diff options
| -rw-r--r-- | erts/emulator/sys/common/erl_sys_common_misc.c | 28 | ||||
| -rw-r--r-- | erts/emulator/test/num_bif_SUITE.erl | 71 |
2 files changed, 84 insertions, 15 deletions
diff --git a/erts/emulator/sys/common/erl_sys_common_misc.c b/erts/emulator/sys/common/erl_sys_common_misc.c index 79f87eb3a9..ddb414580a 100644 --- a/erts/emulator/sys/common/erl_sys_common_misc.c +++ b/erts/emulator/sys/common/erl_sys_common_misc.c @@ -160,7 +160,7 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, { /* Note that some C compilers don't support "static const" propagation * so we use a defines */ - #define SYS_DOUBLE_RND_CONST 0.55555555555555555 + #define SYS_DOUBLE_RND_CONST 0.5 #define FRAC_SIZE 52 #define EXP_SIZE 11 #define EXP_MASK ((1ll << EXP_SIZE) - 1) @@ -256,11 +256,14 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, return p - buffer; } else if (exp >= FRAC_SIZE) { int_part = mantissa << (exp - FRAC_SIZE); + exp = 0; } else if (exp >= 0) { int_part = mantissa >> (FRAC_SIZE - exp); frac_part = (mantissa << (exp + 1)) & FRAC_MASK2; + exp = 0; } else /* if (exp < 0) */ { - frac_part = (mantissa & FRAC_MASK2) >> -(exp + 1); + frac_part = mantissa; + exp = -(exp+1); } if (!int_part) { @@ -298,11 +301,22 @@ sys_double_to_chars_fast(double f, char *buffer, int buffer_size, int decimals, max = decimals; for (i = 0; i < max; i++) { - /* frac_part *= 10; */ - frac_part = (frac_part << 3) + (frac_part << 1); - - *p++ = (char)((frac_part >> (FRAC_SIZE + 1)) + '0'); - frac_part &= FRAC_MASK2; + if (frac_part > (ERTS_UINT64_MAX/16)) { + frac_part /= 16; + exp -= 4; + } + if (FRAC_SIZE + 1 + exp >= 64) { + *p++ = '0'; + frac_part *= 5; + exp--; + } + else + { + frac_part *= 10; + + *p++ = (char)((frac_part >> (FRAC_SIZE + 1 + exp)) + '0'); + frac_part &= (1ll << (FRAC_SIZE + 1 + exp)) - 1; + } } /* Delete trailing zeroes */ diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl index 1c76eb8019..b5ff940e00 100644 --- a/erts/emulator/test/num_bif_SUITE.erl +++ b/erts/emulator/test/num_bif_SUITE.erl @@ -118,6 +118,7 @@ t_float(Config) when is_list(Config) -> %% Tests float_to_list/1, float_to_list/2, float_to_binary/1, float_to_binary/2 t_float_to_string(Config) when is_list(Config) -> + rand_seed(), test_fts("0.00000000000000000000e+00", 0.0), test_fts("2.50000000000000000000e+01", 25.0), test_fts("2.50000000000000000000e+00", 2.5), @@ -167,8 +168,8 @@ t_float_to_string(Config) when is_list(Config) -> test_fts("1.12300",1.123, [{decimals, 5}]), test_fts("1.123",1.123, [{decimals, 5}, compact]), test_fts("1.1234",1.1234,[{decimals, 6}, compact]), - test_fts("1.01",1.005, [{decimals, 2}]), - test_fts("-1.01",-1.005,[{decimals, 2}]), + test_fts("1.00",1.005, [{decimals, 2}]), %% 1.005 is really 1.0049999999... + test_fts("-1.00",-1.005,[{decimals, 2}]), test_fts("0.999",0.999, [{decimals, 3}]), test_fts("-0.999",-0.999,[{decimals, 3}]), test_fts("1.0",0.999, [{decimals, 2}, compact]), @@ -184,6 +185,9 @@ t_float_to_string(Config) when is_list(Config) -> test_fts("123000000000000000000.0",1.23e20, [{decimals, 10}, compact]), test_fts("1.2300000000e+20",1.23e20, [{scientific, 10}, compact]), test_fts("1.23000000000000000000e+20",1.23e20, []), + + fts_rand_float_decimals(1000), + ok. test_fts(Expect, Float) -> @@ -197,6 +201,49 @@ test_fts(Expect, Float, Args) -> BinExpect = float_to_binary(Float,Args). +rand_float_reasonable() -> + F = rand_float(), + case abs(F) > 1.0e238 of + true -> rand_float_reasonable(); + false -> F + end. + +fts_rand_float_decimals(0) -> ok; +fts_rand_float_decimals(N) -> + [begin + F0 = rand_float_reasonable(), + L0 = float_to_list(F0, [{decimals, D}]), + L1 = case D of + 0 -> L0 ++ ".0"; + _ -> L0 + end, + F1 = list_to_float(L1), + Diff = abs(F0-F1), + MaxDiff = max_diff_decimals(F0, D), + ok = case Diff =< MaxDiff of + true -> ok; + false -> + io:format("F0 = ~w ~w\n", [F0, <<F0/float>>]), + io:format("L1 = ~s\n", [L1]), + io:format("F1 = ~w ~w\n", [F1, <<F1/float>>]), + io:format("Diff = ~w, MaxDiff = ~w\n", [Diff, MaxDiff]), + error + end + end + || D <- lists:seq(0,15)], + + fts_rand_float_decimals(N-1). + +max_diff_decimals(F, D) -> + IntBits = floor(math:log2(abs(F))) + 1, + FracBits = (52 - IntBits), + Log10_2 = 0.3010299956639812, % math:log10(2) + MaxDec = floor(FracBits * Log10_2), + + Resolution = math:pow(2, IntBits - 53), + + (math:pow(10, -min(D,MaxDec)) / 2) + Resolution. + %% Tests list_to_float/1. t_string_to_float_safe(Config) when is_list(Config) -> @@ -331,18 +378,26 @@ t_trunc_and_friends(_Config) -> -18446744073709551616 = trunc_and_friends(-float(1 bsl 64)), %% Random. + rand_seed(), t_trunc_and_friends_rand(100), ok. +rand_seed() -> + rand:seed(exrop), + io:format("\n*** rand:export_seed() = ~w\n\n", [rand:export_seed()]), + ok. + +rand_float() -> + F0 = rand:uniform() * math:pow(10, 50*rand:normal()), + case rand:uniform() of + U when U < 0.5 -> -F0; + _ -> F0 + end. + t_trunc_and_friends_rand(0) -> ok; t_trunc_and_friends_rand(N) -> - F0 = rand:uniform() * math:pow(10, 50*rand:normal()), - F = case rand:uniform() of - U when U < 0.5 -> -F0; - _ -> F0 - end, - _ = trunc_and_friends(F), + _ = trunc_and_friends(rand_float()), t_trunc_and_friends_rand(N-1). trunc_and_friends(F) -> |