Explicitely signify if a loop if present

Before we tried to "guess", which causes problems if a loop spans the entire file

src/sfizz/FilePool.cpp

@@ -227,6 +227,7 @@ absl::optional<sfz::FileInformation> sfz::FilePool::getFileInformation(const Fil
 
     if (!fileId.isReverse()) {
         if (instrumentInfo.loop_count > 0) {
+            returnedValue.hasLoop = true;
             returnedValue.loopBegin = instrumentInfo.loops[0].start;
             returnedValue.loopEnd = min(returnedValue.end, instrumentInfo.loops[0].end - 1);
         }

src/sfizz/FilePool.h

@@ -52,6 +52,7 @@ struct FileInformation {
     uint32_t end { Default::sampleEndRange.getEnd() };
     uint32_t loopBegin { Default::loopRange.getStart() };
     uint32_t loopEnd { Default::loopRange.getEnd() };
+    bool hasLoop { false };
     double sampleRate { config::defaultSampleRate };
     int numChannels { 0 };
 };

src/sfizz/Synth.cpp

@@ -482,7 +482,7 @@ void sfz::Synth::finalizeSfzLoad()
 
             region->sampleEnd = std::min(region->sampleEnd, fileInformation->end);
 
-            if (fileInformation->loopBegin != Default::loopRange.getStart() && fileInformation->loopEnd != Default::loopRange.getEnd()) {
+            if (fileInformation->hasLoop) {
                 if (region->loopRange.getStart() == Default::loopRange.getStart())
                     region->loopRange.setStart(fileInformation->loopBegin);
 

tests/FilesT.cpp

@@ -564,6 +564,17 @@ TEST_CASE("[Files] Looped regions taken from files and possibly overriden")
     REQUIRE(synth.getRegionView(2)->loopRange == Range<uint32_t> { 4, 124 });
 }
 
+TEST_CASE("[Files] Looped regions can start at 0")
+{
+    Synth synth;
+    synth.loadSfzString(fs::current_path() / "tests/TestFiles/loop_can_start_at_0.sfz", R"(
+    <region> sample=wavetable_with_loop_at_endings.wav
+    )");
+    REQUIRE( synth.getNumRegions() == 1 );
+    REQUIRE( synth.getRegionView(0)->loopMode == SfzLoopMode::loop_continuous );
+    REQUIRE( synth.getRegionView(0)->loopRange == Range<uint32_t> { 0, synth.getRegionView(0)->sampleEnd } );
+}
+
 TEST_CASE("[Files] Case sentitiveness")
 {
     const fs::path sfzFilePath = fs::current_path() / "tests/TestFiles/case_insensitive.sfz";