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Turns out that shifting a negative signed int is undefined behavior in

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C, too.  Use other mechanism in case gcc decides to abuse that, too.
This commit is contained in:
leitner 2007-01-28 23:36:24 +00:00
parent 3e559e8d89
commit d3d6c828a9
1 changed files with 8 additions and 6 deletions
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14
rangecheck.h
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@ -68,15 +68,17 @@ int range_str4inbuf(const void* buf,size_t len,const void* stringstart);
* So I decided to add some integer overflow protection functionality
* here for addition and subtraction, too. */
/* first, we need a type independent way to find the min and max values
* for each type, so the macros also work for integer types you defined
* yourself */
/* two important assumptions:
* 1. the platform is using two's complement
* 2. there are 8 bits in a byte
*/
#define __MIN_UNSIGNED(type) ((type)0)
#define __MIN_SIGNED(type) (((type)-1)<<(sizeof(type)*8-1))
#define __HALF_MAX_SIGNED(type) ((type)1 << (sizeof(type)*8-2))
#define __MAX_SIGNED(type) (__HALF_MAX_SIGNED(type) - 1 + __HALF_MAX_SIGNED(type))
#define __MIN_SIGNED(type) (-1 - __MAX_SIGNED(type))
/* we use <1 and not <0 to avoid a gcc warning */
#define __MIN(type) ((type)-1 < 1?__MIN_SIGNED(type):__MIN_UNSIGNED(type))
#define __MIN(type) ((type)-1 < 1?__MIN_SIGNED(type):(type)0)
#define __MAX(type) ((type)~__MIN(type))
#define assign(dest,src) ({ typeof(src) __x=(src); typeof(dest) __y=__x; (__x==__y && ((__x<1) == (__y<1))?(void)((dest)=__y),0:1); })