4 files changed, 44 insertions, 2 deletions
diff --git a/erts/emulator/beam/erl_driver.h b/erts/emulator/beam/erl_driver.h
index 316d0ef992..15a4f44a7d 100644
--- a/erts/emulator/beam/erl_driver.h
+++ b/erts/emulator/beam/erl_driver.h
@@ -48,6 +48,10 @@
 #  define SIZEOF_LONG_LONG_SAVED__ SIZEOF_LONG_LONG
 #  undef SIZEOF_LONG_LONG
 #endif
+#ifdef HALFWORD_HEAP_EMULATOR
+#  define HALFWORD_HEAP_EMULATOR_SAVED__ HALFWORD_HEAP_EMULATOR
+#  undef HALFWORD_HEAP_EMULATOR
+#endif
 #include "erl_int_sizes_config.h"
 #if defined(SIZEOF_CHAR_SAVED__) && SIZEOF_CHAR_SAVED__ != SIZEOF_CHAR
 #  error SIZEOF_CHAR mismatch
@@ -65,6 +69,11 @@
 #  error SIZEOF_LONG_LONG mismatch
 #endif
 
+/* This is OK to override by the NIF/driver implementor */
+#if defined(HALFWORD_HEAP_EMULATOR_SAVED__) && !defined(HALFWORD_HEAP_EMULATOR)
+#define HALFWORD_HEAP_EMULATOR HALFWORD_HEAP_EMULATOR_SAVED__
+#endif
+
 #include "erl_drv_nif.h"
 
 #include <stdlib.h>
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index f0c4d81f0b..41a9e17c86 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -512,9 +512,9 @@ int enif_get_int(ErlNifEnv* env, Eterm term, int* ip)
 
 int enif_get_uint(ErlNifEnv* env, Eterm term, unsigned* ip)
 {
-#if SIZEOF_LONG == ERTS_SIZEOF_ETERM
+#if SIZEOF_INT == ERTS_SIZEOF_ETERM
     return term_to_Uint(term, (Uint*)ip);
-#elif SIZEOF_INT == ERTS_SIZEOF_ETERM
+#elif SIZEOF_LONG == ERTS_SIZEOF_ETERM
     Uint i;
     if (!term_to_Uint(term, &i) || i > UINT_MAX) {
 	return 0;
diff --git a/erts/emulator/beam/erl_nif.h b/erts/emulator/beam/erl_nif.h
index 1ccf00293e..d0f6424724 100644
--- a/erts/emulator/beam/erl_nif.h
+++ b/erts/emulator/beam/erl_nif.h
@@ -34,7 +34,37 @@
 
 #include <stdlib.h>
 
+#ifdef SIZEOF_CHAR
+#  define SIZEOF_CHAR_SAVED__ SIZEOF_CHAR
+#  undef SIZEOF_CHAR
+#endif
+#ifdef SIZEOF_SHORT
+#  define SIZEOF_SHORT_SAVED__ SIZEOF_SHORT
+#  undef SIZEOF_SHORT
+#endif
+#ifdef SIZEOF_INT
+#  define SIZEOF_INT_SAVED__ SIZEOF_INT
+#  undef SIZEOF_INT
+#endif
+#ifdef SIZEOF_LONG
+#  define SIZEOF_LONG_SAVED__ SIZEOF_LONG
+#  undef SIZEOF_LONG
+#endif
+#ifdef SIZEOF_LONG_LONG
+#  define SIZEOF_LONG_LONG_SAVED__ SIZEOF_LONG_LONG
+#  undef SIZEOF_LONG_LONG
+#endif
+#ifdef HALFWORD_HEAP_EMULATOR
+#  define HALFWORD_HEAP_EMULATOR_SAVED__ HALFWORD_HEAP_EMULATOR
+#  undef HALFWORD_HEAP_EMULATOR
+#endif
+#include "erl_int_sizes_config.h"
+
+#ifdef HALFWORD_HEAP_EMULATOR
+typedef unsigned int ERL_NIF_TERM;
+#else
 typedef unsigned long ERL_NIF_TERM;
+#endif
 
 struct enif_environment_t;
 typedef struct enif_environment_t ErlNifEnv;
diff --git a/erts/include/erl_int_sizes_config.h.in b/erts/include/erl_int_sizes_config.h.in
index ef49995732..a8a264686e 100644
--- a/erts/include/erl_int_sizes_config.h.in
+++ b/erts/include/erl_int_sizes_config.h.in
@@ -31,3 +31,6 @@
 
 /* The number of bytes in a long long.  */
 #undef SIZEOF_LONG_LONG
+
+/* Define if building a halfword-heap 64bit emulator (needed for NIF's) */
+#undef HALFWORD_HEAP_EMULATOR