avcodec: [loongson] optimize get_cabac_inline.

This optimization improved h264 decoding performance about 4%(from 74fps to 77fps, tested on loongson 3A3000).
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/cabac_functions.h

@@ -45,6 +45,9 @@
 #if ARCH_X86
 #   include "x86/cabac.h"
 #endif
+#if ARCH_MIPS
+#   include "mips/cabac.h"
+#endif
 
 static const uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET;
 static const uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET;

libavcodec/mips/cabac.h

+/*
+ * Loongson SIMD optimized h264chroma
+ *
+ * Copyright (c) 2018 Loongson Technology Corporation Limited
+ * Copyright (c) 2018 Shiyou Yin <yinshiyou-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
+ */
+
+#ifndef AVCODEC_MIPS_CABAC_H
+#define AVCODEC_MIPS_CABAC_H
+
+#include "libavcodec/cabac.h"
+#include "libavutil/mips/mmiutils.h"
+#include "config.h"
+
+#define get_cabac_inline get_cabac_inline_mips
+static av_always_inline int get_cabac_inline(CABACContext *c,
+                                             uint8_t * const state){
+    mips_reg tmp0, tmp1, tmp2, bit;
+
+    __asm__ volatile (
+        "lbu          %[bit],        0(%[state])                   \n\t"
+        "and          %[tmp0],       %[c_range],     0xC0          \n\t"
+        PTR_ADDU     "%[tmp0],       %[tmp0],        %[tmp0]       \n\t"
+        PTR_ADDU     "%[tmp0],       %[tmp0],        %[tables]     \n\t"
+        PTR_ADDU     "%[tmp0],       %[tmp0],        %[bit]        \n\t"
+        /* tmp1: RangeLPS */
+        "lbu          %[tmp1],       %[lps_off](%[tmp0])           \n\t"
+
+        PTR_SUBU     "%[c_range],    %[c_range],     %[tmp1]       \n\t"
+        PTR_SLL      "%[tmp0],       %[c_range],     0x11          \n\t"
+        PTR_SUBU     "%[tmp0],       %[tmp0],        %[c_low]      \n\t"
+
+        /* tmp2: lps_mask */
+        PTR_SRA      "%[tmp2],       %[tmp0],        0x1F          \n\t"
+        /* If tmp0 < 0, lps_mask ==  0xffffffff*/
+        /* If tmp0 >= 0, lps_mask ==  0x00000000*/
+        "beqz         %[tmp2],       1f                            \n\t"
+        PTR_SLL      "%[tmp0],       %[c_range],     0x11          \n\t"
+        PTR_SUBU     "%[c_low],      %[c_low],       %[tmp0]       \n\t"
+        PTR_SUBU     "%[tmp0],       %[tmp1],        %[c_range]    \n\t"
+        PTR_ADDU     "%[c_range],    %[c_range],     %[tmp0]       \n\t"
+        "xor          %[bit],        %[bit],         %[tmp2]       \n\t"
+
+        "1:                                                        \n\t"
+        /* tmp1: *state */
+        PTR_ADDU     "%[tmp0],       %[tables],      %[bit]        \n\t"
+        "lbu          %[tmp1],       %[mlps_off](%[tmp0])          \n\t"
+        /* tmp2: lps_mask */
+        PTR_ADDU     "%[tmp0],       %[tables],      %[c_range]    \n\t"
+        "lbu          %[tmp2],       %[norm_off](%[tmp0])          \n\t"
+
+        "sb           %[tmp1],       0(%[state])                   \n\t"
+        "and          %[bit],        %[bit],         0x01          \n\t"
+        PTR_SLL      "%[c_range],    %[c_range],     %[tmp2]       \n\t"
+        PTR_SLL      "%[c_low],      %[c_low],       %[tmp2]       \n\t"
+
+        "and          %[tmp0],       %[c_low],       %[cabac_mask] \n\t"
+        "bnez         %[tmp0],       1f                            \n\t"
+        PTR_ADDI     "%[tmp0],       %[c_low],       -0X01         \n\t"
+        "xor          %[tmp0],       %[c_low],       %[tmp0]       \n\t"
+        PTR_SRA      "%[tmp0],       %[tmp0],        0x0f          \n\t"
+        PTR_ADDU     "%[tmp0],       %[tmp0],        %[tables]     \n\t"
+        "lbu          %[tmp2],       %[norm_off](%[tmp0])          \n\t"
+#if CABAC_BITS == 16
+        "lbu          %[tmp0],       0(%[c_bytestream])            \n\t"
+        "lbu          %[tmp1],       1(%[c_bytestream])            \n\t"
+        PTR_SLL      "%[tmp0],       %[tmp0],        0x09          \n\t"
+        PTR_SLL      "%[tmp1],       %[tmp1],        0x01          \n\t"
+        PTR_ADDU     "%[tmp0],       %[tmp0],        %[tmp1]       \n\t"
+#else
+        "lbu          %[tmp0],       0(%[c_bytestream])            \n\t"
+        PTR_SLL      "%[tmp0],       %[tmp0],        0x01          \n\t"
+#endif
+        PTR_SUBU     "%[tmp0],       %[tmp0],        %[cabac_mask] \n\t"
+
+        "li           %[tmp1],       0x07                          \n\t"
+        PTR_SUBU     "%[tmp1],       %[tmp1],        %[tmp2]       \n\t"
+        PTR_SLL      "%[tmp0],       %[tmp0],        %[tmp1]       \n\t"
+        PTR_ADDU     "%[c_low],      %[c_low],       %[tmp0]       \n\t"
+
+#if !UNCHECKED_BITSTREAM_READER
+        "bge          %[c_bytestream], %[c_bytestream_end], 1f     \n\t"
+#endif
+        PTR_ADDIU    "%[c_bytestream], %[c_bytestream],     0X02   \n\t"
+        "1:                                                        \n\t"
+    : [bit]"=&r"(bit), [tmp0]"=&r"(tmp0), [tmp1]"=&r"(tmp1), [tmp2]"=&r"(tmp2),
+      [c_range]"+&r"(c->range), [c_low]"+&r"(c->low),
+      [c_bytestream]"+&r"(c->bytestream)
+    : [state]"r"(state), [tables]"r"(ff_h264_cabac_tables),
+#if !UNCHECKED_BITSTREAM_READER
+      [c_bytestream_end]"r"(c->bytestream_end),
+#endif
+      [lps_off]"i"(H264_LPS_RANGE_OFFSET),
+      [mlps_off]"i"(H264_MLPS_STATE_OFFSET + 128),
+      [norm_off]"i"(H264_NORM_SHIFT_OFFSET),
+      [cabac_mask]"i"(CABAC_MASK)
+    : "memory"
+    );
+
+    return bit;
+}
+
+#endif /* AVCODEC_MIPS_CABAC_H */