[libc-commits] [libc] [libc] Add `IN6_IS_ADDR_{LINK, SITE}LOCAL` (PR #168207)

[via libc-commits]

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@@ -33,4 +33,12 @@
 #define INET_ADDRSTRLEN 16
 #define INET6_ADDRSTRLEN 46
 
+#define IN6_IS_ADDR_LINKLOCAL(a)                                               \
+  ((__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[0]) == 0xfe &&            \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xc0) == 0x80)
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lntue wrote:

This is testing `byte 0 == 0xfe` and `byte 1 & mask == 80`, so assuming the high parts of 32-bit address `a`  are at byte 0 and 1, that's big endian.  Are we assuming `a` will be big endian, or does it depend on the host?

https://github.com/llvm/llvm-project/pull/168207