PagedArray.icc

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/*
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/**
 * @file PagedArray.icc
 *
 * Template definitions of PagedArray class.
 *
 * @author Pekka Jääskeläinen 2006 (pekka.jaaskelainen-no.spam-tut.fi)
 * @note rating: red
 */
 
#include "Application.hh"
 
#include <cmath>
#include <cstring>
 
/**
 * Constructor.
 *
 * Initializes the page table.
 *
 * @param size The count of elements in the array.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
PagedArray<ValueType, PageSize, DefaultValue>::PagedArray(std::size_t size) {
    pageTableSize_ =
        static_cast<std::size_t>(
            std::ceil(static_cast<double>(size) / PageSize));
 
    pageTable_ = new ValueType*[pageTableSize_];
    for (std::size_t i = 0; i < pageTableSize_; ++i) {
        pageTable_[i] = NULL;
    }
}
 
 
/**
 * Destructor. 
 *
 * Deallocates tables and cleans up the page table.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
PagedArray<ValueType, PageSize, DefaultValue>::~PagedArray() {
    deletePages();
    delete[] pageTable_;
    pageTable_ = NULL;
}
 
 
/**
 * Deletes all allocated memory chunks, thus effectively sets all memory
 * locations to zero.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
void
PagedArray<ValueType, PageSize, DefaultValue>::deletePages() {
    for (std::size_t i = 0; i < pageTableSize_; ++i) {
        if (pageTable_[i] != NULL) {
            delete[] pageTable_[i];
            pageTable_[i] = NULL;
        }
    }
}
 
/**
 * Reads data to a vector.
 *
 * If the number of values exceeds the size of the given container, 
 * then the container is resized.
 *
 * @param index Index to be read from.
 * @param data Container where read data is stored.
 * @param size Number of minimum addressable units to read.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
void
PagedArray<ValueType, PageSize, DefaultValue>::read(
    IndexType index, 
    ValueVector& data, 
    std::size_t size) {
 
    if (data.size() != size) {
        data.resize(size);
    }
 
    for (size_t i = index; i < index + size; i++) {
        data[i - index] = readData(i);
    }
}
 
/**
 * Returns the amount of allocated memory by the array pages.
 *
 * This is used for debugging the implementation.
 *
 * @return The amount of allocated memory in bytes.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
size_t
PagedArray<ValueType, PageSize, DefaultValue>::allocatedMemory() const {
 
    size_t countOfChunks = 0;
 
    for (std::size_t i = 0; i < sizeof(pageTable_); ++i) {
        if (pageTable_[i] != NULL)
            ++countOfChunks;
    }
    return countOfChunks*PageSize*sizeof(ValueType);
}
 
/**
 * Fills the whole array with the default value.
 *
 * This is needed due to some buggy simulated programs which expect
 * uninitialized data to be zero.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
void
PagedArray<ValueType, PageSize, DefaultValue>::clear() {
    deletePages();
}
 
 
/**
 * Stores data to the array.
 *
 * Does not perform bounds-checking.
 *
 * @param index The index of the data.
 * @param data Data to be stored in a traditional table.
 * @param size Size of the data to store.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
inline void
PagedArray<ValueType, PageSize, DefaultValue>::write(
    IndexType index,
    ValueTable data,
    std::size_t size) {
    for (size_t i = index; i < index + size; ++i) {
        writeData(i, data[i - index]);
    }
}
 
/**
 * Writes a value to the given index.
 *
 * @param index Target index.
 * @param data Data to write.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
inline void
PagedArray<ValueType, PageSize, DefaultValue>::writeData(
    IndexType index, 
    const ValueType& data) {
 
    ValueType* page = pageTable_[index / PageSize];
    if (page == NULL) {
        page = new ValueType[PageSize];
        std::memset(page, 0, PageSize*sizeof(ValueType));
        pageTable_[index / PageSize] = page;
    }
    page[index % PageSize] = data;
}
 
/**
 * Reads a value from a given index.
 *
 * If the page to be read is not yet allocated, doesn't allocate it,
 * but returns the default value instead. This way we avoid memory consumption 
 * explosion for example in simulator/debugger when user wants to browse 
 * through the memory space (which is mostly uninitialized at least in 
 * sequential code) in the memory window.
 *
 * @param index Target index.
 * @return data 
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
inline ValueType
PagedArray<ValueType, PageSize, DefaultValue>::readData(IndexType index) {
    ValueType* page = pageTable_[index / PageSize];
    if (page == NULL) {
        return DefaultValue;
    }
    return page[index % PageSize];
}
 
/**
 * Reads data to an array.
 *
 * A more efficient version. 
 *
 * @param index Index to read from.
 * @param data Pointer to array in which the data should stored. Must have
 *             enough space!
 * @param size Size of chunk to read.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
inline void
PagedArray<ValueType, PageSize, DefaultValue>::read(
    IndexType index, 
    ValueTable data, 
    std::size_t size) {
    for (size_t i = index; i < index + size; i++) {
        data[i - index] = readData(i);
    }
}
 
 
/**
 * Reads data to a vector.
 *
 * The number of minimum addressable units that are read is equal to the
 * size of the container.
 *
 * @param address Memory address to be read from.
 * @param data Container where read data is stored.
 */
template <typename ValueType, int PageSize, ValueType DefaultValue>
inline void
PagedArray<ValueType, PageSize, DefaultValue>::read(
    Word address, 
    ValueVector& data) {
    read(address, data, data.size());
}