## Sorting algorithms

Discussion of chess software programming and technical issues.

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Dann Corbit
Posts: 11895
Joined: Wed Mar 08, 2006 7:57 pm
Location: Redmond, WA USA
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### Re: Sorting algorithms

That is a beautiful routine.
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.

Dann Corbit
Posts: 11895
Joined: Wed Mar 08, 2006 7:57 pm
Location: Redmond, WA USA
Contact:

### Re: Sorting algorithms

As a C++ template:

Code: Select all

``````#include <iostream>
template <typename Etype>
inline void stable_sorting_network&#40; Etype *begin, Etype *end )
&#123;
Etype *p, *q, tmp;

p=begin;
switch&#40; end - begin ) &#123;
default&#58;
case 10&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;4&#93;; Etype py = p&#91;5&#93;; Etype tmp = p&#91;4&#93; = px <= py ? px &#58; py; p&#91;5&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;5&#93;; Etype py = p&#91;6&#93;; Etype tmp = p&#91;5&#93; = px <= py ? px &#58; py; p&#91;6&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;6&#93;; Etype py = p&#91;7&#93;; Etype tmp = p&#91;6&#93; = px <= py ? px &#58; py; p&#91;7&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;7&#93;; Etype py = p&#91;8&#93;; Etype tmp = p&#91;7&#93; = px <= py ? px &#58; py; p&#91;8&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;8&#93;; Etype py = p&#91;9&#93;; Etype tmp = p&#91;8&#93; = px <= py ? px &#58; py; p&#91;9&#93; ^= px ^ tmp; &#125;;
case 9&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;4&#93;; Etype py = p&#91;5&#93;; Etype tmp = p&#91;4&#93; = px <= py ? px &#58; py; p&#91;5&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;5&#93;; Etype py = p&#91;6&#93;; Etype tmp = p&#91;5&#93; = px <= py ? px &#58; py; p&#91;6&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;6&#93;; Etype py = p&#91;7&#93;; Etype tmp = p&#91;6&#93; = px <= py ? px &#58; py; p&#91;7&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;7&#93;; Etype py = p&#91;8&#93;; Etype tmp = p&#91;7&#93; = px <= py ? px &#58; py; p&#91;8&#93; ^= px ^ tmp; &#125;;
case 8&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;4&#93;; Etype py = p&#91;5&#93;; Etype tmp = p&#91;4&#93; = px <= py ? px &#58; py; p&#91;5&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;5&#93;; Etype py = p&#91;6&#93;; Etype tmp = p&#91;5&#93; = px <= py ? px &#58; py; p&#91;6&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;6&#93;; Etype py = p&#91;7&#93;; Etype tmp = p&#91;6&#93; = px <= py ? px &#58; py; p&#91;7&#93; ^= px ^ tmp; &#125;;
case 7&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;4&#93;; Etype py = p&#91;5&#93;; Etype tmp = p&#91;4&#93; = px <= py ? px &#58; py; p&#91;5&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;5&#93;; Etype py = p&#91;6&#93;; Etype tmp = p&#91;5&#93; = px <= py ? px &#58; py; p&#91;6&#93; ^= px ^ tmp; &#125;;
case 6&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;4&#93;; Etype py = p&#91;5&#93;; Etype tmp = p&#91;4&#93; = px <= py ? px &#58; py; p&#91;5&#93; ^= px ^ tmp; &#125;;
case 5&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;3&#93;; Etype py = p&#91;4&#93;; Etype tmp = p&#91;3&#93; = px <= py ? px &#58; py; p&#91;4&#93; ^= px ^ tmp; &#125;;
case 4&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;2&#93;; Etype py = p&#91;3&#93;; Etype tmp = p&#91;2&#93; = px <= py ? px &#58; py; p&#91;3&#93; ^= px ^ tmp; &#125;;
case 3&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
&#123; Etype px = p&#91;1&#93;; Etype py = p&#91;2&#93;; Etype tmp = p&#91;1&#93; = px <= py ? px &#58; py; p&#91;2&#93; ^= px ^ tmp; &#125;;
case 2&#58;
&#123; Etype px = p&#91;0&#93;; Etype py = p&#91;1&#93;; Etype tmp = p&#91;0&#93; = px <= py ? px &#58; py; p&#91;1&#93; ^= px ^ tmp; &#125;;
case 1&#58;
case 0&#58;
break;
&#125;

for ( p = begin + 10; p < end; ++p ) &#123;
tmp = *p;
for ( q = p; q != begin && *( q-1 ) > tmp; --q )
*q = *( q-1 );
*q = tmp;
&#125;
&#125;

int arrdat&#91;&#93; = &#123; 9, 6, 23, 4, 5, 6, 7, 11, 2, 3, 1, 5, 9, 11, 0, 13, -8, 3, 4, 5, 6, 3, 2, 1 &#125;;

int main&#40; void )
&#123;
static const size_t adim = sizeof arrdat / sizeof arrdat&#91;0&#93;;
size_t index;
stable_sorting_network <int> ( &arrdat&#91;0&#93;, &arrdat&#91;adim-1&#93; );
for ( index = 0; index < adim; index++ )
std&#58;&#58;cout << arrdat&#91;index&#93; << std&#58;&#58;endl;
return 0;
&#125;
``````
The top sorting network still remains branchless (at least if you are sorting an array of int):

Code: Select all

``````	.file	"snet.cpp"
.section	.text\$_ZNKSt5ctypeIcE8do_widenEc,"x"
.align 2
.p2align 4,,15
.globl	_ZNKSt5ctypeIcE8do_widenEc
.def	_ZNKSt5ctypeIcE8do_widenEc;	.scl	2;	.type	32;	.endef
.seh_proc	_ZNKSt5ctypeIcE8do_widenEc
_ZNKSt5ctypeIcE8do_widenEc&#58;
.LFB1288&#58;
.seh_endprologue
movl	%edx, %eax
ret
.seh_endproc
.text
.p2align 4,,15
.def	__tcf_0;	.scl	3;	.type	32;	.endef
.seh_proc	__tcf_0
__tcf_0&#58;
.LFB1975&#58;
.seh_endprologue
leaq	_ZStL8__ioinit&#40;%rip&#41;, %rcx
jmp	_ZNSt8ios_base4InitD1Ev
.seh_endproc
.def	__main;	.scl	2;	.type	32;	.endef
.section	.text.startup,"x"
.p2align 4,,15
.globl	main
.def	main;	.scl	2;	.type	32;	.endef
.seh_proc	main
main&#58;
.LFB1532&#58;
pushq	%r13
.seh_pushreg	%r13
pushq	%r12
.seh_pushreg	%r12
pushq	%rbp
.seh_pushreg	%rbp
pushq	%rdi
.seh_pushreg	%rdi
pushq	%rsi
.seh_pushreg	%rsi
pushq	%rbx
.seh_pushreg	%rbx
subq	\$40, %rsp
.seh_stackalloc	40
.seh_endprologue
call	__main
movl	4+arrdat&#40;%rip&#41;, %ecx
movl	arrdat&#40;%rip&#41;, %eax
movl	8+arrdat&#40;%rip&#41;, %r8d
movl	12+arrdat&#40;%rip&#41;, %r9d
movl	16+arrdat&#40;%rip&#41;, %r10d
movl	20+arrdat&#40;%rip&#41;, %r11d
cmpl	%ecx, %eax
movl	%ecx, %edx
movl	24+arrdat&#40;%rip&#41;, %ebx
cmovle	%eax, %edx
xorl	%ecx, %eax
movl	%r8d, %ecx
xorl	%edx, %eax
movl	28+arrdat&#40;%rip&#41;, %esi
movl	32+arrdat&#40;%rip&#41;, %edi
cmpl	%r8d, %eax
movl	36+arrdat&#40;%rip&#41;, %ebp
cmovle	%eax, %ecx
xorl	%r8d, %eax
movl	%r9d, %r8d
xorl	%ecx, %eax
cmpl	%r9d, %eax
cmovle	%eax, %r8d
xorl	%r9d, %eax
movl	%r10d, %r9d
xorl	%r8d, %eax
movl	%r8d, %r12d
cmpl	%r10d, %eax
cmovle	%eax, %r9d
xorl	%r10d, %eax
movl	%r11d, %r10d
xorl	%r9d, %eax
cmpl	%r11d, %eax
cmovle	%eax, %r10d
xorl	%r11d, %eax
movl	%ebx, %r11d
xorl	%r10d, %eax
cmpl	%ebx, %eax
cmovle	%eax, %r11d
xorl	%ebx, %eax
movl	%esi, %ebx
xorl	%r11d, %eax
cmpl	%esi, %eax
cmovle	%eax, %ebx
xorl	%esi, %eax
movl	%edi, %esi
xorl	%ebx, %eax
cmpl	%edi, %eax
cmovle	%eax, %esi
xorl	%edi, %eax
movl	%ebp, %edi
xorl	%esi, %eax
cmpl	%ebp, %eax
cmovle	%eax, %edi
xorl	%ebp, %eax
movl	%ecx, %ebp
xorl	%edi, %eax
cmpl	%ecx, %edx
cmovle	%edx, %ebp
xorl	%ecx, %edx
movl	%r9d, %ecx
xorl	%ebp, %edx
movl	%eax, 36+arrdat&#40;%rip&#41;
cmpl	%r8d, %edx
cmovle	%edx, %r12d
xorl	%r8d, %edx
movl	%r10d, %r8d
xorl	%r12d, %edx
cmpl	%r9d, %edx
cmovle	%edx, %ecx
xorl	%r9d, %edx
movl	%r11d, %r9d
xorl	%ecx, %edx
cmpl	%r10d, %edx
cmovle	%edx, %r8d
xorl	%r10d, %edx
movl	%ebx, %r10d
xorl	%r8d, %edx
cmpl	%r11d, %edx
cmovle	%edx, %r9d
xorl	%r11d, %edx
movl	%edi, %r11d
xorl	%r9d, %edx
cmpl	%ebx, %edx
movl	%edx, %eax
cmovle	%edx, %r10d
xorl	%ebx, %eax
movl	%esi, %edx
xorl	%r10d, %eax
movl	%ebp, %ebx
cmpl	%esi, %eax
cmovle	%eax, %edx
xorl	%esi, %eax
movl	%ecx, %esi
xorl	%edx, %eax
cmpl	%edi, %eax
cmovle	%eax, %r11d
xorl	%edi, %eax
movl	%r8d, %edi
xorl	%r11d, %eax
cmpl	%ebp, %r12d
cmovle	%r12d, %ebx
xorl	%r12d, %ebp
movl	%eax, 32+arrdat&#40;%rip&#41;
xorl	%ebx, %ebp
cmpl	%ecx, %ebp
cmovle	%ebp, %esi
xorl	%ebp, %ecx
xorl	%esi, %ecx
cmpl	%r8d, %ecx
cmovle	%ecx, %edi
xorl	%ecx, %r8d
movl	%r9d, %ecx
xorl	%edi, %r8d
cmpl	%r9d, %r8d
cmovle	%r8d, %ecx
xorl	%r8d, %r9d
movl	%r10d, %r8d
xorl	%ecx, %r9d
cmpl	%r10d, %r9d
cmovle	%r9d, %r8d
xorl	%r9d, %r10d
movl	%edx, %r9d
xorl	%r8d, %r10d
cmpl	%edx, %r10d
cmovle	%r10d, %r9d
xorl	%edx, %r10d
movl	%r11d, %edx
movl	%r10d, %eax
movl	%ebx, %r10d
xorl	%r9d, %eax
cmpl	%r11d, %eax
cmovle	%eax, %edx
xorl	%r11d, %eax
movl	%edi, %r11d
xorl	%edx, %eax
cmpl	%ebx, %esi
cmovle	%esi, %r10d
xorl	%esi, %ebx
movl	%eax, 28+arrdat&#40;%rip&#41;
xorl	%r10d, %ebx
movl	%r8d, %esi
cmpl	%edi, %ebx
cmovle	%ebx, %r11d
xorl	%ebx, %edi
movl	%ecx, %ebx
xorl	%r11d, %edi
cmpl	%ecx, %edi
cmovle	%edi, %ebx
xorl	%edi, %ecx
xorl	%ebx, %ecx
movl	%ebx, %edi
cmpl	%r8d, %ecx
movl	%ecx, %eax
cmovle	%ecx, %esi
xorl	%r8d, %eax
movl	%r9d, %ecx
xorl	%esi, %eax
movl	%edx, %r8d
cmpl	%r9d, %eax
cmovle	%eax, %ecx
xorl	%r9d, %eax
movl	%r10d, %r9d
xorl	%ecx, %eax
cmpl	%edx, %eax
cmovle	%eax, %r8d
xorl	%edx, %eax
xorl	%r8d, %eax
cmpl	%r10d, %r11d
cmovle	%r11d, %r9d
xorl	%r11d, %r10d
movl	%esi, %r11d
xorl	%r9d, %r10d
movl	%eax, 24+arrdat&#40;%rip&#41;
cmpl	%ebx, %r10d
cmovle	%r10d, %edi
xorl	%r10d, %ebx
movl	%ecx, %r10d
xorl	%edi, %ebx
cmpl	%esi, %ebx
cmovle	%ebx, %r11d
xorl	%esi, %ebx
xorl	%r11d, %ebx
cmpl	%ecx, %ebx
movl	%ebx, %eax
cmovle	%ebx, %r10d
xorl	%ecx, %eax
xorl	%r10d, %eax
cmpl	%eax, %r8d
movl	%eax, %ebx
cmovle	%r8d, %ebx
xorl	%r8d, %eax
movl	%edi, %r8d
xorl	%ebx, %eax
cmpl	%edi, %r9d
cmovle	%r9d, %r8d
xorl	%edi, %r9d
movl	%eax, 20+arrdat&#40;%rip&#41;
xorl	%r8d, %r9d
movl	%r11d, %eax
cmpl	%r11d, %r9d
cmovle	%r9d, %eax
xorl	%r11d, %r9d
movl	%r9d, %edx
xorl	%eax, %edx
cmpl	%edx, %r10d
movl	%edx, %r11d
cmovle	%r10d, %r11d
xorl	%r10d, %edx
leaq	44+arrdat&#40;%rip&#41;, %r10
xorl	%r11d, %edx
movl	%r11d, %r9d
cmpl	%edx, %ebx
movl	%edx, %ecx
cmovle	%ebx, %ecx
xorl	%ebx, %edx
xorl	%ecx, %edx
cmpl	%r8d, %eax
movl	%edx, 16+arrdat&#40;%rip&#41;
movl	%r8d, %edx
cmovle	%eax, %edx
xorl	%r8d, %eax
xorl	%edx, %eax
cmpl	%r11d, %eax
cmovle	%eax, %r9d
xorl	%r11d, %eax
leaq	92+arrdat&#40;%rip&#41;, %r11
xorl	%r9d, %eax
cmpl	%eax, %ecx
movl	%eax, %r8d
cmovle	%ecx, %r8d
xorl	%ecx, %eax
movl	%r9d, %ecx
xorl	%r8d, %eax
cmpl	%r9d, %edx
cmovle	%edx, %ecx
xorl	%r9d, %edx
movl	%eax, 12+arrdat&#40;%rip&#41;
xorl	%ecx, %edx
movl	%r8d, %eax
leaq	40+arrdat&#40;%rip&#41;, %r9
cmpl	%r8d, %edx
cmovle	%edx, %eax
xorl	%r8d, %edx
leaq	arrdat&#40;%rip&#41;, %r8
xorl	%eax, %edx
cmpl	%ecx, %eax
movl	%edx, 8+arrdat&#40;%rip&#41;
movl	%ecx, %edx
cmovle	%eax, %edx
xorl	%ecx, %eax
xorl	%edx, %eax
cmpq	%r8, %r9
movl	%edx, arrdat&#40;%rip&#41;
movl	%eax, 4+arrdat&#40;%rip&#41;
movq	%r9, %rax
movl	(%r9&#41;, %ecx
je	.L5
.p2align 4,,10
.L21&#58;
movl	-8&#40;%r10&#41;, %edx
cmpl	%ecx, %edx
jg	.L8
jmp	.L6
.p2align 4,,10
.L9&#58;
movl	-4&#40;%rax&#41;, %edx
cmpl	%edx, %ecx
jge	.L6
.L8&#58;
movl	%edx, (%rax&#41;
subq	\$4, %rax
cmpq	%r8, %rax
jne	.L9
.L6&#58;
cmpq	%r11, %r10
movl	%ecx, (%rax&#41;
jnb	.L20
.L10&#58;
movl	(%r9&#41;, %ecx
cmpq	%r8, %r9
movq	%r9, %rax
jne	.L21
.L5&#58;
movl	%ecx, (%r9&#41;
jmp	.L10
.L20&#58;
leaq	arrdat&#40;%rip&#41;, %rsi
leaq	96+arrdat&#40;%rip&#41;, %r12
movq	.refptr._ZSt4cout&#40;%rip&#41;, %rbp
leaq	_ZNKSt5ctypeIcE8do_widenEc&#40;%rip&#41;, %r13
jmp	.L14
.p2align 4,,10
.L24&#58;
movsbl	67&#40;%rbx&#41;, %edx
.L13&#58;
movq	%rdi, %rcx
call	_ZNSo3putEc
movq	%rax, %rcx
call	_ZNSo5flushEv
cmpq	%rsi, %r12
je	.L22
.L14&#58;
movl	(%rsi&#41;, %edx
movq	%rbp, %rcx
call	_ZNSolsEi
movq	%rax, %rdi
movq	(%rax&#41;, %rax
movq	-24&#40;%rax&#41;, %rax
movq	240&#40;%rdi,%rax&#41;, %rbx
testq	%rbx, %rbx
je	.L23
cmpb	\$0, 56&#40;%rbx&#41;
jne	.L24
movq	%rbx, %rcx
call	_ZNKSt5ctypeIcE13_M_widen_initEv
movq	(%rbx&#41;, %rax
movl	\$10, %edx
movq	48&#40;%rax&#41;, %rax
cmpq	%r13, %rax
je	.L13
movq	%rbx, %rcx
call	*%rax
movsbl	%al, %edx
jmp	.L13
.L22&#58;
xorl	%eax, %eax
popq	%rbx
popq	%rsi
popq	%rdi
popq	%rbp
popq	%r12
popq	%r13
ret
.L23&#58;
nop
.seh_endproc
.p2align 4,,15
.def	_GLOBAL__sub_I_arrdat;	.scl	3;	.type	32;	.endef
.seh_proc	_GLOBAL__sub_I_arrdat
_GLOBAL__sub_I_arrdat&#58;
.LFB1976&#58;
subq	\$40, %rsp
.seh_stackalloc	40
.seh_endprologue
leaq	_ZStL8__ioinit&#40;%rip&#41;, %rcx
call	_ZNSt8ios_base4InitC1Ev
leaq	__tcf_0&#40;%rip&#41;, %rcx
jmp	atexit
.seh_endproc
.section	.ctors,"w"
.align 8
.globl	arrdat
.data
.align 32
arrdat&#58;
.long	9
.long	6
.long	23
.long	4
.long	5
.long	6
.long	7
.long	11
.long	2
.long	3
.long	1
.long	5
.long	9
.long	11
.long	0
.long	13
.long	-8
.long	3
.long	4
.long	5
.long	6
.long	3
.long	2
.long	1
.lcomm _ZStL8__ioinit,1,1
.ident	"GCC&#58; &#40;Rev2, Built by MSYS2 project&#41; 6.3.0"
.def	_ZNSt8ios_base4InitD1Ev;	.scl	2;	.type	32;	.endef
.def	_ZNSo3putEc;	.scl	2;	.type	32;	.endef
.def	_ZNSo5flushEv;	.scl	2;	.type	32;	.endef
.def	_ZNSolsEi;	.scl	2;	.type	32;	.endef
.def	_ZNKSt5ctypeIcE13_M_widen_initEv;	.scl	2;	.type	32;	.endef
.def	_ZSt16__throw_bad_castv;	.scl	2;	.type	32;	.endef
.def	_ZNSt8ios_base4InitC1Ev;	.scl	2;	.type	32;	.endef
.def	atexit;	.scl	2;	.type	32;	.endef
.section	.rdata\$.refptr._ZSt4cout, "dr"
.globl	.refptr._ZSt4cout
.refptr._ZSt4cout&#58;
``````
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.

Dann Corbit
Posts: 11895
Joined: Wed Mar 08, 2006 7:57 pm
Location: Redmond, WA USA
Contact:

### Re: Sorting algorithms

Oops, that was the assembly listing for the original. Still holds true for the template version though:

Code: Select all

``````	.file	"snetep.cpp"
.section	.text\$_ZNKSt5ctypeIcE8do_widenEc,"x"
.align 2
.p2align 4,,15
.globl	_ZNKSt5ctypeIcE8do_widenEc
.def	_ZNKSt5ctypeIcE8do_widenEc;	.scl	2;	.type	32;	.endef
.seh_proc	_ZNKSt5ctypeIcE8do_widenEc
_ZNKSt5ctypeIcE8do_widenEc&#58;
.LFB1294&#58;
.seh_endprologue
movl	%edx, %eax
ret
.seh_endproc
.text
.p2align 4,,15
.def	__tcf_0;	.scl	3;	.type	32;	.endef
.seh_proc	__tcf_0
__tcf_0&#58;
.LFB1981&#58;
.seh_endprologue
leaq	_ZStL8__ioinit&#40;%rip&#41;, %rcx
jmp	_ZNSt8ios_base4InitD1Ev
.seh_endproc
.def	__main;	.scl	2;	.type	32;	.endef
.section	.text.startup,"x"
.p2align 4,,15
.globl	main
.def	main;	.scl	2;	.type	32;	.endef
.seh_proc	main
main&#58;
.LFB1538&#58;
pushq	%r13
.seh_pushreg	%r13
pushq	%r12
.seh_pushreg	%r12
pushq	%rbp
.seh_pushreg	%rbp
pushq	%rdi
.seh_pushreg	%rdi
pushq	%rsi
.seh_pushreg	%rsi
pushq	%rbx
.seh_pushreg	%rbx
subq	\$40, %rsp
.seh_stackalloc	40
.seh_endprologue
call	__main
movl	4+arrdat&#40;%rip&#41;, %ecx
movl	arrdat&#40;%rip&#41;, %eax
movl	8+arrdat&#40;%rip&#41;, %r8d
movl	12+arrdat&#40;%rip&#41;, %r9d
movl	16+arrdat&#40;%rip&#41;, %r10d
movl	20+arrdat&#40;%rip&#41;, %r11d
cmpl	%ecx, %eax
movl	%ecx, %edx
movl	24+arrdat&#40;%rip&#41;, %ebx
cmovle	%eax, %edx
xorl	%ecx, %eax
movl	%r8d, %ecx
xorl	%edx, %eax
movl	28+arrdat&#40;%rip&#41;, %esi
movl	32+arrdat&#40;%rip&#41;, %edi
cmpl	%r8d, %eax
movl	36+arrdat&#40;%rip&#41;, %ebp
cmovle	%eax, %ecx
xorl	%r8d, %eax
movl	%r9d, %r8d
xorl	%ecx, %eax
cmpl	%r9d, %eax
cmovle	%eax, %r8d
xorl	%r9d, %eax
movl	%r10d, %r9d
xorl	%r8d, %eax
movl	%r8d, %r12d
cmpl	%r10d, %eax
cmovle	%eax, %r9d
xorl	%r10d, %eax
movl	%r11d, %r10d
xorl	%r9d, %eax
cmpl	%r11d, %eax
cmovle	%eax, %r10d
xorl	%r11d, %eax
movl	%ebx, %r11d
xorl	%r10d, %eax
cmpl	%ebx, %eax
cmovle	%eax, %r11d
xorl	%ebx, %eax
movl	%esi, %ebx
xorl	%r11d, %eax
cmpl	%esi, %eax
cmovle	%eax, %ebx
xorl	%esi, %eax
movl	%edi, %esi
xorl	%ebx, %eax
cmpl	%edi, %eax
cmovle	%eax, %esi
xorl	%edi, %eax
movl	%ebp, %edi
xorl	%esi, %eax
cmpl	%ebp, %eax
cmovle	%eax, %edi
xorl	%ebp, %eax
movl	%ecx, %ebp
xorl	%edi, %eax
cmpl	%ecx, %edx
cmovle	%edx, %ebp
xorl	%ecx, %edx
movl	%r9d, %ecx
xorl	%ebp, %edx
movl	%eax, 36+arrdat&#40;%rip&#41;
cmpl	%r8d, %edx
cmovle	%edx, %r12d
xorl	%r8d, %edx
movl	%r10d, %r8d
xorl	%r12d, %edx
cmpl	%r9d, %edx
cmovle	%edx, %ecx
xorl	%r9d, %edx
movl	%r11d, %r9d
xorl	%ecx, %edx
cmpl	%r10d, %edx
cmovle	%edx, %r8d
xorl	%r10d, %edx
movl	%ebx, %r10d
xorl	%r8d, %edx
cmpl	%r11d, %edx
cmovle	%edx, %r9d
xorl	%r11d, %edx
movl	%edi, %r11d
xorl	%r9d, %edx
cmpl	%ebx, %edx
movl	%edx, %eax
cmovle	%edx, %r10d
xorl	%ebx, %eax
movl	%esi, %edx
xorl	%r10d, %eax
movl	%ebp, %ebx
cmpl	%esi, %eax
cmovle	%eax, %edx
xorl	%esi, %eax
movl	%ecx, %esi
xorl	%edx, %eax
cmpl	%edi, %eax
cmovle	%eax, %r11d
xorl	%edi, %eax
movl	%r8d, %edi
xorl	%r11d, %eax
cmpl	%ebp, %r12d
cmovle	%r12d, %ebx
xorl	%r12d, %ebp
movl	%eax, 32+arrdat&#40;%rip&#41;
xorl	%ebx, %ebp
cmpl	%ecx, %ebp
cmovle	%ebp, %esi
xorl	%ebp, %ecx
xorl	%esi, %ecx
cmpl	%r8d, %ecx
cmovle	%ecx, %edi
xorl	%ecx, %r8d
movl	%r9d, %ecx
xorl	%edi, %r8d
cmpl	%r9d, %r8d
cmovle	%r8d, %ecx
xorl	%r8d, %r9d
movl	%r10d, %r8d
xorl	%ecx, %r9d
cmpl	%r10d, %r9d
cmovle	%r9d, %r8d
xorl	%r9d, %r10d
movl	%edx, %r9d
xorl	%r8d, %r10d
cmpl	%edx, %r10d
cmovle	%r10d, %r9d
xorl	%edx, %r10d
movl	%r11d, %edx
movl	%r10d, %eax
movl	%ebx, %r10d
xorl	%r9d, %eax
cmpl	%r11d, %eax
cmovle	%eax, %edx
xorl	%r11d, %eax
movl	%edi, %r11d
xorl	%edx, %eax
cmpl	%ebx, %esi
cmovle	%esi, %r10d
xorl	%esi, %ebx
movl	%eax, 28+arrdat&#40;%rip&#41;
xorl	%r10d, %ebx
movl	%r8d, %esi
cmpl	%edi, %ebx
cmovle	%ebx, %r11d
xorl	%ebx, %edi
movl	%ecx, %ebx
xorl	%r11d, %edi
cmpl	%ecx, %edi
cmovle	%edi, %ebx
xorl	%edi, %ecx
xorl	%ebx, %ecx
movl	%ebx, %edi
cmpl	%r8d, %ecx
movl	%ecx, %eax
cmovle	%ecx, %esi
xorl	%r8d, %eax
movl	%r9d, %ecx
xorl	%esi, %eax
movl	%edx, %r8d
cmpl	%r9d, %eax
cmovle	%eax, %ecx
xorl	%r9d, %eax
movl	%r10d, %r9d
xorl	%ecx, %eax
cmpl	%edx, %eax
cmovle	%eax, %r8d
xorl	%edx, %eax
xorl	%r8d, %eax
cmpl	%r10d, %r11d
cmovle	%r11d, %r9d
xorl	%r11d, %r10d
movl	%esi, %r11d
xorl	%r9d, %r10d
movl	%eax, 24+arrdat&#40;%rip&#41;
cmpl	%ebx, %r10d
cmovle	%r10d, %edi
xorl	%r10d, %ebx
movl	%ecx, %r10d
xorl	%edi, %ebx
cmpl	%esi, %ebx
cmovle	%ebx, %r11d
xorl	%esi, %ebx
xorl	%r11d, %ebx
cmpl	%ecx, %ebx
movl	%ebx, %eax
cmovle	%ebx, %r10d
xorl	%ecx, %eax
xorl	%r10d, %eax
cmpl	%eax, %r8d
movl	%eax, %ebx
cmovle	%r8d, %ebx
xorl	%r8d, %eax
movl	%edi, %r8d
xorl	%ebx, %eax
cmpl	%edi, %r9d
cmovle	%r9d, %r8d
xorl	%edi, %r9d
movl	%eax, 20+arrdat&#40;%rip&#41;
xorl	%r8d, %r9d
movl	%r11d, %eax
cmpl	%r11d, %r9d
cmovle	%r9d, %eax
xorl	%r11d, %r9d
movl	%r9d, %edx
xorl	%eax, %edx
cmpl	%edx, %r10d
movl	%edx, %r11d
cmovle	%r10d, %r11d
xorl	%r10d, %edx
leaq	44+arrdat&#40;%rip&#41;, %r10
xorl	%r11d, %edx
movl	%r11d, %r9d
cmpl	%edx, %ebx
movl	%edx, %ecx
cmovle	%ebx, %ecx
xorl	%ebx, %edx
xorl	%ecx, %edx
cmpl	%r8d, %eax
movl	%edx, 16+arrdat&#40;%rip&#41;
movl	%r8d, %edx
cmovle	%eax, %edx
xorl	%r8d, %eax
xorl	%edx, %eax
cmpl	%r11d, %eax
cmovle	%eax, %r9d
xorl	%r11d, %eax
leaq	92+arrdat&#40;%rip&#41;, %r11
xorl	%r9d, %eax
cmpl	%eax, %ecx
movl	%eax, %r8d
cmovle	%ecx, %r8d
xorl	%ecx, %eax
movl	%r9d, %ecx
xorl	%r8d, %eax
cmpl	%r9d, %edx
cmovle	%edx, %ecx
xorl	%r9d, %edx
movl	%eax, 12+arrdat&#40;%rip&#41;
xorl	%ecx, %edx
movl	%r8d, %eax
leaq	40+arrdat&#40;%rip&#41;, %r9
cmpl	%r8d, %edx
cmovle	%edx, %eax
xorl	%r8d, %edx
leaq	arrdat&#40;%rip&#41;, %r8
xorl	%eax, %edx
cmpl	%ecx, %eax
movl	%edx, 8+arrdat&#40;%rip&#41;
movl	%ecx, %edx
cmovle	%eax, %edx
xorl	%ecx, %eax
xorl	%edx, %eax
cmpq	%r8, %r9
movl	%edx, arrdat&#40;%rip&#41;
movl	%eax, 4+arrdat&#40;%rip&#41;
movq	%r9, %rax
movl	(%r9&#41;, %ecx
je	.L5
.p2align 4,,10
.L21&#58;
movl	-8&#40;%r10&#41;, %edx
cmpl	%ecx, %edx
jg	.L8
jmp	.L6
.p2align 4,,10
.L9&#58;
movl	-4&#40;%rax&#41;, %edx
cmpl	%edx, %ecx
jge	.L6
.L8&#58;
movl	%edx, (%rax&#41;
subq	\$4, %rax
cmpq	%r8, %rax
jne	.L9
.L6&#58;
cmpq	%r11, %r10
movl	%ecx, (%rax&#41;
jnb	.L20
.L10&#58;
movl	(%r9&#41;, %ecx
cmpq	%r8, %r9
movq	%r9, %rax
jne	.L21
.L5&#58;
movl	%ecx, (%r9&#41;
jmp	.L10
.L20&#58;
leaq	arrdat&#40;%rip&#41;, %rsi
leaq	96+arrdat&#40;%rip&#41;, %r12
movq	.refptr._ZSt4cout&#40;%rip&#41;, %rbp
leaq	_ZNKSt5ctypeIcE8do_widenEc&#40;%rip&#41;, %r13
jmp	.L14
.p2align 4,,10
.L24&#58;
movsbl	67&#40;%rbx&#41;, %edx
.L13&#58;
movq	%rdi, %rcx
call	_ZNSo3putEc
movq	%rax, %rcx
call	_ZNSo5flushEv
cmpq	%rsi, %r12
je	.L22
.L14&#58;
movl	(%rsi&#41;, %edx
movq	%rbp, %rcx
call	_ZNSolsEi
movq	%rax, %rdi
movq	(%rax&#41;, %rax
movq	-24&#40;%rax&#41;, %rax
movq	240&#40;%rdi,%rax&#41;, %rbx
testq	%rbx, %rbx
je	.L23
cmpb	\$0, 56&#40;%rbx&#41;
jne	.L24
movq	%rbx, %rcx
call	_ZNKSt5ctypeIcE13_M_widen_initEv
movq	(%rbx&#41;, %rax
movl	\$10, %edx
movq	48&#40;%rax&#41;, %rax
cmpq	%r13, %rax
je	.L13
movq	%rbx, %rcx
call	*%rax
movsbl	%al, %edx
jmp	.L13
.L22&#58;
xorl	%eax, %eax
popq	%rbx
popq	%rsi
popq	%rdi
popq	%rbp
popq	%r12
popq	%r13
ret
.L23&#58;
nop
.seh_endproc
.p2align 4,,15
.def	_GLOBAL__sub_I_arrdat;	.scl	3;	.type	32;	.endef
.seh_proc	_GLOBAL__sub_I_arrdat
_GLOBAL__sub_I_arrdat&#58;
.LFB1982&#58;
subq	\$40, %rsp
.seh_stackalloc	40
.seh_endprologue
leaq	_ZStL8__ioinit&#40;%rip&#41;, %rcx
call	_ZNSt8ios_base4InitC1Ev
leaq	__tcf_0&#40;%rip&#41;, %rcx
jmp	atexit
.seh_endproc
.section	.ctors,"w"
.align 8
.globl	arrdat
.data
.align 32
arrdat&#58;
.long	9
.long	6
.long	23
.long	4
.long	5
.long	6
.long	7
.long	11
.long	2
.long	3
.long	1
.long	5
.long	9
.long	11
.long	0
.long	13
.long	-8
.long	3
.long	4
.long	5
.long	6
.long	3
.long	2
.long	1
.lcomm _ZStL8__ioinit,1,1
.ident	"GCC&#58; &#40;Rev2, Built by MSYS2 project&#41; 6.3.0"
.def	_ZNSt8ios_base4InitD1Ev;	.scl	2;	.type	32;	.endef
.def	_ZNSo3putEc;	.scl	2;	.type	32;	.endef
.def	_ZNSo5flushEv;	.scl	2;	.type	32;	.endef
.def	_ZNSolsEi;	.scl	2;	.type	32;	.endef
.def	_ZNKSt5ctypeIcE13_M_widen_initEv;	.scl	2;	.type	32;	.endef
.def	_ZSt16__throw_bad_castv;	.scl	2;	.type	32;	.endef
.def	_ZNSt8ios_base4InitC1Ev;	.scl	2;	.type	32;	.endef
.def	atexit;	.scl	2;	.type	32;	.endef
.section	.rdata\$.refptr._ZSt4cout, "dr"
.globl	.refptr._ZSt4cout
.refptr._ZSt4cout&#58;
``````
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.

AlvaroBegue
Posts: 927
Joined: Tue Mar 09, 2010 2:46 pm
Location: New York
Full name: Álvaro Begué (RuyDos)

### Re: Sorting algorithms

You could increase readability by introducing a function like this:

Code: Select all

``````template <typename T>
void sort_pair&#40;T &a, T &b&#41; &#123;
T mask = (-&#40;a > b&#41;) & &#40;a ^ b&#41;;
&#125;
``````
This is the first implementation that came to mind, which is something I thought of before CPUs had conditional mov instructions. Perhaps other implementations are better. But the point is that you don't need macros or very repetitive code.

hgm
Posts: 25544
Joined: Fri Mar 10, 2006 9:06 am
Location: Amsterdam
Full name: H G Muller
Contact:

### Re: Sorting algorithms

I think it is awful. I would be surprised if it is anywhere near as fast as

Code: Select all

``````void
Sort &#40;Move *moves, unsigned char *key, int nrMoves&#41;
&#123;
unsigned char next&#91;MAXMOVES&#93;;
Move temp&#91;MAXMOVES&#93;;
int i, used = 0;

for&#40;i=0; i<nrMoves; i++) &#123; // disperse
int k = key&#91;i&#93;;
int bit = 1 << k;
temp&#91;i&#93; = moves&#91;i&#93;;
next&#91;i&#93; = &#40;bit & used ? head&#91;k&#93; &#58; 0&#41;; // cmov
used |= bit;
&#125; // one mis-predict at loop end

i = 0;
while&#40;used&#41; &#123; // collect
int b = BSF&#40;used&#41;; // next occupied bin
do &#123;
moves&#91;i++&#93; = temp&#91;j&#93;;
&#125; while&#40;&#40;j = next&#91;j&#93;)); // rarely taken branch, as most bins have 1 move
used -= 1 << b;
&#125;
&#125; // 1 mis-predict at end
``````
Except perhaps for 1 or 2 elements.

Dann Corbit
Posts: 11895
Joined: Wed Mar 08, 2006 7:57 pm
Location: Redmond, WA USA
Contact:

### Re: Sorting algorithms

hgm wrote:I think it is awful. I would be surprised if it is anywhere near as fast as

Code: Select all

``````void
Sort &#40;Move *moves, unsigned char *key, int nrMoves&#41;
&#123;
unsigned char next&#91;MAXMOVES&#93;;
Move temp&#91;MAXMOVES&#93;;
int i, used = 0;

for&#40;i=0; i<nrMoves; i++) &#123; // disperse
int k = key&#91;i&#93;;
int bit = 1 << k;
temp&#91;i&#93; = moves&#91;i&#93;;
next&#91;i&#93; = &#40;bit & used ? head&#91;k&#93; &#58; 0&#41;; // cmov
used |= bit;
&#125; // one mis-predict at loop end

i = 0;
while&#40;used&#41; &#123; // collect
int b = BSF&#40;used&#41;; // next occupied bin
do &#123;
moves&#91;i++&#93; = temp&#91;j&#93;;
&#125; while&#40;&#40;j = next&#91;j&#93;)); // rarely taken branch, as most bins have 1 move
used -= 1 << b;
&#125;
&#125; // 1 mis-predict at end
``````
Except perhaps for 1 or 2 elements.
Yours might be faster for move sorting, but the other routine was general purpose.

Your routine (for instance) assumes that the items are unique.

There was a fencepost error in my driver, since I did not notice that his loop stopped before the last element.

Code: Select all

``````int main&#40; void )
&#123;
static const size_t adim = sizeof arrdat / sizeof arrdat&#91;0&#93;;
size_t index;
stable_sorting_network <int> ( &arrdat&#91;0&#93;, &arrdat&#91;adim&#93; );
for ( index = 0; index < adim; index++ )
std&#58;&#58;cout << arrdat&#91;index&#93; << std&#58;&#58;endl;
return 0;
&#125;
``````
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
But sharing ideas is an even greater virtue. We have another word for this. It is called teaching.

hgm
Posts: 25544
Joined: Fri Mar 10, 2006 9:06 am
Location: Amsterdam
Full name: H G Muller
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### Re: Sorting algorithms

Dann Corbit wrote:Your routine (for instance) assumes that the items are unique.
No, it doesn't. This is why I needed linked lists, to have an arbitrary number of moves with the same key. If the keys were guaranteed to be unique, you could just hash the moves by key to a 256-element array, and then pack that array by squeezing out the unused entries.

It still assumed maximally different keys, though. (Or 64 if 'used' would be made a 64-bit type.) To allow 256 different keys the set that indicates which bins are in use (which allows fast skipping of the unused bins by bit extraction) would have to be divided over multiple machine words, requiring the key to be split into an index into an array used[4], and a bit number 0-63.

And the design is not even optimal, because it was written to sort an existing array in-place. Which then requires making of a copy, and then write it back in sorted order. Which is a stupid thing to do, as you could have generated the moves in a scratch array, and copy it in sorted order to the move stack. Saving you half the read and write accesses on the move data. There also is no need to actually store the keys; the iterations of the first loop could simply be moved to the move generation, using the calculated sort key only as index, never storing it.

petero2
Posts: 612
Joined: Mon Apr 19, 2010 5:07 pm
Location: Sweden
Contact:

### Re: Sorting algorithms

Kempelen wrote:Today I was thinking on what algorithm to use for sorting moves, that be the faster. Currently I am using "selection sort" as it was the first that comes to my mind when writting my engine, but now I trying to investigating what is the best.

Any orientation in this area will be wellcome.
In texel I have not found anything better than "on demand" selection sort. That is, whenever a new move is needed I iterate over all remaining moves and pick the best one. This has the advantage that in CUT nodes you often only have to select one move, so a single pass over the move list is enough.

I don't use a staged move generator in texel, so the average move list size is around 35. I have tried using a heap data structure since it also supports "on demand" sorting, but it was not a win. One trick I use is to not order any moves after the LMP move count limit has been exceeded. The idea being that if you have tried enough moves to start considering the LMP condition, the remaining moves are probably not good, so spending time trying to order them is probably wasted.

I made a 2D histogram searching an opening position (r1bq1rk1/2p1bppp/p1np1n2/1p2p3/4P3/1BP2N2/PP1P1PPP/RNBQR1K1 w - - 1 9) to depth 22.

The horizontal axis is the size of the move list and the depth axis is the number of moves "picked" by the on demand selection sort.

It can be seen that for most nodes only very few moves are picked. The ridges at 3,6,12,24 correspond to the LMP move count limit for depth=1,2,3,4 respectively. The diagonal ridge corresponds to ALL nodes where LMP is not used.

I have not verified this, but I think the peak at move list size 4 corresponds to positions where the side to move is in check and the peak at 36 corresponds to not in check positions.

Raw data for the plot:

Code: Select all

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``````

hgm
Posts: 25544
Joined: Fri Mar 10, 2006 9:06 am
Location: Amsterdam
Full name: H G Muller
Contact:

### Re: Sorting algorithms

Very nice graph. In my experience it is worthwile to take such statistics as a function of remaining depth. Otherwise it is completely dominated by the d=1 nodes, while the statistics in deeper nodes might be completely different. (E.g. because the availability of a hash move is much more common there.)

It seems that when the first move does not cut, it is most likely you eventually will pick all moves. This makes it a bit surprising that the 'on-demand' sorting has any benefits, and that more efficient sorting algorithms (incompatible with on-demand) would not perform better.

lauriet
Posts: 198
Joined: Sun Nov 03, 2013 8:32 am
Contact:

### Re: Sorting algorithms

My program does the following:

Generate Moves;
Assign the move values (PV, TT, Killers etc)
Quick Sort.

So based on the idea of 'dont sort if you dont have to', I mod'ed it to illiminate quicksort and just scan the move list and pick the highest scoring move for each next move.
If its a early cut node you should save time.

The result: No different to the original method ????????