Created pal_consts.h. New exported functions are now prefixed with "snmalloc_".

src/pal/pal.h

@@ -1,5 +1,12 @@
 #pragma once
 
+#include "pal_consts.h"
+
+namespace snmalloc
+{
+  void error(const char* const str);
+}
+
 // If simultating OE, then we need the underlying platform
 #if !defined(OPEN_ENCLAVE) || defined(OPEN_ENCLAVE_SIMULATION)
 #  include "pal_apple.h"

src/pal/pal_consts.h

@@ -0,0 +1,34 @@
+namespace snmalloc
+{
+  /**
+   * Flags in a bitfield of optional features that a PAL may support.  These
+   * should be set in the PAL's `pal_features` static constexpr field.
+   */
+  enum PalFeatures : uint64_t
+  {
+    /**
+     * This PAL supports low memory notifications.  It must implement a
+     * `low_memory_epoch` method that returns a `uint64_t` of the number of
+     * times that a low-memory notification has been raised and an
+     * `expensive_low_memory_check()` method that returns a `bool` indicating
+     * whether low memory conditions are still in effect.
+     */
+    LowMemoryNotification = (1 << 0),
+    /**
+     * This PAL natively supports allocation with a guaranteed alignment.  If
+     * this is not supported, then we will over-allocate and round the
+     * allocation.
+     *
+     * A PAL that does supports this must expose a `request()` method that takes
+     * a size and alignment.  A PAL that does *not* support it must expose a
+     * `request()` method that takes only a size.
+     */
+    AlignedAllocation = (1 << 1)
+  };
+
+  enum ZeroMem
+  {
+    NoZero,
+    YesZero
+  };
+}