Increase precision when finding the remainder after division by pi/2.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6856 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_AllocateHeapNumber) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 0);
   return isolate->heap()->AllocateHeapNumber(0);
 }
 
 
+static int HexToInt(uint16_t c) {
+  if (c >= '0' && c <= '9') return c - '0';
+  ASSERT(c >= 'a' && c <= 'f');
+  return c - 'a' + 10;
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_HeapNumberFromHex) {
+  SealHandleScope shs(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(String, input, 0);
+  RUNTIME_ASSERT(input->length() == 16);
+  // Only used during bootstrapping.
+  RUNTIME_ASSERT(isolate->bootstrapper()->IsActive());
+  double result = 0;
+  uint8_t* bytes = reinterpret_cast<uint8_t*>(&result);

[Jakob Kummerow, 2013/11/19 17:49:54]

Are you sure this compiles? AFAIK this is what we have BitCast for. (You'll
probably want to start with an uint8_t[8] and then BitCast to double.)

+  // Input string is a little-endian hex representation of the double value.
+  for (int i = 0; i < 8; i++) {
+    bytes[i] = HexToInt(input->Get(2 * i)) * 16 +
+               HexToInt(input->Get(2 * i + 1));
+  }
+  return isolate->heap()->AllocateHeapNumber(result);
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberAdd) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 2);
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   CONVERT_DOUBLE_ARG_CHECKED(y, 1);
   return isolate->heap()->NumberFromDouble(x + y);
 }
 
 
@@ skipping 8019 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal