Add lunatic/test/tables.lua, which was used to compare the calc'd sin/atan values.

git-svn-id: https://svn.eduke32.com/eduke32@2989 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/source/lunatic/test/tables.lua

@@ -0,0 +1,115 @@
+#!/usr/bin/env luajit
+
+local ffi = require "ffi"
+local io = require "io"
+local os = require "os"
+local math = require "math"
+
+local tablesfn = arg[1]
+local taylor_n = tonumber(arg[2])
+
+if (tablesfn==nil) then
+    -- taylor_n is a number: use that n for Taylor approximation of atan
+    -- taylor_n==nil: use math.atan
+    print("Usage: ./tables.lua ../path/to/TABLES.DAT [talyor_n]")
+    return 1
+end
+
+local fd, errmsg = io.open(tablesfn)
+if (fd==nil) then
+    print("Failed opening "..tablesfn..": "..errmsg)
+    return 1  -- XXX: not working, neither os.exit(1) as of 20120901
+end
+
+local sintab = ffi.new("int16_t [?]", 2048)
+local sinstr = fd:read(2048*2)
+if (sinstr==nil or #sinstr<2048*2) then
+    print("Failed reading whole sine table")
+    fd:close()
+    return 1
+end
+
+ffi.copy(sintab, sinstr, 2048*2)
+sinstr = nil
+
+--== sintable
+
+local oursin = ffi.new("int16_t [?]", 2048)
+local BANG2RAD = math.pi/1024
+for a=0,2047 do
+    local s = 16384*math.sin(a*BANG2RAD)
+    oursin[a] = s
+
+--    if (a < 1024) then print(a..": "..s) end
+end
+--print("")
+
+for a=0,2047 do
+    local dif = oursin[a]-sintab[a]
+    assert(dif == 0)
+--[[
+    if (dif ~= 0) then
+        print(a..": "..dif)
+    end
+--]]
+    if (a < 512) then
+        assert(sintab[a] == sintab[1024-a])
+    end
+
+    if (a >= 1024) then
+        assert(sintab[a] == -sintab[a-1024])
+    end
+end
+
+--== radarang
+
+local ratab = ffi.new("int16_t [?]", 640)
+local rastr = fd:read(640*2)
+fd:close()
+
+ffi.copy(ratab, rastr, 640*2)
+rastr = nil
+
+local function atan_taylor(x, n)
+    local absx = math.abs(x)
+
+    local at = 0
+    for i=0,n do
+        local twoip2 = 2*i+1
+        local xp = x^twoip2
+        local pmone = (-1)^i
+
+        if (absx < 1) then
+            at = at + (pmone * xp)/twoip2
+        else
+            at = at + pmone/(xp * twoip2)
+        end
+    end
+
+    if (absx > 1) then
+        at = math.pi/2 - at
+    end
+
+    return at
+end
+
+local atan
+if (taylor_n==nil) then
+    atan = math.atan
+else
+    atan = function (x) return atan_taylor(x, taylor_n) end
+end
+
+
+for i=0,639 do
+    local at = -64*atan((640-0.5-i)/160)/BANG2RAD
+    local ra = ratab[i]
+
+    at = math.ceil(at)
+
+--    print(i ..": ".. ra .." ".. at .." ".. at/ra .." ".. at-ra)
+end
+
+--[[
+local ourra = ffi.new("int16_t [?]", 640)
+--]]