103 lines
3.1 KiB
C++
103 lines
3.1 KiB
C++
#ifndef MAGYAR_SORT_H
|
|
#define MAGYAR_SORT_H
|
|
/**
|
|
* single header lib: In-place, fast heavily modified and optimized radix sort.
|
|
*
|
|
* Only unsigned ints for now, but should be able to modify for int and float...
|
|
* This is the counting variant with smart changes (not per-bit).
|
|
*
|
|
* LICENCE: CC3 - look it up, you need to mention me but that is all
|
|
*/
|
|
|
|
#include <cstdio>
|
|
#include <cstdint>
|
|
|
|
namespace MagyarSort {
|
|
|
|
// Only change these if you know what you are doing
|
|
// I use these because I want to see if nibbles are
|
|
// better or something...
|
|
//
|
|
// Bytes of nibbles only:
|
|
// - DIGIT_RANGE and BITS_PER_DIGIT should correspond
|
|
// - DIGITS should also correspond with the uint32_t
|
|
// - and DIGIT_RANGE should be 2^n value (16 or 256)
|
|
static constexpr int DIGITS = 4; // "helyiérték"
|
|
static constexpr int BITS_PER_DIGIT = 8; // "bit / helyiérték"
|
|
static constexpr int DIGIT_RANGE = 256; // "helyiérték állapottér"
|
|
|
|
template<int DIGIT_CHOICE>
|
|
static inline uint32_t getDigit(uint32_t num) noexcept {
|
|
static constexpr int SHIFT = DIGIT_CHOICE * BITS_PER_DIGIT;
|
|
|
|
uint32_t shifted = num >> SHIFT;
|
|
return shifted & (DIGIT_RANGE - 1);
|
|
}
|
|
|
|
/** Functor: no class should be generated I think (compiler should be smart) */
|
|
template<int DIGIT>
|
|
struct OccurenceMagic : public OccurenceMagic<DIGIT - 1> {
|
|
inline OccurenceMagic(uint32_t arr[], size_t i, size_t *radicsOut) noexcept
|
|
: OccurenceMagic<DIGIT -1 >(arr, i, radicsOut) {
|
|
// parents run first so template recursion runs DIGIT=0 first...
|
|
++radicsOut[getDigit<DIGIT>(arr[i]) + DIGIT_RANGE * DIGIT];
|
|
}
|
|
};
|
|
/** Ends template recursion */
|
|
template<>
|
|
struct OccurenceMagic<-1> {
|
|
inline OccurenceMagic(uint32_t arr[], size_t i, size_t *radicsOut) noexcept {
|
|
/* empty */
|
|
}
|
|
};
|
|
|
|
static inline void countOccurences(uint32_t arr[], size_t size, size_t *radicsOut) {
|
|
for(size_t i = 0; i < size; ++i) {
|
|
// Creates no object, struct is empty
|
|
OccurenceMagic<DIGITS - 1>(arr, i, radicsOut);
|
|
}
|
|
}
|
|
|
|
template<int DIGIT_CHOICE>
|
|
static inline void prefixSum(size_t *radics) {
|
|
static constexpr int DSTART = DIGIT_CHOICE * DIGIT_RANGE;
|
|
size_t prev = 0;
|
|
for(int i = DSTART; i < (DSTART + DIGIT_RANGE); ++i) {
|
|
radics[i] += prev;
|
|
prev = radics[i];
|
|
}
|
|
}
|
|
|
|
/** Sort the given array (in-place sorting) with the given size */
|
|
inline void sort(uint32_t arr[], size_t size) noexcept {
|
|
// Holds "digit" occurences, prefix sums, whatevers
|
|
// First "DIGIT_RANGE" elem is for MSB "DIGITS", last is for LSB
|
|
static thread_local size_t radics[DIGITS * DIGIT_RANGE];
|
|
for(int i = 0; i < (DIGITS * DIGIT_RANGE); ++i) { radics[i] = 0; }
|
|
|
|
// Calculate occurences of digits
|
|
countOccurences(arr, size, radics);
|
|
|
|
// Calculate prefix sums
|
|
// TODO: Maybe should use better ILP here?
|
|
// but maybe this is more cache friendly?
|
|
// TODO: manual digits!
|
|
prefixSum<0>(radics);
|
|
prefixSum<1>(radics);
|
|
prefixSum<2>(radics);
|
|
prefixSum<3>(radics);
|
|
|
|
/* // DEBUG:
|
|
*/
|
|
for(size_t j = 0; j < DIGITS; ++j) {
|
|
printf("d%d: ", j);
|
|
for(size_t i = 0; i < DIGIT_RANGE; ++i) {
|
|
printf("%d,", radics[i + DIGIT_RANGE*j]);
|
|
}
|
|
printf("\n\n");
|
|
}
|
|
}
|
|
};
|
|
|
|
#endif
|