From 35089045ea8332c63375ff838e3d93dda8e6b965 Mon Sep 17 00:00:00 2001
From: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Date: Wed, 25 Feb 2026 09:53:28 +0100
Subject: [PATCH] latticeBitParser, lattice: added 128 clock pulses padding
 before preamble: Required by ECP3 family

---
 src/lattice.cpp          |  5 +++--
 src/latticeBitParser.cpp | 19 +++++++++++++++----
 src/latticeBitParser.hpp |  3 ++-
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/lattice.cpp b/src/lattice.cpp
index 1feed06..058f5a7 100644
--- a/src/lattice.cpp
+++ b/src/lattice.cpp
@@ -331,7 +331,7 @@ bool Lattice::program_mem()
 {
 	bool err;
 
-	LatticeBitParser _bit(_filename, false, _verbose);
+	LatticeBitParser _bit(_filename, false, false, _verbose);
 
 	printInfo("Open file: ", false);
 	printSuccess("DONE");
@@ -950,7 +950,8 @@ bool Lattice::program_extFlash(unsigned int offset, bool unprotect_flash)
 		if (_file_extension == "mcs")
 			_bit = new McsParser(_filename, true, _verbose);
 		else if (_file_extension == "bit")
-			_bit = new LatticeBitParser(_filename, false, _verbose);
+			_bit = new LatticeBitParser(_filename, false,
+				_fpga_family==ECP3_FAMILY, _verbose);
 		else
 			_bit = new RawParser(_filename, false);
 		printSuccess("DONE");
diff --git a/src/latticeBitParser.cpp b/src/latticeBitParser.cpp
index b1f43fb..eb86a79 100644
--- a/src/latticeBitParser.cpp
+++ b/src/latticeBitParser.cpp
@@ -21,10 +21,10 @@
 
 using namespace std;
 
-LatticeBitParser::LatticeBitParser(const string &filename, bool machxo2,
+LatticeBitParser::LatticeBitParser(const string &filename, bool machxo2, bool ecp3,
 	bool verbose):
 	ConfigBitstreamParser(filename, ConfigBitstreamParser::BIN_MODE, verbose),
-	_endHeader(0), _is_machXO2(machxo2)
+	_endHeader(0), _is_machXO2(machxo2), _is_ecp3(ecp3)
 {}
 
 LatticeBitParser::~LatticeBitParser()
@@ -135,8 +135,19 @@ int LatticeBitParser::parse()
 
 	/* read All data */
 	if (!_is_machXO2) {
-		_bit_data.resize(_raw_data.size() - _endHeader);
-		std::move(_raw_data.begin()+_endHeader, _raw_data.end(), _bit_data.begin());
+		/* According to FPGA-TN-02192-3.4
+		 * the Lattice ECP3 must trasnmit at least 128 clock pulses before
+		 * receiving the preamble.
+		 * Here the header contains 16 Dummy bit + preamble so only
+		 * 14bits 8x14= 112bits must be added as padding.
+		 */
+		const uint32_t offset = (_is_ecp3) ? 14 : 0;
+		_bit_data.resize(_raw_data.size() - _endHeader + offset);
+		if (_is_ecp3) {
+			std::string tmp(14, 0xff);
+			std::move(tmp.begin(), tmp.end(), _bit_data.begin());
+		}
+		std::move(_raw_data.begin() + _endHeader, _raw_data.end(), _bit_data.begin() + offset);
 		_bit_length = _bit_data.size() * 8;
 	} else {
 		const uint32_t len = _raw_data.size() - _endHeader;
diff --git a/src/latticeBitParser.hpp b/src/latticeBitParser.hpp
index da24b87..916dc57 100644
--- a/src/latticeBitParser.hpp
+++ b/src/latticeBitParser.hpp
@@ -15,7 +15,7 @@
 
 class LatticeBitParser: public ConfigBitstreamParser {
 	public:
-		LatticeBitParser(const std::string &filename, bool machxo2,
+		LatticeBitParser(const std::string &filename, bool machxo2, bool ecp3,
 			bool verbose = false);
 		~LatticeBitParser();
 		int parse() override;
@@ -31,6 +31,7 @@ class LatticeBitParser: public ConfigBitstreamParser {
 		bool parseCfgData();
 		size_t _endHeader;
 		bool _is_machXO2;
+		bool _is_ecp3;
 		/* data storage for machXO2 */
 		std::vector<std::string> _bit_array;
 };