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| author | Sverker Eriksson <[email protected]> | 2017-02-14 15:53:04 +0100 |
|---|---|---|
| committer | Sverker Eriksson <[email protected]> | 2017-02-14 16:02:03 +0100 |
| commit | d73423cdba178c166f25e00a4608ccc8d0465937 (patch) | |
| tree | 78aa57f5dfe7ed6a388d0d28d0c6d9ab335a31f8 | |
| parent | 3b7a6ffddc819bf305353a593904cea9e932e7dc (diff) | |
| download | otp-d73423cdba178c166f25e00a4608ccc8d0465937.tar.gz otp-d73423cdba178c166f25e00a4608ccc8d0465937.tar.bz2 otp-d73423cdba178c166f25e00a4608ccc8d0465937.zip | |
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.
| -rw-r--r-- | erts/emulator/beam/erl_bif_guard.c | 5 | ||||
| -rw-r--r-- | erts/emulator/test/guard_SUITE.erl | 1 | ||||
| -rw-r--r-- | erts/emulator/test/num_bif_SUITE.erl | 3 |
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) -> |