2016-17 Programmi C - Revision history

FedericoB: /* Programs using libraries */ Added program using pipe.

2016-11-13T16:06:03Z

Programs using libraries: Added program using pipe.

FedericoB: /* Programs using libraries */ Added program using exit and wait.

2016-11-13T14:51:11Z

Programs using libraries: Added program using exit and wait.

FedericoB: /* Linux kernel (alike) lists */ Updated comments.

2016-10-28T14:02:24Z

Linux kernel (alike) lists: Updated comments.

FedericoB: /* Linux kernel (alike) lists */ Added program explanation and small improvement of output.

2016-10-28T07:58:44Z

Linux kernel (alike) lists: Added program explanation and small improvement of output.

FedericoB: /* A home-brewed mini-printf (variadic functions, indirect recursion) */ Added program comments.

2016-10-27T20:20:08Z

A home-brewed mini-printf (variadic functions, indirect recursion): Added program comments.

Show changes

FedericoB: /* conversions (math) */ Added program explanation of output.

2016-10-26T08:28:19Z

conversions (math): Added program explanation of output.

FedericoB: /* minishell (history and execs) */ Aggiunti commenti e spiegazione programma.

2016-10-25T10:35:19Z

minishell (history and execs): Aggiunti commenti e spiegazione programma.

FedericoB: /* fantasy of strcpy (time, stdint, string) */ Aggiunta keyword register anche a scan,

2016-10-25T07:28:12Z

fantasy of strcpy (time, stdint, string): Aggiunta keyword register anche a scan,

FedericoB: /* math and printf */ Aggiunti commenti al programma.

2016-10-21T19:47:21Z

math and printf: Aggiunti commenti al programma.

FedericoB: /* fantasy of strcpy (time, stdint, string) */ Aggiunti commenti.

2016-10-21T18:36:27Z

fantasy of strcpy (time, stdint, string): Aggiunti commenti.

@@ Line 1,329: / Line 1,329: @@
 #include <stdlib.h>
 #include <unistd.h>
-#include "sys/wait.h"
+#include <sys/wait.h>
 int main(int argc,char* argv[]) {
@@ Line 1,348: / Line 1,348: @@
 	printf("FINE\n");
+}
 </syntaxhighlight>

← Older revision		Revision as of 14:51, 13 November 2016
Line 1,323:		Line 1,323:
	</syntaxhighlight>		</syntaxhighlight>
	This list structure is declared to support multiple types. On listx.h only the pointer part is declared. It also use macro routine for creating "generic" code. The preprocessor transform the macro routine in real code depending one the data types used for the list.		This list structure is declared to support multiple types. On listx.h only the pointer part is declared. It also use macro routine for creating "generic" code. The preprocessor transform the macro routine in real code depending one the data types used for the list.
		+
		+	== Print child exit status ==
		+	<syntaxhighlight lang=C>
		+	#include <stdio.h>
		+	#include <stdlib.h>
		+	#include <unistd.h>
		+	#include "sys/wait.h"
		+
		+	int main(int argc,char* argv[]) {
		+	int status;
		+	//create a new child process
		+	switch (fork()) {
		+	case 0: //child
		+	//close the process and return as status the number given by argument
		+	exit(atoi(argv[1]));
		+	default: //parent
		+	break;
		+	case -1: //error case
		+	exit(1);
		+	}
		+	//wait for a child status change (like termination) and write it to a variable.
		+	wait(&status);
		+	printf("%d\n",WEXITSTATUS(status));
		+	printf("FINE\n");
		+	}
		+	</syntaxhighlight>

@@ Line 1,167: / Line 1,167: @@
 typedef unsigned int    size_tt;
-//macro for assiging a element of the list without knowing the type of the list
+//macro for obtaining a pointer to the struct given a member of it
 #define container_of(ptr, type, member) ({        \
                  const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
                  (type *)( (char *)__mptr - offsetof(type,member) );})
-//macro for obtaining the address of an element of the list witout knowing the type of the list
+//macro for obtaining the offset of a struct's member.
 #define offsetof(TYPE, MEMBER) ((size_tt) &((TYPE *)0)->MEMBER)

@@ Line 1,163: / Line 1,163: @@
 #ifndef _LISTX_H
 #define _LISTX_H
-−
 #define NULL 0
 typedef unsigned int    size_tt;
-#define container_of(ptr, type, member) ({                      \
+//macro for assiging a element of the list without knowing the type of the list
                  const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
                  (type *)( (char *)__mptr - offsetof(type,member) );})
 #define offsetof(TYPE, MEMBER) ((size_tt) &((TYPE *)0)->MEMBER)
-−
 struct list_head {
          struct list_head *next, *prev;
 };
-−
 #define LIST_HEAD_INIT(name) { &(name), &(name) }
-−
 #define LIST_HEAD(name) \
          struct list_head name = LIST_HEAD_INIT(name)
 static inline void INIT_LIST_HEAD(struct list_head *list)
+{
-         list->next = list;
+         //circular list, so when it's empty next and previus point to list
          list->prev = list;
+}
@@ Line 1,236: / Line 1,241: @@
                  return current->prev;
+}
-−
 #define list_for_each(pos, head) \
          for (pos = (head)->next; pos != (head); pos = pos->next)
-−
 #define list_for_each_prev(pos, head) \
          for (pos = (head)->prev; pos != (head); pos = pos->prev)
 #define list_for_each_entry(pos, head, member)                          \
          for (pos = container_of((head)->next, typeof(*pos), member);      \
          &pos->member != (head);        \
          pos = container_of(pos->member.next, typeof(*pos), member))
-−
 #define list_for_each_entry_reverse(pos, head, member)                  \
          for (pos = container_of((head)->prev, typeof(*pos), member);      \
          &pos->member != (head);        \
          pos = container_of(pos->member.prev, typeof(*pos), member))
-−
 #endif
 </syntaxhighlight>
@@ Line 1,261: / Line 1,267: @@
 #include "stdlib.h"
 #include "stdio.h"
-−
 // Elemento della lista
 typedef struct list_item {
@@ Line 1,267: / Line 1,273: @@
          struct list_head list;
 } list_item_t;
-−
-−
-−
 int main() {
-−
          list_item_t* elem1;
          list_item_t* elem2;
-−
          // Allocazione di memoria per 2 elementi di tipo list_item_t
          elem1=(list_item_t*) malloc(sizeof(list_item_t));
          elem2=(list_item_t*) malloc(sizeof(list_item_t));
-−
          elem1->item=3;
          elem2->item=5;
-−
          // Elemento sentinella
          struct list_head head;
-−
          //Inizializzazione dell'elemento sentinella
          INIT_LIST_HEAD(&head);
-−
          // Test di lista vuota
-         printf("Lista vuota? %d \n",list_empty(&head));
+         printf("Lista vuota? %s \n",list_empty(&head)?"sì":"no");
-−
          // Aggiunta di due elementi alla lista
          list_add(&(elem1->list),&head);
          list_add(&(elem2->list),&head);
-−
          // Test di lista vuota
-         printf("Lista vuota? %d \n",list_empty(&head));
+         printf("Lista vuota? %s \n",list_empty(&head)?"sì":"no");
-−
          // Scorrimento di Lista: Metodo 1
          list_item_t* pos;
@@ Line 1,303: / Line 1,309: @@
                  printf("Elemento corrente: %d \n",pos->item);
+         }
-−
          // Scorrimento di Lista: Metodo 2
          struct list_head* pos2;
@@ Line 1,309: / Line 1,315: @@
                  list_item_t* elem=container_of(pos2,list_item_t,list);
                  printf("Elemento corrente: %d \n",elem->item);
-−
+         }
-−
-−
          return 1;
+}
 </syntaxhighlight>

@@ Line 948: / Line 948: @@
    printf("%d %lx %ld\n", sizeof(l), l, l);
    printf("%d %llx %lld\n", sizeof(ll), ll, ll);
-−
    i = 1 << (sizeof(i) * 8 - 1);
    printf("%d %x %d\n", sizeof(i), i, i);
@@ Line 977: / Line 978: @@
    return 0;
+}
 </syntaxhighlight>

@@ Line 893: / Line 893: @@
 int main(int argc, char *argv[]) {
    while (1) {
      char *cmd = readline("% ");
      if (cmd == NULL)
        break;
      if (*cmd != 0) {
        add_history(cmd);
        system_nosh(cmd);
+     }
@@ Line 906: / Line 909: @@
+}
 </syntaxhighlight>
 == conversions (math) ==

@@ Line 799: / Line 799: @@
      //says to the compiler to keep tmp in a register
      register uint64_t tmp = *src64;
-     uint64_t scan;
+     register uint64_t scan;
      //detect if the current tmp cointans a 0 character
      for (scan = 0xffULL; (tmp & scan) != 0; scan <<= 8)

@@ Line 860: / Line 860: @@
 #include <unistd.h>
 #include <math.h>
-−
 #define DELAY 10000
 #define DURATION 30
-−
 int main(int argc, char *argv[]) {
    double x;
@@ Line 870: / Line 870: @@
      double y = sin(M_PI * i / 100);
      int pos = 40 + (40 * y);
      printf("\r%*s\b",pos,"*");
      fflush(stdout);
      usleep(DELAY);
      printf("\n");
@@ Line 877: / Line 880: @@
+}
 </syntaxhighlight>
 == minishell (history and execs) ==

@@ Line 731: / Line 731: @@
    int i;
    int len;
    for (len = 0; src[len] != 0; len++)
+     ;
    for (i = 0; i <= len; i++)
      dest[i] = src[i];
    return dest;
+}
-−
 char *strcpy1(char *dest, const char *src) {
    int i;
    for (i = 0; src[i] != 0; i++)
+     ;
    for ( ; i >= 0; i--)
      dest[i] = src[i];
    return dest;
+}
-−
 char *strcpy2(char *dest, const char *src) {
    char *rval = dest;
    while ((*dest++ = *src++) != 0)
+     ;
@@ Line 754: / Line 759: @@
+}
 char *strcpy3(char *dest, const char *src) {
    int i;
@@ Line 761: / Line 769: @@
+}
 char *strcpy4(char *dest, const char *src) {
    if ((*dest = *src) != 0)
@@ Line 767: / Line 778: @@
+}
 char *strcpy5(char *dest, const char *src) {
    char *rval = dest;
@@ Line 775: / Line 789: @@
+}
+/**
 char *strcpy6(char *dest, const char *src) {
    uint64_t *src64 = (uint64_t *) src;
    uint64_t *dest64 = (uint64_t *) dest;
    while (1) {
      register uint64_t tmp = *src64;
      uint64_t scan;
      for (scan = 0xffULL; (tmp & scan) != 0; scan <<= 8)
+       ;
-    //printf("%llx %llx %p %p %s\n",scan, tmp, src64, dest64, (char *) src64);
+      //printf("%llx %llx %p %p %s\n",scan, tmp, src64, dest64, (char *) src64);
      if (scan != 0) {
        strcpy2((char *) dest64, (char *) src64);
@@ Line 794: / Line 814: @@
    return dest;
+}
-−
 #define NUMBER_OF_TEST 1000000
-−
 double time_strcpy(char * (*cpy)(char *, const char *), char *d, const char *s)
+{
@@ Line 807: / Line 827: @@
      return (1.0) * time / CLOCKS_PER_SEC;
+}
+/**
 #define TESTSTRCPY(N,D,S) \
    printf("strcpy" #N " %s time %lf\n", strcpy ##N ((D),(S)), time_strcpy(strcpy ##N, (D),(S)))
-−
 int main(int argc, char *argv[]) {
    if (argc != 2)
@@ Line 830: / Line 852: @@
+}
 </syntaxhighlight>
 == math and printf ==