Considering all my branches are badly broken because of the Uncrustify
changes, there have been many changes to the existing PE/COFF libraries
in the mean time (and more external dependencies incoming with PMR), and
even this non-invasive patch has been mostly ignored (thanks for the
review, Ray!), can I now safely assume there is no (and frankly never
was) any actual interest in the reworked PE/COFF library? Things are at
a point where I cannot update all my changes to latest master on my own,
and if nobody provides any active support, you may best mark all related
BZs as WONTFIX to reflect the roadmap.
Best regards,
Marvin
On 23.11.21 11:12, Marvin Häuser wrote:
Ping? :)
On 16.08.21 15:10, Marvin Häuser wrote:
Hey Ray,
On 16/08/2021 11:42, Ni, Ray wrote:
Marvin,
So lucky to have you in the edk2 project looking into these
fundamentals!
Thank you. :)
+ #define ALIGNOF(TYPE) OFFSET_OF (struct { CHAR8 C; TYPE A; }, A)
1. Does struct{} inside a macro conform to C standard? How is the
compatibility with different compilers?
This should work, yes. The C standard defines offsetof as such:
"The macros are [...]
offsetof(type, member-designator)
which expands to an integer constant expression that has type size_t,
the value of
which is the offset in bytes, to the structure member (designated by
member-designator),
from the beginning of its structure (designated by type). The type
and member designator
shall be such that given
static type t;
then the expression &(t.member-designator) evaluates to an address
constant. [...]" [1]
If we plug in t:
static struct { CHAR8 C; TYPE A; } t;
we get a valid static storage duration variable declaration that
satisfies the the last condition because:
"An address constant is [...], a pointer to an lvalue designating an
object of static
storage duration, or [...]" [2]
It worked with all compilers I tinkered with at https://godbolt.org/
I sadly do not have access to any of the compilers where this may be
used effectively (RVCT, EBC).
+#define IS_POW2(Value) ((Value) != 0U && ((Value) & ((Value) -
1U)) ==
+0U)
2. Good to me. I learned this trick when implementing the MtrrLib.
+#define ALIGN_VALUE_ADDEND(Value, Alignment) (((Alignment) - (Value))
+& ((Alignment) - 1U))
3. Is any other open source project using the same macro for the
addend?
This is actually a general question to all new macros.
I would like the macros look familiar to developers from other open
source projects.
Good question, I never really saw it. I only came up with it because
for the new PE loader, we may align the PE memory within an
underaligned buffer, and for that we need the addend. I initially
used to align up and then subtract, but I saw this could be
simplified with ALIGN_VALUE_ADDEND, which was used in ALIGN_VALUE
anyway. If you have a better name, I'll change it.
Best regards,
Marvin
[1] ISO/IEC 9899:2011, 7.19, 3.
[2] ISO/IEC 9899:2011, 6.6, 9.
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