Added MLFQ scheduling, Fixed library dependencies issue

apps/echo/init.c

@@ -1,35 +1,37 @@
 #include "minilibc.h"
-
+long write(int fd, void *buf, unsigned long count);
 int main(void)
 {
 	char wmsg[]   = "Welcome to Echo program (written in C)!\n";
 	char prompt[] = "> ";
 	char token[512];
 	char key[2];
 	int i, p;
-
-	_printf(wmsg);
-	_printf(prompt);
+	write(1,wmsg,sizeof(wmsg));
+	write(1,prompt,sizeof(prompt));
 	p = 0;
 	while (1) {
 		/* Read a key */
-		if (read(0, key, 1) > 0) {
+		if(read(0,key,1)>0){
 			switch (key[0]) {
 				case '\r':
 				case '\n':
 					token[p] = '\0';
-					_printf("Echo: %s\n", token);
-					_printf(prompt);
+					int j = 0;
+					while (token[j] != '\0' && j < p) {
+						write(1, &token[j], 1);
+						j++;
+					}
+					write(1,&"\n",1);
+					write(1,prompt,sizeof(prompt));
 					p = 0;
 					break;
-
 				default:
 					token[p++] = key[0];
 			}
 		}
 	}
 
-	for(;;);
 	return 0;
 }
 

apps/echo/stdlib.c

@@ -27,30 +27,19 @@
 
 int atoi(const char *nptr)
 {
-	char *nstr = (char *)nptr;
-	char isneg = 0;
-	int sum    = 0;
-	int mult   = 1;
+    int res = 0; 
 
-	if(*nstr == '-') {
-		isneg = 1;
-		nstr++;
-	}
+    int sign = 1; 
 
-	while(*nstr++) {
-		if(*nstr && !isdigit(*nstr))
-			return(0);
-	}
+    int i = 0; 
 
-	nstr--;
-	while(nstr-- != (nptr + isneg)) {
-		sum  += (*nstr - '0') * mult;
-		mult *= 10;
-	}
+    if (nptr[0] == '-') { 
+        sign = -1; 
+        i++; 
+    } 
 
-	if(isneg)
-		return(sum * -1);
-	else
-		return(sum);
+    for (; nptr[i] != '\0'; ++i) 
+        res = res * 10 + nptr[i] - '0'; 
+    return sign * res;
 }