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History log of /src/lib/libm/arch/i387/s_log1pf.S
RevisionDateAuthorComments
 1.11  16-Jul-2024  riastradh libm: Fix log-related symbol aliases.

- Do the weak alias dance for log, log2, log10, log1p, and their
f/l variants.

(Not strictly necessary for log2 and log10 since nothing in the
math library itself uses them -- only a computer scientist would
use log2 and only an engineer would use log10 -- but let's just do
it the same for all our forestry.)

- Provide long double aliases on vax.

- Sprinkle RCS ids.
 1.10  16-Sep-2003  wennmach branches: 1.10.108;
Avoid the PIC dance.
 1.9  14-Sep-2003  fvdl Make log1p and log1pf work in shared libraries again.
 1.8  10-Sep-2003  wennmach Reimplement s_log1p.S and s_log1pf.S to use the fyl2xp1 instruction
where necessary.

The log1p() function is provided to compute an accurate value of
log(1 + x), even for tiny values of x. The i387 FPU provides the
fyl2xp1 instruction for this purpose.

However, since the range of the fyl2xp1 function is limited to
-(1 - (sqrt(2) / 2)) <= x <= sqrt(2) - 1
(-0.292893 <= x <= 0.414214)
we need to check if the argument is in the valid range.

In order to reduce the cost for testing the range, we only use
fyl2xp1 if the argument is in the range
-0.25 <= x <= 0.25
which can be checked with just one conditional branch.

Fixes PR lib/22599 by Ray Brownrigg.
 1.7  26-Jul-2003  salo netbsd.org->NetBSD.org
 1.6  19-Jun-2001  fvdl Modify the i387 code so that it can be shared between the i386 port
and the x86_64 port. XXX some files should be distinct.
 1.5  02-Jul-1999  simonb More trailing white space.
 1.4  09-May-1995  jtc Id -> NetBSD
 1.3  28-Apr-1995  jtc Winning Strategies has placed this code into the Public Domain
 1.2  26-Aug-1994  jtc Remove lie (in a comment) about conversion between 80 bit ot 64 bit reals,
since we set up the fpu to do all calculations in 64 bit mode at this time.
 1.1  19-Aug-1994  jtc Assembly language versions of some of the "float" functions.
 1.10.108.1  02-Aug-2025  perseant Sync with HEAD

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