Re: [computer-go] Bitmap Go revisited and mockup implementation
Hi René, David, Confession: I have not tested 19x19. As you have noted, and others before you over the years, a 19x19 board does not fit in one but three 128-bit registers and there would be a rather big penalty as a result, perhaps (likely?) wiping out all of the benefits of bitmaps. Antoine voiced his disappointment about the speed advantage even on 9x9 in the e-mail to the list that served as my basis. My hope, as Hideko Kato points out, is in longer registers or perhaps being able to port this to a GPU. A 64-bit OS with twice the number registers would also surely help out. Nevertheless, I was surprised that I was able to get to almost the same level of speed as Libego provides. As far as I remember, I was not disappointed by the speed itself on 9x9 boards, but mainly with the following 2 points: a) my feeling is that, as you say, it does not scale very well on 19x19 (on current hardware). I don't think other "classical" implementations suffer such a big penalty when scaling from 9x9 to 19x19. b) I also felt that this kind of implementation was not very flexible. For instance, I had another classical implementation, running at equivalent speed, but in which local 3x3 pattern matching was almost for free, as well as other more elaborated information. When I started to think about introducing 3x3 local patterns in the bitmap only implementation, it was clear it would not be for free. At that time, my conclusion was that if one only needs pure random play with no intelligence at all during playouts, then bitmap implementation could compete (at least on 9x9). If one needs more elaborated knowledge (such as small patterns matching, or even knowledge about blocks of stones), then pure bitmap implementation is probably not so competitive. I thus gave up with the idea and jumped to more promising ones. Anyway, I'm glad my post has been usefull to you. And I encourage you to improve your implementation and let us know, especially if you have fun. Starting with something and playing with it is a good way to have new ideas, even if this makes your initial ones look less interesting a while after. Best regards, Antoine ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Bitmap Go revisited and mockup implementation
[I do not know what happens, but this is the second time the computer-go archives miss the body. Maybe its the attachment. I apologize for sending this a second time, this time without attachment. If someone knows what the problem is ... I am using Gmail] Antoine, I apologize for misrepresenting your feelings. What I wanted to convey is that your e-mail expressed that with the same amount of computation, other implementation strategies provide more information, so the information gained for the effort put in is disappointing. In other words, bitmap-go had better be much faster to make up for the lack of information gained ... and it wasn't. That's pretty much what you are saying as well, I believe. As are the others in this thread. I think we can all agree on this. Going into this project, I was well aware that I was going to end up with light playouts only, and that heavy playouts is the way to go except perhaps for some special purposes such as ladder readouts. I was also well aware of the scaling argument. But, I hadn't thought that this would be the first thing thrown at my first post, as there are many programmers that seem to be stuck at 9x9. Nonetheless, bitmap-go as a topic keeps resurfacing on this mailing list every once in a while and nobody ever put solid data and a reference implementation behind it. That is what I wanted to accomplish with my mockup. Confession #2: I have been working on my own MCTS implementation using the standard implementation methods that almost everybody else is using. But there is a never-ending laundry-list of things that I would like to include before I would reach reasonable strength (where reasonable is a moving target). In the mean time, there are many others that have demonstrated much more capable programmers than I ever will be. So, by providing this bitmap-go mockup at least I had the feeling that I was contributing something newsworthy to the conversation. This may have never happened if I would wait until my MCTS program is ready. I imagine that there are others on this list in a similar situation. Besides, this was an interesting side-project and perhaps someone else can benefit from it (go for it Brian!). And, yes, it was fun. Okay, enough mesmerizing, on to the main topic. David, Lukasz, I did modify my mockup to do 19x19 bitmap-go (attached). It is a hardcoded solution using arrays of three 128-bit variables. I did not even attempt to optimize this version, so this is not the best possible solution. Nonetheless, here is a comparison: Example output (9x9): = [game] = 30236.1, [moves] = 111.071 [game] = 30249.7, [moves] = 111.068 [game] = 30145.7, [moves] = 111.089 [game] = 30237.7, [moves] = 111.122 [game] = 30210.1, [moves] = 111.101 [game] = 78.0488 kpps, [moves] = 111.023 [game] = 78.0488 kpps, [moves] = 111.045 [game] = 78.0488 kpps, [moves] = 111.046 [game] = 79.0123 kpps, [moves] = 111.131 [game] = 78.0488 kpps, [moves] = 111.082 [legal] 110/51, [pick] 110/74, [play] 106/168, [score] 44, [win] 0.4187 [legal] 111/51, [pick] 111/74, [play] 106/168, [score] 40, [win] 0.4201 [legal] 111/52, [pick] 111/75, [play] 106/168, [score] 42, [win] 0.4276 [legal] 111/52, [pick] 111/74, [play] 106/169, [score] 41, [win] 0.4092 [legal] 111/52, [pick] 111/74, [play] 106/169, [score] 44, [win] 0.4221 Example output (19x19): === [game] = 316452, [moves] = 455.036 [game] = 316378, [moves] = 455.126 [game] = 316266, [moves] = 455.177 [game] = 316017, [moves] = 455.08 [game] = 316210, [moves] = 455.16 [game] = 7.45052 kpps, [moves] = 455.267 [game] = 7.45921 kpps, [moves] = 455.055 [game] = 7.45921 kpps, [moves] = 455.17 [game] = 7.45921 kpps, [moves] = 455.188 [game] = 7.47664 kpps, [moves] = 455.013 [legal] 454/144, [pick] 454/128, [play] 449/430, [score] 173, [win] 0.4592 [legal] 455/144, [pick] 455/128, [play] 449/431, [score] 173, [win] 0.4655 [legal] 454/144, [pick] 454/128, [play] 449/430, [score] 173, [win] 0.4611 [legal] 454/144, [pick] 454/128, [play] 449/431, [score] 173, [win] 0.4674 [legal] 455/144, [pick] 455/128, [play] 450/430, [score] 175, [win] 0.4661 Summary: function9x9 19x19 ratio --- game [ cc ] 30216 316265 10.47 game [kpps] 787.46 10.45 moves 111 4554.10 legal [ cc ] 52 1442.77 pick [ cc ] 74 1281.73 play [ cc ]168 4302.56 score [ cc ] 42 1734.12 legal+pick+play 294 7022.39 So, it looks that I was overly pessimistic in terms of performance drop per move, which is a factor of 2.4x (with little effort to optimize for 19x19). But, with 4.1x more moves, this still resulted in a 10x speed penalty. With the provided reference numbers, Libego only drops 4.5-5.0x, indicating that there is almost no performance loss per move (1.2x). Is this difference roughly in line with others expectation? With that, I hope this at least provides some data for future dis
Re: [computer-go] Bitmap Go revisited and mockup implementation
It came through fine the first time. Gmail probably hid the duplicate text from you for convenience since it saw that it was text that you already sent out. Or something. I can compile the original (9x9) bitmap Go files in Windows 7 x64, but when I run it I get this: test-error [bitmap_t::lowest_index]: 0 31 test-error [bitmap_t::lowest_index]: 1 30 test-error [bitmap_t::lowest_index]: 2 29 test-error [bitmap_t::lowest_index]: 3 28 test-error [bitmap_t::lowest_index]: 4 27 test-error [bitmap_t::lowest_index]: 5 26 test-error [bitmap_t::lowest_index]: 6 25 test-error [bitmap_t::lowest_index]: 7 24 test-error [bitmap_t::lowest_index]: 8 23 test-error [bitmap_t::lowest_index]: 9 22 test-error [bitmap_t::lowest_index]: 10 21 test-error [bitmap_t::lowest_index]: 11 20 test-error [bitmap_t::lowest_index]: 12 19 test-error [bitmap_t::lowest_index]: 13 18 test-error [bitmap_t::lowest_index]: 14 17 test-error [bitmap_t::lowest_index]: 15 16 test-error [bitmap_t::lowest_index]: 16 15 test-error [bitmap_t::lowest_index]: 17 14 test-error [bitmap_t::lowest_index]: 18 13 test-error [bitmap_t::lowest_index]: 19 12 test-error [bitmap_t::lowest_index]: 20 11 test-error [bitmap_t::lowest_index]: 21 10 test-error [bitmap_t::lowest_index]: 22 9 test-error [bitmap_t::lowest_index]: 23 8 test-error [bitmap_t::lowest_index]: 24 7 test-error [bitmap_t::lowest_index]: 25 6 test-error [bitmap_t::lowest_index]: 26 5 test-error [bitmap_t::lowest_index]: 27 4 test-error [bitmap_t::lowest_index]: 28 3 test-error [bitmap_t::lowest_index]: 29 2 test-error [bitmap_t::lowest_index]: 30 1 test-error [bitmap_t::lowest_index]: 31 0 test-error [bitmap_t::lowest_index]: 32 63 test-error [bitmap_t::lowest_index]: 33 62 test-error [bitmap_t::lowest_index]: 34 61 test-error [bitmap_t::lowest_index]: 35 60 test-error [bitmap_t::lowest_index]: 36 59 test-error [bitmap_t::lowest_index]: 37 58 test-error [bitmap_t::lowest_index]: 38 57 test-error [bitmap_t::lowest_index]: 39 56 test-error [bitmap_t::lowest_index]: 40 55 test-error [bitmap_t::lowest_index]: 41 54 test-error [bitmap_t::lowest_index]: 42 53 test-error [bitmap_t::lowest_index]: 43 52 test-error [bitmap_t::lowest_index]: 44 51 test-error [bitmap_t::lowest_index]: 45 50 test-error [bitmap_t::lowest_index]: 46 49 test-error [bitmap_t::lowest_index]: 47 48 test-error [bitmap_t::lowest_index]: 48 47 test-error [bitmap_t::lowest_index]: 49 46 test-error [bitmap_t::lowest_index]: 50 45 test-error [bitmap_t::lowest_index]: 51 44 test-error [bitmap_t::lowest_index]: 52 43 test-error [bitmap_t::lowest_index]: 53 42 test-error [bitmap_t::lowest_index]: 54 41 test-error [bitmap_t::lowest_index]: 55 40 test-error [bitmap_t::lowest_index]: 56 39 test-error [bitmap_t::lowest_index]: 57 38 test-error [bitmap_t::lowest_index]: 58 37 test-error [bitmap_t::lowest_index]: 59 36 test-error [bitmap_t::lowest_index]: 60 35 test-error [bitmap_t::lowest_index]: 61 34 test-error [bitmap_t::lowest_index]: 62 33 test-error [bitmap_t::lowest_index]: 63 32 test-error [bitmap_t::lowest_index]: 64 95 test-error [bitmap_t::lowest_index]: 65 94 test-error [bitmap_t::lowest_index]: 66 93 test-error [bitmap_t::lowest_index]: 67 92 test-error [bitmap_t::lowest_index]: 68 91 test-error [bitmap_t::lowest_index]: 69 90 test-error [bitmap_t::lowest_index]: 70 89 test-error [bitmap_t::lowest_index]: 71 88 test-error [bitmap_t::lowest_index]: 72 87 test-error [bitmap_t::lowest_index]: 73 86 test-error [bitmap_t::lowest_index]: 74 85 test-error [bitmap_t::lowest_index]: 75 84 test-error [bitmap_t::lowest_index]: 76 83 test-error [bitmap_t::lowest_index]: 77 82 test-error [bitmap_t::lowest_index]: 78 81 test-error [bitmap_t::lowest_index]: 79 80 test-error [bitmap_t::lowest_index]: 80 79 test-error-1 [bitmap_t::is_one_bit]: 0 test-error-1 [bitmap_t::is_one_bit]: 1 test-error-1 [bitmap_t::is_one_bit]: 2 test-error-1 [bitmap_t::is_one_bit]: 3 test-error-1 [bitmap_t::is_one_bit]: 4 test-error-1 [bitmap_t::is_one_bit]: 5 test-error-1 [bitmap_t::is_one_bit]: 6 test-error-1 [bitmap_t::is_one_bit]: 7 test-error-1 [bitmap_t::is_one_bit]: 8 test-error-1 [bitmap_t::is_one_bit]: 9 test-error-1 [bitmap_t::is_one_bit]: 10 test-error-1 [bitmap_t::is_one_bit]: 11 test-error-1 [bitmap_t::is_one_bit]: 12 test-error-1 [bitmap_t::is_one_bit]: 13 test-error-1 [bitmap_t::is_one_bit]: 14 test-error-1 [bitmap_t::is_one_bit]: 15 test-error-1 [bitmap_t::is_one_bit]: 16 test-error-1 [bitmap_t::is_one_bit]: 17 test-error-1 [bitmap_t::is_one_bit]: 18 test-error-1 [bitmap_t::is_one_bit]: 19 test-error-1 [bitmap_t::is_one_bit]: 20 test-error-1 [bitmap_t::is_one_bit]: 21 test-error-1 [bitmap_t::is_one_bit]: 22 test-error-1 [bitmap_t::is_one_bit]: 23 test-error-1 [bitmap_t::is_one_bit]: 24 test-error-1 [bitmap_t::is_one_bit]: 25 test-error-1 [bitmap_t::is_one_bit]: 26 test-error-1 [bitmap_t::is_one_bit]: 27 test-error-1 [bitmap_t::is_one_bit]: 28 test-error-1 [bitmap_t::is_one_bit]: 29 test-error-1 [bitmap_t::is_one_bit]: 30 test-error-1 [bitmap_t::is_one_b
Re: [computer-go] Bitmap Go revisited and mockup implementation
(AMD Phenom CPU) Michael Williams wrote: It came through fine the first time. Gmail probably hid the duplicate text from you for convenience since it saw that it was text that you already sent out. Or something. I can compile the original (9x9) bitmap Go files in Windows 7 x64, but when I run it I get this: test-error [bitmap_t::lowest_index]: 0 31 test-error [bitmap_t::lowest_index]: 1 30 test-error [bitmap_t::lowest_index]: 2 29 test-error [bitmap_t::lowest_index]: 3 28 test-error [bitmap_t::lowest_index]: 4 27 test-error [bitmap_t::lowest_index]: 5 26 test-error [bitmap_t::lowest_index]: 6 25 test-error [bitmap_t::lowest_index]: 7 24 test-error [bitmap_t::lowest_index]: 8 23 test-error [bitmap_t::lowest_index]: 9 22 test-error [bitmap_t::lowest_index]: 10 21 test-error [bitmap_t::lowest_index]: 11 20 test-error [bitmap_t::lowest_index]: 12 19 test-error [bitmap_t::lowest_index]: 13 18 test-error [bitmap_t::lowest_index]: 14 17 test-error [bitmap_t::lowest_index]: 15 16 test-error [bitmap_t::lowest_index]: 16 15 test-error [bitmap_t::lowest_index]: 17 14 test-error [bitmap_t::lowest_index]: 18 13 test-error [bitmap_t::lowest_index]: 19 12 test-error [bitmap_t::lowest_index]: 20 11 test-error [bitmap_t::lowest_index]: 21 10 test-error [bitmap_t::lowest_index]: 22 9 test-error [bitmap_t::lowest_index]: 23 8 test-error [bitmap_t::lowest_index]: 24 7 test-error [bitmap_t::lowest_index]: 25 6 test-error [bitmap_t::lowest_index]: 26 5 test-error [bitmap_t::lowest_index]: 27 4 test-error [bitmap_t::lowest_index]: 28 3 test-error [bitmap_t::lowest_index]: 29 2 test-error [bitmap_t::lowest_index]: 30 1 test-error [bitmap_t::lowest_index]: 31 0 test-error [bitmap_t::lowest_index]: 32 63 test-error [bitmap_t::lowest_index]: 33 62 test-error [bitmap_t::lowest_index]: 34 61 test-error [bitmap_t::lowest_index]: 35 60 test-error [bitmap_t::lowest_index]: 36 59 test-error [bitmap_t::lowest_index]: 37 58 test-error [bitmap_t::lowest_index]: 38 57 test-error [bitmap_t::lowest_index]: 39 56 test-error [bitmap_t::lowest_index]: 40 55 test-error [bitmap_t::lowest_index]: 41 54 test-error [bitmap_t::lowest_index]: 42 53 test-error [bitmap_t::lowest_index]: 43 52 test-error [bitmap_t::lowest_index]: 44 51 test-error [bitmap_t::lowest_index]: 45 50 test-error [bitmap_t::lowest_index]: 46 49 test-error [bitmap_t::lowest_index]: 47 48 test-error [bitmap_t::lowest_index]: 48 47 test-error [bitmap_t::lowest_index]: 49 46 test-error [bitmap_t::lowest_index]: 50 45 test-error [bitmap_t::lowest_index]: 51 44 test-error [bitmap_t::lowest_index]: 52 43 test-error [bitmap_t::lowest_index]: 53 42 test-error [bitmap_t::lowest_index]: 54 41 test-error [bitmap_t::lowest_index]: 55 40 test-error [bitmap_t::lowest_index]: 56 39 test-error [bitmap_t::lowest_index]: 57 38 test-error [bitmap_t::lowest_index]: 58 37 test-error [bitmap_t::lowest_index]: 59 36 test-error [bitmap_t::lowest_index]: 60 35 test-error [bitmap_t::lowest_index]: 61 34 test-error [bitmap_t::lowest_index]: 62 33 test-error [bitmap_t::lowest_index]: 63 32 test-error [bitmap_t::lowest_index]: 64 95 test-error [bitmap_t::lowest_index]: 65 94 test-error [bitmap_t::lowest_index]: 66 93 test-error [bitmap_t::lowest_index]: 67 92 test-error [bitmap_t::lowest_index]: 68 91 test-error [bitmap_t::lowest_index]: 69 90 test-error [bitmap_t::lowest_index]: 70 89 test-error [bitmap_t::lowest_index]: 71 88 test-error [bitmap_t::lowest_index]: 72 87 test-error [bitmap_t::lowest_index]: 73 86 test-error [bitmap_t::lowest_index]: 74 85 test-error [bitmap_t::lowest_index]: 75 84 test-error [bitmap_t::lowest_index]: 76 83 test-error [bitmap_t::lowest_index]: 77 82 test-error [bitmap_t::lowest_index]: 78 81 test-error [bitmap_t::lowest_index]: 79 80 test-error [bitmap_t::lowest_index]: 80 79 test-error-1 [bitmap_t::is_one_bit]: 0 test-error-1 [bitmap_t::is_one_bit]: 1 test-error-1 [bitmap_t::is_one_bit]: 2 test-error-1 [bitmap_t::is_one_bit]: 3 test-error-1 [bitmap_t::is_one_bit]: 4 test-error-1 [bitmap_t::is_one_bit]: 5 test-error-1 [bitmap_t::is_one_bit]: 6 test-error-1 [bitmap_t::is_one_bit]: 7 test-error-1 [bitmap_t::is_one_bit]: 8 test-error-1 [bitmap_t::is_one_bit]: 9 test-error-1 [bitmap_t::is_one_bit]: 10 test-error-1 [bitmap_t::is_one_bit]: 11 test-error-1 [bitmap_t::is_one_bit]: 12 test-error-1 [bitmap_t::is_one_bit]: 13 test-error-1 [bitmap_t::is_one_bit]: 14 test-error-1 [bitmap_t::is_one_bit]: 15 test-error-1 [bitmap_t::is_one_bit]: 16 test-error-1 [bitmap_t::is_one_bit]: 17 test-error-1 [bitmap_t::is_one_bit]: 18 test-error-1 [bitmap_t::is_one_bit]: 19 test-error-1 [bitmap_t::is_one_bit]: 20 test-error-1 [bitmap_t::is_one_bit]: 21 test-error-1 [bitmap_t::is_one_bit]: 22 test-error-1 [bitmap_t::is_one_bit]: 23 test-error-1 [bitmap_t::is_one_bit]: 24 test-error-1 [bitmap_t::is_one_bit]: 25 test-error-1 [bitmap_t::is_one_bit]: 26 test-error-1 [bitmap_t::is_one_bit]: 27 test-error-1 [bitmap_t::is_one_bit]: 28 test-error-1 [bitmap_t::is_one_bit]: 29 test-error-1 [bitmap_t::is_
Re: [computer-go] Bitmap Go revisited and mockup implementation
2009/8/25 René van de Veerdonk : > Nonetheless, bitmap-go as a topic keeps resurfacing on this > mailing list every once in a while and nobody ever put solid data and a > reference implementation behind it. That is what I wanted to accomplish with > my mockup. I think this is interesting information, so I think it's good you tried it. It basically means unless someone has a much smarter idea how to implement bit-sets, the performance is not enough to go through the trouble for most programmers. > So, it looks that I was overly pessimistic in terms of performance drop per > move, which is a factor of 2.4x (with little effort to optimize for 19x19). > But, with 4.1x more moves, this still resulted in a 10x speed penalty. With > the provided reference numbers, Libego only drops 4.5-5.0x, indicating that > there is almost no performance loss per move (1.2x). Is this difference > roughly in line with others expectation? Yes, I'd expect that. The main speed-determining factor in traditional implementations is merging. That depends on the average length of the merge. Obviously this can be much longer on 19x19 as a worst case, but on average I wouldn't expect it to make much difference compared to other board-sizes. Mark ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Bitmap Go revisited and mockup implementation
On an initial look, it seems that the shifting, popcounting, and bitscanning functions can be improved significantly. That's all I looked at closely, perhaps the other board routines could use some reworking too. I'll try my hand at optimizing it if I get the time, but the windowsy code makes it a bit difficult. Zach ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Bitmap Go revisited and mockup implementation
Hi Micheal,
Thanks for the test (Intel -> AMD, Windows XP -> Windows 7, x32 -> x64,
great, three birds with one stone!). So much for portability. But, hooray
for test-cases!
This may be related to the __lzcnt intrinsic, giving you a completely
different result, i.e., 32 - my result. Could you try replacing this
function in bitmap.cpp? I believe I tested this alternative during
development and it generates only slightly worse performing code.
__forceinline
unsigned int bitmap_t::lowest_index () const {
const __m128i comp = _mm_cmpeq_epi32 (_mm_setzero_si128 (), board);
unsigned long m = _mm_movemask_epi8 (comp) ^ 0x;
if (!_BitScanForward (&m, m)) return 127;
/* offending instruction */
//return 8*m + __lzcnt (board.m128i_u32[m/4]);
/* new code follows */
unsigned long n;
_BitScanForward (&n, board.m128i_u32[m/4]);
return 8*m + n;
}
René
PS. x64 ... new playground, you could use __lzcnt64 ... so many things to
try!
On Tue, Aug 25, 2009 at 5:43 PM, Michael Williams <
michaelwilliam...@gmail.com> wrote:
> (AMD Phenom CPU)
>
>
> Michael Williams wrote:
>
>> It came through fine the first time. Gmail probably hid the duplicate
>> text from you for convenience since it saw that it was text that you already
>> sent out. Or something.
>>
>> I can compile the original (9x9) bitmap Go files in Windows 7 x64, but
>> when I run it I get this:
>>
>> test-error [bitmap_t::lowest_index]: 0 31
>> test-error [bitmap_t::lowest_index]: 1 30
>> test-error [bitmap_t::lowest_index]: 2 29
>> test-error [bitmap_t::lowest_index]: 3 28
>> test-error [bitmap_t::lowest_index]: 4 27
>> test-error [bitmap_t::lowest_index]: 5 26
>> test-error [bitmap_t::lowest_index]: 6 25
>> test-error [bitmap_t::lowest_index]: 7 24
>> test-error [bitmap_t::lowest_index]: 8 23
>> test-error [bitmap_t::lowest_index]: 9 22
>> test-error [bitmap_t::lowest_index]: 10 21
>> test-error [bitmap_t::lowest_index]: 11 20
>> test-error [bitmap_t::lowest_index]: 12 19
>> test-error [bitmap_t::lowest_index]: 13 18
>> test-error [bitmap_t::lowest_index]: 14 17
>> test-error [bitmap_t::lowest_index]: 15 16
>> test-error [bitmap_t::lowest_index]: 16 15
>> test-error [bitmap_t::lowest_index]: 17 14
>> test-error [bitmap_t::lowest_index]: 18 13
>> test-error [bitmap_t::lowest_index]: 19 12
>> test-error [bitmap_t::lowest_index]: 20 11
>> test-error [bitmap_t::lowest_index]: 21 10
>> test-error [bitmap_t::lowest_index]: 22 9
>> test-error [bitmap_t::lowest_index]: 23 8
>> test-error [bitmap_t::lowest_index]: 24 7
>> test-error [bitmap_t::lowest_index]: 25 6
>> test-error [bitmap_t::lowest_index]: 26 5
>> test-error [bitmap_t::lowest_index]: 27 4
>> test-error [bitmap_t::lowest_index]: 28 3
>> test-error [bitmap_t::lowest_index]: 29 2
>> test-error [bitmap_t::lowest_index]: 30 1
>> test-error [bitmap_t::lowest_index]: 31 0
>> test-error [bitmap_t::lowest_index]: 32 63
>> test-error [bitmap_t::lowest_index]: 33 62
>> test-error [bitmap_t::lowest_index]: 34 61
>> test-error [bitmap_t::lowest_index]: 35 60
>> test-error [bitmap_t::lowest_index]: 36 59
>> test-error [bitmap_t::lowest_index]: 37 58
>> test-error [bitmap_t::lowest_index]: 38 57
>> test-error [bitmap_t::lowest_index]: 39 56
>> test-error [bitmap_t::lowest_index]: 40 55
>> test-error [bitmap_t::lowest_index]: 41 54
>> test-error [bitmap_t::lowest_index]: 42 53
>> test-error [bitmap_t::lowest_index]: 43 52
>> test-error [bitmap_t::lowest_index]: 44 51
>> test-error [bitmap_t::lowest_index]: 45 50
>> test-error [bitmap_t::lowest_index]: 46 49
>> test-error [bitmap_t::lowest_index]: 47 48
>> test-error [bitmap_t::lowest_index]: 48 47
>> test-error [bitmap_t::lowest_index]: 49 46
>> test-error [bitmap_t::lowest_index]: 50 45
>> test-error [bitmap_t::lowest_index]: 51 44
>> test-error [bitmap_t::lowest_index]: 52 43
>> test-error [bitmap_t::lowest_index]: 53 42
>> test-error [bitmap_t::lowest_index]: 54 41
>> test-error [bitmap_t::lowest_index]: 55 40
>> test-error [bitmap_t::lowest_index]: 56 39
>> test-error [bitmap_t::lowest_index]: 57 38
>> test-error [bitmap_t::lowest_index]: 58 37
>> test-error [bitmap_t::lowest_index]: 59 36
>> test-error [bitmap_t::lowest_index]: 60 35
>> test-error [bitmap_t::lowest_index]: 61 34
>> test-error [bitmap_t::lowest_index]: 62 33
>> test-error [bitmap_t::lowest_index]: 63 32
>> test-error [bitmap_t::lowest_index]: 64 95
>> test-error [bitmap_t::lowest_index]: 65 94
>> test-error [bitmap_t::lowest_index]: 66 93
>> test-error [bitmap_t::lowest_index]: 67 92
>> test-error [bitmap_t::lowest_index]: 68 91
>> test-error [bitmap_t::lowest_index]: 69 90
>> test-error [bitmap_t::lowest_index]: 70 89
>> test-error [bitmap_t::lowest_index]: 71 88
>> test-error [bitmap_t::lowest_index]: 72 87
>> test-error [bitmap_t::lowest_index]: 73 86
>> test-error [bitmap_t::lowest_index]: 74 85
>> test-error [bitmap_t::lowest_index]: 75 84
>> test-error [bitmap_t::lowest_index]: 76 83
>> test-error [bitmap_t::lowest_index]: 77 82
>> test-error [bitmap_t::lowest_index]: 78 81
Re: [computer-go] Bitmap Go revisited and mockup implementation
That doesn't seem to have any effect on the results.
René van de Veerdonk wrote:
Hi Micheal,
Thanks for the test (Intel -> AMD, Windows XP -> Windows 7, x32 -> x64,
great, three birds with one stone!). So much for portability. But,
hooray for test-cases!
This may be related to the __lzcnt intrinsic, giving you a completely
different result, i.e., 32 - my result. Could you try replacing this
function in bitmap.cpp? I believe I tested this alternative during
development and it generates only slightly worse performing code.
__forceinline
unsigned int bitmap_t::lowest_index () const {
const __m128i comp = _mm_cmpeq_epi32 (_mm_setzero_si128 (), board);
unsigned long m = _mm_movemask_epi8 (comp) ^ 0x;
if (!_BitScanForward (&m, m)) return 127;
/* offending instruction */
//return 8*m + __lzcnt (board.m128i_u32[m/4]);
/* new code follows */
unsigned long n;
_BitScanForward (&n, board.m128i_u32[m/4]);
return 8*m + n;
}
René
PS. x64 ... new playground, you could use __lzcnt64 ... so many things
to try!
On Tue, Aug 25, 2009 at 5:43 PM, Michael Williams
mailto:michaelwilliam...@gmail.com>> wrote:
(AMD Phenom CPU)
Michael Williams wrote:
It came through fine the first time. Gmail probably hid the
duplicate text from you for convenience since it saw that it was
text that you already sent out. Or something.
I can compile the original (9x9) bitmap Go files in Windows 7
x64, but when I run it I get this:
test-error [bitmap_t::lowest_index]: 0 31
test-error [bitmap_t::lowest_index]: 1 30
test-error [bitmap_t::lowest_index]: 2 29
test-error [bitmap_t::lowest_index]: 3 28
test-error [bitmap_t::lowest_index]: 4 27
test-error [bitmap_t::lowest_index]: 5 26
test-error [bitmap_t::lowest_index]: 6 25
test-error [bitmap_t::lowest_index]: 7 24
test-error [bitmap_t::lowest_index]: 8 23
test-error [bitmap_t::lowest_index]: 9 22
test-error [bitmap_t::lowest_index]: 10 21
test-error [bitmap_t::lowest_index]: 11 20
test-error [bitmap_t::lowest_index]: 12 19
test-error [bitmap_t::lowest_index]: 13 18
test-error [bitmap_t::lowest_index]: 14 17
test-error [bitmap_t::lowest_index]: 15 16
test-error [bitmap_t::lowest_index]: 16 15
test-error [bitmap_t::lowest_index]: 17 14
test-error [bitmap_t::lowest_index]: 18 13
test-error [bitmap_t::lowest_index]: 19 12
test-error [bitmap_t::lowest_index]: 20 11
test-error [bitmap_t::lowest_index]: 21 10
test-error [bitmap_t::lowest_index]: 22 9
test-error [bitmap_t::lowest_index]: 23 8
test-error [bitmap_t::lowest_index]: 24 7
test-error [bitmap_t::lowest_index]: 25 6
test-error [bitmap_t::lowest_index]: 26 5
test-error [bitmap_t::lowest_index]: 27 4
test-error [bitmap_t::lowest_index]: 28 3
test-error [bitmap_t::lowest_index]: 29 2
test-error [bitmap_t::lowest_index]: 30 1
test-error [bitmap_t::lowest_index]: 31 0
test-error [bitmap_t::lowest_index]: 32 63
test-error [bitmap_t::lowest_index]: 33 62
test-error [bitmap_t::lowest_index]: 34 61
test-error [bitmap_t::lowest_index]: 35 60
test-error [bitmap_t::lowest_index]: 36 59
test-error [bitmap_t::lowest_index]: 37 58
test-error [bitmap_t::lowest_index]: 38 57
test-error [bitmap_t::lowest_index]: 39 56
test-error [bitmap_t::lowest_index]: 40 55
test-error [bitmap_t::lowest_index]: 41 54
test-error [bitmap_t::lowest_index]: 42 53
test-error [bitmap_t::lowest_index]: 43 52
test-error [bitmap_t::lowest_index]: 44 51
test-error [bitmap_t::lowest_index]: 45 50
test-error [bitmap_t::lowest_index]: 46 49
test-error [bitmap_t::lowest_index]: 47 48
test-error [bitmap_t::lowest_index]: 48 47
test-error [bitmap_t::lowest_index]: 49 46
test-error [bitmap_t::lowest_index]: 50 45
test-error [bitmap_t::lowest_index]: 51 44
test-error [bitmap_t::lowest_index]: 52 43
test-error [bitmap_t::lowest_index]: 53 42
test-error [bitmap_t::lowest_index]: 54 41
test-error [bitmap_t::lowest_index]: 55 40
test-error [bitmap_t::lowest_index]: 56 39
test-error [bitmap_t::lowest_index]: 57 38
test-error [bitmap_t::lowest_index]: 58 37
test-error [bitmap_t::lowest_index]: 59 36
test-error [bitmap_t::lowest_index]: 60 35
test-error [bitmap_t::lowest_index]: 61 34
test-error [bitmap_t::lowest_index]: 62 33
test-error [bitmap_t::lowest_index]: 63 32
test-error [bitmap_t::lowest_index]: 64 95
test-error [bitmap_t::lowest_index]: 65 94
test-error [bitmap_t::lowest_index]: 66 93
test-error [bitmap_t::lowest_index]: 67 92
test-error [bitmap_t::lowest_index]
Re: [computer-go] Bitmap Go revisited and mockup implementation
Zach, I can't help the windowsiness, but thanks for taking a look already. Popcounting I believe to be optimal for 32-bit only instructions, especially since I would like to keep the intermediate byte-count to help speed up the random pick function. There is a really neat trick to speed up the final accumulations, but I couldn't find the sse2 instructions to implement it. Bitscanning is indeed awkward the way I implemented it, but I didn't see a better way to do it as there is no compare instruction that yields a boolean as the result. I would be interested to see what you come up with for shifting, I believe that this is where a lot of time is spend. René On Tue, Aug 25, 2009 at 6:20 PM, Zach Wegner wrote: > On an initial look, it seems that the shifting, popcounting, and > bitscanning functions can be improved significantly. That's all I > looked at closely, perhaps the other board routines could use some > reworking too. > > I'll try my hand at optimizing it if I get the time, but the windowsy > code makes it a bit difficult. > > Zach > ___ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ > ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Bitmap Go revisited and mockup implementation
A couple of notes. Some of us on this computer-go forum are also Chess programmers and many of write 64 bit chess programs. I am one of them but I know there are others. My 64 bit chess program runs almost 2X faster if I compile it to run on a 64 bit OS - in other words I'm using real 64 bit values to represent the bit boards.So this really is a big deal - you can expect a pretty good gain. I also toyed with a bit board style go program and started working on one long ago. You still need several 64 bit words to represent the state of each color.I started to write some routines that did shift, popcount, etc as fast as possible. Basically you had to compile the program for each board size, and it figured out how many bits were needed and simulated (using struct) an integer data type that was large enough. About half way through I decided not to proceed - at the time I had some idea that I was more interested in and I never picked it back up - assuming that it would be too slow (but I didn't prove it.) I think you could look at glaurung (the chess program) to find great routines for the common bit operations. I think the author of Glaurung does it about as fast as it can be done and even has assembly code for finding the right-most bit, or something like that. But you could probably learn something from looking at that program. I'm not sure how useful this might be for go, but there are some pretty clever tricks with minimal perfect hashing - that you might find some use for. Perhaps there is a way to make this work for eye-detection or someting. There is some great explanations here: http://chessprogramming.wikispaces.com/I think you want to look under move generation perhaps. Perhaps this cannot be used for GO, but it's fun to read anyway :-) The only issue of course is that you need more than 64 bits for go - but the general principles might be made to work. - Don 2009/8/25 René van de Veerdonk > Antoine, > I apologize for misrepresenting your feelings. What I wanted to convey is > that your e-mail expressed that with the same amount of computation, other > implementation strategies provide more information, so the information > gained for the effort put in is disappointing. In other words, bitmap-go had > better be much faster to make up for the lack of information gained ... and > it wasn't. That's pretty much what you are saying as well, I believe. As are > the others in this thread. I think we can all agree on this. > > Going into this project, I was well aware that I was going to end up with > light playouts only, and that heavy playouts is the way to go except perhaps > for some special purposes such as ladder readouts. I was also well aware of > the scaling argument. But, I hadn't thought that this would be the first > thing thrown at my first post, as there are many programmers that seem to be > stuck at 9x9. Nonetheless, bitmap-go as a topic keeps resurfacing on this > mailing list every once in a while and nobody ever put solid data and a > reference implementation behind it. That is what I wanted to accomplish with > my mockup. > > Confession #2: I have been working on my own MCTS implementation using the > standard implementation methods that almost everybody else is using. But > there is a never-ending laundry-list of things that I would like to include > before I would reach reasonable strength (where reasonable is a moving > target). In the mean time, there are many others that have demonstrated much > more capable programmers than I ever will be. So, by providing this > bitmap-go mockup at least I had the feeling that I was contributing > something newsworthy to the conversation. This may have never happened if I > would wait until my MCTS program is ready. I imagine that there are others > on this list in a similar situation. Besides, this was an interesting > side-project and perhaps someone else can benefit from it (go for it > Brian!). And, yes, it was fun. > > Okay, enough mesmerizing, on to the main topic. > > David, Lukasz, > > I did modify my mockup to do 19x19 bitmap-go (attached). It is a hardcoded > solution using arrays of three 128-bit variables. I did not even attempt to > optimize this version, so this is not the best possible solution. > Nonetheless, here is a comparison: > > Example output (9x9): > = > > [game] = 30236.1, [moves] = 111.071 > [game] = 30249.7, [moves] = 111.068 > [game] = 30145.7, [moves] = 111.089 > [game] = 30237.7, [moves] = 111.122 > [game] = 30210.1, [moves] = 111.101 > > [game] = 78.0488 kpps, [moves] = 111.023 > [game] = 78.0488 kpps, [moves] = 111.045 > [game] = 78.0488 kpps, [moves] = 111.046 > [game] = 79.0123 kpps, [moves] = 111.131 > [game] = 78.0488 kpps, [moves] = 111.082 > > [legal] 110/51, [pick] 110/74, [play] 106/168, [score] 44, [win] 0.4187 > [legal] 111/51, [pick] 111/74, [play] 106/168, [score] 40, [win] 0.4201 > [legal] 111/52, [pick] 111/75, [play] 106/168, [
Re: [computer-go] Bitmap Go revisited and mockup implementation
Mark,
I would argue that 10x vs 5x is not a deal-breaker if bitmaps would support
your particular goals better. They do provide the advantage of automatically
providing you all the liberties of strings, for instance. Requests on how to
do that efficiently come by on this mailing list on a regular basis. But I
agree that it does not look very good in general.
As for merging being time consuming. The merge portion of the play function
looks like this:
/* merge friendly strings */
bool single_stone_string = true;
do {
bitmap_t adj_strings = bm_adjacent & bm_my_points;
while (!adj_strings.is_empty ()) {
unsigned int i = adj_strings.lowest_index ();
do {
i = anchor[i];
} while (i != anchor[i]);
anchor[i] = move;
single_stone_string = false;
adj_strings.clear (string[i]);
bm_string.set (string[i]);
bm_liberty.set (liberty[i]);
}
bm_liberty.clear (bm_move);
atari.clear (bm_string);
} while (false);
The difference between 9x9 and 19x19 is in the average length of the linked
list anchor[]. The merge itself should be the same work, other than the fact
that for 19x19 I now have to perform the work on three elements per bitmap
as compared to just one for 9x9. Moving away from a linked list may prove
beneficial for 19x19, but than you need to ensure that all the anchors for a
string are correctly set during merge. That means looping over all the
stones in the string, which I do not believe to be very efficient with
bitmaps as it requires cumbersome bit-scanning.
René
On Tue, Aug 25, 2009 at 6:09 PM, Mark Boon wrote:
> 2009/8/25 René van de Veerdonk :
> > Nonetheless, bitmap-go as a topic keeps resurfacing on this
> > mailing list every once in a while and nobody ever put solid data and a
> > reference implementation behind it. That is what I wanted to accomplish
> with
> > my mockup.
>
> I think this is interesting information, so I think it's good you
> tried it. It basically means unless someone has a much smarter idea
> how to implement bit-sets, the performance is not enough to go through
> the trouble for most programmers.
>
> > So, it looks that I was overly pessimistic in terms of performance drop
> per
> > move, which is a factor of 2.4x (with little effort to optimize for
> 19x19).
> > But, with 4.1x more moves, this still resulted in a 10x speed penalty.
> With
> > the provided reference numbers, Libego only drops 4.5-5.0x, indicating
> that
> > there is almost no performance loss per move (1.2x). Is this difference
> > roughly in line with others expectation?
>
> Yes, I'd expect that. The main speed-determining factor in traditional
> implementations is merging. That depends on the average length of the
> merge. Obviously this can be much longer on 19x19 as a worst case, but
> on average I wouldn't expect it to make much difference compared to
> other board-sizes.
>
> Mark
> ___
> computer-go mailing list
> computer-go@computer-go.org
> http://www.computer-go.org/mailman/listinfo/computer-go/
>
___
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Bitmap Go revisited and mockup implementation
Debug build:
testing _BitScanForward (&m, 0): 0 842032512
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 840277132
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Release build:
testing _BitScanForward (&m, 0): 0 16843009
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 4
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Sucks when they produce different results.
René van de Veerdonk wrote:
Micheal,
Thanks for trying. Could you try one or two more things?
(1) Replace the _BitScanForward in the new code to _BitScanReverse. This
probably won't help.
(2) Add this to bitmapgo.cpp:
/* sandbox */
const bool sandbox = true;
void test_sandbox () {
unsigned long m = 220;
unsigned char test_it = _BitScanForward (&m, 0);
std::cout << "testing _BitScanForward (&m, 0): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanForward (&m, 1);
std::cout << "testing _BitScanForward (&m, 1): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanForward (&m, 256);
std::cout << "testing _BitScanForward (&m, 256): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 0);
std::cout << "testing _BitScanReverse (&m, 0): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 1);
std::cout << "testing _BitScanReverse (&m, 1): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 256);
std::cout << "testing _BitScanReverse (&m, 256): "
<< (int) test_it << " " << m << "\n";
}
and add a line something like this in the main program:
if (test && sandbox) test_sandbox (); /* new line */
if (test && verify) test = test_bitmap_t::test (); /* already there */
That does not solve anything, but it may tell me if those functions are
doing for you what they do for me.
My output is:
testing _BitScanForward (&m, 0): 0 16843009
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 3432104
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Thanks, I really appreciate your help !
René
On Tue, Aug 25, 2009 at 6:38 PM, Michael Williams
mailto:michaelwilliam...@gmail.com>> wrote:
That doesn't seem to have any effect on the results.
René van de Veerdonk wrote:
Hi Micheal,
Thanks for the test (Intel -> AMD, Windows XP -> Windows 7, x32
-> x64, great, three birds with one stone!). So much for
portability. But, hooray for test-cases!
This may be related to the __lzcnt intrinsic, giving you a
completely different result, i.e., 32 - my result. Could you try
replacing this function in bitmap.cpp? I believe I tested this
alternative during development and it generates only slightly
worse performing code.
__forceinline
unsigned int bitmap_t::lowest_index () const {
const __m128i comp = _mm_cmpeq_epi32 (_mm_setzero_si128 (), board);
unsigned long m = _mm_movemask_epi8 (comp) ^ 0x;
if (!_BitScanForward (&m, m)) return 127;
/* offending instruction */
//return 8*m + __lzcnt (board.m128i_u32[m/4]);
/* new code follows */
unsigned long n;
_BitScanForward (&n, board.m128i_u32[m/4]);
return 8*m + n;
}
René
PS. x64 ... new playground, you could use __lzcnt64 ... so many
things to try!
On Tue, Aug 25, 2009 at 5:43 PM, Michael Williams
mailto:michaelwilliam...@gmail.com>
>> wrote:
(AMD Phenom CPU)
Michael Williams wrote:
It came through fine the first time. Gmail probably hid the
duplicate text from you for convenience since it saw that
it was
text that you already sent out. Or something.
I can compile the original (9x9) bitmap Go files in Windows 7
x64, but when I run it I get this:
test-error [bitmap_t::lowest_index]: 0 31
test-error [bitmap_t::lowest_index]: 1 30
test-error [bitmap_t::lowest_index]: 2 29
test-error [bitmap_t::lowest_index]: 3 28
test-error [bitmap_t::lowest_index]: 4 27
test-error [bitmap_t::lowest_index]: 5 26
test-error [bitmap_t::lowest_index]: 6 25
test-error [bitmap_t::lowest_index]: 7 24
test-error [bitmap_t::lowest_index]: 8 23
test-error [bitmap_t::lowest_index]: 9 22
test-error [bitmap_t::lowest_index]: 10 21
test-error [bitmap_t::lowest_index]: 11 20
test-error [bitmap_t::lowest_index]: 12 19
test-error [bitmap_t::lowe
Re: [computer-go] Bitmap Go revisited and mockup implementation
No. The code is now:
__forceinline
unsigned int bitmap_t::lowest_index () const {
const __m128i comp = _mm_cmpeq_epi32 (_mm_setzero_si128 (), board);
unsigned long m = _mm_movemask_epi8 (comp) ^ 0x;
if (!_BitScanForward (&m, m)) return 127;
/* offending instruction */
//return 8*m + __lzcnt (board.m128i_u32[m/4]);
/* new code follows */
unsigned long n;
_BitScanForward (&n, board.m128i_u32[m/4]);
return 8*m + (32-n);
}
Debug:
testing _BitScanForward (&m, 0): 0 1099227377
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 1103042705
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
test-error [bitmap_t::lowest_index]: 0 32
Release:
testing _BitScanForward (&m, 0): 0 16843009
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 4
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
test-error [bitmap_t::lowest_index]: 0 32
René van de Veerdonk wrote:
Micheal,
Your output is actually correct. The output is undefined when the second
argument to _BitScanForward is zero and that is what I am explicitly
testing for in the method bitmap_t::lowest_index, which is supposed to
return an index to any set bit (despite the name). Your output shows
that it returns a number that is off in a very predictable way (it seems
that replacing "8*m + n" with "8*m + (32-n)" on the last line may do the
trick for you, but it breaks my local copy). So, now I am positively
baffled.
Help?
René
On Tue, Aug 25, 2009 at 7:25 PM, Michael Williams
mailto:michaelwilliam...@gmail.com>> wrote:
Debug build:
testing _BitScanForward (&m, 0): 0 842032512
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 840277132
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Release build:
testing _BitScanForward (&m, 0): 0 16843009
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 4
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Sucks when they produce different results.
René van de Veerdonk wrote:
Micheal,
Thanks for trying. Could you try one or two more things?
(1) Replace the _BitScanForward in the new code to
_BitScanReverse. This probably won't help.
(2) Add this to bitmapgo.cpp:
/* sandbox */
const bool sandbox = true;
void test_sandbox () {
unsigned long m = 220;
unsigned char test_it = _BitScanForward (&m, 0);
std::cout << "testing _BitScanForward (&m, 0): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanForward (&m, 1);
std::cout << "testing _BitScanForward (&m, 1): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanForward (&m, 256);
std::cout << "testing _BitScanForward (&m, 256): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 0);
std::cout << "testing _BitScanReverse (&m, 0): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 1);
std::cout << "testing _BitScanReverse (&m, 1): "
<< (int) test_it << " " << m << "\n";
test_it = _BitScanReverse (&m, 256);
std::cout << "testing _BitScanReverse (&m, 256): "
<< (int) test_it << " " << m << "\n";
}
and add a line something like this in the main program:
if (test && sandbox) test_sandbox (); /* new line */
if (test && verify) test = test_bitmap_t::test (); /* already
there */
That does not solve anything, but it may tell me if those
functions are doing for you what they do for me.
My output is:
testing _BitScanForward (&m, 0): 0 16843009
testing _BitScanForward (&m, 1): 1 0
testing _BitScanForward (&m, 256): 1 8
testing _BitScanReverse (&m, 0): 0 3432104
testing _BitScanReverse (&m, 1): 1 0
testing _BitScanReverse (&m, 256): 1 8
Thanks, I really appreciate your help !
René
On Tue, Aug 25, 2009 at 6:38 PM, Michael Williams
mailto:michaelwilliam...@gmail.com>
>> wrote:
That doesn't seem to have any effect on the results.
René van de Veerdonk wrote:
Hi Micheal,
Thanks for the test (Intel -> AMD, Windows XP -> Windows
7, x32
-> x64, great, three birds with one stone!). So much for
portability. But, hooray for test-cases!
This may be related to the __lzcnt intrinsic, giving you a
completely d
