[x265] [PATCH 3 of 3] api: introduce x265_api_get()

[Steve Borho]

# HG changeset patch
# User Steve Borho <steve at borho.org>
# Date 1427916381 18000
#      Wed Apr 01 14:26:21 2015 -0500
# Node ID 87d5faa366339aca529c6798b4d95b8944b6e16f
# Parent  6cdd761a469295dc1bca00b15cea97b7f3dc97f3
api: introduce x265_api_get()

diff -r 6cdd761a4692 -r 87d5faa36633 source/encoder/api.cpp
--- a/source/encoder/api.cpp	Wed Apr 01 14:44:19 2015 -0500
+++ b/source/encoder/api.cpp	Wed Apr 01 14:26:21 2015 -0500
@@ -218,3 +218,45 @@
 {
     return x265_free(p);
 }
+
+static const x265_api libapi =
+{
+    &x265_param_alloc,
+    &x265_param_free,
+    &x265_param_default,
+    &x265_param_parse,
+    &x265_param_apply_profile,
+    &x265_param_default_preset,
+    &x265_picture_alloc,
+    &x265_picture_free,
+    &x265_picture_init,
+    &x265_encoder_open,
+    &x265_encoder_parameters,
+    &x265_encoder_headers,
+    &x265_encoder_encode,
+    &x265_encoder_get_stats,
+    &x265_encoder_log,
+    &x265_encoder_close,
+    &x265_cleanup,
+    x265_version_str,
+    x265_build_info_str,
+    x265_max_bit_depth,
+};
+
+extern "C"
+const x265_api* x265_api_get(int buildNum, x265_param* p, int* err)
+{
+    if (buildNum != X265_BUILD)
+    {
+        if (err) *err = X265_API_VERSION_MISMATCH;
+        return NULL;
+    }
+
+    if (p && p->internalBitDepth != X265_DEPTH)
+    {
+        if (err) *err = X265_API_BITDEPTH_MISMATCH;
+        return NULL;
+    }
+
+    return &libapi;
+}
diff -r 6cdd761a4692 -r 87d5faa36633 source/x265.def.in
--- a/source/x265.def.in	Wed Apr 01 14:44:19 2015 -0500
+++ b/source/x265.def.in	Wed Apr 01 14:26:21 2015 -0500
@@ -19,3 +19,4 @@
 x265_encoder_log
 x265_encoder_close
 x265_cleanup
+x265_api_get_${X265_BUILD}
diff -r 6cdd761a4692 -r 87d5faa36633 source/x265.h
--- a/source/x265.h	Wed Apr 01 14:44:19 2015 -0500
+++ b/source/x265.h	Wed Apr 01 14:26:21 2015 -0500
@@ -1232,6 +1232,62 @@
  *       release library static allocations, reset configured CTU size */
 void x265_cleanup(void);
 
+
+/* === Multi-lib API ===
+ * By using this method to gain access to the libx265 interfaces, you allow shim
+ * implementations of x265_api_get() to choose between various available libx265
+ * libraries based on the encoder parameters. The most likely use case is to
+ * choose between 8bpp and 16bpp builds of libx265. */
+
+typedef struct x265_api
+{
+    /* libx265 public API functions, documented above with x265_ prefixes */
+    x265_param*   (*param_alloc)(void);
+    void          (*param_free)(x265_param*);
+    void          (*param_default)(x265_param*);
+    int           (*param_parse)(x265_param*, const char*, const char*);
+    int           (*param_apply_profile)(x265_param*, const char*);
+    int           (*param_default_preset)(x265_param*, const char*, const char *);
+    x265_picture* (*picture_alloc)(void);
+    void          (*picture_free)(x265_picture*);
+    void          (*picture_init)(x265_param*, x265_picture*);
+    x265_encoder* (*encoder_open)(x265_param*);
+    void          (*encoder_parameters)(x265_encoder*, x265_param*);
+    int           (*encoder_headers)(x265_encoder*, x265_nal**, uint32_t*);
+    int           (*encoder_encode)(x265_encoder*, x265_nal**, uint32_t*, x265_picture*, x265_picture*);
+    void          (*encoder_get_stats)(x265_encoder*, x265_stats*, uint32_t);
+    void          (*encoder_log)(x265_encoder*, int, char**);
+    void          (*encoder_close)(x265_encoder*);
+    void          (*cleanup)(void);
+    const char*   version_str;
+    const char*   build_info_str;
+    int           max_bit_depth;
+} x265_api;
+
+/* Force a link error in the case of linking against an incompatible API version.
+ * Glue #defines exist to force correct macro expansion; the final output of the macro
+ * is x265_api_get_##X265_BUILD (for purposes of dlopen). */
+#define x265_api_glue1(x, y) x ## y
+#define x265_api_glue2(x, y) x265_api_glue1(x, y)
+#define x265_api_get x265_api_glue2(x265_api_get_, X265_BUILD)
+
+/* x265_api_get:
+ *   Retrieve the programming interface for a linked x265 library.
+ *   If an API version mismatch is
+ *   detected between the X265_BUILD number in the x265.h header you are
+ *   compiling against and the library you are linking with, it will return NULL
+ *   and set err to X265_API_VERSION_MISMATCH.  If the param's internalBitDepth
+ *   is not supported by any available library, it will return NULL and set err
+ *   to X265_API_BITDEPTH_MISMATCH.
+ *
+ *   buildNum must be set to X265_BUILD
+ *   p        may be NULL, in which case you will get the default libx265 API
+ *   err      may be NULL */
+#define X265_API_NO_ERROR           0
+#define X265_API_BITDEPTH_MISMATCH  1
+#define X265_API_VERSION_MISMATCH   2
+const x265_api* x265_api_get(int buildNum, x265_param* p, int* err);
+
 #ifdef __cplusplus
 }
 #endif