From 9773ac0b833769eb5373687eb0377c28d9f4a22a Mon Sep 17 00:00:00 2001
From: Dimitri Stolnikov <horiz0n@gmx.net>
Date: Tue, 3 Apr 2012 19:40:50 +0200
Subject: [PATCH] define LIBUSB_CALL if not available with old libusb

Signed-off-by: Steve Markgraf <steve@steve-m.de>
---
 src/rtl-sdr.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/rtl-sdr.c b/src/rtl-sdr.c
index 2d03b97..0b71071 100644
--- a/src/rtl-sdr.c
+++ b/src/rtl-sdr.c
@@ -29,6 +29,16 @@
 
 #include <libusb.h>
 
+/*
+ * All libusb callback functions should be marked with the LIBUSB_CALL macro
+ * to ensure that they are compiled with the same calling convention as libusb.
+ *
+ * If the macro isn't available in older libusb versions, we simply define it.
+ */
+#ifndef LIBUSB_CALL
+#define LIBUSB_CALL
+#endif
+
 #include <rtl-sdr.h>
 #include "tuner_e4000.h"
 #include "tuner_fc0012.h"