From d259c03079b7671bed4802ea41a83190e3110c13 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 1 Oct 2019 00:05:32 +1000
Subject: [PATCH] AP_HAL: BetterStream add a read(uint8_t*buffer, uint16_t
 count method

---
 libraries/AP_HAL/utility/BetterStream.cpp | 12 ++++++++++++
 libraries/AP_HAL/utility/BetterStream.h   |  9 +++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_HAL/utility/BetterStream.cpp b/libraries/AP_HAL/utility/BetterStream.cpp
index d140ec7456..de9387eb5c 100644
--- a/libraries/AP_HAL/utility/BetterStream.cpp
+++ b/libraries/AP_HAL/utility/BetterStream.cpp
@@ -19,3 +19,15 @@ size_t AP_HAL::BetterStream::write(const char *str)
 {
     return write((const uint8_t *)str, strlen(str));
 }
+
+ssize_t AP_HAL::BetterStream::read(uint8_t *buffer, uint16_t count) {
+    uint16_t offset = 0;
+    while (count--) {
+        const int16_t x = read();
+        if (x == -1) {
+            return offset;
+        }
+        buffer[offset++] = (uint8_t)x;
+    }
+    return offset;
+}
diff --git a/libraries/AP_HAL/utility/BetterStream.h b/libraries/AP_HAL/utility/BetterStream.h
index 9924f337f8..0881fdefaa 100644
--- a/libraries/AP_HAL/utility/BetterStream.h
+++ b/libraries/AP_HAL/utility/BetterStream.h
@@ -19,11 +19,12 @@
 //
 #pragma once
 
-#include <stdarg.h>
-
 #include <AP_Common/AP_Common.h>
 #include <AP_HAL/AP_HAL_Namespace.h>
 
+#include <stdarg.h>
+#include <unistd.h>
+
 class AP_HAL::BetterStream {
 public:
 
@@ -48,6 +49,10 @@ public:
     // returns false if discard failed (e.g. port locked)
     virtual bool discard_input() = 0; // discard all bytes available for reading
 
+    // returns -1 on error (e.g. port locked), number of bytes read
+    // otherwise
+    virtual ssize_t read(uint8_t *buffer, uint16_t count);
+
     /* NB txspace was traditionally a member of BetterStream in the
      * FastSerial library. As far as concerns go, it belongs with available() */
     virtual uint32_t txspace() = 0;