libc/printf: Use compiler-provided 64 bit math, phase 1
The _to_float() implementation had a somewhat kludgey hand-written 64
bit math implementation, which is unhelpful on Zephyr as all our
toolchains provide a working uint64_t runtime. This is at best just
dupicated code from libgcc, and at worst less efficient.
This patch replaces the existing 64 bit minilibrary but keeps the
uint32_t[2] API as is for ease of validation and review.
One exception is _ldiv5, a specialized divide-by-five implementation.
The 64 bit division routines are large on some architectures (ARM and
ARC in particular), not pulled in by a default Zephyr build, and will
swamp the benefit from this patch. So this includes a
refactored/improved _ldiv5 which leverages libgcc for multiword shifts
instead of just using raw division.
Note also the "noinline" attribute on _ladd(). This is a workaround
for an apparent compiler bug when built with -Og or -Os (hand-hacking
the Makefiles to build with -O0 works), perhaps due to my aliasing the
int array with a long long. This will go away in phase 2.
Change-Id: I63e8c82dabe2bfaa75b63ddb59e5f11d51be538e
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
1 file changed
