diff options
Diffstat (limited to 'stdio-common')
| -rw-r--r-- | stdio-common/Makefile | 9 | ||||
| -rw-r--r-- | stdio-common/printf_fp.c | 53 | ||||
| -rw-r--r-- | stdio-common/tst-printf-round.c | 110 |
3 files changed, 142 insertions, 30 deletions
diff --git a/stdio-common/Makefile b/stdio-common/Makefile index 5d7ab532f4..9811572431 100644 --- a/stdio-common/Makefile +++ b/stdio-common/Makefile @@ -57,7 +57,7 @@ tests := tstscanf test_rdwr test-popen tstgetln test-fseek \ bug19 bug19a tst-popen2 scanf13 scanf14 scanf15 bug20 bug21 bug22 \ scanf16 scanf17 tst-setvbuf1 tst-grouping bug23 bug24 \ bug-vfprintf-nargs tst-long-dbl-fphex tst-fphex-wide tst-sprintf3 \ - bug25 + bug25 tst-printf-round test-srcs = tst-unbputc tst-printf @@ -128,3 +128,10 @@ CPPFLAGS += $(libio-mtsafe) $(objpfx)tst-setvbuf1.out: tst-setvbuf1.expect $(objpfx)tst-setvbuf1 $(built-program-cmd) > $@ 2>&1 cmp tst-setvbuf1.expect $@ + +ifeq ($(build-shared),yes) +link-libm = $(common-objpfx)math/libm.so +else +link-libm = $(common-objpfx)math/libm.a +endif +$(objpfx)tst-printf-round: $(link-libm) diff --git a/stdio-common/printf_fp.c b/stdio-common/printf_fp.c index 5f3c904254..6e2b57c039 100644 --- a/stdio-common/printf_fp.c +++ b/stdio-common/printf_fp.c @@ -39,6 +39,8 @@ #include <unistd.h> #include <stdlib.h> #include <wchar.h> +#include <stdbool.h> +#include <rounding-mode.h> #ifdef COMPILE_WPRINTF # define CHAR_T wchar_t @@ -197,9 +199,6 @@ ___printf_fp (FILE *fp, /* Temporary bignum value. */ MPN_VAR(tmp); - /* Digit which is result of last hack_digit() call. */ - wchar_t digit; - /* The type of output format that will be used: 'e'/'E' or 'f'. */ int type; @@ -955,34 +954,31 @@ ___printf_fp (FILE *fp, } /* Do rounding. */ - digit = hack_digit (); - if (digit > L'4') + wchar_t last_digit = wcp[-1] != decimalwc ? wcp[-1] : wcp[-2]; + wchar_t next_digit = hack_digit (); + bool more_bits; + if (next_digit != L'0' && next_digit != L'5') + more_bits = true; + else if (fracsize == 1 && frac[0] == 0) + /* Rest of the number is zero. */ + more_bits = false; + else if (scalesize == 0) + { + /* Here we have to see whether all limbs are zero since no + normalization happened. */ + size_t lcnt = fracsize; + while (lcnt >= 1 && frac[lcnt - 1] == 0) + --lcnt; + more_bits = lcnt > 0; + } + else + more_bits = true; + int rounding_mode = get_rounding_mode (); + if (round_away (is_neg, (last_digit - L'0') & 1, next_digit >= L'5', + more_bits, rounding_mode)) { wchar_t *wtp = wcp; - if (digit == L'5' - && ((*(wcp - 1) != decimalwc && (*(wcp - 1) & 1) == 0) - || ((*(wcp - 1) == decimalwc && (*(wcp - 2) & 1) == 0)))) - { - /* This is the critical case. */ - if (fracsize == 1 && frac[0] == 0) - /* Rest of the number is zero -> round to even. - (IEEE 754-1985 4.1 says this is the default rounding.) */ - goto do_expo; - else if (scalesize == 0) - { - /* Here we have to see whether all limbs are zero since no - normalization happened. */ - size_t lcnt = fracsize; - while (lcnt >= 1 && frac[lcnt - 1] == 0) - --lcnt; - if (lcnt == 0) - /* Rest of the number is zero -> round to even. - (IEEE 754-1985 4.1 says this is the default rounding.) */ - goto do_expo; - } - } - if (fracdig_no > 0) { /* Process fractional digits. Terminate if not rounded or @@ -1076,7 +1072,6 @@ ___printf_fp (FILE *fp, } } - do_expo: /* Now remove unnecessary '0' at the end of the string. */ while (fracdig_no > fracdig_min + added_zeros && *(wcp - 1) == L'0') { diff --git a/stdio-common/tst-printf-round.c b/stdio-common/tst-printf-round.c new file mode 100644 index 0000000000..2bd46079ac --- /dev/null +++ b/stdio-common/tst-printf-round.c @@ -0,0 +1,110 @@ +/* Test for correct rounding of printf floating-point output. + Copyright (C) 2012 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <fenv.h> +#include <stdio.h> +#include <string.h> + +struct dec_test { + double d; + const char *fmt; + const char *rd, *rn, *rz, *ru; +}; + +static const struct dec_test dec_tests[] = { + { 1.5, "%.0f", "1", "2", "1", "2" }, + { -1.5, "%.0f", "-2", "-2", "-1", "-1" }, + { 2.5, "%.0f", "2", "2", "2", "3" }, + { -2.5, "%.0f", "-3", "-2", "-2", "-2" }, + { 1.4999, "%.0f", "1", "1", "1", "2" }, + { -1.4999, "%.0f", "-2", "-1", "-1", "-1" }, + { 1.5001, "%.0f", "1", "2", "1", "2" }, + { -1.5001, "%.0f", "-2", "-2", "-1", "-1" }, + { 2.4999, "%.0f", "2", "2", "2", "3" }, + { -2.4999, "%.0f", "-3", "-2", "-2", "-2" }, + { 2.5001, "%.0f", "2", "3", "2", "3" }, + { -2.5001, "%.0f", "-3", "-3", "-2", "-2" }, + { 1.0 / 3.0, "%f", "0.333333", "0.333333", "0.333333", "0.333334" }, + { -1.0 / 3.0, "%f", "-0.333334", "-0.333333", "-0.333333", "-0.333333" }, + { 0.2500001, "%.2e", "2.50e-01", "2.50e-01", "2.50e-01", "2.51e-01" }, + { -0.2500001, "%.2e", "-2.51e-01", "-2.50e-01", "-2.50e-01", "-2.50e-01" }, + { 1000001.0, "%.1e", "1.0e+06", "1.0e+06", "1.0e+06", "1.1e+06" }, + { -1000001.0, "%.1e", "-1.1e+06", "-1.0e+06", "-1.0e+06", "-1.0e+06" }, +}; + +static int +test_dec_in_one_mode (double d, const char *fmt, const char *expected, + const char *mode_name) +{ + char buf[100]; + int ret = snprintf (buf, sizeof buf, fmt, d); + if (ret <= 0 || ret >= (int) sizeof buf) + { + printf ("snprintf for %a returned %d\n", d, ret); + return 1; + } + if (strcmp (buf, expected) == 0) + return 0; + else + { + printf ("snprintf (\"%s\", %a) returned \"%s\" not \"%s\" (%s)\n", + fmt, d, buf, expected, mode_name); + return 1; + } +} + +static int +do_test (void) +{ + int save_round_mode = fegetround (); + int result = 0; + + for (size_t i = 0; i < sizeof (dec_tests) / sizeof (dec_tests[0]); i++) + { + result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt, + dec_tests[i].rn, "default rounding mode"); +#ifdef FE_DOWNWARD + if (!fesetround (FE_DOWNWARD)) + { + result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt, + dec_tests[i].rd, "FE_DOWNWARD"); + fesetround (save_round_mode); + } +#endif +#ifdef FE_TOWARDZERO + if (!fesetround (FE_TOWARDZERO)) + { + result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt, + dec_tests[i].rz, "FE_TOWARDZERO"); + fesetround (save_round_mode); + } +#endif +#ifdef FE_UPWARD + if (!fesetround (FE_UPWARD)) + { + result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt, + dec_tests[i].ru, "FE_UPWARD"); + fesetround (save_round_mode); + } +#endif + } + return result; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" |