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| author | Nick Mathewson <nickm@torproject.org> | 2018-06-29 10:23:52 -0400 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2018-06-29 12:21:52 -0400 |
| commit | 207fc4cffe21b58b7f0447706a903e5f66b8bcd8 (patch) | |
| tree | 227fddeea8281eac9b95a351c4f733ada1906034 /src/lib/cc | |
| parent | 77bc65bbc495095d4d2679631e06a498ea1e2529 (diff) | |
| download | tor-207fc4cffe21b58b7f0447706a903e5f66b8bcd8.tar.gz tor-207fc4cffe21b58b7f0447706a903e5f66b8bcd8.zip | |
Move SUBTYPE_P into compat_compiler.h
Diffstat (limited to 'src/lib/cc')
| -rw-r--r-- | src/lib/cc/compat_compiler.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/lib/cc/compat_compiler.h b/src/lib/cc/compat_compiler.h index 67d945cfaf..c631a7e821 100644 --- a/src/lib/cc/compat_compiler.h +++ b/src/lib/cc/compat_compiler.h @@ -253,6 +253,18 @@ */ #define STRUCT_VAR_P(st, off) ((void*) ( ((char*)(st)) + (off) ) ) +/** Macro: yield a pointer to an enclosing structure given a pointer to + * a substructure at offset <b>off</b>. Example: + * <pre> + * struct base { ... }; + * struct subtype { int x; struct base b; } x; + * struct base *bp = &x.base; + * struct *sp = SUBTYPE_P(bp, struct subtype, b); + * </pre> + */ +#define SUBTYPE_P(p, subtype, basemember) \ + ((void*) ( ((char*)(p)) - offsetof(subtype, basemember) )) + /** Macro: Yields the number of elements in array x. */ #define ARRAY_LENGTH(x) ((sizeof(x)) / sizeof(x[0])) |