From: Peter Senna Tschudin <peter.senna@xxxxxxxxx>
The tools/usb/ffs-test.c file defines cpu_to_le16/32 by using the C
library htole16/32 function calls. However, cpu_to_le16/32 are used when
initializing structures, i.e in a context where a function call is not
allowed.
It works fine on little endian systems because htole16/32 are defined by
the C library as no-ops. But on big-endian systems, they are actually
doing something, which might involve calling a function, causing build
failures, such as:
ffs-test.c:48:25: error: initializer element is not constant
#define cpu_to_le32(x) htole32(x)
^~~~~~~
ffs-test.c:128:12: note: in expansion of macro ‘cpu_to_le32’
.magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
^~~~~~~~~~~
To solve this, we code cpu_to_le16/32 in a way that allows them to be
used when initializing structures. This fix was imported from
meta-openembedded/android-tools/fix-big-endian-build.patch written by
Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>.
CC: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Senna Tschudin <peter.senna@xxxxxxxxx>
---
tools/usb/ffs-test.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/tools/usb/ffs-test.c b/tools/usb/ffs-test.c
index 95dd14648ba5..0f395dfb7774 100644
--- a/tools/usb/ffs-test.c
+++ b/tools/usb/ffs-test.c
@@ -44,12 +44,25 @@
/******************** Little Endian Handling ********************************/
-#define cpu_to_le16(x) htole16(x)
-#define cpu_to_le32(x) htole32(x)
+/*
+ * cpu_to_le16/32 are used when initializing structures, a context where a
+ * function call is not allowed. To solve this, we code cpu_to_le16/32 in a way
+ * that allows them to be used when initializing structures.
+ */
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define cpu_to_le16(x) (x)
+#define cpu_to_le32(x) (x)
+#else
+#define cpu_to_le16(x) ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
+#define cpu_to_le32(x) \
+ ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8) | \
+ (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24))
+#endif
+
#define le32_to_cpu(x) le32toh(x)
#define le16_to_cpu(x) le16toh(x)
-
/******************** Messages and Errors ***********************************/
static const char argv0[] = "ffs-test";
--
2.17.1
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