--- layout: fc_discuss_archives title: Message 29 from Frama-C-discuss on December 2009 ---
Boris, I think your function is similar to the following one (we called it fill_array). /*@ requires 0 <= length; requires \valid_range(a, 0, length-1); assigns a[0..length-1]; ensures \forall integer i; 0 <= i < length ==> a[i] == value; */ void fill_array (int* a, int length, int value ) { /*@ loop invariant 0 <= i <= length; loop assigns a[0..i-1]; loop invariant \forall integer k; 0 <= k < i ==> a[k] == value; */ for (int i = 0; i < length; i++) a[i] = value; } Simplify and Z3 can proof all 16 verification conditions. Regards Jens On Dec 2, 2009, at 5:13 PM, Hollas Boris (CR/AEY1) wrote: > This is a re-implementation of the memset function. It uses void-pointers as in C. > > typedef unsigned int size_t; > typedef unsigned char uint8; > > /*! > * \brief Standard Libc memset() function. > * \param[out] pDest Pointer to target buffer of length > * \a num bytes. > * \param[in] value Value to set in each byte of \a pDest. > * \param[in] num Number of bytes in \a pDest to > * set to \a value. > * \return Pointer to target buffer. > */ > > /*@ requires (\valid((uint8*)pDest +(0..num-1))) && > @ (0 <= value <= 255) && > @ (0 < num); > @ ensures (\forall int i; 0 <= i < num > @ ==> (((uint8*)pDest)[i] == value)) && > @ (\result == pDest); > @*/ > void *memset( void *pDest, const int value, const size_t num ) > { > size_t i; > > /*@ loop invariant \forall int k; 0 <= k < i > @ ==> ((uint8 *)pDest)[k] == (uint8)value; > @*/ > for( i=0; i < num; i++ ) > { > ((uint8 *)pDest)[i] = (uint8)value; > } > > return pDest; > } > > > > When I try to verify it, Jessie reports > > string.c:31:[jessie] user error: Casting from type struct char_P * to type struct unsigned_char_P * not allowed in logic > string.c:31:[jessie] warning: Dropping definition of function memset > string.c:19:[jessie] user error: Casting from type struct char_P * to type struct unsigned_char_P * not allowed in logic > [jessie] warning: Unsupported feature(s). > Jessie plugin can not be used on your code. > > > This error message puzzles me as there are no structs. Can a function that is equivalent to the memset function built into C be verified with Jessie? > > -Boris > > _______________________________________________ > Frama-c-discuss mailing list > Frama-c-discuss at lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/frama-c-discuss -- Dr.-Ing. Jens Gerlach http://www.first.fraunhofer.de/device_soft_en -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.gforge.inria.fr/pipermail/frama-c-discuss/attachments/20091202/995811a6/attachment-0001.htm