Implement C99 floating-point environment for Alpha.

Delivering FPE with non-masked exceptions doesn't work on Alpha; I
suspect there's a bug in the kernel trap handler.

FE_INEXACT is intentionally left out of FE_ALL_EXCEPT;  since the
inexact exception is not being maintained.  Otherwise it will lead
to the bogus results.

1 files changed, 362 insertions, 0 deletions

diff --git a/lib/libm/arch/alpha/fenv.c b/lib/libm/arch/alpha/fenv.c
new file mode 100644
index 00000000000..f0db3a3dbee
--- /dev/null
+++ b/lib/libm/arch/alpha/fenv.c
@@ -0,0 +1,362 @@
+/*	$OpenBSD: fenv.c,v 1.1 2011/04/23 22:39:14 martynas Exp $	*/
+
+/*
+ * Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <machine/sysarch.h>
+
+#include <fenv.h>
+
+/*
+ * 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().
+ */
+fenv_t __fe_dfl_env = {
+	0,
+	0,
+	FE_TONEAREST
+};
+
+/*
+ * The feclearexcept() function clears the supported floating-point exceptions
+ * represented by `excepts'.
+ */
+int
+feclearexcept(int excepts)
+{
+	unsigned int fpsticky;
+	struct alpha_fp_except_args a;
+
+	excepts &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point sticky flags */
+	fpsticky = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	/* Clear the requested floating-point exceptions */
+	fpsticky &= ~excepts;
+
+	/* Load the floating-point sticky flags */
+	a.mask = fpsticky;
+	sysarch(ALPHA_FPSETSTICKY, &a);
+
+	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 int fpsticky;
+
+	excepts &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point sticky flags */
+	fpsticky = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	/* Store the results in flagp */
+	*flagp = fpsticky & excepts;
+
+	return (0);
+}
+
+/*
+ * The feraiseexcept() function raises the supported floating-point exceptions
+ * represented by the argument `excepts'.
+ */
+int
+feraiseexcept(int excepts)
+{
+	excepts &= FE_ALL_EXCEPT;
+
+	fesetexceptflag((fexcept_t *)&excepts, excepts);
+
+	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)
+{
+	unsigned int fpsticky;
+	struct alpha_fp_except_args a;
+
+	excepts &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point sticky flags */
+	fpsticky = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	/* Set the requested status flags */
+	fpsticky &= ~excepts;
+	fpsticky |= *flagp & excepts;
+
+	/* Load the floating-point sticky flags */
+	a.mask = fpsticky;
+	sysarch(ALPHA_FPSETSTICKY, &a);
+
+	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 int fpsticky;
+
+	excepts &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point sticky flags */
+	fpsticky = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	return (fpsticky & excepts);
+}
+
+/*
+ * The fegetround() function gets the current rounding direction.
+ */
+int
+fegetround(void)
+{
+	unsigned long fpcr;
+
+	/* Store the current floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mf_fpcr %0" : "=f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+
+	return ((fpcr >> _ROUND_SHIFT) & _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 long fpcr;
+
+	/* Check whether requested rounding direction is supported */
+	if (round & ~_ROUND_MASK)
+		return (-1);
+
+	/* Store the current floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mf_fpcr %0" : "=f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+
+	/*
+	 * Set the rounding direction
+	 */
+	fpcr &= ~((unsigned long)_ROUND_MASK << _ROUND_SHIFT);
+	fpcr |= (unsigned long)round << _ROUND_SHIFT;
+
+	/* Load the floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mt_fpcr %0" : : "f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+
+	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)
+{
+	unsigned long fpcr;
+
+	/* Store the current floating-point sticky flags */
+	envp->__excepts = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	/* Store the current floating-point masks */
+	envp->__mask = sysarch(ALPHA_FPGETMASK, 0L);
+
+	/* Store the current floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mf_fpcr %0" : "=f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+	envp->__round = (fpcr >> _ROUND_SHIFT) & _ROUND_MASK;
+
+	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)
+{
+	struct alpha_fp_except_args a;
+
+	/* Store the current floating-point environment */
+	fegetenv(envp);
+
+	/* Clear exception flags */
+	a.mask = envp->__excepts;
+	a.mask &= ~FE_ALL_EXCEPT;
+	sysarch(ALPHA_FPSETSTICKY, &a);
+
+	/* Mask all exceptions */
+	a.mask = envp->__excepts;
+	a.mask &= ~FE_ALL_EXCEPT;
+	sysarch(ALPHA_FPSETMASK, &a);
+
+	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)
+{
+	unsigned long fpcr;
+	struct alpha_fp_except_args a;
+
+	/* Load the floating-point sticky flags */
+	a.mask = envp->__excepts & FE_ALL_EXCEPT;
+	sysarch(ALPHA_FPSETSTICKY, &a);
+
+	/* Load the floating-point masks */
+	a.mask = envp->__mask & FE_ALL_EXCEPT;
+	sysarch(ALPHA_FPSETMASK, &a);
+
+	/* Store the current floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mf_fpcr %0" : "=f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+
+	fpcr &= ~((unsigned long)_ROUND_MASK << _ROUND_SHIFT);
+	fpcr |= ((unsigned long)envp->__round & _ROUND_MASK) << _ROUND_SHIFT;
+
+	/* Load the floating-point control register */
+	__asm__ __volatile__ ("trapb");
+	__asm__ __volatile__ ("mt_fpcr %0" : : "f" (fpcr));
+	__asm__ __volatile__ ("trapb");
+
+	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 int fpsticky;
+
+	/* Store the current floating-point sticky flags */
+	fpsticky = sysarch(ALPHA_FPGETSTICKY, 0L);
+
+	/* Install new floating-point environment */
+	fesetenv(envp);
+
+	/* Raise any previously accumulated exceptions */
+	feraiseexcept(fpsticky);
+
+	return (0);
+}
+
+/*
+ * The following functions are extentions to the standard
+ */
+int
+feenableexcept(int mask)
+{
+	unsigned int fpmask, omask;
+	struct alpha_fp_except_args a;
+
+	mask &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point masks */
+	fpmask = sysarch(ALPHA_FPGETMASK, 0L);
+
+	omask = fpmask & FE_ALL_EXCEPT;
+	fpmask |= mask;
+
+	/* Load the floating-point masks */
+	a.mask = fpmask;
+	sysarch(ALPHA_FPSETMASK, &a);
+
+	return (omask);
+
+}
+
+int
+fedisableexcept(int mask)
+{
+	unsigned int fpmask, omask;
+	struct alpha_fp_except_args a;
+
+	mask &= FE_ALL_EXCEPT;
+
+	/* Store the current floating-point masks */
+	fpmask = sysarch(ALPHA_FPGETMASK, 0L);
+
+	omask = fpmask & FE_ALL_EXCEPT;
+	fpmask &= ~mask;
+
+	/* Load the floating-point masks */
+	a.mask = fpmask;
+	sysarch(ALPHA_FPSETMASK, &a);
+
+	return (omask);
+}
+
+int
+fegetexcept(void)
+{
+	unsigned int fpmask;
+
+	/* Store the current floating-point masks */
+	fpmask = sysarch(ALPHA_FPGETMASK, 0L);
+
+	return (fpmask & FE_ALL_EXCEPT);
+}