glibc/math/fromfp.h

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Add fromfp functions. TS 18661-1 defines fromfp functions (fromfp, fromfpx, ufromfp, ufromfpx, and float and long double variants) to convert from floating-point to an integer type with any signedness and any given width up to that of intmax_t, in any of the five IEEE rounding modes (the usual four for binary floating point, plus rounding to nearest with ties rounding away from zero), with control of whether in-range non-integer values should result in the "inexact" exception being raised. This patch implements these functions for glibc. These implementations are (apart from raising exceptions) pure integer implementations; it's entirely possible optimized versions could be devised for some architectures. A common math/fromfp.h header provides various common helper code that can readily be shared between the implementations for different types. For each type, the bulk of the implementation is also shared between the four functions, with wrappers that define UNSIGNED and INEXACT macros appropriately before including the main implementation. As the functions return intmax_t and uintmax_t without math.h being allowed to expose those typedef names, they are declared using __intmax_t and __uintmax_t as obtained from <bits/types.h>. The FP_INT_* rounding direction macros are defined as ascending integers in the order the names are listed in the TS; I see no significant value in allowing architectures to vary the values of them. The libm-test machinery is duly adapted to handle unsigned int arguments, and intmax_t and uintmax_t results. Because each test input is generally tested for four functions, five rounding modes and several different widths, the libm-test.inc additions are very large. Thus, the diffs in the body of this message exclude the libm-test.inc changes, with the full patch being attached gzipped. The bulk of the new tests were generated (expanded from a test input plus rounding results and information about where it lies in the relevant interval between integers, to libm-test tests for all relevant combinations of function, rounding direction and width) by a script that's included in the patch as math/gen-fromfp-tests.py (input data math/gen-fromfp-tests-inputs); as an ad hoc script that's not really expected to be rerun, it's not very polished, but it's at least plausibly useful for adding any further tests for these functions in future. I may split the libm-test tests up by function in future (so both libm-test.inc and auto-libm-test-out are split into separate files, and the tests for each function are also built and run separately), but not for 2.25. For no obvious reason, adding tgmath tests for the new functions resulted in -Wuninitialized errors from test-tgmath.c about the variable i being used uninitialized. Those errors were correct - the variable is read by the frexp version in test-tgmath.c (where real frexp would write through that pointer instead of reading it) - but I don't know why this patch would result in the pre-existing issue being newly detected. The patch initializes the variable to avoid those errors. With these changes, glibc 2.25 should have all the library features from TS 18661-1 other than the functions that round result to narrower type (and constant rounding directions, but I'm considering those mainly a compiler feature not a library one). Tested for x86_64, x86, mips64 and powerpc. * math/bits/mathcalls.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfp): New declaration. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfpx): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfpx): Likewise. * math/tgmath.h (__TGMATH_TERNARY_FIRST_REAL_RET_ONLY): New macro. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfpx): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfpx): Likewise. * math/math.h: Include <bits/types.h>. [__GLIBC_USE (IEC_60559_BFP_EXT)] (FP_INT_UPWARD): New enum constant and macro. (FP_INT_DOWNWARD): Likewise. (FP_INT_TOWARDZERO): Likewise. (FP_INT_TONEARESTFROMZERO): Likewise. (FP_INT_TONEAREST): Likewise. * math/Versions (fromfp): New libm symbol at version GLIBC_2.25. (fromfpf): Likewise. (fromfpl): Likewise. (ufromfp): Likewise. (ufromfpf): Likewise. (ufromfpl): Likewise. (fromfpx): Likewise. (fromfpxf): Likewise. (fromfpxl): Likewise. (ufromfpx): Likewise. (ufromfpxf): Likewise. (ufromfpxl): Likewise. * math/Makefile (libm-calls): Add s_fromfpF, s_ufromfpF, s_fromfpxF and s_ufromfpxF. * math/gen-fromfp-tests.py: New file. * math/gen-fromfp-tests-inputs: Likewise. * math/libm-test.inc: Include <stdint.h> (check_intmax_t): New function. (check_uintmax_t): Likewise. (struct test_fiu_M_data): New type. (struct test_fiu_U_data): Likewise. (RUN_TEST_fiu_M): New macro. (RUN_TEST_LOOP_fiu_M): Likewise. (RUN_TEST_fiu_U): Likewise. (RUN_TEST_LOOP_fiu_U): Likewise. (fromfp_test_data): New array. (fromfp_test): New function. (fromfpx_test_data): New array. (fromfpx_test): New function. (ufromfp_test_data): New array. (ufromfp_test): New function. (ufromfpx_test_data): New array. (ufromfpx_test): New function. (main): Call fromfp_test, fromfpx_test, ufromfp_test and ufromfpx_test. * math/gen-libm-test.pl (parse_args): Handle u, M and U descriptor characters. * math/test-tgmath-ret.c: Include <stdint.h>. (rm): New variable. (width): Likewise. (CHECK_RET_CONST_TYPE): Take extra arguments and pass them to called function. (CHECK_RET_CONST_FLOAT): Take extra arguments and pass them to CHECK_RET_CONST_TYPE. (CHECK_RET_CONST_DOUBLE): Likewise. (CHECK_RET_CONST_LDOUBLE): Likewise. (CHECK_RET_CONST): Take extra arguments and pass them to calls macros. (fromfp): New CHECK_RET_CONST call. (ufromfp): Likewise. (fromfpx): Likewise. (ufromfpx): Likewise. (do_test): Call check_return_fromfp, check_return_ufromfp, check_return_fromfpx and check_return_ufromfpx. * math/test-tgmath.c: Include <stdint.h> (NCALLS): Increase to 138. (F(compile_test)): Initialize i. Call fromfp functions. (F(fromfp)): New function. (F(fromfpx)): Likewise. (F(ufromfp)): Likewise. (F(ufromfpx)): Likewise. * manual/arith.texi (Rounding Functions): Document FP_INT_UPWARD, FP_INT_DOWNWARD, FP_INT_TOWARDZERO, FP_INT_TONEARESTFROMZERO, FP_INT_TONEAREST, fromfp, fromfpf, fromfpl, ufromfp, ufromfpf, ufromfpl, fromfpx, fromfpxf, fromfpxl, ufromfpx, ufromfpxf and ufromfpxl. * manual/libm-err-tab.pl (@all_functions): Add fromfp, fromfpx, ufromfp and ufromfpx. * math/fromfp.h: New file. * sysdeps/ieee754/dbl-64/s_fromfp.c: Likewise. * sysdeps/ieee754/dbl-64/s_fromfp_main.c: Likewise. * sysdeps/ieee754/dbl-64/s_fromfpx.c: Likewise. * sysdeps/ieee754/dbl-64/s_ufromfp.c: Likewise. * sysdeps/ieee754/dbl-64/s_ufromfpx.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpf.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpf_main.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpxf.c: Likewise. * sysdeps/ieee754/flt-32/s_ufromfpf.c: Likewise. * sysdeps/ieee754/flt-32/s_ufromfpxf.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add fromfp, ufromfp, fromfpx and ufromfpx. (CFLAGS-nldbl-fromfp.c): New variable. (CFLAGS-nldbl-fromfpx.c): Likewise. (CFLAGS-nldbl-ufromfp.c): Likewise. (CFLAGS-nldbl-ufromfpx.c): Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-compat.h: Include <stdint.h>. * sysdeps/ieee754/ldbl-opt/nldbl-fromfp.c: New file. * sysdeps/ieee754/ldbl-opt/nldbl-fromfpx.c: Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-ufromfp.c: Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-ufromfpx.c: Likewise. * sysdeps/nacl/libm.abilist: Update. * sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.
2016-12-31 00:40:59 +00:00
/* Round to integer type. Common helper functions.
Copyright (C) 2016-2017 Free Software Foundation, Inc.
Add fromfp functions. TS 18661-1 defines fromfp functions (fromfp, fromfpx, ufromfp, ufromfpx, and float and long double variants) to convert from floating-point to an integer type with any signedness and any given width up to that of intmax_t, in any of the five IEEE rounding modes (the usual four for binary floating point, plus rounding to nearest with ties rounding away from zero), with control of whether in-range non-integer values should result in the "inexact" exception being raised. This patch implements these functions for glibc. These implementations are (apart from raising exceptions) pure integer implementations; it's entirely possible optimized versions could be devised for some architectures. A common math/fromfp.h header provides various common helper code that can readily be shared between the implementations for different types. For each type, the bulk of the implementation is also shared between the four functions, with wrappers that define UNSIGNED and INEXACT macros appropriately before including the main implementation. As the functions return intmax_t and uintmax_t without math.h being allowed to expose those typedef names, they are declared using __intmax_t and __uintmax_t as obtained from <bits/types.h>. The FP_INT_* rounding direction macros are defined as ascending integers in the order the names are listed in the TS; I see no significant value in allowing architectures to vary the values of them. The libm-test machinery is duly adapted to handle unsigned int arguments, and intmax_t and uintmax_t results. Because each test input is generally tested for four functions, five rounding modes and several different widths, the libm-test.inc additions are very large. Thus, the diffs in the body of this message exclude the libm-test.inc changes, with the full patch being attached gzipped. The bulk of the new tests were generated (expanded from a test input plus rounding results and information about where it lies in the relevant interval between integers, to libm-test tests for all relevant combinations of function, rounding direction and width) by a script that's included in the patch as math/gen-fromfp-tests.py (input data math/gen-fromfp-tests-inputs); as an ad hoc script that's not really expected to be rerun, it's not very polished, but it's at least plausibly useful for adding any further tests for these functions in future. I may split the libm-test tests up by function in future (so both libm-test.inc and auto-libm-test-out are split into separate files, and the tests for each function are also built and run separately), but not for 2.25. For no obvious reason, adding tgmath tests for the new functions resulted in -Wuninitialized errors from test-tgmath.c about the variable i being used uninitialized. Those errors were correct - the variable is read by the frexp version in test-tgmath.c (where real frexp would write through that pointer instead of reading it) - but I don't know why this patch would result in the pre-existing issue being newly detected. The patch initializes the variable to avoid those errors. With these changes, glibc 2.25 should have all the library features from TS 18661-1 other than the functions that round result to narrower type (and constant rounding directions, but I'm considering those mainly a compiler feature not a library one). Tested for x86_64, x86, mips64 and powerpc. * math/bits/mathcalls.h [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfp): New declaration. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfpx): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfpx): Likewise. * math/tgmath.h (__TGMATH_TERNARY_FIRST_REAL_RET_ONLY): New macro. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfp): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (fromfpx): Likewise. [__GLIBC_USE (IEC_60559_BFP_EXT)] (ufromfpx): Likewise. * math/math.h: Include <bits/types.h>. [__GLIBC_USE (IEC_60559_BFP_EXT)] (FP_INT_UPWARD): New enum constant and macro. (FP_INT_DOWNWARD): Likewise. (FP_INT_TOWARDZERO): Likewise. (FP_INT_TONEARESTFROMZERO): Likewise. (FP_INT_TONEAREST): Likewise. * math/Versions (fromfp): New libm symbol at version GLIBC_2.25. (fromfpf): Likewise. (fromfpl): Likewise. (ufromfp): Likewise. (ufromfpf): Likewise. (ufromfpl): Likewise. (fromfpx): Likewise. (fromfpxf): Likewise. (fromfpxl): Likewise. (ufromfpx): Likewise. (ufromfpxf): Likewise. (ufromfpxl): Likewise. * math/Makefile (libm-calls): Add s_fromfpF, s_ufromfpF, s_fromfpxF and s_ufromfpxF. * math/gen-fromfp-tests.py: New file. * math/gen-fromfp-tests-inputs: Likewise. * math/libm-test.inc: Include <stdint.h> (check_intmax_t): New function. (check_uintmax_t): Likewise. (struct test_fiu_M_data): New type. (struct test_fiu_U_data): Likewise. (RUN_TEST_fiu_M): New macro. (RUN_TEST_LOOP_fiu_M): Likewise. (RUN_TEST_fiu_U): Likewise. (RUN_TEST_LOOP_fiu_U): Likewise. (fromfp_test_data): New array. (fromfp_test): New function. (fromfpx_test_data): New array. (fromfpx_test): New function. (ufromfp_test_data): New array. (ufromfp_test): New function. (ufromfpx_test_data): New array. (ufromfpx_test): New function. (main): Call fromfp_test, fromfpx_test, ufromfp_test and ufromfpx_test. * math/gen-libm-test.pl (parse_args): Handle u, M and U descriptor characters. * math/test-tgmath-ret.c: Include <stdint.h>. (rm): New variable. (width): Likewise. (CHECK_RET_CONST_TYPE): Take extra arguments and pass them to called function. (CHECK_RET_CONST_FLOAT): Take extra arguments and pass them to CHECK_RET_CONST_TYPE. (CHECK_RET_CONST_DOUBLE): Likewise. (CHECK_RET_CONST_LDOUBLE): Likewise. (CHECK_RET_CONST): Take extra arguments and pass them to calls macros. (fromfp): New CHECK_RET_CONST call. (ufromfp): Likewise. (fromfpx): Likewise. (ufromfpx): Likewise. (do_test): Call check_return_fromfp, check_return_ufromfp, check_return_fromfpx and check_return_ufromfpx. * math/test-tgmath.c: Include <stdint.h> (NCALLS): Increase to 138. (F(compile_test)): Initialize i. Call fromfp functions. (F(fromfp)): New function. (F(fromfpx)): Likewise. (F(ufromfp)): Likewise. (F(ufromfpx)): Likewise. * manual/arith.texi (Rounding Functions): Document FP_INT_UPWARD, FP_INT_DOWNWARD, FP_INT_TOWARDZERO, FP_INT_TONEARESTFROMZERO, FP_INT_TONEAREST, fromfp, fromfpf, fromfpl, ufromfp, ufromfpf, ufromfpl, fromfpx, fromfpxf, fromfpxl, ufromfpx, ufromfpxf and ufromfpxl. * manual/libm-err-tab.pl (@all_functions): Add fromfp, fromfpx, ufromfp and ufromfpx. * math/fromfp.h: New file. * sysdeps/ieee754/dbl-64/s_fromfp.c: Likewise. * sysdeps/ieee754/dbl-64/s_fromfp_main.c: Likewise. * sysdeps/ieee754/dbl-64/s_fromfpx.c: Likewise. * sysdeps/ieee754/dbl-64/s_ufromfp.c: Likewise. * sysdeps/ieee754/dbl-64/s_ufromfpx.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpf.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpf_main.c: Likewise. * sysdeps/ieee754/flt-32/s_fromfpxf.c: Likewise. * sysdeps/ieee754/flt-32/s_ufromfpf.c: Likewise. * sysdeps/ieee754/flt-32/s_ufromfpxf.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-128/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-128ibm/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpl_main.c: Likewise. * sysdeps/ieee754/ldbl-96/s_fromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_ufromfpl.c: Likewise. * sysdeps/ieee754/ldbl-96/s_ufromfpxl.c: Likewise. * sysdeps/ieee754/ldbl-opt/Makefile (libnldbl-calls): Add fromfp, ufromfp, fromfpx and ufromfpx. (CFLAGS-nldbl-fromfp.c): New variable. (CFLAGS-nldbl-fromfpx.c): Likewise. (CFLAGS-nldbl-ufromfp.c): Likewise. (CFLAGS-nldbl-ufromfpx.c): Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-compat.h: Include <stdint.h>. * sysdeps/ieee754/ldbl-opt/nldbl-fromfp.c: New file. * sysdeps/ieee754/ldbl-opt/nldbl-fromfpx.c: Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-ufromfp.c: Likewise. * sysdeps/ieee754/ldbl-opt/nldbl-ufromfpx.c: Likewise. * sysdeps/nacl/libm.abilist: Update. * sysdeps/unix/sysv/linux/aarch64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/alpha/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/arm/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/hppa/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/i386/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/ia64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/coldfire/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/m68k/m680x0/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/microblaze/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/nios2/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libm-le.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/s390/s390-64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sh/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/tile/tilepro/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/64/libm.abilist: Likewise. * sysdeps/unix/sysv/linux/x86_64/x32/libm.abilist: Likewise.
2016-12-31 00:40:59 +00:00
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 <errno.h>
#include <fenv.h>
#include <float.h>
#include <math.h>
#include <math_private.h>
#include <stdbool.h>
#include <stdint.h>
/* The including file should have defined UNSIGNED to 0 (signed return
type) or 1 (unsigned return type), INEXACT to 0 (no inexact
exceptions) or 1 (raise inexact exceptions) and RET_TYPE to the
return type (intmax_t or uintmax_t). */
/* Return the maximum unbiased exponent for an argument (negative if
NEGATIVE is set) that might be in range for a call to a fromfp
function with width WIDTH (greater than 0, and not exceeding that
of intmax_t). The truncated argument may still be out of range in
the case of negative arguments, and if not out of range it may
become out of range as a result of rounding. */
static int
fromfp_max_exponent (bool negative, int width)
{
if (UNSIGNED)
return negative ? -1 : width - 1;
else
return negative ? width - 1 : width - 2;
}
/* Return the result of rounding an integer value X (passed as the
absolute value; NEGATIVE is true if the value is negative), where
HALF_BIT is true if the bit with value 0.5 is set and MORE_BITS is
true if any lower bits are set, in the rounding direction
ROUND. */
static uintmax_t
fromfp_round (bool negative, uintmax_t x, bool half_bit, bool more_bits,
int round)
{
switch (round)
{
case FP_INT_UPWARD:
return x + (!negative && (half_bit || more_bits));
case FP_INT_DOWNWARD:
return x + (negative && (half_bit || more_bits));
case FP_INT_TOWARDZERO:
default:
/* Unknown rounding directions are defined to mean unspecified
rounding; treat this as truncation. */
return x;
case FP_INT_TONEARESTFROMZERO:
return x + half_bit;
case FP_INT_TONEAREST:
return x + (half_bit && ((x & 1) || more_bits));
}
}
/* Integer rounding, of a value whose exponent EXPONENT did not exceed
the maximum exponent MAX_EXPONENT and so did not necessarily
overflow, has produced X (possibly wrapping to 0); the sign is
negative if NEGATIVE is true. Return whether this overflowed the
allowed width. */
static bool
fromfp_overflowed (bool negative, uintmax_t x, int exponent, int max_exponent)
{
if (UNSIGNED)
{
if (negative)
return x != 0;
else if (max_exponent == INTMAX_WIDTH - 1)
return exponent == INTMAX_WIDTH - 1 && x == 0;
else
return x == (1ULL << (max_exponent + 1));
}
else
{
if (negative)
return exponent == max_exponent && x != (1ULL << max_exponent);
else
return x == (1ULL << (max_exponent + 1));
}
}
/* Handle a domain error for a call to a fromfp function with an
argument which is negative if NEGATIVE is set, and specified width
(not exceeding that of intmax_t) WIDTH. The return value is
unspecified (with it being unclear if the result needs to fit
within WIDTH bits in this case); we choose to saturate to the given
number of bits (treating NaNs like any other value). */
static RET_TYPE
fromfp_domain_error (bool negative, unsigned int width)
{
feraiseexcept (FE_INVALID);
__set_errno (EDOM);
/* The return value is unspecified; we choose to saturate to the
given number of bits (treating NaNs like any other value). */
if (UNSIGNED)
{
if (negative)
return 0;
else if (width == INTMAX_WIDTH)
return -1;
else
return (1ULL << width) - 1;
}
else
{
if (width == 0)
return 0;
else if (negative)
return -(1ULL << (width - 1));
else
return (1ULL << (width - 1)) - 1;
}
}
/* Given X, the absolute value of a floating-point number (negative if
NEGATIVE is set) truncated towards zero, where HALF_BIT is true if
the bit with value 0.5 is set and MORE_BITS is true if any lower
bits are set, round it in the rounding direction ROUND, handle
errors and exceptions and return the appropriate return value for a
fromfp function. X originally had floating-point exponent
EXPONENT, which does not exceed MAX_EXPONENT, the return value from
fromfp_max_exponent with width WIDTH. */
static RET_TYPE
fromfp_round_and_return (bool negative, uintmax_t x, bool half_bit,
bool more_bits, int round, int exponent,
int max_exponent, unsigned int width)
{
uintmax_t uret = fromfp_round (negative, x, half_bit, more_bits, round);
if (fromfp_overflowed (negative, uret, exponent, max_exponent))
return fromfp_domain_error (negative, width);
if (INEXACT && (half_bit || more_bits))
{
/* There is no need for this to use the specific floating-point
type for which this header is included, and there is no need
for this header to know that type at all, so just use float
here. */
float force_inexact = 1.0f + FLT_MIN;
math_force_eval (force_inexact);
}
if (UNSIGNED)
/* A negative argument not rounding to zero will already have
produced a domain error. */
return uret;
else
return negative ? -uret : uret;
}