Lunatic: xmath module + timing test for distance functions.

git-svn-id: https://svn.eduke32.com/eduke32@3488 1a8010ca-5511-0410-912e-c29ae57300e0

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

@@ -0,0 +1,56 @@
+
+local ffi = require "ffi"
+local math = require "math"
+local os = require "os"
+
+local xmath = require "xmath"
+
+local ldist = xmath.ldist
+local sqrt = math.sqrt
+
+local function printf(fmt, ...)
+    print(string.format(fmt, ...))
+end
+
+local function edist(p1, p2)
+    return sqrt(p1.x*p1.x + p2.x*p2.x)
+end
+
+local vec2 = ffi.typeof("struct { int32_t x, y; }")
+
+local numpoints = 1e4
+local Nsq = numpoints*numpoints
+printf("number of points: %d, testing %d distances", numpoints, Nsq)
+
+local B = 8192
+
+local pts = {}
+for i=1,numpoints do
+    pts[i] = vec2(math.random(-B, B), math.random(B, -B))
+end
+
+-- test edist
+local t = os.clock()
+
+local sum = 0
+for i=1,numpoints do
+    for j=1,numpoints do
+        sum = sum+edist(pts[i], pts[j])
+    end
+end
+
+t = os.clock()-t
+printf("edist: %.03fns per call, mean=%.03f", (1e9*t)/Nsq, sum/Nsq)
+
+-- test ldist
+t = os.clock()
+
+local sum = 0
+for i=1,numpoints do
+    for j=1,numpoints do
+        sum = sum+ldist(pts[i], pts[j])
+    end
+end
+
+t = os.clock()-t
+printf("ldist: %.03fns per call, mean=%.03f", (1e9*t)/Nsq, sum/Nsq)

polymer/eduke32/source/lunatic/xmath.lua

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+-- "Extended" math module for Lunatic.
+
+local ffi = require("ffi")
+
+local bit = require("bit")
+local math = require("math")
+
+local assert = assert
+
+
+module(...)
+
+
+local BANG2RAD = math.pi/1024
+local isintab = ffi.new("int16_t [?]", 2048)
+local dsintab = ffi.new("double [?]", 2048)
+
+for a=0,511 do
+    local s = math.sin(a*BANG2RAD)
+    isintab[a] = 16384*s
+    dsintab[a] = s
+end
+
+isintab[512] = 16384
+dsintab[512] = 1
+
+for i=513,1023 do
+    isintab[i] = isintab[1024-i];
+    dsintab[i] = dsintab[1024-i];
+end
+
+for i=1024,2047 do
+    isintab[i] = -isintab[i-1024];
+    dsintab[i] = -dsintab[i-1024];
+end
+
+
+local band = bit.band
+
+local function ksc_common(ang)
+    ang = band(ang, 2047)
+    assert(ang < 2048+0ULL)  -- might have been passed NaN
+    return ang
+end
+
+-- k{sin,cos}: 16384-scaled output, 2048-based angle input
+function ksin(ang)
+    return isintab[ksc_common(ang)]
+end
+
+function kcos(ang)
+    return isintab[ksc_common(ang+512)]
+end
+
+
+local sin, cos = math.sin, math.cos
+
+-- {sin,cos}b: [-1..1] output, 2048-based angle input
+function sinb(ang)
+    return dsintab[ksc_common(ang)]
+end
+
+function cosb(ang)
+    return dsintab[ksc_common(ang+512)]
+end
+
+
+-- Approximations to 2D and 3D Euclidean distances (also see common.c)
+local abs = math.abs
+local arshift = bit.arshift
+
+local function dist_common(pos1, pos2)
+    local x = abs(pos1.x - pos2.x)
+    local y = abs(pos1.y - pos2.y)
+    if (x < y) then
+        x, y = y, x
+    end
+    return x, y
+end
+
+function ldist(pos1, pos2)
+    local x, y = dist_common(pos1, pos2)
+
+    local t = y + arshift(y,1)
+    return x - arshift(x,5) - arshift(x,7) + arshift(t,2) + arshift(t,6)
+end
+
+function dist(pos1, pos2)
+    local x, y = dist_common(pos1, pos2)
+    local z = abs(arshift(pos1.z - pos2.z, 4))
+
+    if (x < z) then
+        x, z = z, x
+    end
+
+    local t = y + z
+    return x - arshift(x,4) + arshift(t,2) + arshift(t,3)
+end