = false);
 		void display(int value, char force = 0);
 		void done();
diff --git a/src/xilinx.cpp b/src/xilinx.cpp
index 6a4cc6f..2f0f6e8 100644
--- a/src/xilinx.cpp
+++ b/src/xilinx.cpp
@@ -135,7 +135,7 @@ Xilinx::Xilinx(Jtag *jtag, const std::string &filename,
 	SPIInterface(filename, verbose, 256, verify, skip_load_bridge,
 				 skip_reset),
 	_device_package(device_package), _spiOverJtagPath(spiOverJtagPath),
-	_irlen(6), _filename(filename), _secondary_filename(secondary_filename)
+	_irlen(6), _secondary_filename(secondary_filename)
 {
 	if (prg_type == Device::RD_FLASH) {
 		_mode = Device::READ_MODE;
diff --git a/src/xilinx.hpp b/src/xilinx.hpp
index 34b2f22..4df75af 100644
--- a/src/xilinx.hpp
+++ b/src/xilinx.hpp
@@ -208,7 +208,6 @@ class Xilinx: public Device, SPIInterface {
 		char _cpld_base_name[7]; /**< cpld name (without package size) */
 		int _irlen; /**< IR bit length */
 		std::map<std::string, std::vector<uint8_t>> _ircode_map; /**< bscan instructions based on model */
-		std::string _filename; /* path to the primary flash file */
 		std::string _secondary_filename; /* path to the secondary flash file (SPIx8) */
 		std::string _secondary_file_extension; /* file type for the secondary flash file */
 		int _flash_chips; /* bitfield to select the target in boards with two flash chips */