bn: fix Red#imod #178
bn: fix Red#imod #178
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fanatid
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lib/bn.js
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| return a.umod(this.m)._forceRed(this); | ||
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| var mod = a.umod(this.m)._forceRed(this); | ||
| if (mod !== a) mod.copy(a); |
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This might be not so good performance-wise. Any ideas?
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Should we introduce iumod instead?
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Agree that this can introduce performance issues... I thought about new method .move instead .copy.
Should we introduce
iumodinstead?
do you mean BN#iumod?
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.move might actually work great here!
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Do you want it as separate method or only as few lines in Red#imod? What about BN#iumod? It's doesn't cost it?
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@fanatid do you mean new method for .move? If so, I think yes
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BN#move added in fa40b8c
lib/bn.js
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| return a.umod(this.m)._forceRed(this); | ||
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| var mod = a.umod(this.m)._forceRed(this); | ||
| if (mod !== a) mod.move(a); |
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is it even worth checking if they are different? (performance diff?)
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In one case mod === a. Not sure does it cost check it or not...
Line 2413 in 98ac84e
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right, if mod === a, no need to move, but, as move guarantees that a == mod, why bother verifying?
It looks like an optimization, but, IMHO serves to confuse.
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Changed to a.umod(this.m)._forceRed(this).move(a);
| @@ -262,4 +262,13 @@ describe('BN.js/Reduction context', function () { | |||
| red.prime.split(input, output); | |||
| assert.equal(input.cmp(output), 0); | |||
| }); | |||
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| it('imod should change host object', function () { | |||
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maybe indicate (via redIMul)
lib/bn.js
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| @@ -327,6 +327,13 @@ | |||
| dest.red = this.red; | |||
| }; | |||
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| BN.prototype.move = function move (dest) { | |||
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Oh, shouldn't it be private? It looks like this could lead to funny state issues if used as a part of API.
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I'll not mind of making it private. Do you want see it as separate function or as "inline" function?
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IMO, it makes sense to have it on a prototype. Just prefix it with _. @dcousens what do you think?
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@indutny I think the public interface semantics of move can be assumed that the originating object is reset or garbage after use.
I think it is fine to have on the public interface; however, I don't mind either way.
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@fanatid prefix it with _?
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@dcousens added prefix _, let me know if I should squash commits
Issue #177