first commit of the new libm!

thanks to the hard work of Szabolcs Nagy (nsz), identifying the best
(from correctness and license standpoint) implementations from freebsd
and openbsd and cleaning them up! musl should now fully support c99
float and long double math functions, and has near-complete complex
math support. tgmath should also work (fully on gcc-compatible
compilers, and mostly on any c99 compiler).

based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from
nsz's libm git repo, with some additions (dummy versions of a few
missing long double complex functions, etc.) by me.

various cleanups still need to be made, including re-adding (if
they're correct) some asm functions that were dropped.

1 files changed, 137 insertions, 0 deletions

diff --git a/src/internal/longdbl.h b/src/internal/longdbl.h
new file mode 100644
index 00000000..25ec8021
--- /dev/null
+++ b/src/internal/longdbl.h
@@ -0,0 +1,137 @@
+#ifndef _LDHACK_H
+#define _LDHACK_H
+
+#include <float.h>
+#include <stdint.h>
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+union ldshape {
+	long double value;
+	struct {
+		uint64_t m;
+		uint16_t exp:15;
+		uint16_t sign:1;
+		uint16_t pad;
+	} bits;
+};
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+union ldshape {
+	long double value;
+	struct {
+		uint64_t mlo;
+		uint64_t mhi:48;
+		uint16_t exp:15;
+		uint16_t sign:1;
+	} bits;
+};
+#else
+#error Unsupported long double representation
+#endif
+
+
+// FIXME: hacks to make freebsd+openbsd long double code happy
+
+// union and macros for freebsd
+
+#if LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+
+union IEEEl2bits {
+	long double e;
+	struct {
+		uint32_t manl:32;
+		uint32_t manh:32;
+		uint32_t exp:15;
+		uint32_t sign:1;
+		uint32_t pad:16;
+	} bits;
+	struct {
+		uint64_t man:64;
+		uint32_t expsign:16;
+		uint32_t pad:16;
+	} xbits;
+};
+
+#define LDBL_MANL_SIZE 32
+#define LDBL_MANH_SIZE 32
+#define LDBL_NBIT (1ull << LDBL_MANH_SIZE-1)
+#undef LDBL_IMPLICIT_NBIT
+#define mask_nbit_l(u) ((u).bits.manh &= ~LDBL_NBIT)
+
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+/*
+// ld128 float.h
+//#define LDBL_MAX 1.189731495357231765085759326628007016E+4932L
+#define LDBL_MAX 0x1.ffffffffffffffffffffffffffffp+16383
+#define LDBL_MAX_EXP 16384
+#define LDBL_HAS_INFINITY 1
+//#define LDBL_MIN 3.362103143112093506262677817321752603E-4932L
+#define LDBL_MIN 0x1p-16382
+#define LDBL_HAS_QUIET_NAN 1
+#define LDBL_HAS_DENORM 1
+//#define LDBL_EPSILON 1.925929944387235853055977942584927319E-34L
+#define LDBL_EPSILON 0x1p-112
+#define LDBL_MANT_DIG 113
+#define LDBL_MIN_EXP (-16381)
+#define LDBL_MAX_10_EXP 4932
+#define LDBL_DENORM_MIN 0x0.0000000000000000000000000001p-16381
+#define LDBL_MIN_10_EXP (-4931)
+#define LDBL_DIG 33
+*/
+
+union IEEEl2bits {
+	long double e;
+	struct {
+		uint64_t manl:64;
+		uint64_t manh:48;
+		uint32_t exp:15;
+		uint32_t sign:1;
+	} bits;
+	struct {
+		uint64_t unused0:64;
+		uint64_t unused1:48;
+		uint32_t expsign:16;
+	} xbits;
+};
+
+#define LDBL_MANL_SIZE 64
+#define LDBL_MANH_SIZE 48
+#define LDBL_NBIT (1ull << LDBL_MANH_SIZE)
+#define LDBL_IMPLICIT_NBIT 1
+#define mask_nbit_l(u)
+
+#endif
+
+
+// macros for openbsd
+
+#define GET_LDOUBLE_WORDS(se,mh,ml, f) do{ \
+	union IEEEl2bits u; \
+	u.e = (f); \
+	(se) = u.xbits.expsign; \
+	(mh) = u.bits.manh; \
+	(ml) = u.bits.manl; \
+}while(0)
+
+#define SET_LDOUBLE_WORDS(f,  se,mh,ml) do{ \
+	union IEEEl2bits u; \
+	u.xbits.expsign = (se); \
+	u.bits.manh = (mh); \
+	u.bits.manl = (ml); \
+	(f) = u.e; \
+}while(0)
+
+#define GET_LDOUBLE_EXP(se, f) do{ \
+	union IEEEl2bits u; \
+	u.e = (f); \
+	(se) = u.xbits.expsign; \
+}while(0)
+
+#define SET_LDOUBLE_EXP(f, se) do{ \
+	union IEEEl2bits u; \
+	u.e = (f); \
+	u.xbits.expsign = (se); \
+	(f) = u.e; \
+}while(0)
+
+#endif