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12be4e0d5a
(1) The bit for the 1.0 part of bp[k] was right shifted by 4. This seems to have been caused by a typo in converting e_pow.c to e_powf.c. (2) The lower 12 bits of ax+bp[k] were not discarded, so t_h was actually plain ax+bp[k]. This seems to have been caused by a logic error in the conversion. These bugs gave wrong results like: powf(-1.1, 101.0) = -15158.703 (should be -15158.707) hex values: BF8CCCCD 42CA0000 C66CDAD0 C66CDAD4 Fixing (1) gives a result wrong in the opposite direction (hex C66CDAD8), and fixing (2) gives the correct result. ucbtest has been reporting this particular wrong result on i386 systems with unpatched libraries for 9 years. I finally figured out the extent of the bugs. On i386's they are normally hidden by extra precision. We use the trick of representing floats as a sum of 2 floats (one much smaller) to get extra precision in intermediate calculations without explicitly using more than float precision. This trick is just a pessimization when extra precision is available naturally (as it always is when dealing with IEEE single precision, so the float precision part of the library is mostly misimplemented). (1) and (2) break the trick in different ways, except on i386's it turns out that the intermediate calculations are done in enough precision to mask both the bugs and the limited precision of the float variables (as far as ucbtest can check). ucbtest detects the bugs because it forces float precision, but this is not a normal mode of operation so the bug normally has little effect on i386's. On systems that do float arithmetic in float precision, e.g., amd64's, there is no accidental extra precision and the bugs just give wrong results. |
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bin | ||
contrib | ||
crypto | ||
etc | ||
games | ||
gnu | ||
include | ||
kerberos5 | ||
lib | ||
libexec | ||
release | ||
rescue | ||
sbin | ||
secure | ||
share | ||
sys | ||
tools | ||
usr.bin | ||
usr.sbin | ||
COPYRIGHT | ||
installworld_newk | ||
installworld_oldk | ||
MAINTAINERS | ||
Makefile | ||
Makefile.inc1 | ||
README | ||
UPDATING | ||
UPDATING.64BTT |
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html