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integer_sort.hpp: shifted from low level code to C++ STL and copy -> …
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…copy_n
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@fenilgmehta
fenilgmehta committed Mar 31, 2019
1 parent 2c455eb commit 64c227d
Showing 1 changed file with 24 additions and 33 deletions.
57 changes: 24 additions & 33 deletions src/integer_sort.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -414,7 +414,8 @@ namespace ir_sort {
// for (i = 0; i < parameter::length; ++i) {
// start_arr[i] = buffer[i];
// }
std::copy(buffer, std::next(buffer, parameter::length), start_arr);
// std::copy(buffer, std::next(buffer, parameter::length), start_arr);
std::copy_n(buffer, parameter::length, start_arr);
}
}

Expand Down Expand Up @@ -449,7 +450,8 @@ namespace ir_sort {
// for last column which contains the bit which decides the sign of a number

if (parameter::iterations_required % 2) {
std::copy(buffer, std::next(buffer, parameter::length), start_arr);
// std::copy(buffer, std::next(buffer, parameter::length), start_arr);
std::copy_n(buffer, parameter::length, start_arr);
}
}

Expand Down Expand Up @@ -626,14 +628,14 @@ namespace ir_sort {
// SUBORDINATE VARIABLES
int_fast64_t arrMaxElement = getIndex(
arr[high]); // "arrMaxElement" is used to store the largest element in "arr"
auto *arr_index = new IndexType[sortArrayLength]; // this array is used to store the index of partially sorted array
auto *copyArray_index = new IndexType[sortArrayLength]; // this array is used to store the index of partially sorted array
std::vector<IndexType> arr_index(sortArrayLength); // this array is used to store the index of partially sorted array
std::vector<IndexType> copyArray_index(sortArrayLength); // this array is used to store the index of partially sorted array
auto *p_arr_index = &arr_index[0];
auto *p_copyArray_index = &copyArray_index[0];
ArrayElementType *p_arr = &arr[low];
high -= low;

auto *indexTracker = new IndexType[sortArrayLength];
std::vector<IndexType> indexTracker(sortArrayLength);

// REQUIRED VARIABLES
int_fast64_t i; // IMPORTANT: used for iterations
Expand All @@ -660,27 +662,26 @@ namespace ir_sort {
// the size of the array "box" is "boxArraySize" so that the numbers from 0 to "boxArraySize - 1" can be tracked in the column being scanned
uint_fast64_t box[boxArraySize];

// this will fill the arr_index with the values from 0, 1, 2, 3, ..., (high - 1)
// for (i = 0; i <= high; ++i) arr_index[i] = i;
// this will fill the arr_index with the values from 0, 1, 2, 3, ..., high
// std::iota(arr_index.begin(), arr_index.end(), 0);
std::iota(&arr_index[0], &arr_index[high] + 1, 0);

// START ACTUAL SORTING
// This condition is used so that all the digits of each element are checked and "arr" is sorted according to the digit considered
while (iterationsRequired-- > 0) {
// default values of all the elements of the array "box" = 0
for (i = 0; i < boxArraySize;) {
box[i++] = 0;
}
std::fill_n(box, boxArraySize, 0);

// this for loop will note number of zeros, ones, twos ... "boxArraySize - 1" present in the column
for (i = 0; i <= high; ++i) {
box[(getIndex(p_arr[i]) >> bitsShiftFactor) & modNum]++;
}

// this for loop is used to add the values of the previous element to the next element of the array "box"
for (i = 1; i < boxArraySize; ++i) {
box[i] += box[i - 1];
}
// for (i = 1; i < boxArraySize; ++i) {
// box[i] += box[i - 1];
// }
std::partial_sum(&box[0], &box[boxArraySize], &box[0]);

// this statement will copy all the elements of "arr" to "arr_index"
// BEFORE this step,
Expand Down Expand Up @@ -724,10 +725,6 @@ namespace ir_sort {
p_arr_index[indexTracker[i]] = p_arr_index[i];
indexTracker[p_arr_index[i]] = indexTracker[i];
}

delete[] indexTracker;
delete[] arr_index;
delete[] copyArray_index;
}


Expand All @@ -748,16 +745,15 @@ namespace ir_sort {
if (high - low > (1ll << 32)) using IndexType = int64_t;

// SUBORDINATE VARIABLES
int_fast64_t arrMaxElement = getIndex(
arr[high]); // "arrMaxElement" is used to store the largest element in "arr"
auto *arr_index = new IndexType[sortArrayLength]; // this array is used to store the index of partially sorted array
auto *copyArray_index = new IndexType[sortArrayLength]; // this array is used to store the index of partially sorted array
int_fast64_t arrMaxElement = getIndex(arr[high]); // "arrMaxElement" is used to store the largest element in "arr"
std::vector<IndexType> arr_index(sortArrayLength); // this array is used to store the index of partially sorted array
std::vector<IndexType> copyArray_index(sortArrayLength); // this array is used to store the index of partially sorted array
auto *p_arr_index = &arr_index[0];
auto *p_copyArray_index = &copyArray_index[0];
ArrayElementType *p_arr = &arr[low];
high -= low;

auto *indexTracker = new IndexType[sortArrayLength];
std::vector<IndexType> indexTracker(sortArrayLength);

// REQUIRED VARIABLES
int_fast64_t i; // IMPORTANT: used for iterations
Expand All @@ -784,27 +780,26 @@ namespace ir_sort {
// the size of the array "box" is "boxArraySize" so that the numbers from 0 to "boxArraySize - 1" can be tracked in the column being scanned
uint_fast64_t box[boxArraySize];

// this will fill the arr_index with the values from 0, 1, 2, 3, ..., (high - 1)
// this will fill the arr_index with the values from 0, 1, 2, 3, ..., high
// for (i = 0; i <= high; ++i) arr_index[i] = i;
std::iota(&arr_index[0], &arr_index[high] + 1, 0);

// START ACTUAL SORTING
// This condition is used so that all the digits of each element are checked and "arr" is sorted according to the digit considered
while (iterationsRequired-- > 0) {
// default values of all the elements of the array "box" = 0
for (i = 0; i < boxArraySize;) {
box[i++] = 0;
}
std::fill_n(box, boxArraySize, 0);

// this for loop will note number of zeros, ones, twos ... "boxArraySize - 1" present in the column
for (i = 0; i <= high; ++i) {
box[(getIndex(p_arr[i]) >> bitsShiftFactor) & modNum]++;
}

// this for loop is used to add the values of the previous element to the next element of the array "box"
for (i = 1; i < boxArraySize; ++i) {
box[i] += box[i - 1];
}
// for (i = 1; i < boxArraySize; ++i) {
// box[i] += box[i - 1];
// }
std::partial_sum(&box[0], &box[boxArraySize], &box[0]);

// this statement will copy all the elements of "arr" to "arr_index"
// BEFORE this step,
Expand Down Expand Up @@ -879,10 +874,6 @@ namespace ir_sort {
p_arr_index[indexTracker[i]] = p_arr_index[i];
indexTracker[p_arr_index[i]] = indexTracker[i];
}

delete[] indexTracker;
delete[] arr_index;
delete[] copyArray_index;
}

} // namespace ir_sort
Expand Down

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