gallium: Fix uninitialized variable warning in compute test.
[mesa.git] / src / gallium / auxiliary / os / os_memory_aligned.h
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27
28
29 /*
30 * Memory alignment wrappers.
31 */
32
33
34 #ifndef _OS_MEMORY_H_
35 #error "Must not be included directly. Include os_memory.h instead"
36 #endif
37
38
39 #include "pipe/p_compiler.h"
40
41
42
43 /**
44 * Add two size_t values with integer overflow check.
45 * TODO: leverage __builtin_add_overflow where available
46 */
47 static inline bool
48 add_overflow_size_t(size_t a, size_t b, size_t *res)
49 {
50 *res = a + b;
51 return *res < a || *res < b;
52 }
53
54
55 /**
56 * Return memory on given byte alignment
57 */
58 static inline void *
59 os_malloc_aligned(size_t size, size_t alignment)
60 {
61 char *ptr, *buf;
62 size_t alloc_size;
63
64 /*
65 * Calculate
66 *
67 * alloc_size = size + alignment + sizeof(void *)
68 *
69 * while checking for overflow.
70 */
71 if (add_overflow_size_t(size, alignment, &alloc_size) ||
72 add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
73 return NULL;
74 }
75
76 ptr = (char *) os_malloc(alloc_size);
77 if (!ptr)
78 return NULL;
79
80 buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
81 *(char **)(buf - sizeof(void *)) = ptr;
82
83 return buf;
84 }
85
86
87 /**
88 * Free memory returned by os_malloc_aligned().
89 */
90 static inline void
91 os_free_aligned(void *ptr)
92 {
93 if (ptr) {
94 void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
95 void *realAddr = *cubbyHole;
96 os_free(realAddr);
97 }
98 }