mirror of
https://github.com/DrBeef/Raze.git
synced 2024-11-16 17:31:27 +00:00
54 lines
977 B
Lua
54 lines
977 B
Lua
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local string = require "string"
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local getticks
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local bit = require("bit")
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local print = print
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if (string.dump) then
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-- stand-alone
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local os = require "os"
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function getticks()
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return os.clock()*1000
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end
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else
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-- embedded
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getticks = gv.gethitickms
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module(...)
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end
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-- from http://bitop.luajit.org/api.html
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local band, bxor = bit.band, bit.bxor
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local rshift, rol = bit.rshift, bit.rol
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local m = 1000000
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function sieve()
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local count = 0
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local p = {}
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for i=0,(m+31)/32 do p[i] = -1 end
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local t = getticks()
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for i=2,m do
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if band(rshift(p[rshift(i, 5)], i), 1) ~= 0 then
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count = count + 1
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for j=i+i,m,i do
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local jx = rshift(j, 5)
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p[jx] = band(p[jx], rol(-2, j))
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end
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end
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end
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print(string.format("Found %d primes up to %d (%.02f ms)", count, m,
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getticks()-t))
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end
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if (string.dump) then
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sieve()
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end
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