diff --git a/include/video.h b/include/video.h
index 34e79a2..0877148 100755
--- a/include/video.h
+++ b/include/video.h
@@ -1,6 +1,9 @@
 /*******************************************************************************/
 /* COS2000 - Compatible Operating System - LGPL v3 - Hordé Nicolas             */
 /*                                                                             */
+
+#include "stdarg.h"
+
 typedef struct console {
   u8 attrib;
   s16 cursX;
@@ -22,3 +25,4 @@ u8* itoa(u64 num, u8* str, u8 base, u64 dim, u8 achar);
 u8* sitoa(u64 num, u8 * str, u64 dim);
 u8* rtoadouble(double num, u8 * str, u8 precisioni , u8 precisionf);
 u8* rtoasingle(float num, u8 * str, u8 precisioni , u8 precisionf);
+u32 format(const u8 * string, va_list args, u32 (*fonction)(u8* src, u8** dest, u32 len), u8* dest);
diff --git a/lib/multiboot.c b/lib/multiboot.c
index 019c9fc..0a78df2 100644
--- a/lib/multiboot.c
+++ b/lib/multiboot.c
@@ -28,7 +28,7 @@ for (tag = (struct multiboot_tag *) (addr + 8);
             tag->type != MULTIBOOT_TAG_TYPE_END;
             tag = (struct multiboot_tag *) ((u8 *) tag + ((tag->size + 7) & ~7)))
          {
-           printf ("--- Tag % 4u, Taille % 4u\r\n", tag->type, tag->size);
+           printf ("--- Tag % hu, Taille % hu\r\n", tag->type, tag->size);
            switch (tag->type)
              {
              case MULTIBOOT_TAG_TYPE_CMDLINE:
@@ -51,7 +51,7 @@ for (tag = (struct multiboot_tag *) (addr + 8);
                        ((u64)((struct multiboot_tag_basic_meminfo *) tag)->mem_upper)<<10);
                break;
              case MULTIBOOT_TAG_TYPE_BOOTDEV:
-               printf ("Peripherique de demarrage : %x,%u,%u\r\n\r\n",
+               printf ("Peripherique de demarrage : %X,%u,%u\r\n\r\n",
                        ((struct multiboot_tag_bootdev *) tag)->biosdev,
                        ((struct multiboot_tag_bootdev *) tag)->slice,
                        ((struct multiboot_tag_bootdev *) tag)->part);
@@ -62,7 +62,7 @@ for (tag = (struct multiboot_tag *) (addr + 8);
                  printf ("*** Plan de memoire ***\r\n");
                  for (mmap = ((struct multiboot_tag_mmap *) tag)->entries;(u8 *) mmap < (u8 *) tag + tag->size; mmap = (multiboot_memory_map_t *)
                         ((unsigned long) mmap + ((struct multiboot_tag_mmap *) tag)->entry_size))
-                   printf (" adresse: %lx,"" taille:%lx, type:%x\r\n",
+                   printf (" adresse: %lX,"" taille:%lX, type:%X\r\n",
                            (u64) (mmap->addr),
                            (u64) (mmap->len),
                            (u32) (mmap->type));
diff --git a/lib/shell.c b/lib/shell.c
index 0747ce2..205efde 100644
--- a/lib/shell.c
+++ b/lib/shell.c
@@ -224,28 +224,29 @@ int readidt()
 		u32 offset =
 		    desc[index].offset0_15 + (desc[index].offset16_31 << 16);
 		u32 type = desc[index].type & 0x0F00;
-        u8 *type2;
+        u8 *typestr1, *typestr2;
         if (i>=32 & i<=39)
-            type2="IRQ master";
+            typestr1="IRQ master";
         else if (i>=96 & i<=103)
-            type2="IRQ slave ";
+            typestr1="IRQ slave ";
         else if (i<19)
-            type2="EXCEPTION ";    
+            typestr1="EXCEPTION ";    
         else
-            type2="INTERRUPT ";
-		printf("\r\%s % hu %hY:%Y - ", type2,i++, select, offset, type);
+            typestr1="INTERRUPT ";
 		if (type == INTGATE)
-			print("INTGATE");
+			typestr2="INTGATE";
 		else if (type == TRAPGATE)
-			print("TRAPGATE");
+			typestr2="TRAPGATE";
 		else if (type == TASKGATE)
-			print("TASKGATE");
+			typestr2="TASKGATE";
 		else if (type == CALLGATE)
-			print("CALLGATE");
+			typestr2="CALLGATE";
 		else if (type == LDTDES)
-			print("LDTDES");
+			typestr2="LDTDES";
 		else
 			print("inconnu");
+		printf("%s % hu %hY:%Y - %s\r\n", typestr1, i++, select, offset, typestr2);
+
 		if (i % 32 == 0) {
 			print("\r\n<Appuyez sur une touche>\r\n");
 			waitascii();
diff --git a/lib/video.c b/lib/video.c
index 230da08..8af9d69 100755
--- a/lib/video.c
+++ b/lib/video.c
@@ -299,13 +299,54 @@ u32 print(u8 * string)
 }
 
 /*******************************************************************************/
-/* affiche une chaine de caractère formaté a l'ecran */
+/* Fonction d'affichage (pour printf) */
 
-#define buffersize 1024
+u32 printstr(u8* src, u8** dest, u32 len) {
+	for(u32 i=0;i<len;i++)
+		putchar(*(src++));
+	return len;
+}
+
+/*******************************************************************************/
+/* Fonction d'enregistrement dans une variable (pour sprintf) */
+
+u32 storestr(u8* src, u8** dest, u32 len) {
+    memcpy(src, *dest, len, 1);
+    *dest=*dest+len;
+    return len;
+}
+
+/*******************************************************************************/
+/* affiche une chaine de caractère formaté a l'ecran */
 
 u32 printf(const u8 * string, ...)
 {
-	va_list args,argstemp;
+	va_list args;
+	va_start(args, string);
+    format(string, args, &printstr, NULL);
+    va_end(args);
+}
+
+/*******************************************************************************/
+/* met une chaine de caractère formaté dans une variable */
+
+u32 sprintf(u8 *variable, const u8 *string, ...)
+{
+	va_list args;
+	va_start(args, string);
+
+    format(string, args, &storestr, variable);
+    va_end(args);
+}
+
+
+/*******************************************************************************/
+/* affiche une chaine de caractère formaté a l'ecran */
+
+#define maxsize 1024
+
+u32 format(const u8 * string, va_list args, u32 (*fonction)(u8* src, u8** dest, u32 len), u8* dest)
+{
 	u64 sizes[] = { 0xFF, 0xFFFF, 0xFFFFFFFF, 0xFFFFFFFFFFFFFFFF };
 	u8 units[][4] = { "o\000\000", "kio", "mio", "gio", "tio", "pio" };
 	u8 strbase2[] = "0xb\000";
@@ -314,17 +355,18 @@ u32 printf(const u8 * string, ...)
 	u8 hexadecimal[] = "*0x\000";
 	u8 achar, temp;
 	u8 asize, charadd, unit, precisioni, precisionf;
-	u8 buffer[buffersize];
+	u8 buffer[maxsize];
+    u8* bufferend;
+    u32 buffersize;
 	u8 *str = string;
 	u8 *strtemp;
 	u32 i = 0, counter = 0;
 	u64 num;
 	bool flag = false, intok = false, decok = false;
 
-	va_start(args, string);
 	for (achar = *str; achar != '\000'; i++, achar = *(str + i)) {
 		if (achar != '%' && !flag) {
-			putchar(achar);
+			fonction((str + i),&dest,1);
 			counter++;
 			asize = 2;
             precisioni = 0;
@@ -412,10 +454,11 @@ u32 printf(const u8 * string, ...)
                     break;
                 }
                 else if (asize==2)
-                    rtoasingle((float)va_arg(args, double), &buffer, precisioni, precisionf);
+                    bufferend=rtoasingle((float)va_arg(args, double), &buffer, precisioni, precisionf);
                 else
-                    rtoadouble((double)va_arg(args, double), &buffer, precisioni, precisionf);
-				counter += print(&buffer);
+                    bufferend=rtoadouble((double)va_arg(args, double), &buffer, precisioni, precisionf);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 'u':
@@ -429,8 +472,9 @@ u32 printf(const u8 * string, ...)
                     num = (u64) va_arg(args, u64);
 				if (charadd == 0xFF)
 					charadd = '0';
-				itoa(num, &buffer, 10, sizes[asize], charadd);
-				counter += print(&buffer);
+				bufferend=itoa(num, &buffer, 10, sizes[asize], charadd);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 'o':
@@ -444,14 +488,15 @@ u32 printf(const u8 * string, ...)
                     num = (u64) va_arg(args, u64);
 				if (charadd == 0xFF)
 					charadd = '0';
-				itoa(num, &buffer, 8, sizes[asize], charadd);
-				print(&strbase8);
-				counter += print(&buffer) + 1;
+				counter += fonction(&strbase8,&dest,1);
+				bufferend=itoa(num, &buffer, 8, sizes[asize], charadd);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 'c':
-				temp = (u8) va_arg(args, int);
-				putchar(temp);
+				temp = (u8) va_arg(args, u8);
+			    fonction(&temp,string,1);
 				counter++;
 				flag = false;
 				break;
@@ -472,9 +517,10 @@ u32 printf(const u8 * string, ...)
                     num=num>>10;
                     unit++;
                 }   
-				sitoa(num, &buffer, sizes[asize]);
-				counter += print(&buffer);
-                print(units[unit]);
+				bufferend=sitoa(num, &buffer, sizes[asize]);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
+				counter += fonction(units[unit],&dest,3);
 				flag = false;
 				break;
 			case 'd':
@@ -489,22 +535,24 @@ u32 printf(const u8 * string, ...)
                     num = (u64) va_arg(args, u64);
 				if (charadd == 0xFF)
 					charadd = ' ';
-				sitoa(num, &buffer, sizes[asize]);
-				counter += print(&buffer);
+				bufferend=sitoa(num, &buffer, sizes[asize]);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 's':
 				strtemp = (u8 *) va_arg(args, u8 *);
-				counter += print(strtemp);
+				counter += fonction(strtemp,&dest,strlen(strtemp));
 				flag = false;
 				break;
 			case 'p':
 				num = (u32) va_arg(args, int);
 				if (charadd == 0xFF)
 					charadd = '0';
-				print(&hexadecimal);
-				itoa(num, buffer, 16, sizes[asize], '0');
-				counter += print(&buffer) + 2;
+                counter += fonction(&hexadecimal,&dest,3);
+				bufferend=itoa(num, &buffer, 16, sizes[asize], '0');
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 'x':
@@ -521,11 +569,12 @@ u32 printf(const u8 * string, ...)
                     num = (u64) va_arg(args, u64);
 				if (charadd == 0xFF)
 					charadd = '0';
-				itoa(num, &buffer, 16, sizes[asize], charadd);
+				if (achar == 'X') counter += fonction(&strbase16,&dest,2);
+				bufferend=itoa(num, &buffer, 16, sizes[asize], charadd);
+                buffersize=bufferend-&buffer[0];
 				if (achar == 'X'||achar == 'Y')
 					strtoupper(&buffer);
-				if (achar == 'X') print(&strbase16);
-				counter += print(&buffer) + 1;
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			case 'b':
@@ -539,9 +588,10 @@ u32 printf(const u8 * string, ...)
                     num = (u64) va_arg(args, u64);
 				if (charadd == 0xFF)
 					charadd = '0';
-				itoa(num, &buffer, 2, sizes[asize], charadd);
-				print(&strbase2);
-				counter += print(&buffer) + 1;
+                counter += fonction(&strbase2,&dest,2);
+				bufferend=itoa(num, &buffer, 2, sizes[asize], charadd);
+                buffersize=bufferend-&buffer[0];
+				counter += fonction(&buffer,&dest,buffersize);
 				flag = false;
 				break;
 			default:
@@ -549,7 +599,7 @@ u32 printf(const u8 * string, ...)
 			}
 		}
 	}
-	va_end(args);
+    
 	return counter;
 }
 
@@ -562,6 +612,9 @@ u8 *rtoadouble(double num, u8 * str, u8 precisioni , u8 precisionf) {
   u8 i,j,integerpart,fracpart;
   if (precisioni==0) precisioni=12;
   if (precisionf==0) precisionf=8;  
+  double round=0.5;
+  for (i=0;i<precisionf;i++) round/=10;
+  num+=round;
   bool intok=false;     
   if (num<0) {                                                  
       num=-num;
diff --git a/system/system.c b/system/system.c
index 52b4871..799ca0e 100755
--- a/system/system.c
+++ b/system/system.c
@@ -50,7 +50,7 @@ int main(u32 magic, u32 addr)
 	/*  Efface l'ecran   */
 
 	print("\033[2J\000");
-	printf(ansilogo);
+	print(ansilogo);
 
 	print("\033[37m\033[0m -Chargement noyaux");
 	ok();
@@ -106,9 +106,11 @@ int main(u32 magic, u32 addr)
 	printf(" -Installation des appels systemes utilisateur");
 	initsyscall();
 	ok();
+    static u8 tester[]="ceci est un test";
+    static u8 strings[255];
+    sprintf(&strings," pour voir : %u %d %f %s",123456789,-2522,3.14f,tester);
+    print(&strings);
 
-    float test=-12101412121212121212.5555555555555555f; 
-	printf(" -Test float & double :\r\n %e \r\n %f\r\n %1.2f\r\n %.2f\r\n %4.1f\r\n %10.5f\r\n %6f\r\n %8f",test,test,test,test,test,test,test,test);
 retry:
 	shell();
 }