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https://github.com/DrBeef/Raze.git
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148 lines
3.6 KiB
Lua
Executable file
148 lines
3.6 KiB
Lua
Executable file
#!/usr/bin/env luajit
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-- Usage: luajit bittest.lua <number or "x"> [-ffi] [-bchk]
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local require = require
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local string = require "string"
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local math = require "math"
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local bitar = require "bitar"
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local print = print
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local tonumber = tonumber
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local getticks
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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.gethiticks
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module(...)
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end
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-- based on example from http://bitop.luajit.org/api.html
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local m = string.dump and tonumber(arg[1]) or 1e7
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local maxidx = math.floor(m/32)
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local ffiar_p, boundchk_p = false, false
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if (string.dump) then
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if (arg[2]=="-ffi" or arg[3]=="-ffi") then
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ffiar_p = true
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end
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if (arg[2]=="-bchk" or arg[3]=="-bchk") then
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boundchk_p = true
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end
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end
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function sieve()
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local count = 0
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local p = {}
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if (ffiar_p) then
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-- stand-alone using unchecked int32_t array: on x86_64 approx. 80 ms
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-- for m = 1e7 (enabling bound checking makes it be around 100 ms)
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local ffi = require "ffi"
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local pp = ffi.new("int32_t [?]", maxidx + 1)
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p = pp
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if (boundchk_p) then
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local mt = {
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__index = function(tab,idx)
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if (idx >= 0 and idx <= maxidx) then
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return pp[idx]
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end
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end,
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__newindex = function(tab,idx,val)
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if (idx >= 0 and idx <= maxidx) then
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pp[idx] = val
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end
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end,
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}
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p = setmetatable({}, mt)
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end
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for i=0,maxidx do p[i] = -1; end
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else
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p = bitar.new(m, 1)
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end
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local t = getticks()
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if (ffiar_p) then
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local bit = require "bit"
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for i=2,m do
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if (bit.band(p[bit.rshift(i, 5)], bit.lshift(1, i)) ~= 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 = bit.rshift(j, 5)
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p[jx] = bit.band(p[jx], bit.rol(0xfffffffe, j));
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end
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end
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end
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else
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for i=2,m do
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if (p:isset(i)) then
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count = count + 1
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for j=i+i,m,i do p:set0(j); end
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end
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end
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end
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-- When using bitar module: x86_64: approx. 110 ms
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print(string.format("[%s] Found %d primes up to %d (%.02f ms)",
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ffiar_p and "ffi-ar"..(boundchk_p and ", bchk" or "") or "tab-ar",
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count, m, getticks()-t))
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return p, count
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end
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if (string.dump) then
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local function printf(fmt, ...) print(string.format(fmt, ...)) end
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local p, count = sieve()
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local t = getticks()
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if (ffiar_p) then
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return
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end
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-- test serialization
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local ser = tostring(p)
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local maxbidx_str = string.match(ser, '%(([0-9]+),')
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local p2 = bitar.new(tonumber(maxbidx_str), string.match(ser, "'(.*)'"))
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printf("serialization + new: %.02f ms", tostring(getticks()-t))
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assert(p==p2)
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if (m >= 2) then
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assert(#p == count+2) -- +2 is because 0 and 1 are set even though they're not primes
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end
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if (not ffiar_p) then
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math.randomseed(os.time())
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local maxbidx = math.random(0, 65536)
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local p3 = bitar.new(maxbidx, 1)
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assert(#p3 == maxbidx+1) -- bits 0 to maxbidx inclusive are set
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end
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--[[
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print(p)
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print(p-p) -- test set difference
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print(-p)
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--]]
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-- Set difference of self with self is the same as set intersection of self
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-- with complement of self:
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assert(p-p == p*(-p))
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end
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