Merge pull request #46491 from jbsauvan/hgc-tpg-fix-vfe-compression

[HGCAL trigger] Fix rounding in floating point compression

Author: cmsbuild

L1Trigger/L1THGCal/src/HGCalVFECompressionImpl.cc

@@ -49,7 +49,9 @@ void HGCalVFECompressionImpl::compressSingle(const uint64_t value,
   const uint32_t floatval = (exponent << mantissaBits_) | mantissa;
 
   // we will never want to round up maximum code here
-  if (!rounding_ || floatval == saturationCode_) {
+  // Also, rounding doesn't apply if exponent==1 since there is no actual compression
+  // from the conversion to floating point in that case
+  if (!rounding_ || floatval == saturationCode_ || exponent <= 1) {
     compressedCode = floatval;
     compressedValue = ((1ULL << mantissaBits_) | mantissa) << (exponent - 1);
   } else {