Add ParticleIDWrapper::make_invalid() (#3735)

Add faster functions to ParticleIDWrapper: make_invalid, make_valid and is_valid.

Src/Particle/AMReX_Particle.H

@@ -102,6 +102,41 @@ struct ParticleIDWrapper
  r = (sign) ? lval : -lval;
  return r;
  }
+
+ /** Mark the particle as invalid
+ *
+ * Swaps the is_valid (sign) bit to invalid.
+ * This is NOT identical to id = -id, but it is equally reversible via make_valid().
+ */
+ AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+ void make_invalid () noexcept
+ {
+ // RHS mask: 0111...
+ m_idata &= ~(uint64_t(1) << 63);
+ }
+
+ /** Mark the particle as valid
+ *
+ * Swaps the is_valid (sign) bit to valid.
+ * This is NOT identical to id = -id, but it is equally reversible via make_invalid().
+ */
+ AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+ void make_valid () noexcept
+ {
+ // RHS mask: 1000...
+ m_idata |= uint64_t(1) << 63;
+ }
+
+ /** Check the particle is valid, via the sign of the id.
+ *
+ * Returns true if the particle is valid (the id is positive), otherwise false (invalid particle).
+ */
+ [[nodiscard]] AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+ bool is_valid () const noexcept
+ {
+ // the leftmost bit is our id's valid sign
+ return m_idata >> 63;
+ }
 };
 
 struct ParticleCPUWrapper
@@ -173,6 +208,17 @@ struct ConstParticleIDWrapper
  r = (sign) ? lval : -lval;
  return r;
  }
+
+ /** Check the sign of the id.
+ *
+ * Returns true if the id is positive, otherwise false (invalid particle).
+ */
+ [[nodiscard]] AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+ bool is_valid () const noexcept
+ {
+ // the leftmost bit is our id's valid sign
+ return m_idata >> 63;
+ }
 };
 
 struct ConstParticleCPUWrapper