samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/benchmark_nbody.t

@@ -0,0 +1,150 @@
+local C = terralib.includecstring[[
+
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+]]
+
+pi = 3.141592653589793
+solar_mass = (4 * pi * pi)
+days_per_year = 365.24
+
+struct planet {
+  x : double;
+  y : double;
+  z : double;
+  vx : double;
+  vy : double;
+  vz : double;
+  mass : double;
+}
+
+terra advance(nbodies : int, bodies : &planet, dt : double)
+  
+  for i = 0, nbodies do
+    var b = &bodies[i]
+    for j = i + 1, nbodies do
+      var b2 = &bodies[j]
+      
+      var dx = b.x - b2.x;
+      var dy = b.y - b2.y;
+      var dz = b.z - b2.z;
+      var distance = C.sqrt(dx * dx + dy * dy + dz * dz);
+      var mag = dt / (distance * distance * distance);
+      --C.printf("%f %f %f %f %f\n",dx,dy,dz,distance,mag);
+      b.vx = b.vx - dx * b2.mass * mag;
+      b.vy = b.vy - dy * b2.mass * mag;
+      b.vz = b.vz - dz * b2.mass * mag;
+      b2.vx = b2.vx + dx * b.mass * mag;
+      b2.vy = b2.vy + dy * b.mass * mag;
+      b2.vz = b2.vz + dz * b.mass * mag;
+      --C.printf("%f %f %f %f %f %f\n",b.vx,b.vy,b.vz,b2.vx,b2.vy,b2.vz)
+    end
+  end
+  for i = 0,nbodies do
+    var b = &bodies[i]
+    b.x = b.x + dt * b.vx;
+    b.y = b.y + dt * b.vy;
+    b.z = b.z + dt * b.vz;
+  end
+end
+
+terra energy(nbodies : int, bodies : &planet)
+  var e = 0.0
+  for i = 0, nbodies do
+    var b = &bodies[i]
+    e = e + 0.5 * b.mass * (b.vx * b.vx + b.vy * b.vy + b.vz * b.vz);
+    for j = i + 1, nbodies do
+      var b2 = &bodies[j]
+      var dx = b.x - b2.x
+      var dy = b.y - b2.y
+      var dz = b.z - b2.z
+      var distance = C.sqrt(dx * dx + dy * dy + dz * dz)
+      e = e - (b.mass * b2.mass) / distance
+    end
+  end
+  return e
+end
+
+terra offset_momentum(nbodies : int, bodies : &planet)
+  var px,py,pz = 0.0,0.0,0.0
+  
+  for i = 0,nbodies do
+    px = px + bodies[i].vx * bodies[i].mass
+    py = py + bodies[i].vy * bodies[i].mass
+    pz = pz + bodies[i].vz * bodies[i].mass
+  end
+  bodies[0].vx = - px / solar_mass
+  bodies[0].vy = - py / solar_mass
+  bodies[0].vz = - pz / solar_mass
+end
+
+NBODIES = 5
+
+terra main(argc : int, argv : &&int8)
+    var bodies = array(
+      planet {                               -- sun */
+        0, 0, 0, 0, 0, 0, solar_mass
+      },
+      planet {                               -- jupiter */
+        4.84143144246472090e+00,
+        -1.16032004402742839e+00,
+        -1.03622044471123109e-01,
+        1.66007664274403694e-03 * days_per_year,
+        7.69901118419740425e-03 * days_per_year,
+        -6.90460016972063023e-05 * days_per_year,
+        9.54791938424326609e-04 * solar_mass
+      },
+      planet {                               -- saturn */
+        8.34336671824457987e+00,
+        4.12479856412430479e+00,
+        -4.03523417114321381e-01,
+        -2.76742510726862411e-03 * days_per_year,
+        4.99852801234917238e-03 * days_per_year,
+        2.30417297573763929e-05 * days_per_year,
+        2.85885980666130812e-04 * solar_mass
+      },
+      planet {                               -- uranus */
+        1.28943695621391310e+01,
+        -1.51111514016986312e+01,
+        -2.23307578892655734e-01,
+        2.96460137564761618e-03 * days_per_year,
+        2.37847173959480950e-03 * days_per_year,
+        -2.96589568540237556e-05 * days_per_year,
+        4.36624404335156298e-05 * solar_mass
+      },
+      planet {                               -- neptune */
+        1.53796971148509165e+01,
+        -2.59193146099879641e+01,
+        1.79258772950371181e-01,
+        2.68067772490389322e-03 * days_per_year,
+        1.62824170038242295e-03 * days_per_year,
+        -9.51592254519715870e-05 * days_per_year,
+        5.15138902046611451e-05 * solar_mass
+      }
+    )
+    var n = C.atoi(argv[1])    
+    offset_momentum(NBODIES, bodies)
+    C.printf ("%.9f\n", energy(NBODIES, bodies))
+    for i = 0,n do
+        advance(NBODIES, bodies, 0.01)
+    end
+    C.printf ("%.9f\n", energy(NBODIES, bodies));
+  return 0
+end
+
+terra run()
+    main(2,array("what","1000000"))
+end
+
+--run:compile()
+
+
+--local test = require("test")
+
+--print(test.time(run))
+
+terralib.saveobj("benchmark_nbody",{ main = main } )
+energy:disas()
+energy:printpretty()