feat(userspace/libc): implementation <fenv.h> header

FIXME: testing required!
Signed-off-by: EnderIce2 <enderice2@protonmail.com>

Userspace/libc/src/std/fenv.c

@@ -0,0 +1,201 @@
+/*
+	This file is part of Fennix C Library.
+
+	Fennix C Library is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Fennix 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 General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Fennix C Library. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <sys/types.h>
+#include <fenv.h>
+
+export int feclearexcept(int excepts)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	status &= ~excepts;
+	__asm__ __volatile__("fldcw %0" : : "m"(*&status));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fegetenv(fenv_t *envp)
+{
+#if defined(__amd64__) || defined(__i386__)
+	__asm__ __volatile__("fnstenv %0" : "=m"(*envp));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fegetexceptflag(fexcept_t *flagp, int excepts)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	*flagp = status & excepts;
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fegetround(void)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int cw;
+	__asm__ __volatile__("fnstcw %0" : "=m"(*&cw));
+	return cw & 0x0C00;
+#elif defined(__arm__)
+	return FE_TONEAREST;
+#elif defined(__aarch64__)
+	return FE_TONEAREST;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int feholdexcept(fenv_t *envp)
+{
+#if defined(__amd64__) || defined(__i386__)
+	__asm__ __volatile__("fnstenv %0" : "=m"(*envp));
+	unsigned int cw;
+	__asm__ __volatile__("fnclex");
+	__asm__ __volatile__("fnstcw %0" : "=m"(*&cw));
+	cw |= 0x3F; /* Set non-stop mode for all exceptions */
+	__asm__ __volatile__("fldcw %0" : : "m"(*&cw));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int feraiseexcept(int excepts)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	status |= excepts;
+	__asm__ __volatile__("fldcw %0" : : "m"(*&status));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fesetenv(const fenv_t *envp)
+{
+#if defined(__amd64__) || defined(__i386__)
+	__asm__ __volatile__("fldenv %0" : : "m"(*envp));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fesetexceptflag(const fexcept_t *flagp, int excepts)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	status &= ~excepts;
+	status |= *flagp & excepts;
+	__asm__ __volatile__("fldcw %0" : : "m"(*&status));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fesetround(int round)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int cw;
+	if (round != FE_TONEAREST && round != FE_DOWNWARD && round != FE_UPWARD && round != FE_TOWARDZERO)
+		return -1;
+	__asm__ __volatile__("fnstcw %0" : "=m"(*&cw));
+	cw &= ~0x0C00;
+	cw |= round;
+	__asm__ __volatile__("fldcw %0" : : "m"(*&cw));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int fetestexcept(int excepts)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	return status & excepts;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}
+
+export int feupdateenv(const fenv_t *envp)
+{
+#if defined(__amd64__) || defined(__i386__)
+	unsigned int status;
+	__asm__ __volatile__("fnstsw %0" : "=m"(*&status));
+	__asm__ __volatile__("fldenv %0" : : "m"(*envp));
+	__asm__ __volatile__("fldcw %0" : : "m"(*&status));
+	return 0;
+#elif defined(__arm__)
+	return 0;
+#elif defined(__aarch64__)
+	return 0;
+#else
+#error "Unsupported architecture"
+#endif
+}