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REVISED CHECKS FOR PACKED REGISTER ALIGNMENT

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This now relies on a is_aligned implementation. This will needs to be adapted
once register width is defined through an enumeration.

See #12.
This commit is contained in:
Nicolas Clauvelin 2018-03-15 16:16:42 -04:00
parent 1590e7c0e3
commit c217f34e0c
1 changed files with 33 additions and 12 deletions
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41
register/RegisterPack.h
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@ -19,6 +19,9 @@
namespace cppreg { namespace cppreg {
//! cppreg::internals namespace.
namespace internals {
//! Memory map implementation. //! Memory map implementation.
/** /**
* @tparam Address Memory base address. * @tparam Address Memory base address.
@ -55,6 +58,22 @@ namespace cppreg {
); );
//! is_aligned implementation.
/**
* @tparam Address Address to be checked for alignment.
* @tparam alignment Alignment constraint.
*/
template <Address_t Address, std::size_t alignment>
struct is_aligned : std::integral_constant<
bool,
(Address & (alignment - 1)) == 0
> {
};
}
//! Register pack base implementation. //! Register pack base implementation.
/** /**
* @tparam PackBase Pack base address. * @tparam PackBase Pack base address.
@ -109,7 +128,7 @@ namespace cppreg {
>; >;
//! Memory map type. //! Memory map type.
using mem_map_t = memory_map< using mem_map_t = internals::memory_map<
RegisterPack::pack_base, RegisterPack::pack_base,
RegisterPack::size_in_bytes, RegisterPack::size_in_bytes,
RegWidth RegWidth
@ -135,16 +154,18 @@ namespace cppreg {
static_assert((BitOffset / 8u) <= RegisterPack::size_in_bytes, static_assert((BitOffset / 8u) <= RegisterPack::size_in_bytes,
"packed register is overflowing the pack"); "packed register is overflowing the pack");
// Safety check to detect if the register is mis-aligned. // A packed register of width N bits requires:
// A register is mis-aligned if it its offset is not a multiple of // - the pack address to be N-bits aligned (N/8 aligned),
// its size and if the pack base address alignment is different from // - the pack address with offset to be N-bits aligned (N/8 aligned).
// its type alignment. static_assert(
static_assert(( internals::is_aligned<RegisterPack::pack_base, (RegWidth / 8)>
(BitOffset % RegWidth) == 0 ::value
&& &&
(RegisterPack::pack_base % (RegWidth / 8u) == 0) internals::is_aligned<
), RegisterPack::pack_base + (BitOffset / 8), (RegWidth / 8)
"register mis-alignment with respect to pack base"); >::value,
"register is mis-aligned in the pack"
);
}; };