Add afterpoint argument in ftoa function

Author: DreamPearl

src/usr/include/stdlib.h

@@ -13,7 +13,7 @@ int atoi(const char *s);
 // for others the result can be undefined.
 // And only base 10 is considered as signed int.
 void itoa(int num, char *s, int base);
-void ftoa(double num, char *s);
+void ftoa(double num, char *s, int afterpoint);
 int min(int, int);
 int max(int, int);
 int abs(int a);

src/usr/lib/stdio.c

@@ -61,7 +61,7 @@ static int vsnprintf(char *s, size_t n, const char *fmt, va_list args) {
             }
             break;
         case 'f':
-            ftoa(va_arg(args, double), sbuffer);
+            ftoa(va_arg(args, double), sbuffer, 8);
             innerstr = sbuffer;
             while (len < n && (*innerstr) != '\0') {
                 s[len++] = *(innerstr++);

src/usr/lib/stdlib.c

@@ -67,7 +67,7 @@ void itoa(int num, char *s, int base) {
     }
 }
 
-void ftoa(double num, char *s) {
+void ftoa(double num, char *s, int afterpoint) {
     // not a good implementation
     if (isnan(num)) {
         *(s++) = 'n';
@@ -98,7 +98,7 @@ void ftoa(double num, char *s) {
     *(s++) = '0';
     *(s++) = '.';
 
-    for (int i = 0; i < 8; i++) {
+    for (int i = 0; i < afterpoint; i++) {
         num *= 10;
         int msb = num;
         *(s++) = '0' + msb;