From 0835f40ae25f97360dc393928796387d3cd6b16e Mon Sep 17 00:00:00 2001
From: Guilherme Andrade <g@gandrade.net>
Date: Wed, 19 Apr 2017 00:43:37 +0100
Subject: erts: Add enif_phash2 and enif_phash2_ranged

These allow one to hash VM terms from NIF code.
---
 erts/emulator/beam/erl_nif.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'erts/emulator/beam/erl_nif.c')

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index f86b9739fa..14abf461a3 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -55,6 +55,7 @@
 #include "dtrace-wrapper.h"
 #include "erl_process.h"
 #include "erl_bif_unique.h"
+#include "erl_utils.h"
 #undef ERTS_WANT_NFUNC_SCHED_INTERNALS__
 #define ERTS_WANT_NFUNC_SCHED_INTERNALS__
 #include "erl_nfunc_sched.h"
@@ -1213,6 +1214,25 @@ int enif_compare(Eterm lhs, Eterm rhs)
     return result;
 }
 
+#if SIZEOF_LONG < 4
+/* This *really* shouldn't happen */
+#  error Incompatible long word size
+#endif
+
+unsigned long enif_phash2(Eterm term)
+{
+    return make_hash2(term) & ((1 << 27) - 1);
+}
+
+unsigned long enif_phash2_ranged(Eterm term, unsigned long range)
+{
+#if SIZEOF_LONG > 4
+    if (range > (unsigned long) UINT32_MAX)
+        range = 0;
+#endif
+    return make_hash2_within_range(term, range);
+}
+
 int enif_get_tuple(ErlNifEnv* env, Eterm tpl, int* arity, const Eterm** array)
 {
     Eterm* ptr;
-- 
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