Porting my Integer Sorting Algorithms to D

["Nordlöw"]

I did some more benchmarking:

These are all using non-inplace radix sort.
This can be useful in some cases where in-place is not needed.

Performance gain increase with size input array compared to 
std::sort as radix sort in "some regard" is O(n) and quick sort 
is O(n*log n).

Break sizes (when radix sort wins) for different element types:
uint8: <1024
uint16: <1024
uint32: >= 4096
float: >= 8192
double: >= 16384

Number of tries: 3
Do in place: 0
Element Count: 1024
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 2390us 16 0.483x 0.892x 0.386x 0.898x
double 809us 16 0.152x 0.155x 0.059x 0.0822x
uint8_t 1104us 8 10.9x 10.9x 1.65x 2.9x
uint16_t 1813us 16 1.38x 1.4x 0.889x 1.44x
uint32_t 707us 16 0.286x 0.281x 0.137x 0.231x
Element Count: 2048
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 1511us 16 0.518x 0.513x 0.21x 0.28x
double 1520us 16 0.268x 0.27x 0.0997x 0.144x
uint8_t 2603us 8 11.8x 11.8x 3.81x 12.2x
uint16_t 1451us 16 1.03x 1.1x 0.675x 1.03x
uint32_t 1531us 16 0.592x 0.575x 0.44x 0.583x
Element Count: 4096
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 3099us 16 0.939x 0.904x 0.785x 0.925x
double 3411us 16 0.504x 0.483x 0.13x 0.392x
uint8_t 2777us 8 6.69x 6.64x 1.7x 7.37x
uint16_t 3133us 16 1.91x 1.9x 0.458x 1.46x
uint32_t 3681us 16 1.15x 1.14x 0.229x 0.539x
Element Count: 8192
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 6760us 16 1.49x 1.54x 0.422x 0.921x
double 7285us 16 0.84x 0.825x 0.333x 0.897x
uint8_t 5895us 8 7.19x 6.89x 5.59x 7.77x
uint16_t 6730us 16 3.18x 3.23x 1.5x 3.52x
uint32_t 7095us 16 1.75x 1.7x 0.4x 1.89x
Element Count: 16384
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 14410us 16 2.28x 2.19x 0.732x 2.29x
double 15066us 16 1.19x 1.08x 0.539x 1.23x
uint8_t 12104us 8 7.8x 7.65x 7.22x 7.84x
uint16_t 14570us 16 4.81x 4.69x 0.906x 4.96x
uint32_t 15034us 16 2.61x 2.48x 0.537x 2.6x
Element Count: 32768
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 30764us 16 2.82x 2.62x 2.61x 2.67x
double 31569us 16 1.6x 1.46x 0.764x 1.58x
uint8_t 26176us 8 8.23x 8.52x 2.8x 8.49x
uint16_t 30947us 16 6.45x 6.13x 6.32x 6.91x
uint32_t 32785us 16 3.53x 3.39x 1.09x 3.89x
Element Count: 65536
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 63166us 16 3.24x 3.12x 2.12x 3.25x
double 71154us 16 1.83x 1.81x 1.66x 2.02x
uint8_t 56285us 8 8.52x 8.43x 4.22x 9.35x
uint16_t 64761us 16 7.68x 8.02x 2.54x 8.32x
uint32_t 68576us 16 4.16x 3.93x 2.45x 4.4x
Element Count: 131072
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 137296us 16 3.42x 3.47x 3.13x 3.73x
double 139881us 16 2.08x 1.85x 1.93x 2.08x
uint8_t 111393us 8 9.04x 9.15x 5.99x 9.45x
uint16_t 128848us 16 8.47x 8.12x 4.65x 8.53x
uint32_t 134586us 16 4.64x 4.29x 2.37x 4.56x
Element Count: 262144
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 275099us 16 3.87x 3.66x 3.02x 3.86x
double 294763us 16 2.22x 1.93x 2.82x 2.18x
uint8_t 233671us 8 9.53x 9.65x 5.06x 9.92x
uint16_t 259553us 16 8.93x 8.43x 5.6x 9.33x
uint32_t 282111us 16 5.16x 4.57x 4.37x 5.09x
Element Count: 524288
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 573934us 16 3.96x 3.8x 3.25x 4.05x
double 622996us 16 2.16x 2.05x 2.74x 2.29x
uint8_t 482522us 8 10x 9.82x 5.71x 10.1x
uint16_t 525446us 16 9.3x 8.76x 5.64x 9.49x
uint32_t 595237us 16 5.42x 4.95x 4.86x 5.44x
Element Count: 1048576
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 1202785us 16 4.22x 3.99x 4.9x 4.24x
double 1322048us 16 2.39x 2.13x 3.51x 2.45x
uint8_t 1009387us 8 10.3x 10.2x 8.83x 10.5x
uint16_t 1070777us 16 9.6x 9x 9.45x 9.59x
uint32_t 1242144us 16 5.37x 5.09x 6.07x 5.54x
Element Count: 2097152
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 2539646us 16 4.42x 4.15x 5.77x 4.46x
double 2686074us 16 2.46x 2.19x 3.64x 2.45x
uint8_t 2136319us 8 10.8x 10.7x 9.93x 10.8x
uint16_t 2199277us 16 9.7x 9x 11.1x 9.6x
uint32_t 2619062us 16 5.78x 5.28x 7.01x 5.83x
Element Count: 4194304
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 5388683us 16 4.64x 4.46x 6.76x 4.72x
double 5617282us 16 2.54x 2.29x 4x 2.56x
uint8_t 4449453us 8 11.1x 10.9x 12.7x 11.2x
uint16_t 4546878us 16 9.96x 9.24x 12.8x 9.91x
uint32_t 5466031us 16 5.87x 5.43x 7.94x 5.92x
Element Count: 8388608
ElementType Reference(std::sort) Radix radix_sort 
descending_radix_sort parallel_radix_sort tbb_parallel_radix_sort
float 11029468us 16 4.73x 4.51x 6.91x 4.75x
double 11801211us 16 2.65x 2.38x 4.21x 2.62x
uint8_t 9363439us 8 11.4x 11.3x 13.5x 11.4x
uint16_t 9569329us 16 10.2x 9.4x 14x 10x
uint32_t 11413279us 16 6.05x 5.56x 8.58x 5.94x