improved efficiency of printing out struct queue messages
diff --git a/aos/common/print_field_helpers.h b/aos/common/print_field_helpers.h
new file mode 100644
index 0000000..48acdf6
--- /dev/null
+++ b/aos/common/print_field_helpers.h
@@ -0,0 +1,41 @@
+#ifndef AOS_COMMON_PRINT_FIELD_HELPERS_H_
+#define AOS_COMMON_PRINT_FIELD_HELPERS_H_
+
+#include <stdint.h>
+
+#include <type_traits>
+
+namespace aos {
+
+template<typename T>
+inline bool PrintInteger(char *buf, T val, size_t *output) {
+  static const bool is_signed = ::std::is_signed<T>::value;
+
+  size_t len = 0;
+  if (is_signed && val <= 0) {
+    while (*output > len && (val != 0 || len == 0)) {
+      buf[len++] = '0' - (val % 10);
+      val /= 10;
+    }
+    buf[len++] = '-';
+  } else {
+    while (*output > len && (val != 0 || len == 0)) {
+      buf[len++] = '0' + (val % 10);
+      val /= 10;
+    }
+  }
+  // If we have enough space.
+  if (*output >= len) {
+    for (size_t i = 0; i < (len >> 1); i++) {
+      std::swap(buf[len - 1 - i], buf[i]);
+    }
+    *output -= len;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+}  // namespace aos
+
+#endif  // AOS_COMMON_PRINT_FIELD_HELPERS_H_
diff --git a/aos/common/queue_types.cc b/aos/common/queue_types.cc
index 93cf135..8c22d90 100644
--- a/aos/common/queue_types.cc
+++ b/aos/common/queue_types.cc
@@ -148,12 +148,12 @@
                         type_cache::Get(type.fields[i]->type))) {
         return false;
       }
+      // Ignore the trailing '\0' that the subcall put on.
+      output -= 1;
     }
 
-    // Update the input and output pointers, ignoring the trailing '\0' that the
-    // subcall put on.
-    output += output_bytes_before - *output_bytes - 1;
-    *output_bytes += 1;
+    // Update the input and output pointers.
+    output += output_bytes_before - *output_bytes;
     input =
         static_cast<const char *>(input) + input_bytes_before - *input_bytes;
   }
@@ -208,10 +208,8 @@
         return false;
       }
       CHECK_EQ(0u, input_bytes);
-      // Update the output pointer, ignoring the trailing '\0' that
-      // the subcall put on.
-      output += output_bytes_before - *output_bytes - 1;
-      *output_bytes += 1;
+      // Update the output pointer.
+      output += output_bytes_before - *output_bytes;
     }
 
     if (*output_bytes < 1) return false;
diff --git a/aos/common/queue_types.h b/aos/common/queue_types.h
index b95c946..eb0527e 100644
--- a/aos/common/queue_types.h
+++ b/aos/common/queue_types.h
@@ -102,6 +102,7 @@
 //
 // Prints the value from 1 primitive message field into output.
 // The implementation of this is generated by the ruby code.
+// Does not include a trailing '\0' in what it subtracts from *output_bytes.
 bool PrintField(char *output, size_t *output_bytes, const void *input,
                 size_t *input_bytes, uint32_t type)
     __attribute__((warn_unused_result));