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finish Frama-C homework

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This commit is contained in:
Yorick Barbanneau 2023-05-09 21:48:51 +02:00
parent 97a81f159a
commit 0bbf6ffde1
8 changed files with 142 additions and 24 deletions
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31
content/conception_formelle/99-DM_framac/code/test.c Normal file
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#include <limits.h>
#include "abs.h"
/*@
requires 0 < n < INT_MAX;
requires \valid_read(tab+(0..n-1));
requires \forall integer a,b; 0 <= a < b < n ==> tab[a] - tab[b] <= INT_MAX;
ensures \forall integer a,b; 0 <= a < b < n ==> \result >= abs(tab[a]-tab[b]);
*/
int max_dist ( int *tab, int n)
{
int max = tab[0];
int min = tab[0];
unsigned int i = 1;
/*@
loop assigns i, max, min;
loop invariant I1: \at(i, LoopEntry) <= i <= n;
loop invariant I2: min <= max;
loop invariant I3: \forall integer j; (\at(i, LoopEntry) <= j < i ==> max >= tab[j] >= min);
loop variant n - i;
*/
while ( i < n)
{
if ( tab[i] > max) max = tab[i];
if ( tab[i] < min) min = tab[i];
i++;
}
//@ assert INT_MIN <= max <= INT_MAX;
//@ assert INT_MIN <= min <= INT_MAX;
return max - min;
}