lavc/aarch64/fdct: add neon-optimized fdct for aarch64

The code is imported from libjpeg-turbo-3.0.1. The neon registers used
have been changed to avoid modifying v8-v15.
Reviewed-by: Martin Storsjö <martin@martin.st>

libavcodec/aarch64/Makefile

 # subsystems
 OBJS-$(CONFIG_AC3DSP)                   += aarch64/ac3dsp_init_aarch64.o
+OBJS-$(CONFIG_FDCTDSP)                  += aarch64/fdctdsp_init_aarch64.o
 OBJS-$(CONFIG_FMTCONVERT)               += aarch64/fmtconvert_init.o
 OBJS-$(CONFIG_H264CHROMA)               += aarch64/h264chroma_init_aarch64.o
 OBJS-$(CONFIG_H264DSP)                  += aarch64/h264dsp_init_aarch64.o
@@ -37,6 +38,7 @@ ARMV8-OBJS-$(CONFIG_VIDEODSP)           += aarch64/videodsp.o
 # subsystems
 NEON-OBJS-$(CONFIG_AAC_DECODER)         += aarch64/sbrdsp_neon.o
 NEON-OBJS-$(CONFIG_AC3DSP)              += aarch64/ac3dsp_neon.o
+NEON-OBJS-$(CONFIG_FDCTDSP)             += aarch64/fdctdsp_neon.o
 NEON-OBJS-$(CONFIG_FMTCONVERT)          += aarch64/fmtconvert_neon.o
 NEON-OBJS-$(CONFIG_H264CHROMA)          += aarch64/h264cmc_neon.o
 NEON-OBJS-$(CONFIG_H264DSP)             += aarch64/h264dsp_neon.o              \

libavcodec/aarch64/fdct.h

+/*
+ * 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
+ */
+
+#ifndef AVCODEC_AARCH64_FDCT_H
+#define AVCODEC_AARCH64_FDCT_H
+
+#include <stdint.h>
+
+void ff_fdct_neon(int16_t *block);
+
+#endif /* AVCODEC_AARCH64_FDCT_H */

libavcodec/aarch64/fdctdsp_init_aarch64.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 "libavutil/attributes.h"
+#include "libavutil/cpu.h"
+#include "libavutil/aarch64/cpu.h"
+#include "libavcodec/avcodec.h"
+#include "libavcodec/fdctdsp.h"
+#include "fdct.h"
+
+av_cold void ff_fdctdsp_init_aarch64(FDCTDSPContext *c, AVCodecContext *avctx,
+                                     unsigned high_bit_depth)
+{
+    int cpu_flags = av_get_cpu_flags();
+
+    if (have_neon(cpu_flags)) {
+        if (!high_bit_depth) {
+            if (avctx->dct_algo == FF_DCT_AUTO ||
+                avctx->dct_algo == FF_DCT_NEON) {
+                c->fdct = ff_fdct_neon;
+            }
+        }
+    }
+}

libavcodec/avcodec.h

@@ -1538,6 +1538,7 @@ typedef struct AVCodecContext {
 #define FF_DCT_MMX     3
 #define FF_DCT_ALTIVEC 5
 #define FF_DCT_FAAN    6
+#define FF_DCT_NEON    7
 
     /**
      * IDCT algorithm, see FF_IDCT_* below.

libavcodec/fdctdsp.c

@@ -42,7 +42,9 @@ av_cold void ff_fdctdsp_init(FDCTDSPContext *c, AVCodecContext *avctx)
         c->fdct248 = ff_fdct248_islow_8;
     }
 
-#if ARCH_PPC
+#if ARCH_AARCH64
+    ff_fdctdsp_init_aarch64(c, avctx, high_bit_depth);
+#elif ARCH_PPC
     ff_fdctdsp_init_ppc(c, avctx, high_bit_depth);
 #elif ARCH_X86
     ff_fdctdsp_init_x86(c, avctx, high_bit_depth);

libavcodec/fdctdsp.h

@@ -32,6 +32,8 @@ typedef struct FDCTDSPContext {
 
 FF_VISIBILITY_PUSH_HIDDEN
 void ff_fdctdsp_init(FDCTDSPContext *c, struct AVCodecContext *avctx);
+void ff_fdctdsp_init_aarch64(FDCTDSPContext *c, struct AVCodecContext *avctx,
+                             unsigned high_bit_depth);
 void ff_fdctdsp_init_ppc(FDCTDSPContext *c, struct AVCodecContext *avctx,
                          unsigned high_bit_depth);
 void ff_fdctdsp_init_x86(FDCTDSPContext *c, struct AVCodecContext *avctx,

libavcodec/options_table.h

@@ -158,6 +158,7 @@ static const AVOption avcodec_options[] = {
 {"mmx", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_DCT_MMX }, INT_MIN, INT_MAX, V|E, .unit = "dct"},
 {"altivec", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_DCT_ALTIVEC }, INT_MIN, INT_MAX, V|E, .unit = "dct"},
 {"faan", "floating point AAN DCT", 0, AV_OPT_TYPE_CONST, {.i64 = FF_DCT_FAAN }, INT_MIN, INT_MAX, V|E, .unit = "dct"},
+{"neon", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_DCT_NEON }, INT_MIN, INT_MAX, V|E, .unit = "dct"},
 {"lumi_mask", "compresses bright areas stronger than medium ones", OFFSET(lumi_masking), AV_OPT_TYPE_FLOAT, {.dbl = 0 }, -FLT_MAX, FLT_MAX, V|E},
 {"tcplx_mask", "temporal complexity masking", OFFSET(temporal_cplx_masking), AV_OPT_TYPE_FLOAT, {.dbl = 0 }, -FLT_MAX, FLT_MAX, V|E},
 {"scplx_mask", "spatial complexity masking", OFFSET(spatial_cplx_masking), AV_OPT_TYPE_FLOAT, {.dbl = 0 }, -FLT_MAX, FLT_MAX, V|E},

libavcodec/tests/aarch64/dct.c

@@ -19,9 +19,11 @@
 #include "config.h"
 
 #include "libavutil/cpu.h"
+#include "libavcodec/aarch64/fdct.h"
 #include "libavcodec/aarch64/idct.h"
 
 static const struct algo fdct_tab_arch[] = {
+    { "neon", ff_fdct_neon, FF_IDCT_PERM_NONE, AV_CPU_FLAG_NEON },
     { 0 }
 };