src/rseq-alloc-utils.h

   1 // SPDX-License-Identifier: MIT
   2 // SPDX-FileCopyrightText: 2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3
   4 #ifndef _RSEQ_ALLOC_UTILS_H
   5 #define _RSEQ_ALLOC_UTILS_H
   6
   7 #define RSEQ_ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
   8
   9 #define __rseq_align_mask(v, mask)      (((v) + (mask)) & ~(mask))
  10 #define rseq_align(v, align)            __rseq_align_mask(v, (__typeof__(v)) (align) - 1)
  11
  12 static inline
  13 unsigned int rseq_fls_u64(uint64_t x)
  14 {
  15         unsigned int r = 64;
  16
  17         if (!x)
  18                 return 0;
  19
  20         if (!(x & 0xFFFFFFFF00000000ULL)) {
  21                 x <<= 32;
  22                 r -= 32;
  23         }
  24         if (!(x & 0xFFFF000000000000ULL)) {
  25                 x <<= 16;
  26                 r -= 16;
  27         }
  28         if (!(x & 0xFF00000000000000ULL)) {
  29                 x <<= 8;
  30                 r -= 8;
  31         }
  32         if (!(x & 0xF000000000000000ULL)) {
  33                 x <<= 4;
  34                 r -= 4;
  35         }
  36         if (!(x & 0xC000000000000000ULL)) {
  37                 x <<= 2;
  38                 r -= 2;
  39         }
  40         if (!(x & 0x8000000000000000ULL)) {
  41                 x <<= 1;
  42                 r -= 1;
  43         }
  44         return r;
  45 }
  46
  47 static inline
  48 unsigned int rseq_fls_u32(uint32_t x)
  49 {
  50         unsigned int r = 32;
  51
  52         if (!x)
  53                 return 0;
  54         if (!(x & 0xFFFF0000U)) {
  55                 x <<= 16;
  56                 r -= 16;
  57         }
  58         if (!(x & 0xFF000000U)) {
  59                 x <<= 8;
  60                 r -= 8;
  61         }
  62         if (!(x & 0xF0000000U)) {
  63                 x <<= 4;
  64                 r -= 4;
  65         }
  66         if (!(x & 0xC0000000U)) {
  67                 x <<= 2;
  68                 r -= 2;
  69         }
  70         if (!(x & 0x80000000U)) {
  71                 x <<= 1;
  72                 r -= 1;
  73         }
  74         return r;
  75 }
  76
  77 static inline
  78 unsigned int rseq_fls_ulong(unsigned long x)
  79 {
  80 #if RSEQ_BITS_PER_LONG == 32
  81         return rseq_fls_u32(x);
  82 #else
  83         return rseq_fls_u64(x);
  84 #endif
  85 }
  86
  87 /*
  88  * Return the minimum order for which x <= (1UL << order).
  89  * Return -1 if x is 0.
  90  */
  91 static inline
  92 int rseq_get_count_order_ulong(unsigned long x)
  93 {
  94         if (!x)
  95                 return -1;
  96
  97         return rseq_fls_ulong(x - 1);
  98 }
  99
 100 #define RSEQ_DEFAULT_PAGE_SIZE  4096
 101
 102 static inline
 103 long rseq_get_page_len(void)
 104 {
 105         long page_len = sysconf(_SC_PAGE_SIZE);
 106
 107         if (page_len < 0)
 108                 page_len = RSEQ_DEFAULT_PAGE_SIZE;
 109         return page_len;
 110 }
 111
 112 static inline
 113 int rseq_hweight_ulong(unsigned long v)
 114 {
 115         return __builtin_popcountl(v);
 116 }
 117
 118 #endif /* _RSEQ_ALLOC_UTILS_H */