From f5d7aa90c4dd87808df9d7327fc2b5e724880547 Mon Sep 17 00:00:00 2001
From: id101010 <aaron@duckpond.ch>
Date: Thu, 10 Nov 2016 02:08:40 +0100
Subject: [PATCH] Prevented memory under and overun

---
 bfckr.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/bfckr.c b/bfckr.c
index ca611e6..784afba 100644
--- a/bfckr.c
+++ b/bfckr.c
@@ -15,11 +15,12 @@
 
 // Amount of memory on the band tape
 #define MEMORY_SIZE     10000
-#define MAX_INPUT_SIZE  1000
+#define MAX_INPUT_SIZE  10000
 
 // Memory initialized with zeros and its pointer
 char memory[MEMORY_SIZE] = {0};
 char *p = memory;
+int memcnt = 0;
 
 // Prototypes
 void bfuck_parser(char *input);
@@ -44,11 +45,23 @@ void bfuck_parser(char *input)
     for(size_t i = 0; input[i] != 0; i++) { // where i is the instruction pointer
         switch(input[i]) {
         case '>':
-            ++p; // increment data pointer
+            if(memcnt >= MEMORY_SIZE) { // prevent overrun
+                p = &memory[0];
+                memcnt = 0;
+            } else {
+                ++p; // increment data pointer
+                ++memcnt;
+            }
             break;
 
         case '<':
-            --p; // decrement data pointer
+            if(memcnt < 0) { // prevent underun
+                p = &memory[MEMORY_SIZE - 1];
+                memcnt = MEMORY_SIZE - 1;
+            } else {
+                --p; // decrement data pointer
+                --memcnt;
+            }
             break;
 
         case '+':