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00751d655e
The generic bit reversal implementation is controlled by !HAVE_ARCH_BITREVERSE. This makes it difficult for architectures to provide a hardware-accelerated implementation while being able to fall back to the generic version if needed. This patch adds GENERIC_BITREVERSE, so bitreverse API is controlled by BITREVERSE, GENERIC_BITREVERSE and HAVE_ARCH_BITREVERSE options. The relationship between them is described as follows: - BITREVERSE is selected by user code; it's required to generate the API; - Architectures may select HAVE_ARCH_BITREVERSE and provide an arch implementation in arch/$(ARCH)/include/asm/bitrev.h. - if HAVE_ARCH_BITREVERSE isn't set, BITREVERSE selects GENERIC_BITREVERSE; - if GENERIC_BITREVERSE is set and HAVE_ARCH_BITREVERSE is not, the kernel provides generic implementation only, and wires bitrevXX() to it. - if HAVE_ARCH_BITREVERSE is set and GENERIC_BITREVERSE is not, the arch code provides __arch_bitrevXX(), and it is wired to bitrevXX(); - if both GENERIC_BITREVERSE and HAVE_ARCH_BITREVERSE are selected, the kernel generates generic___bitrev(), but wires bitrev() to the __arch_bitrev(). The last option allows architectures to use generic___bitrev() as a fallback option. Drivers and core code should never select GENERIC_BITREVERSE or HAVE_ARCH_BITREVERSE explicitly. Architectures that require generic bitreverse API as a fallback should explicitly enable GENERIC_BITREVERSE together with HAVE_ARCH_BITREVERSE. Signed-off-by: Yury Norov <ynorov@nvidia.com>
44 lines
1.8 KiB
44 lines
1.8 KiB