The leading blank lines are apparently an artefact of an older source
control system. They are not required and they look like accidents,
because starting a source file with a blank line is not a regular habit
of software developers nowadays.
This is a cherry-pick of commit 37cc20add8fb5b83bb5299a26cd3b41e0f776017
from branch 'libpng18'.
Signed-off-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
In the previous commit 9e538750d99c8f1accf7e93878e4fde47c069908
we removed the obsolete assembler implementation `filter_neon.S`.
In this commit we add a stand-in for the original file, restoring
the original source tree structure, for the benefit of continuing
hassle-free libpng source upgrades in the 1.6.x line.
This file contains hand-coded assembler implementations of the filter
functions for 32-bit Arm platforms. These are only used when the
compiler doesn't support neon intrinsics (added to GCC 4.3 in 2008) or
is exactly GCC 4.5.4 (released 2012), both of which are sufficiently
unlikely to be true that it's fair to say the assembler is no longer
used.
This commit deletes filter_neon.S and removes the now obsolete
preprocessor logic in pngpriv.h.
Signed-off-by: Bill Roberts <bill.roberts@arm.com>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
or intrinsics to be turned on during the build by defining
PNG_ARM_NEON_IMPLEMENTATION to the correct value (2 or 1). The
default is "undefined" and the build type is selected in pngpriv.h.
pnglibconf.h, allowing more of the decisions to be made internally
(pngpriv.h) during the compile. Without this, symbol prefixing is broken
under certain circumstances on ARM platforms. Now only the API parts of
the optimizations ('check' vs 'api') are exposed in the public header files
except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
decision about whether or not to use the optimizations.
option:
--enable-arm-neon=always will stop the run-time checks. New checks
within arm/arm_init.c will cause the code not to be compiled unless
__ARM_NEON__ is set. This should make it fail safe (if someone asks
for it on then the build will fail if it can't be done.)
Fixed ALIGNED_MEMORY support.
