Function syncSubQuregToGpu

quest/src/api/qureg.cpp:412–430

void syncSubQuregToGpu(Qureg qureg, qindex localStartInd, qindex numLocalAmps) {
    validate_quregFields(qureg, __func__);
    validate_localAmpIndices(qureg, localStartInd, numLocalAmps, __func__); 
    
    // the above validation communicates for node consensus in
    // distributed settings, because params can differ per-node.
    // note also this function accepts statevectors AND density
    // matrices, because the latter does not need a bespoke
    // (row,col) interface, because the user can only access/modify
    // local density matrix amps via a flat index anyway!

    // we permit this function to do nothing when not GPU-accelerated
    if (!qureg.isGpuAccelerated)
        return;

    // otherwise, every node merely copies its local subset, which
    // may differ per-node, in an embarrassingly parallel manner
    gpu_copyCpuToGpu(&qureg.cpuAmps[localStartInd], &qureg.gpuAmps[localStartInd], numLocalAmps);
}
void syncSubQuregFromGpu(Qureg qureg, qindex localStartInd, qindex numLocalAmps) {
    validate_quregFields(qureg, __func__);
    validate_localAmpIndices(qureg, localStartInd, numLocalAmps, __func__);