cheets: Add external/wayland and external/cheets-libffi
wayland-client will be used by the hardware composer.
libffi is required by libwayland-client.
BUG=b/25324609
TEST=drm_hwcomposer.cpp compiles/links when including "wayland-client.h"
and calling wl_display_connect(NULL)
Change-Id: I2d05e174b5044b11fae798d93ef2fd1090b70f1f
diff --git a/man/ffi_call.3 b/man/ffi_call.3
new file mode 100644
index 0000000..5351513
--- /dev/null
+++ b/man/ffi_call.3
@@ -0,0 +1,103 @@
+.Dd February 15, 2008
+.Dt ffi_call 3
+.Sh NAME
+.Nm ffi_call
+.Nd Invoke a foreign function.
+.Sh SYNOPSIS
+.In ffi.h
+.Ft void
+.Fo ffi_call
+.Fa "ffi_cif *cif"
+.Fa "void (*fn)(void)"
+.Fa "void *rvalue"
+.Fa "void **avalue"
+.Fc
+.Sh DESCRIPTION
+The
+.Nm ffi_call
+function provides a simple mechanism for invoking a function without
+requiring knowledge of the function's interface at compile time.
+.Fa fn
+is called with the values retrieved from the pointers in the
+.Fa avalue
+array. The return value from
+.Fa fn
+is placed in storage pointed to by
+.Fa rvalue .
+.Fa cif
+contains information describing the data types, sizes and alignments of the
+arguments to and return value from
+.Fa fn ,
+and must be initialized with
+.Nm ffi_prep_cif
+before it is used with
+.Nm ffi_call .
+.Pp
+.Fa rvalue
+must point to storage that is sizeof(ffi_arg) or larger for non-floating point
+types. For smaller-sized return value types, the
+.Nm ffi_arg
+or
+.Nm ffi_sarg
+integral type must be used to hold
+the return value.
+.Sh EXAMPLES
+.Bd -literal
+#include <ffi.h>
+#include <stdio.h>
+
+unsigned char
+foo(unsigned int, float);
+
+int
+main(int argc, const char **argv)
+{
+ ffi_cif cif;
+ ffi_type *arg_types[2];
+ void *arg_values[2];
+ ffi_status status;
+
+ // Because the return value from foo() is smaller than sizeof(long), it
+ // must be passed as ffi_arg or ffi_sarg.
+ ffi_arg result;
+
+ // Specify the data type of each argument. Available types are defined
+ // in <ffi/ffi.h>.
+ arg_types[0] = &ffi_type_uint;
+ arg_types[1] = &ffi_type_float;
+
+ // Prepare the ffi_cif structure.
+ if ((status = ffi_prep_cif(&cif, FFI_DEFAULT_ABI,
+ 2, &ffi_type_uint8, arg_types)) != FFI_OK)
+ {
+ // Handle the ffi_status error.
+ }
+
+ // Specify the values of each argument.
+ unsigned int arg1 = 42;
+ float arg2 = 5.1;
+
+ arg_values[0] = &arg1;
+ arg_values[1] = &arg2;
+
+ // Invoke the function.
+ ffi_call(&cif, FFI_FN(foo), &result, arg_values);
+
+ // The ffi_arg 'result' now contains the unsigned char returned from foo(),
+ // which can be accessed by a typecast.
+ printf("result is %hhu", (unsigned char)result);
+
+ return 0;
+}
+
+// The target function.
+unsigned char
+foo(unsigned int x, float y)
+{
+ unsigned char result = x - y;
+ return result;
+}
+.Ed
+.Sh SEE ALSO
+.Xr ffi 3 ,
+.Xr ffi_prep_cif 3