usr: libc: Add math.h + musl math impl port

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/__fpclassifyl.c b/lib/libc/src/musl-math/__fpclassifyl.c
new file mode 100644
index 0000000..fb62dd9
--- /dev/null
+++ b/lib/libc/src/musl-math/__fpclassifyl.c
@@ -0,0 +1,42 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+int __fpclassifyl(long double x)
+{
+	return __fpclassify(x);
+}
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+int __fpclassifyl(long double x)
+{
+	union ldshape u = {x};
+	int e = u.i.se & 0x7fff;
+	int msb = u.i.m>>63;
+	if (!e && !msb)
+		return u.i.m ? FP_SUBNORMAL : FP_ZERO;
+	if (e == 0x7fff) {
+		/* The x86 variant of 80-bit extended precision only admits
+		 * one representation of each infinity, with the mantissa msb
+		 * necessarily set. The version with it clear is invalid/nan.
+		 * The m68k variant, however, allows either, and tooling uses
+		 * the version with it clear. */
+		if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ && !msb)
+			return FP_NAN;
+		return u.i.m << 1 ? FP_NAN : FP_INFINITE;
+	}
+	if (!msb)
+		return FP_NAN;
+	return FP_NORMAL;
+}
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+int __fpclassifyl(long double x)
+{
+	union ldshape u = {x};
+	int e = u.i.se & 0x7fff;
+	u.i.se = 0;
+	if (!e)
+		return u.i2.lo | u.i2.hi ? FP_SUBNORMAL : FP_ZERO;
+	if (e == 0x7fff)
+		return u.i2.lo | u.i2.hi ? FP_NAN : FP_INFINITE;
+	return FP_NORMAL;
+}
+#endif