musl/src/math, branch v1.1.7

add aarch64 port

2015-03-12T00:12:35+00:00

This adds complete aarch64 target support including bigendian subarch.

Some of the long double math functions are known to be broken otherwise
interfaces should be fully functional, but at this point consider this
port experimental.

Initial work on this port was done by Sireesh Tripurari and Kevin Bortis.

math: add dummy implementations of 128 bit long double functions

2015-03-11T22:54:53+00:00

This is in preparation for the aarch64 port only to have the long
double math symbols available on ld128 platforms. The implementations
should be fixed up later once we have proper tests for these functions.

Added bigendian handling for ld128 bit manipulations too.

math: add ld128 exp2l based on the freebsd implementation

2015-03-11T22:54:50+00:00

Changed the special case handling and bit manipulation to better
match the double version.

math: fix fmodl for IEEE binary128

2015-02-09T00:16:35+00:00

This trivial copy-paste bug went unnoticed due to lack of testing.
No currently supported target archs are affected.

math: fix __fpclassifyl(-0.0) for IEEE binary128

2015-02-08T16:41:56+00:00

The sign bit was not cleared before checking for 0 so -0.0
was misclassified as FP_SUBNORMAL instead of FP_ZERO.

add parenthesis in fma.c to clarify intent and silence warnings

2015-02-08T16:40:54+00:00

math: use fnstsw consistently instead of fstsw in x87 asm

2014-11-05T21:13:58+00:00

fnstsw does not wait for pending unmasked x87 floating-point exceptions
and it is the same as fstsw when all exceptions are masked which is the
only environment libc supports.

math: fix x86_64 and x32 asm not to use sahf instruction

2014-11-05T20:40:29+00:00

Some early x86_64 cpus (released before 2006) did not support sahf/lahf
instructions so they should be avoided (intel manual says they are only
supported if CPUID.80000001H:ECX.LAHF-SAHF[bit 0] = 1).

The workaround simplifies exp2l and expm1l because fucomip can be
used instead of the fucomp;fnstsw;sahf sequence copied from i386.

In fmodl and remainderl sahf is replaced by a simple bit test.

math: use the rounding idiom consistently

2014-10-31T15:35:40+00:00

the idiomatic rounding of x is

  n = x + toint - toint;

where toint is either 1/EPSILON (x is non-negative) or 1.5/EPSILON
(x may be negative and nearest rounding mode is assumed) and EPSILON is
according to the evaluation precision (the type of toint is not very
important, because single precision float can represent the 1/EPSILON of
ieee binary128).

in case of FLT_EVAL_METHOD!=0 this avoids a useless store to double or
float precision, and the long double code became cleaner with
1/LDBL_EPSILON instead of ifdefs for toint.

__rem_pio2f and __rem_pio2 functions slightly changed semantics:
on i386 a double-rounding is avoided so close to half-way cases may
get evaluated differently eg. as sin(pi/4-eps) instead of cos(pi/4+eps)

fix rint.c and rintf.c when FLT_EVAL_METHOD!=0

2014-10-31T15:35:40+00:00

The old code used the rounding idiom incorrectly:

  y = (double)(x + 0x1p52) - 0x1p52;

the cast is useless if FLT_EVAL_METHOD==0 and causes a second rounding
if FLT_EVAL_METHOD==2 which can give incorrect result in nearest rounding
mode, so the correct idiom is to add/sub a power-of-2 according to the
characteristics of double_t.

This did not cause actual bug because only i386 is affected where rint
is implemented in asm.

Other rounding functions use a similar idiom, but they give correct
results because they only rely on getting a neighboring integer result
and the rounding direction is fixed up separately independently of the
current rounding mode. However they should be fixed to use the idiom
correctly too.