From 0d630c9ee349a87b92c1fe7c1974ae1ef16708d4 Mon Sep 17 00:00:00 2001
From: Eric Kohl <eric.kohl@reactos.org>
Date: Sat, 27 Nov 1999 11:32:43 +0000
Subject: [PATCH] added atoi() and atol()

svn path=/trunk/; revision=802
---
 reactos/ntoskrnl/rtl/stdlib.c | 74 +++++++++++++++++++++++++++++++++--
 1 file changed, 71 insertions(+), 3 deletions(-)

diff --git a/reactos/ntoskrnl/rtl/stdlib.c b/reactos/ntoskrnl/rtl/stdlib.c
index 699045f92b9..95c7e838c9f 100644
--- a/reactos/ntoskrnl/rtl/stdlib.c
+++ b/reactos/ntoskrnl/rtl/stdlib.c
@@ -11,6 +11,7 @@
 /* INCLUDES *****************************************************************/
 
 #include <ctype.h>
+#include <limits.h>
 #include <stdlib.h>
 
 /* GLOBALS   ****************************************************************/
@@ -19,17 +20,84 @@ static unsigned long long next = 0;
 
 /* FUNCTIONS ****************************************************************/
 
-#if 0
 int atoi(const char *str)
 {
 	return (int)atol (str);
 }
 
+
+/*
+ * NOTE: no error 
+ */
+
 long atol(const char *str)
 {
-	return strtol(str, 0, 10);
+  const char *s = str;
+  unsigned long acc;
+  int c;
+  unsigned long cutoff;
+  int neg = 0, any, cutlim;
+
+  /*
+   * Skip white space and pick up leading +/- sign if any.
+   */
+  do {
+    c = *s++;
+  } while (isspace(c));
+  if (c == '-')
+  {
+    neg = 1;
+    c = *s++;
+  }
+  else if (c == '+')
+    c = *s++;
+
+  /*
+   * Compute the cutoff value between legal numbers and illegal
+   * numbers.  That is the largest legal value, divided by the
+   * base.  An input number that is greater than this value, if
+   * followed by a legal input character, is too big.  One that
+   * is equal to this value may be valid or not; the limit
+   * between valid and invalid numbers is then based on the last
+   * digit.  For instance, if the range for longs is
+   * [-2147483648..2147483647] and the input base is 10,
+   * cutoff will be set to 214748364 and cutlim to either
+   * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
+   * a value > 214748364, or equal but the next digit is > 7 (or 8),
+   * the number is too big, and we will return a range error.
+   *
+   * Set any if any `digits' consumed; make it negative to indicate
+   * overflow.
+   */
+  cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
+  cutlim = cutoff % (unsigned long)10;
+  cutoff /= (unsigned long)10;
+  for (acc = 0, any = 0;; c = *s++)
+  {
+    if (isdigit(c))
+      c -= '0';
+    else
+      break;
+    if (c >= 10)
+      break;
+    if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
+      any = -1;
+    else
+    {
+      any = 1;
+      acc *= 10;
+      acc += c;
+    }
+  }
+  if (any < 0)
+  {
+    acc = neg ? LONG_MIN : LONG_MAX;
+  }
+  else if (neg)
+    acc = -acc;
+
+  return acc;
 }
-#endif
 
 
 /*