Added README and clamped code point values.

1 files changed, 21 insertions, 3 deletions

diff --git a/ascii2map.c b/ascii2map.c
index 30a2c44..f24cb77 100644
--- a/ascii2map.c
+++ b/ascii2map.c
@@ -105,6 +105,24 @@ static void EndOutput(FILE *fp)
 }
 
 
+static unsigned CodePoint(char c)
+{
+    int offset = c - code_point;
+
+    if (offset < 0)
+    {
+        offset = 0;
+    }
+
+    if (offset > 255)
+    {
+        offset = 255;
+    }
+
+    return (unsigned)offset;
+}
+
+
 static void Output(FILE *fp, char c)
 {
     static int column;
@@ -138,7 +156,7 @@ static void Output(FILE *fp, char c)
             }
             else
             {
-                fprintf(fp, "%u", c - code_point);
+                fprintf(fp, "%u", CodePoint(c));
             }
 
             break;
@@ -150,7 +168,7 @@ static void Output(FILE *fp, char c)
             }
             else
             {
-                putc(c - code_point, fp);
+                putc(CodePoint(c), fp);
             }
 
             break;
@@ -177,7 +195,7 @@ static void Output(FILE *fp, char c)
             }
             else
             {
-                fprintf(fp, "%u", c - code_point);
+                fprintf(fp, "%u", CodePoint(c));
             }
 
             break;