Function allocSuperOp

quest/src/api/channels.cpp:125–159

SuperOp allocSuperOp(int numQubits) {

    // this inner function will NOT validate, verify whether 
    // allocations succeeded, nor attempt to free memory if not

    // prior validation ensures these never overflow
    qindex numRows = powerOf2(2 * numQubits);
    qindex numElems = numRows * numRows;

    // attempt top allocate 1D memory
    qcomp* cpuMem = cpu_allocArray(numElems); // nullptr if failed
    qcomp* gpuMem = nullptr;
    if (getQuESTEnv().isGpuAccelerated)
        gpuMem = gpu_allocArray(numElems); // nullptr if failed

    // prepare output SuperOp (avoiding C++20 designated initialiser)
    SuperOp out;
    out.numQubits = numQubits;
    out.numRows = numRows;

    // attemptedly allocate 2D alias for 1D CPU memory
    out.cpuElems = cpu_allocAndInitMatrixWrapper(cpuMem, numRows); // nullptr if failed
    out.cpuElemsFlat = cpuMem;
    out.gpuElemsFlat = gpuMem;

    // attemptedly allocate (un-initialised) flags in the heap so that struct copies are mutable
    out.wasGpuSynced = cpu_allocHeapFlag(); // nullptr if failed

    // if heap flag allocated, mark it as unsynced (caller will handle if allocation failed)
    if (mem_isAllocated(out.wasGpuSynced))
        *(out.wasGpuSynced) = 0;

    // caller will handle if any above allocations failed
    return out;
}


extern "C" SuperOp createSuperOp(int numQubits) {