MoonchildProductions/UXP#2897: Fix ffvpx build on loongarch64

media/ffvpx/libavcodec/loongarch/videodsp_init.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ * Contributed by Xiwei Gu <guxiwei-hf@loongson.cn>
+ *
+ * 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 "libavcodec/videodsp.h"
+#include "libavutil/attributes.h"
+
+static void prefetch_loongarch(const uint8_t *mem, ptrdiff_t stride, int h)
+{
+    register const uint8_t *p = mem;
+
+    __asm__ volatile (
+        "1:                                     \n\t"
+        "preld      0,     %[p],     0          \n\t"
+        "preld      0,     %[p],     32         \n\t"
+        "addi.d     %[h],  %[h],     -1         \n\t"
+        "add.d      %[p],  %[p],     %[stride]  \n\t"
+
+        "blt        $r0,   %[h],     1b         \n\t"
+        : [p] "+r" (p), [h] "+r" (h)
+        : [stride] "r" (stride)
+    );
+}
+
+av_cold void ff_videodsp_init_loongarch(VideoDSPContext *ctx, int bpc)
+{
+    ctx->prefetch = prefetch_loongarch;
+}