configure: Add wasm as a fake arch

And add wasm simd128 flag, so we can add simd128 optimizations.
It can be enabled by put -msimd128 to extra cflags. There is
no runtime detection on simd128 support yet. I think that needs to
be done with JavaScript.

Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/libavutil/wasm/cpu.c b/libavutil/wasm/cpu.c
new file mode 100644
index 0000000000..a8e990dd29
--- /dev/null
+++ b/libavutil/wasm/cpu.c
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2024 Zhao Zhili
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdint.h>
+
+#include "libavutil/cpu_internal.h"
+
+int ff_get_cpu_flags_wasm(void)
+{
+    int flags = 0;
+#if HAVE_SIMD128
+    flags |= AV_CPU_FLAG_SIMD128;
+#endif
+    return flags;
+}
+
+size_t ff_get_cpu_max_align_wasm(void)
+{
+#if HAVE_SIMD128
+    return 16;
+#else
+    return 8;
+#endif
+}
+