fix bug and add zero instruction

5 files changed, 16 insertions, 1 deletions

diff --git a/readme.md b/readme.md
index f741485..87ed15a 100644
--- a/readme.md
+++ b/readme.md
@@ -41,6 +41,8 @@ Just like brainfuck, cells wrap from 0 to 255, and vice versa, and also the tape
 
 `%` Clear screen
 
+`$` Zero n cells where n is the value of the current cell
+
 `\` Comment out the rest of the line
 
 ## Usage
@@ -52,6 +54,12 @@ For example:
 $ brainfucked helloworld.bfd
 ```
 
+Brainfucked can also read from standard in, so the following would also work.
+
+```
+$ cat helloworld.bfd | brainfucked
+```
+
 ## License
 
 This project is Licensed under the [WTFPL](http://www.wtfpl.net/)
diff --git a/src/interpreter.c b/src/interpreter.c
index 273d985..982108e 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -62,8 +62,8 @@ next:
             break;
         }
         case EnterTape: {
-            memcpy(&tape, tape_ptr(tape), sizeof(Tape*));
             stack_push(&tape_stack, tape);
+            memcpy(&tape, tape_ptr(tape), sizeof(Tape*));
             break;
         }
         case LeaveTape: {
@@ -82,6 +82,9 @@ next:
         case Clear:
             printf("\033c");
             break;
+        case Zero:
+            memset(tape_ptr(tape), 0, tape_get(tape));
+            break;
         case Eof:
             goto end;
     }
diff --git a/src/main.c b/src/main.c
index c51a88f..7032ca5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,6 +20,7 @@
 /// ` Output null terminated string at current cell
 /// ~ Input string into current cells with max length in current cell
 /// % Clear screen
+/// $ Set n cells to 0 where n is the count of the current cell
 
 int main(int argc, char** argv) {
     
diff --git a/src/program.c b/src/program.c
index 0fac9d5..c839461 100644
--- a/src/program.c
+++ b/src/program.c
@@ -48,6 +48,8 @@ retest:
             return GetString;
         case '%':
             return Clear;
+        case '$':
+            return Zero;
         case '\n':
         case '\t':
         case ' ':
diff --git a/src/types.h b/src/types.h
index 413d313..9241787 100644
--- a/src/types.h
+++ b/src/types.h
@@ -19,6 +19,7 @@ typedef enum {
     PutString,
     GetString,
     Clear,
+    Zero,
     Eof
 } Symbol;