diff options
author | Corinna Vinschen <corinna@vinschen.de> | 2021-03-24 10:51:20 +0100 |
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committer | Ken Brown <kbrown@cornell.edu> | 2021-04-14 10:07:15 -0400 |
commit | 2f458738e89d61f71a7b1db611a6ddae9ced7f66 (patch) | |
tree | 3c01bf6dca45cecfc72687172e8fb2e1ae01b143 | |
parent | e0627be512e9a35ff4699e943c36b9343d146e97 (diff) | |
download | newlib-2f458738e89d61f71a7b1db611a6ddae9ced7f66.zip newlib-2f458738e89d61f71a7b1db611a6ddae9ced7f66.tar.gz newlib-2f458738e89d61f71a7b1db611a6ddae9ced7f66.tar.bz2 |
fenv: move shared x86 fenv.c to libm/machine/shared_x86
Include this file from both sharing architectures, i386 and x86_64.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
-rw-r--r-- | newlib/libm/machine/i386/fenv.c | 2 | ||||
-rw-r--r-- | newlib/libm/machine/shared_x86/fenv.c | 477 | ||||
-rw-r--r-- | newlib/libm/machine/x86_64/fenv.c | 474 |
3 files changed, 480 insertions, 473 deletions
diff --git a/newlib/libm/machine/i386/fenv.c b/newlib/libm/machine/i386/fenv.c index 1a97f56..4679f03 100644 --- a/newlib/libm/machine/i386/fenv.c +++ b/newlib/libm/machine/i386/fenv.c @@ -4,4 +4,4 @@ * (c) Copyright 2019 Joel Sherrill <joel@rtems.org> */ -#include "../x86_64/fenv.c" +#include "../shared_x86/fenv.c" diff --git a/newlib/libm/machine/shared_x86/fenv.c b/newlib/libm/machine/shared_x86/fenv.c new file mode 100644 index 0000000..ccc08e2 --- /dev/null +++ b/newlib/libm/machine/shared_x86/fenv.c @@ -0,0 +1,477 @@ +/* + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2010-2019 Red Hat, Inc. + */ + +#define _GNU_SOURCE // for FE_NOMASK_ENV + +#include <fenv.h> +#include <errno.h> +#include <string.h> // for memcpy +#include <stdbool.h> + +/* x87 supports subnormal numbers so we need it below. */ +#define __FE_DENORM (1 << 1) +/* mask (= 0x3f) to disable all exceptions at initialization */ +#define __FE_ALL_EXCEPT_X86 (FE_ALL_EXCEPT | __FE_DENORM) + +/* Mask and shift amount for rounding bits. */ +#define FE_CW_ROUND_MASK (0x0c00) +#define FE_CW_ROUND_SHIFT (10) +/* Same, for SSE MXCSR. */ +#define FE_MXCSR_ROUND_MASK (0x6000) +#define FE_MXCSR_ROUND_SHIFT (13) + +/* Mask and shift amount for precision bits. */ +#define FE_CW_PREC_MASK (0x0300) +#define FE_CW_PREC_SHIFT (8) + +/* In x87, exception status bits and mask bits occupy + corresponding bit positions in the status and control + registers, respectively. In SSE, they are both located + in the control-and-status register, with the status bits + corresponding to the x87 positions, and the mask bits + shifted by this amount to the left. */ +#define FE_SSE_EXCEPT_MASK_SHIFT (7) + +/* These are writable so we can initialise them at startup. */ +static fenv_t fe_nomask_env; + +/* These pointers provide the outside world with read-only access to them. */ +const fenv_t *_fe_nomask_env = &fe_nomask_env; + +/* Assume i686 or above (hence SSE available) these days, with the + compiler feels free to use it (depending on compile- time flags of + course), but we should avoid needlessly breaking any purely integer mode + apps (or apps compiled with -mno-sse), so we only manage SSE state in this + fenv module if we detect that SSE instructions are available at runtime. + If we didn't do this, all applications run on older machines would bomb + out with an invalid instruction exception right at startup; let's not + be *that* WJM! */ +static inline bool use_sse(void) +{ + unsigned int edx, eax; + + /* Check for presence of SSE: invoke CPUID #1, check EDX bit 25. */ + eax = 1; + __asm__ volatile ("cpuid" : "=d" (edx), "+a" (eax) :: "%ecx", "%ebx"); + /* If this flag isn't set we'll avoid trying to execute any SSE. */ + if ((edx & (1 << 25)) != 0) + return true; + + return false; +} + +/* forward declaration */ +static void _feinitialise (void); + +/* This function enables traps for each of the exceptions as indicated + by the parameter except. The individual exceptions are described in + [ ... glibc manual xref elided ...]. Only the specified exceptions are + enabled, the status of the other exceptions is not changed. + The function returns the previous enabled exceptions in case the + operation was successful, -1 otherwise. */ +int +feenableexcept (int excepts) +{ + unsigned short cw, old_cw; + unsigned int mxcsr = 0; + + if (excepts & ~FE_ALL_EXCEPT) + return -1; + + /* Get control words. */ + __asm__ volatile ("fnstcw %0" : "=m" (old_cw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + + /* Enable exceptions by clearing mask bits. */ + cw = old_cw & ~excepts; + mxcsr &= ~(excepts << FE_SSE_EXCEPT_MASK_SHIFT); + + /* Store updated control words. */ + __asm__ volatile ("fldcw %0" :: "m" (cw)); + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); + + /* Return old value. We assume SSE and x87 stay in sync. Note that + we are returning a mask of enabled exceptions, which is the opposite + of the flags in the register, which are set to disable (mask) their + related exceptions. */ + return (~old_cw) & FE_ALL_EXCEPT; +} + +/* This function disables traps for each of the exceptions as indicated + by the parameter except. The individual exceptions are described in + [ ... glibc manual xref elided ...]. Only the specified exceptions are + disabled, the status of the other exceptions is not changed. + The function returns the previous enabled exceptions in case the + operation was successful, -1 otherwise. */ +int +fedisableexcept (int excepts) +{ + unsigned short cw, old_cw; + unsigned int mxcsr = 0; + + if (excepts & ~FE_ALL_EXCEPT) + return -1; + + /* Get control words. */ + __asm__ volatile ("fnstcw %0" : "=m" (old_cw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + + /* Disable exceptions by setting mask bits. */ + cw = old_cw | excepts; + mxcsr |= (excepts << FE_SSE_EXCEPT_MASK_SHIFT); + + /* Store updated control words. */ + __asm__ volatile ("fldcw %0" :: "m" (cw)); + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); + + /* Return old value. We assume SSE and x87 stay in sync. Note that + we are returning a mask of enabled exceptions, which is the opposite + of the flags in the register, which are set to disable (mask) their + related exceptions. */ + return (~old_cw) & FE_ALL_EXCEPT; +} + +/* This function returns a bitmask of all currently enabled exceptions. It + returns -1 in case of failure. */ +int +fegetexcept (void) +{ + unsigned short cw; + + /* Get control word. We assume SSE and x87 stay in sync. */ + __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); + + /* Exception is *dis*abled when mask bit is set. */ + return (~cw) & FE_ALL_EXCEPT; +} + +/* Store the floating-point environment in the variable pointed to by envp. + The function returns zero in case the operation was successful, a non-zero + value otherwise. */ +int +fegetenv (fenv_t *envp) +{ + /* fnstenv disables all exceptions in the x87 FPU; as this is not what is + desired here, reload the cfg saved from the x87 FPU, back to the FPU */ + __asm__ volatile ("fnstenv %0\n\ + fldenv %0" + : "=m" (envp->_fpu) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (envp->_sse_mxcsr) : ); + return 0; +} + +/* Store the current floating-point environment in the object pointed to + by envp. Then clear all exception flags, and set the FPU to trap no + exceptions. Not all FPUs support trapping no exceptions; if feholdexcept + cannot set this mode, it returns nonzero value. If it succeeds, it + returns zero. */ +int +feholdexcept (fenv_t *envp) +{ + unsigned int mxcsr; + fegetenv (envp); + mxcsr = envp->_sse_mxcsr & ~FE_ALL_EXCEPT; + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); + __asm__ volatile ("fnclex"); + fedisableexcept (FE_ALL_EXCEPT); + return 0; +} + +/* Set the floating-point environment to that described by envp. The + function returns zero in case the operation was successful, a non-zero + value otherwise. */ +int +fesetenv (const fenv_t *envp) +{ + if ((envp == FE_DFL_ENV || envp == FE_NOMASK_ENV) && + envp->_fpu._fpu_cw == 0) + _feinitialise (); + + __asm__ volatile ("fldenv %0" :: "m" (envp->_fpu) ); + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (envp->_sse_mxcsr)); + return 0; +} + +/* Like fesetenv, this function sets the floating-point environment to + that described by envp. However, if any exceptions were flagged in the + status word before feupdateenv was called, they remain flagged after + the call. In other words, after feupdateenv is called, the status + word is the bitwise OR of the previous status word and the one saved + in envp. The function returns zero in case the operation was successful, + a non-zero value otherwise. */ +int +feupdateenv (const fenv_t *envp) +{ + fenv_t envcopy; + unsigned int mxcsr = 0; + unsigned short sw; + + /* Don't want to modify *envp, but want to update environment atomically, + so take a copy and merge the existing exceptions into it. */ + memcpy (&envcopy, envp, sizeof *envp); + __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + envcopy._fpu._fpu_sw |= (sw & FE_ALL_EXCEPT); + envcopy._sse_mxcsr |= (mxcsr & FE_ALL_EXCEPT); + + return fesetenv (&envcopy); +} + +/* This function clears all of the supported exception flags indicated by + excepts. The function returns zero in case the operation was successful, + a non-zero value otherwise. */ +int +feclearexcept (int excepts) +{ + fenv_t fenv; + + if (excepts & ~FE_ALL_EXCEPT) + return EINVAL; + + /* Need to save/restore whole environment to modify status word. */ + fegetenv (&fenv); + + /* Mask undesired bits out. */ + fenv._fpu._fpu_sw &= ~excepts; + fenv._sse_mxcsr &= ~excepts; + + /* Set back into FPU state. */ + return fesetenv (&fenv); +} + +/* This function raises the supported exceptions indicated by + excepts. If more than one exception bit in excepts is set the order + in which the exceptions are raised is undefined except that overflow + (FE_OVERFLOW) or underflow (FE_UNDERFLOW) are raised before inexact + (FE_INEXACT). Whether for overflow or underflow the inexact exception + is also raised is also implementation dependent. The function returns + zero in case the operation was successful, a non-zero value otherwise. */ +int +feraiseexcept (int excepts) +{ + fenv_t fenv; + + if (excepts & ~FE_ALL_EXCEPT) + return EINVAL; + + /* Need to save/restore whole environment to modify status word. */ + __asm__ volatile ("fnstenv %0" : "=m" (fenv) : ); + + /* Set desired exception bits. */ + fenv._fpu._fpu_sw |= excepts; + + /* Set back into FPU state. */ + __asm__ volatile ("fldenv %0" :: "m" (fenv)); + + /* And trigger them - whichever are unmasked. */ + __asm__ volatile ("fwait"); + + return 0; +} + +/* Test whether the exception flags indicated by the parameter except + are currently set. If any of them are, a nonzero value is returned + which specifies which exceptions are set. Otherwise the result is zero. */ +int +fetestexcept (int excepts) +{ + unsigned short sw; + unsigned int mxcsr = 0; + + if (excepts & ~FE_ALL_EXCEPT) + return EINVAL; + + /* Get status registers. */ + __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + + /* Mask undesired bits out and return result. */ + return (sw | mxcsr) & excepts; +} +/* This function stores in the variable pointed to by flagp an + implementation-defined value representing the current setting of the + exception flags indicated by excepts. The function returns zero in + case the operation was successful, a non-zero value otherwise. */ +int +fegetexceptflag (fexcept_t *flagp, int excepts) +{ + unsigned short sw; + unsigned int mxcsr = 0; + + if (excepts & ~FE_ALL_EXCEPT) + return EINVAL; + + /* Get status registers. */ + __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + + /* Mask undesired bits out and set result. */ + *flagp = (sw | mxcsr) & excepts; + + return 0; +} + +/* This function restores the flags for the exceptions indicated by + excepts to the values stored in the variable pointed to by flagp. */ +int +fesetexceptflag (const fexcept_t *flagp, int excepts) +{ + fenv_t fenv; + + if (excepts & ~FE_ALL_EXCEPT) + return EINVAL; + + /* Need to save/restore whole environment to modify status word. */ + fegetenv (&fenv); + + /* Set/Clear desired exception bits. */ + fenv._fpu._fpu_sw &= ~excepts; + fenv._fpu._fpu_sw |= excepts & *flagp; + fenv._sse_mxcsr &= ~excepts; + fenv._sse_mxcsr |= excepts & *flagp; + + /* Set back into FPU state. */ + return fesetenv (&fenv); +} + +/* Returns the currently selected rounding mode, represented by one of the + values of the defined rounding mode macros. */ +int +fegetround (void) +{ + unsigned short cw; + + /* Get control word. We assume SSE and x87 stay in sync. */ + __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); + + return (cw & FE_CW_ROUND_MASK) >> FE_CW_ROUND_SHIFT; +} + +/* Changes the currently selected rounding mode to round. If round does + not correspond to one of the supported rounding modes nothing is changed. + fesetround returns zero if it changed the rounding mode, a nonzero value + if the mode is not supported. */ +int +fesetround (int round) +{ + unsigned short cw; + unsigned int mxcsr = 0; + + /* Will succeed for any valid value of the input parameter. */ + if (round < FE_TONEAREST || round > FE_TOWARDZERO) + return EINVAL; + + /* Get control words. */ + __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); + if (use_sse()) + __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); + + /* Twiddle bits. */ + cw &= ~FE_CW_ROUND_MASK; + cw |= (round << FE_CW_ROUND_SHIFT); + mxcsr &= ~FE_MXCSR_ROUND_MASK; + mxcsr |= (round << FE_MXCSR_ROUND_SHIFT); + + /* Set back into FPU state. */ + __asm__ volatile ("fldcw %0" :: "m" (cw)); + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); + + /* Indicate success. */ + return 0; +} + +#if defined(__CYGWIN__) +/* Returns the currently selected precision, represented by one of the + values of the defined precision macros. */ +int +fegetprec (void) +{ + unsigned short cw; + + /* Get control word. */ + __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); + + return (cw & FE_CW_PREC_MASK) >> FE_CW_PREC_SHIFT; +} + +/* http://www.open-std.org/jtc1/sc22//WG14/www/docs/n752.htm: + + The fesetprec function establishes the precision represented by its + argument prec. If the argument does not match a precision macro, the + precision is not changed. + + The fesetprec function returns a nonzero value if and only if the + argument matches a precision macro (that is, if and only if the requested + precision can be established). */ +int +fesetprec (int prec) +{ + unsigned short cw; + + /* Will succeed for any valid value of the input parameter. */ + switch (prec) + { + case FE_FLTPREC: + case FE_DBLPREC: + case FE_LDBLPREC: + break; + default: + return 0; + } + + /* Get control word. */ + __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); + + /* Twiddle bits. */ + cw &= ~FE_CW_PREC_MASK; + cw |= (prec << FE_CW_PREC_SHIFT); + + /* Set back into FPU state. */ + __asm__ volatile ("fldcw %0" :: "m" (cw)); + + /* Indicate success. */ + return 1; +} +#endif + +/* Set up the FPU and SSE environment at the start of execution. */ +static void +_feinitialise (void) +{ + extern fenv_t __fe_dfl_env; + + /* Reset FPU: extended prec, all exceptions cleared and masked off. */ + __asm__ volatile ("fninit"); + /* The default cw value, 0x37f, is rounding mode zero. The MXCSR has + no precision control, so the only thing to do is set the exception + mask bits. */ + + /* initialize the MXCSR register: mask all exceptions */ + unsigned int mxcsr = __FE_ALL_EXCEPT_X86 << FE_SSE_EXCEPT_MASK_SHIFT; + if (use_sse()) + __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); + + /* Setup unmasked environment, but leave __FE_DENORM masked. */ + feenableexcept (FE_ALL_EXCEPT); + fegetenv (&fe_nomask_env); + + /* Restore default exception masking (all masked). */ + fedisableexcept (FE_ALL_EXCEPT); + + /* Finally cache state as default environment. */ + fegetenv (&__fe_dfl_env); +} diff --git a/newlib/libm/machine/x86_64/fenv.c b/newlib/libm/machine/x86_64/fenv.c index ccc08e2..4679f03 100644 --- a/newlib/libm/machine/x86_64/fenv.c +++ b/newlib/libm/machine/x86_64/fenv.c @@ -1,477 +1,7 @@ /* * SPDX-License-Identifier: BSD-2-Clause * - * Copyright (c) 2010-2019 Red Hat, Inc. + * (c) Copyright 2019 Joel Sherrill <joel@rtems.org> */ -#define _GNU_SOURCE // for FE_NOMASK_ENV - -#include <fenv.h> -#include <errno.h> -#include <string.h> // for memcpy -#include <stdbool.h> - -/* x87 supports subnormal numbers so we need it below. */ -#define __FE_DENORM (1 << 1) -/* mask (= 0x3f) to disable all exceptions at initialization */ -#define __FE_ALL_EXCEPT_X86 (FE_ALL_EXCEPT | __FE_DENORM) - -/* Mask and shift amount for rounding bits. */ -#define FE_CW_ROUND_MASK (0x0c00) -#define FE_CW_ROUND_SHIFT (10) -/* Same, for SSE MXCSR. */ -#define FE_MXCSR_ROUND_MASK (0x6000) -#define FE_MXCSR_ROUND_SHIFT (13) - -/* Mask and shift amount for precision bits. */ -#define FE_CW_PREC_MASK (0x0300) -#define FE_CW_PREC_SHIFT (8) - -/* In x87, exception status bits and mask bits occupy - corresponding bit positions in the status and control - registers, respectively. In SSE, they are both located - in the control-and-status register, with the status bits - corresponding to the x87 positions, and the mask bits - shifted by this amount to the left. */ -#define FE_SSE_EXCEPT_MASK_SHIFT (7) - -/* These are writable so we can initialise them at startup. */ -static fenv_t fe_nomask_env; - -/* These pointers provide the outside world with read-only access to them. */ -const fenv_t *_fe_nomask_env = &fe_nomask_env; - -/* Assume i686 or above (hence SSE available) these days, with the - compiler feels free to use it (depending on compile- time flags of - course), but we should avoid needlessly breaking any purely integer mode - apps (or apps compiled with -mno-sse), so we only manage SSE state in this - fenv module if we detect that SSE instructions are available at runtime. - If we didn't do this, all applications run on older machines would bomb - out with an invalid instruction exception right at startup; let's not - be *that* WJM! */ -static inline bool use_sse(void) -{ - unsigned int edx, eax; - - /* Check for presence of SSE: invoke CPUID #1, check EDX bit 25. */ - eax = 1; - __asm__ volatile ("cpuid" : "=d" (edx), "+a" (eax) :: "%ecx", "%ebx"); - /* If this flag isn't set we'll avoid trying to execute any SSE. */ - if ((edx & (1 << 25)) != 0) - return true; - - return false; -} - -/* forward declaration */ -static void _feinitialise (void); - -/* This function enables traps for each of the exceptions as indicated - by the parameter except. The individual exceptions are described in - [ ... glibc manual xref elided ...]. Only the specified exceptions are - enabled, the status of the other exceptions is not changed. - The function returns the previous enabled exceptions in case the - operation was successful, -1 otherwise. */ -int -feenableexcept (int excepts) -{ - unsigned short cw, old_cw; - unsigned int mxcsr = 0; - - if (excepts & ~FE_ALL_EXCEPT) - return -1; - - /* Get control words. */ - __asm__ volatile ("fnstcw %0" : "=m" (old_cw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - - /* Enable exceptions by clearing mask bits. */ - cw = old_cw & ~excepts; - mxcsr &= ~(excepts << FE_SSE_EXCEPT_MASK_SHIFT); - - /* Store updated control words. */ - __asm__ volatile ("fldcw %0" :: "m" (cw)); - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); - - /* Return old value. We assume SSE and x87 stay in sync. Note that - we are returning a mask of enabled exceptions, which is the opposite - of the flags in the register, which are set to disable (mask) their - related exceptions. */ - return (~old_cw) & FE_ALL_EXCEPT; -} - -/* This function disables traps for each of the exceptions as indicated - by the parameter except. The individual exceptions are described in - [ ... glibc manual xref elided ...]. Only the specified exceptions are - disabled, the status of the other exceptions is not changed. - The function returns the previous enabled exceptions in case the - operation was successful, -1 otherwise. */ -int -fedisableexcept (int excepts) -{ - unsigned short cw, old_cw; - unsigned int mxcsr = 0; - - if (excepts & ~FE_ALL_EXCEPT) - return -1; - - /* Get control words. */ - __asm__ volatile ("fnstcw %0" : "=m" (old_cw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - - /* Disable exceptions by setting mask bits. */ - cw = old_cw | excepts; - mxcsr |= (excepts << FE_SSE_EXCEPT_MASK_SHIFT); - - /* Store updated control words. */ - __asm__ volatile ("fldcw %0" :: "m" (cw)); - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); - - /* Return old value. We assume SSE and x87 stay in sync. Note that - we are returning a mask of enabled exceptions, which is the opposite - of the flags in the register, which are set to disable (mask) their - related exceptions. */ - return (~old_cw) & FE_ALL_EXCEPT; -} - -/* This function returns a bitmask of all currently enabled exceptions. It - returns -1 in case of failure. */ -int -fegetexcept (void) -{ - unsigned short cw; - - /* Get control word. We assume SSE and x87 stay in sync. */ - __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); - - /* Exception is *dis*abled when mask bit is set. */ - return (~cw) & FE_ALL_EXCEPT; -} - -/* Store the floating-point environment in the variable pointed to by envp. - The function returns zero in case the operation was successful, a non-zero - value otherwise. */ -int -fegetenv (fenv_t *envp) -{ - /* fnstenv disables all exceptions in the x87 FPU; as this is not what is - desired here, reload the cfg saved from the x87 FPU, back to the FPU */ - __asm__ volatile ("fnstenv %0\n\ - fldenv %0" - : "=m" (envp->_fpu) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (envp->_sse_mxcsr) : ); - return 0; -} - -/* Store the current floating-point environment in the object pointed to - by envp. Then clear all exception flags, and set the FPU to trap no - exceptions. Not all FPUs support trapping no exceptions; if feholdexcept - cannot set this mode, it returns nonzero value. If it succeeds, it - returns zero. */ -int -feholdexcept (fenv_t *envp) -{ - unsigned int mxcsr; - fegetenv (envp); - mxcsr = envp->_sse_mxcsr & ~FE_ALL_EXCEPT; - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); - __asm__ volatile ("fnclex"); - fedisableexcept (FE_ALL_EXCEPT); - return 0; -} - -/* Set the floating-point environment to that described by envp. The - function returns zero in case the operation was successful, a non-zero - value otherwise. */ -int -fesetenv (const fenv_t *envp) -{ - if ((envp == FE_DFL_ENV || envp == FE_NOMASK_ENV) && - envp->_fpu._fpu_cw == 0) - _feinitialise (); - - __asm__ volatile ("fldenv %0" :: "m" (envp->_fpu) ); - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (envp->_sse_mxcsr)); - return 0; -} - -/* Like fesetenv, this function sets the floating-point environment to - that described by envp. However, if any exceptions were flagged in the - status word before feupdateenv was called, they remain flagged after - the call. In other words, after feupdateenv is called, the status - word is the bitwise OR of the previous status word and the one saved - in envp. The function returns zero in case the operation was successful, - a non-zero value otherwise. */ -int -feupdateenv (const fenv_t *envp) -{ - fenv_t envcopy; - unsigned int mxcsr = 0; - unsigned short sw; - - /* Don't want to modify *envp, but want to update environment atomically, - so take a copy and merge the existing exceptions into it. */ - memcpy (&envcopy, envp, sizeof *envp); - __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - envcopy._fpu._fpu_sw |= (sw & FE_ALL_EXCEPT); - envcopy._sse_mxcsr |= (mxcsr & FE_ALL_EXCEPT); - - return fesetenv (&envcopy); -} - -/* This function clears all of the supported exception flags indicated by - excepts. The function returns zero in case the operation was successful, - a non-zero value otherwise. */ -int -feclearexcept (int excepts) -{ - fenv_t fenv; - - if (excepts & ~FE_ALL_EXCEPT) - return EINVAL; - - /* Need to save/restore whole environment to modify status word. */ - fegetenv (&fenv); - - /* Mask undesired bits out. */ - fenv._fpu._fpu_sw &= ~excepts; - fenv._sse_mxcsr &= ~excepts; - - /* Set back into FPU state. */ - return fesetenv (&fenv); -} - -/* This function raises the supported exceptions indicated by - excepts. If more than one exception bit in excepts is set the order - in which the exceptions are raised is undefined except that overflow - (FE_OVERFLOW) or underflow (FE_UNDERFLOW) are raised before inexact - (FE_INEXACT). Whether for overflow or underflow the inexact exception - is also raised is also implementation dependent. The function returns - zero in case the operation was successful, a non-zero value otherwise. */ -int -feraiseexcept (int excepts) -{ - fenv_t fenv; - - if (excepts & ~FE_ALL_EXCEPT) - return EINVAL; - - /* Need to save/restore whole environment to modify status word. */ - __asm__ volatile ("fnstenv %0" : "=m" (fenv) : ); - - /* Set desired exception bits. */ - fenv._fpu._fpu_sw |= excepts; - - /* Set back into FPU state. */ - __asm__ volatile ("fldenv %0" :: "m" (fenv)); - - /* And trigger them - whichever are unmasked. */ - __asm__ volatile ("fwait"); - - return 0; -} - -/* Test whether the exception flags indicated by the parameter except - are currently set. If any of them are, a nonzero value is returned - which specifies which exceptions are set. Otherwise the result is zero. */ -int -fetestexcept (int excepts) -{ - unsigned short sw; - unsigned int mxcsr = 0; - - if (excepts & ~FE_ALL_EXCEPT) - return EINVAL; - - /* Get status registers. */ - __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - - /* Mask undesired bits out and return result. */ - return (sw | mxcsr) & excepts; -} -/* This function stores in the variable pointed to by flagp an - implementation-defined value representing the current setting of the - exception flags indicated by excepts. The function returns zero in - case the operation was successful, a non-zero value otherwise. */ -int -fegetexceptflag (fexcept_t *flagp, int excepts) -{ - unsigned short sw; - unsigned int mxcsr = 0; - - if (excepts & ~FE_ALL_EXCEPT) - return EINVAL; - - /* Get status registers. */ - __asm__ volatile ("fnstsw %0" : "=m" (sw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - - /* Mask undesired bits out and set result. */ - *flagp = (sw | mxcsr) & excepts; - - return 0; -} - -/* This function restores the flags for the exceptions indicated by - excepts to the values stored in the variable pointed to by flagp. */ -int -fesetexceptflag (const fexcept_t *flagp, int excepts) -{ - fenv_t fenv; - - if (excepts & ~FE_ALL_EXCEPT) - return EINVAL; - - /* Need to save/restore whole environment to modify status word. */ - fegetenv (&fenv); - - /* Set/Clear desired exception bits. */ - fenv._fpu._fpu_sw &= ~excepts; - fenv._fpu._fpu_sw |= excepts & *flagp; - fenv._sse_mxcsr &= ~excepts; - fenv._sse_mxcsr |= excepts & *flagp; - - /* Set back into FPU state. */ - return fesetenv (&fenv); -} - -/* Returns the currently selected rounding mode, represented by one of the - values of the defined rounding mode macros. */ -int -fegetround (void) -{ - unsigned short cw; - - /* Get control word. We assume SSE and x87 stay in sync. */ - __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); - - return (cw & FE_CW_ROUND_MASK) >> FE_CW_ROUND_SHIFT; -} - -/* Changes the currently selected rounding mode to round. If round does - not correspond to one of the supported rounding modes nothing is changed. - fesetround returns zero if it changed the rounding mode, a nonzero value - if the mode is not supported. */ -int -fesetround (int round) -{ - unsigned short cw; - unsigned int mxcsr = 0; - - /* Will succeed for any valid value of the input parameter. */ - if (round < FE_TONEAREST || round > FE_TOWARDZERO) - return EINVAL; - - /* Get control words. */ - __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); - if (use_sse()) - __asm__ volatile ("stmxcsr %0" : "=m" (mxcsr) : ); - - /* Twiddle bits. */ - cw &= ~FE_CW_ROUND_MASK; - cw |= (round << FE_CW_ROUND_SHIFT); - mxcsr &= ~FE_MXCSR_ROUND_MASK; - mxcsr |= (round << FE_MXCSR_ROUND_SHIFT); - - /* Set back into FPU state. */ - __asm__ volatile ("fldcw %0" :: "m" (cw)); - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); - - /* Indicate success. */ - return 0; -} - -#if defined(__CYGWIN__) -/* Returns the currently selected precision, represented by one of the - values of the defined precision macros. */ -int -fegetprec (void) -{ - unsigned short cw; - - /* Get control word. */ - __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); - - return (cw & FE_CW_PREC_MASK) >> FE_CW_PREC_SHIFT; -} - -/* http://www.open-std.org/jtc1/sc22//WG14/www/docs/n752.htm: - - The fesetprec function establishes the precision represented by its - argument prec. If the argument does not match a precision macro, the - precision is not changed. - - The fesetprec function returns a nonzero value if and only if the - argument matches a precision macro (that is, if and only if the requested - precision can be established). */ -int -fesetprec (int prec) -{ - unsigned short cw; - - /* Will succeed for any valid value of the input parameter. */ - switch (prec) - { - case FE_FLTPREC: - case FE_DBLPREC: - case FE_LDBLPREC: - break; - default: - return 0; - } - - /* Get control word. */ - __asm__ volatile ("fnstcw %0" : "=m" (cw) : ); - - /* Twiddle bits. */ - cw &= ~FE_CW_PREC_MASK; - cw |= (prec << FE_CW_PREC_SHIFT); - - /* Set back into FPU state. */ - __asm__ volatile ("fldcw %0" :: "m" (cw)); - - /* Indicate success. */ - return 1; -} -#endif - -/* Set up the FPU and SSE environment at the start of execution. */ -static void -_feinitialise (void) -{ - extern fenv_t __fe_dfl_env; - - /* Reset FPU: extended prec, all exceptions cleared and masked off. */ - __asm__ volatile ("fninit"); - /* The default cw value, 0x37f, is rounding mode zero. The MXCSR has - no precision control, so the only thing to do is set the exception - mask bits. */ - - /* initialize the MXCSR register: mask all exceptions */ - unsigned int mxcsr = __FE_ALL_EXCEPT_X86 << FE_SSE_EXCEPT_MASK_SHIFT; - if (use_sse()) - __asm__ volatile ("ldmxcsr %0" :: "m" (mxcsr)); - - /* Setup unmasked environment, but leave __FE_DENORM masked. */ - feenableexcept (FE_ALL_EXCEPT); - fegetenv (&fe_nomask_env); - - /* Restore default exception masking (all masked). */ - fedisableexcept (FE_ALL_EXCEPT); - - /* Finally cache state as default environment. */ - fegetenv (&__fe_dfl_env); -} +#include "../shared_x86/fenv.c" |