1 files changed, 52 insertions, 0 deletions
diff --git a/system/doc/tutorial/erl_comm.c b/system/doc/tutorial/erl_comm.c
new file mode 100644
index 0000000000..303c6dc170
--- /dev/null
+++ b/system/doc/tutorial/erl_comm.c
@@ -0,0 +1,52 @@
+/* erl_comm.c */
+
+typedef unsigned char byte;
+
+read_cmd(byte *buf)
+{
+  int len;
+
+  if (read_exact(buf, 2) != 2)
+    return(-1);
+  len = (buf[0] << 8) | buf[1];
+  return read_exact(buf, len);
+}
+
+write_cmd(byte *buf, int len)
+{
+  byte li;
+
+  li = (len >> 8) & 0xff;
+  write_exact(&li, 1);
+  
+  li = len & 0xff;
+  write_exact(&li, 1);
+
+  return write_exact(buf, len);
+}
+
+read_exact(byte *buf, int len)
+{
+  int i, got=0;
+
+  do {
+    if ((i = read(0, buf+got, len-got)) <= 0)
+      return(i);
+    got += i;
+  } while (got<len);
+
+  return(len);
+}
+
+write_exact(byte *buf, int len)
+{
+  int i, wrote = 0;
+
+  do {
+    if ((i = write(1, buf+wrote, len-wrote)) <= 0)
+      return (i);
+    wrote += i;
+  } while (wrote<len);
+
+  return (len);
+}