swscale: aarch64: Add a NEON implementation of interleaveBytes

This allows speeding up format conversions from yuv420 to nv12.

                             Cortex A53      A72      A73
interleave_bytes_c:             86077.5  51433.0  66972.0
interleave_bytes_neon:          19701.7  23019.2  15859.2
interleave_bytes_aligned_c:     86603.0  52017.2  67484.2
interleave_bytes_aligned_neon:   9061.0   7623.0   6309.0
Signed-off-by: Martin Storsjö <martin@martin.st>

libswscale/aarch64/Makefile

-OBJS        += aarch64/swscale.o                \
+OBJS        += aarch64/rgb2rgb.o                \
+               aarch64/swscale.o                \
                aarch64/swscale_unscaled.o       \
 
 NEON-OBJS   += aarch64/hscale.o                 \
                aarch64/output.o                 \
+               aarch64/rgb2rgb_neon.o           \
                aarch64/yuv2rgb_neon.o           \

libswscale/aarch64/rgb2rgb.c

+/*
+ * 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 "config.h"
+#include "libavutil/attributes.h"
+#include "libavutil/aarch64/cpu.h"
+#include "libavutil/cpu.h"
+#include "libavutil/bswap.h"
+#include "libswscale/rgb2rgb.h"
+#include "libswscale/swscale.h"
+#include "libswscale/swscale_internal.h"
+
+void ff_interleave_bytes_neon(const uint8_t *src1, const uint8_t *src2,
+                              uint8_t *dest, int width, int height,
+                              int src1Stride, int src2Stride, int dstStride);
+
+av_cold void rgb2rgb_init_aarch64(void)
+{
+    int cpu_flags = av_get_cpu_flags();
+
+    if (have_neon(cpu_flags)) {
+        interleaveBytes = ff_interleave_bytes_neon;
+    }
+}

libswscale/aarch64/rgb2rgb_neon.S

+/*
+ * Copyright (c) 2020 Martin Storsjo
+ *
+ * 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 "libavutil/aarch64/asm.S"
+
+// void ff_interleave_bytes_neon(const uint8_t *src1, const uint8_t *src2,
+//                               uint8_t *dest, int width, int height,
+//                               int src1Stride, int src2Stride, int dstStride);
+function ff_interleave_bytes_neon, export=1
+        sub             w5,  w5,  w3
+        sub             w6,  w6,  w3
+        sub             w7,  w7,  w3, lsl #1
+1:
+        ands            w8,  w3,  #0xfffffff0 // & ~15
+        b.eq            3f
+2:
+        ld1             {v0.16b}, [x0], #16
+        ld1             {v1.16b}, [x1], #16
+        subs            w8,  w8,  #16
+        st2             {v0.16b, v1.16b}, [x2], #32
+        b.gt            2b
+
+        tst             w3,  #15
+        b.eq            9f
+
+3:
+        tst             w3,  #8
+        b.eq            4f
+        ld1             {v0.8b}, [x0], #8
+        ld1             {v1.8b}, [x1], #8
+        st2             {v0.8b, v1.8b}, [x2], #16
+4:
+        tst             w3,  #4
+        b.eq            5f
+
+        ld1             {v0.s}[0], [x0], #4
+        ld1             {v1.s}[0], [x1], #4
+        zip1            v0.8b,   v0.8b,   v1.8b
+        st1             {v0.8b}, [x2], #8
+
+5:
+        ands            w8,  w3,  #3
+        b.eq            9f
+6:
+        ldrb            w9,  [x0], #1
+        ldrb            w10, [x1], #1
+        subs            w8,  w8,  #1
+        bfi             w9,  w10, #8,  #8
+        strh            w9,  [x2], #2
+        b.gt            6b
+
+9:
+        subs            w4,  w4,  #1
+        b.eq            0f
+        add             x0,  x0,  w5, sxtw
+        add             x1,  x1,  w6, sxtw
+        add             x2,  x2,  w7, sxtw
+        b               1b
+
+0:
+        ret
+endfunc

libswscale/rgb2rgb.c

@@ -137,6 +137,8 @@ void (*yuyvtoyuv422)(uint8_t *ydst, uint8_t *udst, uint8_t *vdst,
 av_cold void ff_sws_rgb2rgb_init(void)
 {
     rgb2rgb_init_c();
+    if (ARCH_AARCH64)
+        rgb2rgb_init_aarch64();
     if (ARCH_X86)
         rgb2rgb_init_x86();
 }

libswscale/rgb2rgb.h

@@ -169,6 +169,7 @@ extern void (*yuyvtoyuv422)(uint8_t *ydst, uint8_t *udst, uint8_t *vdst, const u
 
 void ff_sws_rgb2rgb_init(void);
 
+void rgb2rgb_init_aarch64(void);
 void rgb2rgb_init_x86(void);
 
 #endif /* SWSCALE_RGB2RGB_H */