mirror of
https://github.com/git/git.git
synced 2024-05-23 13:46:09 +02:00
add SWAP macro
Add a macro for exchanging the values of variables. It allows users to avoid repetition and takes care of the temporary variable for them. It also makes sure that the storage sizes of its two parameters are the same. Its memcpy(1) calls are optimized away by current compilers. Also add a conservative semantic patch for transforming only swaps of variables of the same type. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
parent
4e59582ff7
commit
568edcb95a
|
@ -0,0 +1,28 @@
|
|||
@ swap_with_declaration @
|
||||
type T;
|
||||
identifier tmp;
|
||||
T a, b;
|
||||
@@
|
||||
- T tmp = a;
|
||||
+ T tmp;
|
||||
+ tmp = a;
|
||||
a = b;
|
||||
b = tmp;
|
||||
|
||||
@ swap @
|
||||
type T;
|
||||
T tmp, a, b;
|
||||
@@
|
||||
- tmp = a;
|
||||
- a = b;
|
||||
- b = tmp;
|
||||
+ SWAP(a, b);
|
||||
|
||||
@ extends swap @
|
||||
identifier unused;
|
||||
@@
|
||||
{
|
||||
...
|
||||
- T unused;
|
||||
... when != unused
|
||||
}
|
|
@ -527,6 +527,16 @@ static inline int ends_with(const char *str, const char *suffix)
|
|||
return strip_suffix(str, suffix, &len);
|
||||
}
|
||||
|
||||
#define SWAP(a, b) do { \
|
||||
void *_swap_a_ptr = &(a); \
|
||||
void *_swap_b_ptr = &(b); \
|
||||
unsigned char _swap_buffer[sizeof(a)]; \
|
||||
memcpy(_swap_buffer, _swap_a_ptr, sizeof(a)); \
|
||||
memcpy(_swap_a_ptr, _swap_b_ptr, sizeof(a) + \
|
||||
BUILD_ASSERT_OR_ZERO(sizeof(a) == sizeof(b))); \
|
||||
memcpy(_swap_b_ptr, _swap_buffer, sizeof(a)); \
|
||||
} while (0)
|
||||
|
||||
#if defined(NO_MMAP) || defined(USE_WIN32_MMAP)
|
||||
|
||||
#ifndef PROT_READ
|
||||
|
|
Loading…
Reference in New Issue