LIBDVM2 (1158351), страница 12

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The copying is executed until the exhaustion of the source or target elements. The elements are copied according to the C language discipline of allocating of the elements in the memory, that is the right index is changed more faster then the left one. If the initial value of the index by some dimension of the source or target array is greater or equal to its last value, then the index of this dimension is not changed during copy operation. Note, that Run-Time Library considers the last index value of any dimension as a minimum of the defined value in the function call and the real size of this dimension minus 1.

To use a full scope of the source or target array without requesting the size of the object by some dimension (see section 17.2), Run-Time Library supposes that the value of the initial index value can be equal to -1. In that case, the initial index value is supposed to be equal to zero, the step be equal to 1, and the last index value be equal to the size of the dimension minus 1.

One of the arrays (but not the both) can be not distributed but rather a normal one replicated among all the processors (Run-Time Library determines this case if the pointer of the array is not the pointer to the header of the distributed array). The types of the elements of replicated and distributed arrays must be the same. It is assumed that the replicated array is one-dimensional, and that the elements of this array are allocated in the memory consequently and continuously. Run-Time Library ignores the parameters of the indexes of such array.

If the one of the arrays is not a distributed one, then the copy mode is determined by the value of the *CopyRegimPtr flag:

• if the flag *CopyRegimPtr is positive, then Run-Time Library assumes that the «normal» array is allocated on the I/O processor only.

• if *CopyRegimPtr is negative (it is allowable only for “normal” array to be read), then the distributed array, specified by the parameter ToArrayHeader, will be filled by an element with address, specified by the parameter FromArrayHeader.

If both arrays are non-distributed ones, then the copying is not executed.

If both arrays are distributed ones, then these arrays can be different in the rank and in the size of each dimension, but the types of the element of the arrays have to be the same.

The function returns the number of the copied elements.

13.3. Asynchronous coping distributed arrays.

Described above functions arwelm_ , arwelf_ , acopel_ , aelmcp_ and aarrcp_ starts coping operations, executed by the functions rwelm_, rwelmf_, copelm_, elmcpy_, and arrcpy_. All parameters of considered functions, except of the last one, are similar to the same named parameters of their synchronous analogous. The last parameter *CopyFlagPtr is the pointer to the flag of completion of the started coping operation.

Waiting for completion of coping is performed by the function

long waitcp_ (AddrType *CopyFlagPtr);

13.4. Access to elements of local part of distributed array.

Let n be the rank of the distributed array. Then the header of this array in the call of the function crtda_ can be declared for example as:

long ArrayHeader[n+1];

Let the base pointer corresponding to the type of the elements of the distributed array be BasePtr. Then the element (I₁, ... , I_n) from the local part of the distributed array can be accessed through linear index in the following manner:

For C the value of the base pointer in crtda_ function call may be NULL. In that case the element of the local part of the distributed array may be accessed in the following manner:

where: Type is the type of the element of the distributed array.

Run-Time Library calculates the coefficients ArrayHeader[1], ... ,ArrayHeader[n-1] and the address constant ArrayHeader[n] in the functions of the array alignment align_ and realn_ in the following manner.

Let:

Then:

Note, that Run-Time Library allocates (during the execution of the functions align_ and realn_) the local part of the distributed array in the memory in so manner that the difference ArrayPtr - BasePtr must be multiple of the TypeSize.

The access to the elements of the local part of the distributed array is performed either directly by its header and the base pointer, or by the functions rlocel_ , wlocel_ and clocel_ (that is less effective) described below.

13.4.1. Requesting if array element is allocated in local part of distributed array.

The number of specified indexes has to be equal to the rank of the distributed array.

The function returns non-zero value, if specified element is allocated in the local part of the specified distributed array, and zero in other case.

13.4.2. Requesting initial and last index values of local part of distributed array.

The sizes of the arrays InitIndexArray and LastIndexArray must be equal to the distributed array rank.

The function returns non-zero value, if the specified array has a local part and zero in other case. If the array has no the local part, the arrays InitIndexArray and LastIndexArray are not updated.

13.4.3. Reading element of local part of distributed array.

The function can be executed successfully only by the processor, in whose memory the specified element is allocated.

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