Fixing ATOI function and GRUB2 Crashing

apps/echo/stdlib.c

@@ -27,30 +27,26 @@
 
 int atoi(const char *nptr)
 {
-	char *nstr = (char *)nptr;
-	char isneg = 0;
-	int sum    = 0;
-	int mult   = 1;
+	int sum = 0; 
 
-	if(*nstr == '-') {
-		isneg = 1;
-		nstr++;
-	}
+    int sign = 0; 
 
-	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++; 
+    } 
+
+	while(nptr[i] != '\0'){
+		if(!(nptr[i]>='0' && nptr[i]<='9'))
+			return __INT32_MAX__;
+        sum = (sum * 10) + (nptr[i] - '0'); 
+		++i;
 	}
 
-	if(isneg)
-		return(sum * -1);
-	else
-		return(sum);
+	if(sign==1)
+    	return (-1) * sum;
+	return sum;
 }
 

apps/time/Makefile

@@ -0,0 +1,25 @@
+##
+# Makefile for calc.
+#
+CC=gcc
+CFLAGS=-m32 -Os -mpush-args -fno-pie -fomit-frame-pointer -fno-builtin -nostartfiles -nostdlib -nodefaultlibs
+AS=as
+LD=ld
+OUTPUT=time
+
+OBJECTS=crt0.o syscalls.o printf.o stdlib.o time.o
+
+all: $(OBJECTS)
+	$(LD) $(OBJECTS) -melf_i386 -Ttext=C0000C --oformat=binary -o $(OUTPUT)
+	#$(LD) $(OBJECTS) -melf_i386 -o $(OUTPUT)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $<
+
+%.o: %.s
+	$(AS) --32 $< -o $@
+
+clean:
+	@rm $(OBJECTS) || true
+	@[ -f $(OUTPUT) ] && rm $(OUTPUT) || true
+

apps/time/crt0.s

@@ -0,0 +1,9 @@
+.global _start,main
+
+.text
+_start:
+	call main
+
+loop:
+	jmp loop
+

apps/time/minilibc.h

@@ -0,0 +1,18 @@
+
+#ifndef _MINILIBC
+#define _MINILIBC
+
+#include "stdarg.h"
+
+#define CHECK_BIT(a, b)		((a >> b) & 0x01)
+#define SET_BIT(a, b)		a |= (0x01 << b)
+
+long write(int fd, void *buf, unsigned long count);
+long read(int fd, void *buf, unsigned long count);
+int vsprintf(char *str, const char *format, va_list ap);
+int sprintf(char *str, const char *format, ...);
+int _printf(const char *format, ...);
+int atoi(const char *nptr);
+
+#endif
+