1 | /* Helper macros for pointer arithmetic. |
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2 | Copyright (C) 2012-2022 Free Software Foundation, Inc. |

3 | This file is part of the GNU C Library. |

4 | |

5 | The GNU C Library is free software; you can redistribute it and/or |

6 | modify it under the terms of the GNU Lesser General Public |

7 | License as published by the Free Software Foundation; either |

8 | version 2.1 of the License, or (at your option) any later version. |

9 | |

10 | The GNU C Library is distributed in the hope that it will be useful, |

11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |

12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |

13 | Lesser General Public License for more details. |

14 | |

15 | You should have received a copy of the GNU Lesser General Public |

16 | License along with the GNU C Library; if not, see |

17 | <https://www.gnu.org/licenses/>. */ |

18 | |

19 | #ifndef _LIBC_POINTER_ARITH_H |

20 | #define _LIBC_POINTER_ARITH_H 1 |

21 | |

22 | #include <stdint.h> |

23 | |

24 | /* 1 if 'type' is a pointer type, 0 otherwise. */ |

25 | # define __pointer_type(type) (__builtin_classify_type ((type) 0) == 5) |

26 | |

27 | /* intptr_t if P is true, or T if P is false. */ |

28 | # define __integer_if_pointer_type_sub(T, P) \ |

29 | __typeof__ (*(0 ? (__typeof__ (0 ? (T *) 0 : (void *) (P))) 0 \ |

30 | : (__typeof__ (0 ? (intptr_t *) 0 : (void *) (!(P)))) 0)) |

31 | |

32 | /* intptr_t if EXPR has a pointer type, or the type of EXPR otherwise. */ |

33 | # define __integer_if_pointer_type(expr) \ |

34 | __integer_if_pointer_type_sub(__typeof__ ((__typeof__ (expr)) 0), \ |

35 | __pointer_type (__typeof__ (expr))) |

36 | |

37 | /* Cast an integer or a pointer VAL to integer with proper type. */ |

38 | # define cast_to_integer(val) ((__integer_if_pointer_type (val)) (val)) |

39 | |

40 | /* Cast an integer VAL to void * pointer. */ |

41 | # define cast_to_pointer(val) ((void *) (uintptr_t) (val)) |

42 | |

43 | /* Align a value by rounding down to closest size. |

44 | e.g. Using size of 4096, we get this behavior: |

45 | {4095, 4096, 4097} = {0, 4096, 4096}. */ |

46 | #define ALIGN_DOWN(base, size) ((base) & -((__typeof__ (base)) (size))) |

47 | |

48 | /* Align a value by rounding up to closest size. |

49 | e.g. Using size of 4096, we get this behavior: |

50 | {4095, 4096, 4097} = {4096, 4096, 8192}. |

51 | |

52 | Note: The size argument has side effects (expanded multiple times). */ |

53 | #define ALIGN_UP(base, size) ALIGN_DOWN ((base) + (size) - 1, (size)) |

54 | |

55 | /* Same as ALIGN_DOWN(), but automatically casts when base is a pointer. */ |

56 | #define PTR_ALIGN_DOWN(base, size) \ |

57 | ((__typeof__ (base)) ALIGN_DOWN ((uintptr_t) (base), (size))) |

58 | |

59 | /* Same as ALIGN_UP(), but automatically casts when base is a pointer. */ |

60 | #define PTR_ALIGN_UP(base, size) \ |

61 | ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size))) |

62 | |

63 | /* Check if BASE is aligned on SIZE */ |

64 | #define PTR_IS_ALIGNED(base, size) \ |

65 | ((((uintptr_t) (base)) & (size - 1)) == 0) |

66 | |

67 | /* Returns the ptrdiff_t diference between P1 and P2. */ |

68 | #define PTR_DIFF(p1, p2) \ |

69 | ((ptrdiff_t)((uintptr_t)(p1) - (uintptr_t)(p2))) |

70 | |

71 | #endif |

72 |