Wren testing

wren/optional/wren_opt_random.c

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+#include "wren_opt_random.h"
+
+#if WREN_OPT_RANDOM
+
+#include <string.h>
+#include <time.h>
+
+#include "wren.h"
+#include "wren_vm.h"
+
+#include "wren_opt_random.wren.inc"
+
+// Implements the well equidistributed long-period linear PRNG (WELL512a).
+//
+// https://en.wikipedia.org/wiki/Well_equidistributed_long-period_linear
+typedef struct
+{
+  uint32_t state[16];
+  uint32_t index;
+} Well512;
+
+// Code from: http://www.lomont.org/Math/Papers/2008/Lomont_PRNG_2008.pdf
+static uint32_t advanceState(Well512* well)
+{
+  uint32_t a, b, c, d;
+  a = well->state[well->index];
+  c = well->state[(well->index + 13) & 15];
+  b =  a ^ c ^ (a << 16) ^ (c << 15);
+  c = well->state[(well->index + 9) & 15];
+  c ^= (c >> 11);
+  a = well->state[well->index] = b ^ c;
+  d = a ^ ((a << 5) & 0xda442d24U);
+
+  well->index = (well->index + 15) & 15;
+  a = well->state[well->index];
+  well->state[well->index] = a ^ b ^ d ^ (a << 2) ^ (b << 18) ^ (c << 28);
+  return well->state[well->index];
+}
+
+static void randomAllocate(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenSetSlotNewForeign(vm, 0, 0, sizeof(Well512));
+  well->index = 0;
+}
+
+static void randomSeed0(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenGetSlotForeign(vm, 0);
+
+  srand((uint32_t)time(NULL));
+  for (int i = 0; i < 16; i++)
+  {
+    well->state[i] = rand();
+  }
+}
+
+static void randomSeed1(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenGetSlotForeign(vm, 0);
+
+  srand((uint32_t)wrenGetSlotDouble(vm, 1));
+  for (int i = 0; i < 16; i++)
+  {
+    well->state[i] = rand();
+  }
+}
+
+static void randomSeed16(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenGetSlotForeign(vm, 0);
+
+  for (int i = 0; i < 16; i++)
+  {
+    well->state[i] = (uint32_t)wrenGetSlotDouble(vm, i + 1);
+  }
+}
+
+static void randomFloat(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenGetSlotForeign(vm, 0);
+
+  // A double has 53 bits of precision in its mantissa, and we'd like to take
+  // full advantage of that, so we need 53 bits of random source data.
+
+  // First, start with 32 random bits, shifted to the left 21 bits.
+  double result = (double)advanceState(well) * (1 << 21);
+
+  // Then add another 21 random bits.
+  result += (double)(advanceState(well) & ((1 << 21) - 1));
+
+  // Now we have a number from 0 - (2^53). Divide be the range to get a double
+  // from 0 to 1.0 (half-inclusive).
+  result /= 9007199254740992.0;
+
+  wrenSetSlotDouble(vm, 0, result);
+}
+
+static void randomInt0(WrenVM* vm)
+{
+  Well512* well = (Well512*)wrenGetSlotForeign(vm, 0);
+
+  wrenSetSlotDouble(vm, 0, (double)advanceState(well));
+}
+
+const char* wrenRandomSource()
+{
+  return randomModuleSource;
+}
+
+WrenForeignClassMethods wrenRandomBindForeignClass(WrenVM* vm,
+                                                   const char* module,
+                                                   const char* className)
+{
+  ASSERT(strcmp(className, "Random") == 0, "Should be in Random class.");
+  WrenForeignClassMethods methods;
+  methods.allocate = randomAllocate;
+  methods.finalize = NULL;
+  return methods;
+}
+
+WrenForeignMethodFn wrenRandomBindForeignMethod(WrenVM* vm,
+                                                const char* className,
+                                                bool isStatic,
+                                                const char* signature)
+{
+  ASSERT(strcmp(className, "Random") == 0, "Should be in Random class.");
+  
+  if (strcmp(signature, "<allocate>") == 0) return randomAllocate;
+  if (strcmp(signature, "seed_()") == 0) return randomSeed0;
+  if (strcmp(signature, "seed_(_)") == 0) return randomSeed1;
+  
+  if (strcmp(signature, "seed_(_,_,_,_,_,_,_,_,_,_,_,_,_,_,_,_)") == 0)
+  {
+    return randomSeed16;
+  }
+  
+  if (strcmp(signature, "float()") == 0) return randomFloat;
+  if (strcmp(signature, "int()") == 0) return randomInt0;
+  
+  ASSERT(false, "Unknown method.");
+  return NULL;
+}
+
+#endif