X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fshared%2Fmacro.h;h=179b24c9838971d1609d1ce74d027f497ea55801;hb=cf8bd44339b00330fdbc91041d6731ba8aba9fec;hp=70c5fb50a74b9ab49a9eb4823a8fd9e3f4be884f;hpb=7df23077e45e55a6fc15eb99fe2ae439678e37e0;p=elogind.git

diff --git a/src/shared/macro.h b/src/shared/macro.h
index 70c5fb50a..179b24c98 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -133,46 +133,55 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
                 })
 
 #undef MAX
-#define MAX(a,b)                                 \
-        __extension__ ({                         \
-                        typeof(a) _a = (a);      \
-                        typeof(b) _b = (b);      \
-                        _a > _b ? _a : _b;       \
+#define MAX(a,b)                                        \
+        __extension__ ({                                \
+                        const typeof(a) _a = (a);       \
+                        const typeof(b) _b = (b);       \
+                        _a > _b ? _a : _b;              \
                 })
 
-#define MAX3(x,y,z)                              \
-        __extension__ ({                         \
-                        typeof(x) _c = MAX(x,y); \
-                        MAX(_c, z);              \
+/* evaluates to (void) if _A or _B are not constant or of different types */
+#define CONST_MAX(_A, _B) \
+        __extension__ (__builtin_choose_expr(                           \
+                __builtin_constant_p(_A) &&                             \
+                __builtin_constant_p(_B) &&                             \
+                __builtin_types_compatible_p(typeof(_A), typeof(_B)),   \
+                ((_A) > (_B)) ? (_A) : (_B),                            \
+                (void)0))
+
+#define MAX3(x,y,z)                                     \
+        __extension__ ({                                \
+                        const typeof(x) _c = MAX(x,y);  \
+                        MAX(_c, z);                     \
                 })
 
 #undef MIN
-#define MIN(a,b)                                \
-        __extension__ ({                        \
-                        typeof(a) _a = (a);     \
-                        typeof(b) _b = (b);     \
-                        _a < _b ? _a : _b;      \
+#define MIN(a,b)                                        \
+        __extension__ ({                                \
+                        const typeof(a) _a = (a);       \
+                        const typeof(b) _b = (b);       \
+                        _a < _b ? _a : _b;              \
                 })
 
-#define MIN3(x,y,z)                              \
-        __extension__ ({                         \
-                        typeof(x) _c = MIN(x,y); \
-                        MIN(_c, z);              \
+#define MIN3(x,y,z)                                     \
+        __extension__ ({                                \
+                        const typeof(x) _c = MIN(x,y);  \
+                        MIN(_c, z);                     \
                 })
 
-#define LESS_BY(A,B)                            \
-        __extension__ ({                        \
-                        typeof(A) _A = (A);     \
-                        typeof(B) _B = (B);     \
-                        _A > _B ? _A - _B : 0;  \
+#define LESS_BY(A,B)                                    \
+        __extension__ ({                                \
+                        const typeof(A) _A = (A);       \
+                        const typeof(B) _B = (B);       \
+                        _A > _B ? _A - _B : 0;          \
                 })
 
 #ifndef CLAMP
 #define CLAMP(x, low, high)                                             \
         __extension__ ({                                                \
-                        typeof(x) _x = (x);                             \
-                        typeof(low) _low = (low);                       \
-                        typeof(high) _high = (high);                    \
+                        const typeof(x) _x = (x);                       \
+                        const typeof(low) _low = (low);                 \
+                        const typeof(high) _high = (high);              \
                         ((_x > _high) ? _high : ((_x < _low) ? _low : _x)); \
                 })
 #endif
@@ -241,6 +250,9 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
 #define PTR_TO_UINT64(p) ((uint64_t) ((uintptr_t) (p)))
 #define UINT64_TO_PTR(u) ((void *) ((uintptr_t) (u)))
 
+#define PTR_TO_SIZE(p) ((size_t) ((uintptr_t) (p)))
+#define SIZE_TO_PTR(u) ((void *) ((uintptr_t) (u)))
+
 #define memzero(x,l) (memset((x), 0, (l)))
 #define zero(x) (memzero(&(x), sizeof(x)))