From 3a3a57435c6c128938e56843122b25dcb432a677 Mon Sep 17 00:00:00 2001
From: Jacob Davis <jod23@noreply.localhost>
Date: Tue, 25 Aug 2026 15:26:33 -0400
Subject: [PATCH] Initial commit

---
 Makefile     | 27 +++++++++++++++
 root2mat.cpp | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 Makefile
 create mode 100644 root2mat.cpp

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..50e50ab
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,27 @@
+# Compiler
+CXX := g++
+
+# ROOT flags
+ROOTCFLAGS := $(shell root-config --cflags)
+ROOTLIBS   := $(shell root-config --libs)
+
+# Compilation flags
+CXXFLAGS := -O2 -Wall -Wextra -std=c++17 $(ROOTCFLAGS)
+
+# Target executable
+TARGET := root2mat
+
+# Source files
+SOURCES := root2mat.cpp
+
+# Default rule
+all: $(TARGET)
+
+$(TARGET): $(SOURCES)
+	$(CXX) $(CXXFLAGS) $^ -o $@ $(ROOTLIBS)
+
+# Clean rule
+clean:
+	rm -f $(TARGET)
+
+.PHONY: all clean
diff --git a/root2mat.cpp b/root2mat.cpp
new file mode 100644
index 0000000..79f841b
--- /dev/null
+++ b/root2mat.cpp
@@ -0,0 +1,93 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <string>
+#include <cstdint>
+
+// ROOT Headers
+#include <TFile.h>
+#include <TH2.h>
+
+void root2mat(const std::string& inputRoot, const std::string& histName, const std::string& outputMat) {
+    constexpr int X_SIZE = 4096;
+    constexpr int Y_SIZE = 4096;
+    constexpr size_t TOTAL_BINS = static_cast<size_t>(X_SIZE) * Y_SIZE;
+
+    // Open ROOT file
+    TFile* inFile = TFile::Open(inputRoot.c_str(), "READ");
+    if (!inFile || inFile->IsZombie()) {
+        std::cerr << "Error: Could not open input ROOT file " << inputRoot << std::endl;
+        return;
+    }
+
+    // Get 2D histogram
+    TH2* h2 = dynamic_cast<TH2*>(inFile->Get(histName.c_str()));
+    if (!h2) {
+        std::cerr << "Error: Could not find TH2 histogram named '" << histName << "' in file." << std::endl;
+        inFile->Close();
+        delete inFile;
+        return;
+    }
+
+    // Determine target format and integer depth based on output extension
+    bool is32Bit = false;
+    if (outputMat.length() >= 4 && outputMat.substr(outputMat.length() - 4) == ".spn") {
+        is32Bit = true;
+    } else if (outputMat.length() >= 4 && outputMat.substr(outputMat.length() - 4) == ".mat") {
+        is32Bit = false;
+    } else {
+        std::cerr << "Error: Unsupported output file extension. Must be .mat or .spn" << std::endl;
+        inFile->Close();
+        delete inFile;
+        return;
+    }
+
+    std::cout << "Extracting '" << histName << "' into " << X_SIZE << " x " << Y_SIZE 
+              << " binary matrix (" << (is32Bit ? "32-bit .spn" : "16-bit .mat") << ")..." << std::endl;
+
+    // Open output binary file
+    std::ofstream outFile(outputMat, std::ios::binary);
+    if (!outFile.is_open()) {
+        std::cerr << "Error: Could not create output file " << outputMat << std::endl;
+        inFile->Close();
+        delete inFile;
+        return;
+    }
+
+    // Extract bin contents row-by-row matching column-major order (x * Y_SIZE + y)
+    if (is32Bit) {
+        std::vector<int32_t> buffer(TOTAL_BINS);
+        for (int x = 0; x < X_SIZE; ++x) {
+            for (int y = 0; y < Y_SIZE; ++y) {
+                // ROOT bins are 1-indexed
+                buffer[x * Y_SIZE + y] = static_cast<int32_t>(h2->GetBinContent(x + 1, y + 1));
+            }
+        }
+        outFile.write(reinterpret_cast<const char*>(buffer.data()), TOTAL_BINS * sizeof(int32_t));
+    } else {
+        std::vector<int16_t> buffer(TOTAL_BINS);
+        for (int x = 0; x < X_SIZE; ++x) {
+            for (int y = 0; y < Y_SIZE; ++y) {
+                // ROOT bins are 1-indexed[cite: 1]
+                buffer[x * Y_SIZE + y] = static_cast<int16_t>(h2->GetBinContent(x + 1, y + 1));
+            }
+        }
+        outFile.write(reinterpret_cast<const char*>(buffer.data()), TOTAL_BINS * sizeof(int16_t));
+    }
+
+    outFile.close();
+    inFile->Close();
+    delete inFile;
+
+    std::cout << "Successfully written matrix to " << outputMat << std::endl;
+}
+
+int main(int argc, char* argv[]) {
+    if (argc < 4) {
+        std::cout << "Usage: " << argv[0] << " <input.root> <hist_name> <output.mat/.spn>\n";
+        return 1;
+    }
+
+    root2mat(argv[1], argv[2], argv[3]);
+    return 0;
+}
\ No newline at end of file