On Wed, Jul 20, 2016 at 5:05 AM, Pavel Pisa <p...@cmp.felk.cvut.cz> wrote: > Hello Gedare, > > thanks for review. > > On Tuesday 19 of July 2016 17:21:16 Gedare Bloom wrote: >> > + line_power = arm_ccsidr_get_line_power(ccsidr); >> > + associativity = arm_ccsidr_get_associativity(ccsidr); >> > + way_shift = __builtin_clz(associativity - 1); >> >> Can we use a non-GCCism here, or wrap it in to a support function? >> > > The code is copy of arm_cp15_data_cache_invalidate_all_levels() > with replaced cache operation line. > > There has been already __builtin_clz in the source and it is used > in more places in the code. I have not found reasonable portable > replacement which would compile well (this result in single > assembler instruction on ARMv5+, x86 etc.). > > The ffs ffsl etc has been adopted by standard. But I cannot > find something like clz, fls in the standards. There is only > floating point log2 in math.h. > > So I see as option to define CLZ somehow centrally in CPUkit > header to __builtin_clz for GCC. ARM and even Microsoft compilers > have equivalent operation (under other name) directly available > by compiler as well. > > But such update of __builtin_clz should go to other patch which > takes care of all RTEMS use locations. > OK that is fine. This should be similar to defining _Bitfield_Find_first_bit() at score/include/rtems/score/prioritybitmapimpl.h. They're really almost identical code.
> Best wishes, > > Pavel > _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
