| /* $OpenBSD: fenv.c,v 1.3 2012/12/05 23:20:02 deraadt Exp $ */ |
| /* $NetBSD: fenv.c,v 1.1 2010/07/31 21:47:53 joerg Exp $ */ |
| |
| /*- |
| * Copyright (c) 2004-2005 David Schultz <das (at) FreeBSD.ORG> |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #include <fenv.h> |
| #include <machine/fpu.h> |
| |
| #define SSE_MASK_SHIFT 7 |
| |
| /* |
| * The following symbol is simply the bitwise-inclusive OR of all floating-point |
| * rounding direction constants defined above. |
| */ |
| #define X87_ROUND_MASK (FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | FE_TOWARDZERO) |
| #define SSE_ROUND_SHIFT 3 |
| |
| /* |
| * The following constant represents the default floating-point environment |
| * (that is, the one installed at program startup) and has type pointer to |
| * const-qualified fenv_t. |
| * |
| * It can be used as an argument to the functions within the <fenv.h> header |
| * that manage the floating-point environment, namely fesetenv() and |
| * feupdateenv(). |
| * |
| * x87 fpu registers are 16bit wide. The upper bits, 31-16, are marked as |
| * RESERVED. |
| */ |
| const fenv_t __fe_dfl_env = { |
| { |
| 0xffff0000 | __INITIAL_NPXCW__, /* Control word register */ |
| 0xffff0000, /* Status word register */ |
| 0xffffffff, /* Tag word register */ |
| { |
| 0x00000000, |
| 0x00000000, |
| 0x00000000, |
| 0xffff0000 |
| } |
| }, |
| __INITIAL_MXCSR__ /* MXCSR register */ |
| }; |
| |
| |
| /* |
| * The feclearexcept() function clears the supported floating-point exceptions |
| * represented by `excepts'. |
| */ |
| int |
| feclearexcept(int excepts) |
| { |
| fenv_t fenv; |
| unsigned int mxcsr; |
| |
| excepts &= FE_ALL_EXCEPT; |
| |
| /* Store the current x87 floating-point environment */ |
| __asm__ __volatile__ ("fnstenv %0" : "=m" (fenv)); |
| |
| /* Clear the requested floating-point exceptions */ |
| fenv.__x87.__status &= ~excepts; |
| |
| /* Load the x87 floating-point environent */ |
| __asm__ __volatile__ ("fldenv %0" : : "m" (fenv)); |
| |
| /* Same for SSE environment */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| mxcsr &= ~excepts; |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (0); |
| } |
| |
| /* |
| * The fegetexceptflag() function stores an implementation-defined |
| * representation of the states of the floating-point status flags indicated by |
| * the argument excepts in the object pointed to by the argument flagp. |
| */ |
| int |
| fegetexceptflag(fexcept_t *flagp, int excepts) |
| { |
| unsigned short status; |
| unsigned int mxcsr; |
| |
| excepts &= FE_ALL_EXCEPT; |
| |
| /* Store the current x87 status register */ |
| __asm__ __volatile__ ("fnstsw %0" : "=am" (status)); |
| |
| /* Store the MXCSR register */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| |
| /* Store the results in flagp */ |
| *flagp = (status | mxcsr) & excepts; |
| |
| return (0); |
| } |
| |
| /* |
| * The feraiseexcept() function raises the supported floating-point exceptions |
| * represented by the argument `excepts'. |
| * |
| * The standard explicitly allows us to execute an instruction that has the |
| * exception as a side effect, but we choose to manipulate the status register |
| * directly. |
| * |
| * The validation of input is being deferred to fesetexceptflag(). |
| */ |
| int |
| feraiseexcept(int excepts) |
| { |
| excepts &= FE_ALL_EXCEPT; |
| |
| fesetexceptflag((fexcept_t *)&excepts, excepts); |
| __asm__ __volatile__ ("fwait"); |
| |
| return (0); |
| } |
| |
| /* |
| * This function sets the floating-point status flags indicated by the argument |
| * `excepts' to the states stored in the object pointed to by `flagp'. It does |
| * NOT raise any floating-point exceptions, but only sets the state of the flags. |
| */ |
| int |
| fesetexceptflag(const fexcept_t *flagp, int excepts) |
| { |
| fenv_t fenv; |
| unsigned int mxcsr; |
| |
| excepts &= FE_ALL_EXCEPT; |
| |
| /* Store the current x87 floating-point environment */ |
| __asm__ __volatile__ ("fnstenv %0" : "=m" (fenv)); |
| |
| /* Set the requested status flags */ |
| fenv.__x87.__status &= ~excepts; |
| fenv.__x87.__status |= *flagp & excepts; |
| |
| /* Load the x87 floating-point environent */ |
| __asm__ __volatile__ ("fldenv %0" : : "m" (fenv)); |
| |
| /* Same for SSE environment */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| mxcsr &= ~excepts; |
| mxcsr |= *flagp & excepts; |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (0); |
| } |
| |
| /* |
| * The fetestexcept() function determines which of a specified subset of the |
| * floating-point exception flags are currently set. The `excepts' argument |
| * specifies the floating-point status flags to be queried. |
| */ |
| int |
| fetestexcept(int excepts) |
| { |
| unsigned short status; |
| unsigned int mxcsr; |
| |
| excepts &= FE_ALL_EXCEPT; |
| |
| /* Store the current x87 status register */ |
| __asm__ __volatile__ ("fnstsw %0" : "=am" (status)); |
| |
| /* Store the MXCSR register state */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| |
| return ((status | mxcsr) & excepts); |
| } |
| |
| /* |
| * The fegetround() function gets the current rounding direction. |
| */ |
| int |
| fegetround(void) |
| { |
| unsigned short control; |
| |
| /* |
| * We assume that the x87 and the SSE unit agree on the |
| * rounding mode. Reading the control word on the x87 turns |
| * out to be about 5 times faster than reading it on the SSE |
| * unit on an Opteron 244. |
| */ |
| __asm__ __volatile__ ("fnstcw %0" : "=m" (control)); |
| |
| return (control & X87_ROUND_MASK); |
| } |
| |
| /* |
| * The fesetround() function establishes the rounding direction represented by |
| * its argument `round'. If the argument is not equal to the value of a rounding |
| * direction macro, the rounding direction is not changed. |
| */ |
| int |
| fesetround(int round) |
| { |
| unsigned short control; |
| unsigned int mxcsr; |
| |
| /* Check whether requested rounding direction is supported */ |
| if (round & ~X87_ROUND_MASK) |
| return (-1); |
| |
| /* Store the current x87 control word register */ |
| __asm__ __volatile__ ("fnstcw %0" : "=m" (control)); |
| |
| /* Set the rounding direction */ |
| control &= ~X87_ROUND_MASK; |
| control |= round; |
| |
| /* Load the x87 control word register */ |
| __asm__ __volatile__ ("fldcw %0" : : "m" (control)); |
| |
| /* Same for the SSE environment */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| mxcsr &= ~(X87_ROUND_MASK << SSE_ROUND_SHIFT); |
| mxcsr |= round << SSE_ROUND_SHIFT; |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (0); |
| } |
| |
| /* |
| * The fegetenv() function attempts to store the current floating-point |
| * environment in the object pointed to by envp. |
| */ |
| int |
| fegetenv(fenv_t *envp) |
| { |
| /* Store the current x87 floating-point environment */ |
| __asm__ __volatile__ ("fnstenv %0" : "=m" (*envp)); |
| |
| /* Store the MXCSR register state */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (envp->__mxcsr)); |
| |
| /* |
| * When an FNSTENV instruction is executed, all pending exceptions are |
| * essentially lost (either the x87 FPU status register is cleared or |
| * all exceptions are masked). |
| * |
| * 8.6 X87 FPU EXCEPTION SYNCHRONIZATION - |
| * Intel(R) 64 and IA-32 Architectures Softare Developer's Manual - Vol1 |
| */ |
| __asm__ __volatile__ ("fldcw %0" : : "m" (envp->__x87.__control)); |
| |
| return (0); |
| } |
| |
| /* |
| * The feholdexcept() function saves the current floating-point environment |
| * in the object pointed to by envp, clears the floating-point status flags, and |
| * then installs a non-stop (continue on floating-point exceptions) mode, if |
| * available, for all floating-point exceptions. |
| */ |
| int |
| feholdexcept(fenv_t *envp) |
| { |
| unsigned int mxcsr; |
| |
| /* Store the current x87 floating-point environment */ |
| __asm__ __volatile__ ("fnstenv %0" : "=m" (*envp)); |
| |
| /* Clear all exception flags in FPU */ |
| __asm__ __volatile__ ("fnclex"); |
| |
| /* Store the MXCSR register state */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (envp->__mxcsr)); |
| |
| /* Clear exception flags in MXCSR */ |
| mxcsr = envp->__mxcsr; |
| mxcsr &= ~FE_ALL_EXCEPT; |
| |
| /* Mask all exceptions */ |
| mxcsr |= FE_ALL_EXCEPT << SSE_MASK_SHIFT; |
| |
| /* Store the MXCSR register */ |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (0); |
| } |
| |
| /* |
| * The fesetenv() function attempts to establish the floating-point environment |
| * represented by the object pointed to by envp. The argument `envp' points |
| * to an object set by a call to fegetenv() or feholdexcept(), or equal a |
| * floating-point environment macro. The fesetenv() function does not raise |
| * floating-point exceptions, but only installs the state of the floating-point |
| * status flags represented through its argument. |
| */ |
| int |
| fesetenv(const fenv_t *envp) |
| { |
| /* Load the x87 floating-point environent */ |
| __asm__ __volatile__ ("fldenv %0" : : "m" (*envp)); |
| |
| /* Store the MXCSR register */ |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (envp->__mxcsr)); |
| |
| return (0); |
| } |
| |
| /* |
| * The feupdateenv() function saves the currently raised floating-point |
| * exceptions in its automatic storage, installs the floating-point environment |
| * represented by the object pointed to by `envp', and then raises the saved |
| * floating-point exceptions. The argument `envp' shall point to an object set |
| * by a call to feholdexcept() or fegetenv(), or equal a floating-point |
| * environment macro. |
| */ |
| int |
| feupdateenv(const fenv_t *envp) |
| { |
| unsigned short status; |
| unsigned int mxcsr; |
| |
| /* Store the x87 status register */ |
| __asm__ __volatile__ ("fnstsw %0" : "=am" (status)); |
| |
| /* Store the MXCSR register */ |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| |
| /* Install new floating-point environment */ |
| fesetenv(envp); |
| |
| /* Raise any previously accumulated exceptions */ |
| feraiseexcept(status | mxcsr); |
| |
| return (0); |
| } |
| |
| /* |
| * The following functions are extentions to the standard |
| */ |
| int |
| feenableexcept(int mask) |
| { |
| unsigned int mxcsr, omask; |
| unsigned short control; |
| |
| mask &= FE_ALL_EXCEPT; |
| |
| __asm__ __volatile__ ("fnstcw %0" : "=m" (control)); |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| |
| omask = ~(control | (mxcsr >> SSE_MASK_SHIFT)) & FE_ALL_EXCEPT; |
| control &= ~mask; |
| __asm__ __volatile__ ("fldcw %0" : : "m" (control)); |
| |
| mxcsr &= ~(mask << SSE_MASK_SHIFT); |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (omask); |
| } |
| |
| int |
| fedisableexcept(int mask) |
| { |
| unsigned int mxcsr, omask; |
| unsigned short control; |
| |
| mask &= FE_ALL_EXCEPT; |
| |
| __asm__ __volatile__ ("fnstcw %0" : "=m" (control)); |
| __asm__ __volatile__ ("stmxcsr %0" : "=m" (mxcsr)); |
| |
| omask = ~(control | (mxcsr >> SSE_MASK_SHIFT)) & FE_ALL_EXCEPT; |
| control |= mask; |
| __asm__ __volatile__ ("fldcw %0" : : "m" (control)); |
| |
| mxcsr |= mask << SSE_MASK_SHIFT; |
| __asm__ __volatile__ ("ldmxcsr %0" : : "m" (mxcsr)); |
| |
| return (omask); |
| } |
| |
| int |
| fegetexcept(void) |
| { |
| unsigned short control; |
| |
| /* |
| * We assume that the masks for the x87 and the SSE unit are |
| * the same. |
| */ |
| __asm__ __volatile__ ("fnstcw %0" : "=m" (control)); |
| |
| return (~control & FE_ALL_EXCEPT); |
| } |