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authorSverker Eriksson <[email protected]>2017-02-14 15:53:04 +0100
committerSverker Eriksson <[email protected]>2017-02-14 16:02:03 +0100
commitd73423cdba178c166f25e00a4608ccc8d0465937 (patch)
tree78aa57f5dfe7ed6a388d0d28d0c6d9ab335a31f8 /erts
parent3b7a6ffddc819bf305353a593904cea9e932e7dc (diff)
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erts: Fix round/1 for large floats
1> round(6209607916799025.0). 6209607916799026 Problem: Adding/subtracting 0.5 and large double floats between (1 bsl 52) and (1 bsl 53) does not give reliable results. Solution: Use round() function in math.h.
Diffstat (limited to 'erts')
-rw-r--r--erts/emulator/beam/erl_bif_guard.c5
-rw-r--r--erts/emulator/test/guard_SUITE.erl1
-rw-r--r--erts/emulator/test/num_bif_SUITE.erl3
3 files changed, 6 insertions, 3 deletions
diff --git a/erts/emulator/beam/erl_bif_guard.c b/erts/emulator/beam/erl_bif_guard.c
index b42d2dc28b..74cf7cf11a 100644
--- a/erts/emulator/beam/erl_bif_guard.c
+++ b/erts/emulator/beam/erl_bif_guard.c
@@ -157,7 +157,7 @@ BIF_RETTYPE round_1(BIF_ALIST_1)
GET_DOUBLE(BIF_ARG_1, f);
/* round it and return the resultant integer */
- res = double_to_integer(BIF_P, (f.fd > 0.0) ? f.fd + 0.5 : f.fd - 0.5);
+ res = double_to_integer(BIF_P, round(f.fd));
BIF_RET(res);
}
@@ -597,8 +597,7 @@ Eterm erts_gc_round_1(Process* p, Eterm* reg, Uint live)
}
GET_DOUBLE(arg, f);
- return gc_double_to_integer(p, (f.fd > 0.0) ? f.fd + 0.5 : f.fd - 0.5,
- reg, live);
+ return gc_double_to_integer(p, round(f.fd), reg, live);
}
Eterm erts_gc_trunc_1(Process* p, Eterm* reg, Uint live)
diff --git a/erts/emulator/test/guard_SUITE.erl b/erts/emulator/test/guard_SUITE.erl
index e155e5f49f..54ee710363 100644
--- a/erts/emulator/test/guard_SUITE.erl
+++ b/erts/emulator/test/guard_SUITE.erl
@@ -317,6 +317,7 @@ guard_bifs(Config) when is_list(Config) ->
try_gbif('float/1', Big, float(id(Big))),
try_gbif('trunc/1', Float, 387924.0),
try_gbif('round/1', Float, 387925.0),
+ try_gbif('round/1', 6209607916799025.0, 6209607916799025),
try_gbif('length/1', [], 0),
try_gbif('length/1', [a], 1),
diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl
index d1c9648017..bb85738454 100644
--- a/erts/emulator/test/num_bif_SUITE.erl
+++ b/erts/emulator/test/num_bif_SUITE.erl
@@ -293,6 +293,9 @@ t_round(Config) when is_list(Config) ->
4294967297 = round(id(4294967296.9)),
-4294967296 = -round(id(4294967296.1)),
-4294967297 = -round(id(4294967296.9)),
+
+ 6209607916799025 = round(id(6209607916799025.0)),
+ -6209607916799025 = round(id(-6209607916799025.0)),
ok.
t_trunc(Config) when is_list(Config) ->