Add erlang:monotonic_time/0

Signed-off-by: Peter M <petermm@gmail.com>

Author: petermm

src/libAtomVM/nifs.c

@@ -127,6 +127,7 @@ static term nif_erlang_float_to_list(Context *ctx, int argc, term argv[]);
 static term nif_erlang_list_to_binary_1(Context *ctx, int argc, term argv[]);
 static term nif_erlang_list_to_integer(Context *ctx, int argc, term argv[]);
 static term nif_erlang_list_to_float_1(Context *ctx, int argc, term argv[]);
+static term nif_erlang_monotonic_time_0(Context *ctx, int argc, term argv[]);
 static term nif_erlang_monotonic_time_1(Context *ctx, int argc, term argv[]);
 static term nif_erlang_iolist_size_1(Context *ctx, int argc, term argv[]);
 static term nif_erlang_iolist_to_binary_1(Context *ctx, int argc, term argv[]);
@@ -499,7 +500,13 @@ static const struct Nif concat_nif =
     .nif_ptr = nif_erlang_concat_2
 };
 
-static const struct Nif monotonic_time_nif =
+static const struct Nif monotonic_time_0_nif =
+{
+    .base.type = NIFFunctionType,
+    .nif_ptr = nif_erlang_monotonic_time_0
+};
+
+static const struct Nif monotonic_time_1_nif =
 {
     .base.type = NIFFunctionType,
     .nif_ptr = nif_erlang_monotonic_time_1
@@ -1626,6 +1633,18 @@ term nif_erlang_make_ref_0(Context *ctx, int argc, term argv[])
     return term_from_ref_ticks(ref_ticks, &ctx->heap);
 }
 
+term nif_erlang_monotonic_time_0(Context *ctx, int argc, term argv[])
+{
+    UNUSED(argc);
+    UNUSED(argv);
+
+    struct timespec ts;
+    sys_monotonic_time(&ts);
+
+    // Return nanoseconds as the native unit
+    return make_maybe_boxed_int64(ctx, ((int64_t) ts.tv_sec) * 1000000000UL + ts.tv_nsec);
+}
+
 term nif_erlang_monotonic_time_1(Context *ctx, int argc, term argv[])
 {
     UNUSED(ctx);

src/libAtomVM/nifs.gperf

@@ -100,7 +100,8 @@ erlang:system_flag/2, &system_flag_nif
 erlang:whereis/1, &whereis_nif
 erlang:++/2, &concat_nif
 erlang:--/2, &erlang_lists_subtract_nif
-erlang:monotonic_time/1, &monotonic_time_nif
+erlang:monotonic_time/0, &monotonic_time_0_nif
+erlang:monotonic_time/1, &monotonic_time_1_nif
 erlang:system_time/1, &system_time_nif
 erlang:tuple_to_list/1, &tuple_to_list_nif
 erlang:universaltime/0, &universaltime_nif

tests/erlang_tests/test_monotonic_time.erl

@@ -23,14 +23,24 @@
 -export([start/0]).
 
 start() ->
+    % Test monotonic_time/1 with millisecond
     T1 = erlang:monotonic_time(millisecond),
     receive
     after 1 -> ok
     end,
     T2 = erlang:monotonic_time(millisecond),
-    test_diff(T2 - T1).
-
-test_diff(X) when is_integer(X) andalso X >= 0 ->
-    1;
-test_diff(X) when X < 0 ->
-    0.
+    Diff1 = T2 - T1,
+    
+    % Test monotonic_time/0 (native nanoseconds)
+    T3 = erlang:monotonic_time(),
+    receive
+    after 1 -> ok
+    end,
+    T4 = erlang:monotonic_time(),
+    Diff2 = T4 - T3,
+    
+    % Both tests must pass: millisecond diff >= 0, nanosecond diff >= 1000
+    case {is_integer(Diff1) andalso Diff1 >= 0, is_integer(Diff2) andalso Diff2 >= 1000} of
+        {true, true} -> 1;
+        _ -> 0
+    end.