#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>

#define PRINT_ERRNO  printf("Errno = [%d] = [%s]\n", errno, strerror((errno)));

void clean_stdin(void)
{
    int c;
    do
    {
        c = getchar();
    }
    while (c != '\n' && c != EOF);
}

int UI_getLongHexa(char *chaine)
{
    char str[1000] = {0};   // buffer pour l'entree clavier
    char * endptr = NULL;
    long number = 0;

    // Nettoyer errno
    errno = 0;

    // Saisie utilisateur
    if(fgets(str, 1000, stdin) == NULL)
    {
        // Erreur lecture
        PRINT_ERRNO
        clean_stdin();
        return -1;
    }

    // Delete '\n' that "fgets()" puts at the end of "input"
    if( (endptr=strchr(str,'\n')) != NULL)
    {
        *endptr = '\0';
        endptr = NULL;
    }

    //Convertion
    number = strtol(str, &endptr, 16);
    if (   (str[0]!='\0')
        && (*endptr=='\0')
        && ((number!=LONG_MAX) || ((number==LONG_MAX) && (errno!=ERANGE)))
        && ((number!=LONG_MIN) || ((number==LONG_MIN) && (errno!=ERANGE))) )
    {
       strcpy(chaine, str);
       return 0; // nombre OK
    }
    else
    {
        PRINT_ERRNO
        return -2; // erreur de convertion
    }
}


unsigned long twoComplementOf(unsigned long nombre)
{
    #warning Potentiel depassement de format !
    return (~nombre+1);
}

int main(void)
{

    printf("-1 = %X\n\n", -1);

    puts("Entrer des nombres hexadecimaux : \n\n");
    char *str = malloc(1000);
    unsigned long number = -1;
    int isvalid = -1;

    while( number != 0 )
    {
        printf("0x");
        isvalid = UI_getLongHexa(str);

        if(isvalid==0)
        {
            printf("\tChaine valide obtenue = [%s]\n", str);

            number = strtol(str, NULL, 16); // on a deja verifie que la chaine est convertible

            // Traitement particulier pour les nombres negatifs
            if( !(str[0]>='0' && str[0]<'8') )
            {
                // Extend MSB
                switch(strlen(str))
                {
                    case(1):
                        number = 0xFFFFFFF0UL | number;
                        break;
                    case(2):
                        number = 0xFFFFFF00UL | number;
                        break;
                    case(3):
                        number = 0xFFFFF000UL | number;
                        break;
                    case(4):
                        number = 0xFFFF0000UL | number;
                        break;
                    case(5):
                        number = 0xFFF00000UL | number;
                        break;
                    case(6):
                        number = 0xFF000000UL | number;
                        break;
                    case(7):
                        number = 0xF0000000UL | number;
                        break;
                    case(8):
                        number = 0x00000000UL | number;
                        break;
                    default:
                        printf("WTF?\n");
                        number = 0;
                        break;
                }
                // Convertion
                printf("\tNombre apres extension : %lX\n", number);
                number = (long)twoComplementOf((unsigned long)number) * (-1); // fonction qui travaille sur des unsigned
            }

            // Affichage du resultat
            printf("=%ld\n\n", number);
        }
        else
        {
            number = -1;
            printf("\tInvalide !\n\n");
        }
    }

    puts(".......Fin");
    return 666;
}