x86/h264_cabac: convert decode_significance from inline asm to externaldecode_significance

This is vastly more readable and more portable.

5 files changed, 221 insertions, 209 deletions

diff --git a/libavcodec/h264_cabac.c b/libavcodec/h264_cabac.c
index 86f0a412fa..ca4646b3dd 100644
--- a/libavcodec/h264_cabac.c
+++ b/libavcodec/h264_cabac.c
@@ -42,7 +42,7 @@
 #include "mpegutils.h"
 
 #if ARCH_X86
-#include "x86/h264_cabac.c"
+#include "x86/h264_cabac.h"
 #endif
 
 /* Cabac pre state table */
diff --git a/libavcodec/x86/Makefile b/libavcodec/x86/Makefile
index 194135dafb..b6a2f67248 100644
--- a/libavcodec/x86/Makefile
+++ b/libavcodec/x86/Makefile
@@ -162,6 +162,7 @@ X86ASM-OBJS-$(CONFIG_FLAC_DECODER)     += x86/flacdsp.o
 ifdef CONFIG_GPL
 X86ASM-OBJS-$(CONFIG_FLAC_ENCODER)     += x86/flac_dsp_gpl.o
 endif
+X86ASM-OBJS-$(CONFIG_H264_DECODER)     += x86/h264_cabac.o
 X86ASM-OBJS-$(CONFIG_HEVC_DECODER)     += x86/hevc_add_res.o            \
                                           x86/hevc_deblock.o            \
                                           x86/hevc_idct.o               \
diff --git a/libavcodec/x86/h264_cabac.asm b/libavcodec/x86/h264_cabac.asm
new file mode 100644
index 0000000000..6cea03e664
--- /dev/null
+++ b/libavcodec/x86/h264_cabac.asm
@@ -0,0 +1,179 @@
+;*******************************************************************************
+;* x86-optimized H.264 CABAC decoding (non-SIMD)
+;* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
+;* Copyright (c) 2020 Anton Khirnov <anton@khirnov.net>
+;*
+;* 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/x86/x86util.asm"
+
+%define H264_NORM_SHIFT_OFFSET                 0
+%define H264_LPS_RANGE_OFFSET                  512
+%define H264_MLPS_STATE_OFFSET                 1024
+%define H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET 1280
+
+%define CC_OFF_LOW            0
+%define CC_OFF_RANGE          4
+%define CC_OFF_BYTESTREAM     24
+%define CC_OFF_BYTESTREAM_END 32
+
+cextern h264_cabac_tables
+
+SECTION .text
+
+%macro GET_CABAC 0
+    push rcx
+
+    movzx bitd,     byte [statep]
+    mov   tmpd,     ranged
+    and   ranged,   0xc0
+    lea   ecx,      [bitd + ranged * 2]
+    movzx ranged,   byte [tablesq + rcx + H264_LPS_RANGE_OFFSET]
+    sub   tmpd,     ranged
+    mov   ecx,      tmpd
+    shl   tmpd,     17
+    cmp   tmpd,     lowd
+    cmova ranged,   ecx
+    sbb   rcx,      rcx
+    and   tmpd,     ecx
+    xor   bitq,     rcx
+    sub   lowd,     tmpd
+
+    movzx ecx,      byte [tablesq + H264_NORM_SHIFT_OFFSET       + rangeq]
+    shl   ranged,   cl
+    shl   lowd,     cl
+
+    movzx tmpd,     byte [tablesq + H264_MLPS_STATE_OFFSET + 128 + bitq]
+    mov   [statep], tmpb
+
+    test  loww,     loww
+    jnz   %%finish
+
+    movzx tmpd,        word [bytestreamq]
+    cmp   bytestreamq, bytestream_endq
+    jge   %%skip_bs_advance
+    add   bytestreamq, 2
+%%skip_bs_advance:
+
+    lea   ecx,  [lowd - 1]
+    xor   ecx,  lowd
+    shr   ecx,  15
+    bswap tmpd
+    shr   tmpd, 15
+
+    movzx ecx,  byte [tablesq + rcx + H264_NORM_SHIFT_OFFSET]
+    sub   tmpd, 0xffff
+    neg   ecx
+    add   ecx,  7
+    shl   tmpd, cl
+    add   lowd, tmpd
+%%finish:
+    pop rcx
+%endmacro
+
+%macro DECODE_SIGNIFICANCE 1
+    ; store the values we won't need until the end on stack
+    mov qword [rsp],           4
+    sub       [rsp],           indexq
+    mov qword [rsp + gprsize], ccq
+
+    ; load CABACContext fields
+    mov lowd,            [ccq + CC_OFF_LOW]
+    mov ranged,          [ccq + CC_OFF_RANGE]
+    mov bytestreamq,     [ccq + CC_OFF_BYTESTREAM]
+    mov bytestream_endq, [ccq + CC_OFF_BYTESTREAM_END]
+
+    ; recycle the cabac context register for tables
+    %define tablesq ccq
+    lea tablesq, [h264_cabac_tables]
+
+%if %1
+    %define loop_count 63
+    %define statep stateq
+%else
+    sub     max_coeffd, 1
+    %define loop_count  max_coeffd
+    %define statep      significant_coeff_ctx_baseq + counterq
+%endif
+
+    xor counterq, counterq
+
+.loop:
+%if %1
+    movzx stated, byte [sig_offq + counterq]
+    add   stateq, significant_coeff_ctx_baseq
+%endif
+
+    GET_CABAC
+
+    test bitq, 1
+    jz .continue
+
+%if %1
+    movzx stated, byte [tablesq + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET + counterq]
+    add   stateq, last_coeff_ctx_baseq
+%else
+    add significant_coeff_ctx_baseq, last_offq
+%endif
+
+    GET_CABAC
+
+%if !%1
+    sub significant_coeff_ctx_baseq, last_offq
+%endif
+
+    mov [indexq], counterd
+
+    test bitq, 1
+    jnz  .finish
+
+    add  indexq, 4
+
+.continue:
+    add counterd, 1
+    cmp counterd, loop_count
+    jb .loop
+
+    mov [indexq], counterd
+
+.finish:
+    ; update CABACContext
+    mov ccq,                       [rsp + gprsize]
+    mov [ccq + CC_OFF_LOW],        lowd
+    mov [ccq + CC_OFF_RANGE],      ranged
+    mov [ccq + CC_OFF_BYTESTREAM], bytestreamq
+
+    add indexq, [rsp]
+    shr indexq, 2
+
+    movifnidn rax, indexq
+
+    RET
+%endmacro
+
+; int ff_h264_decode_significance_x86(CABACContext *cc, int max_coeff,
+;       uint8_t *significant_coeff_ctx_base, int *index, ptrdiff_t last_off)
+cglobal h264_decode_significance_x86, 5, 12, 0, gprsize * 2,        \
+        cc, max_coeff, significant_coeff_ctx_base, index, last_off, \
+        bytestream, bytestream_end, low, range, bit, counter, tmp
+DECODE_SIGNIFICANCE 0
+
+cglobal h264_decode_significance_8x8_x86, 5, 13, 0, gprsize * 2,              \
+        cc, significant_coeff_ctx_base, index, last_coeff_ctx_base, sig_off,  \
+        bytestream, bytestream_end, low, range, bit, counter, tmp, state
+DECODE_SIGNIFICANCE 1
diff --git a/libavcodec/x86/h264_cabac.c b/libavcodec/x86/h264_cabac.c
deleted file mode 100644
index 2edc6d7e74..0000000000
--- a/libavcodec/x86/h264_cabac.c
+++ /dev/null
@@ -1,208 +0,0 @@
-/*
- * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
- * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
- *
- * 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
- */
-
-/**
- * @file
- * H.264 / AVC / MPEG-4 part10 codec.
- * non-SIMD x86-specific optimizations for H.264
- * @author Michael Niedermayer <michaelni@gmx.at>
- */
-
-#include <stddef.h>
-
-#include "libavcodec/cabac.h"
-#include "cabac.h"
-
-#if HAVE_INLINE_ASM
-
-#if ARCH_X86_64
-#define REG64 "r"
-#else
-#define REG64 "m"
-#endif
-
-//FIXME use some macros to avoid duplicating get_cabac (cannot be done yet
-//as that would make optimization work hard)
-#if HAVE_7REGS && !BROKEN_COMPILER
-#define decode_significance decode_significance_x86
-static int decode_significance_x86(CABACContext *c, int max_coeff,
-                                   uint8_t *significant_coeff_ctx_base,
-                                   int *index, x86_reg last_off){
-    void *end= significant_coeff_ctx_base + max_coeff - 1;
-    int minusstart= -(intptr_t)significant_coeff_ctx_base;
-    int minusindex= 4-(intptr_t)index;
-    int bit;
-    x86_reg coeff_count;
-
-#ifdef BROKEN_RELOCATIONS
-    void *tables;
-
-    __asm__ volatile(
-        "lea   "MANGLE(ff_h264_cabac_tables)", %0      \n\t"
-        : "=&r"(tables)
-        : NAMED_CONSTRAINTS_ARRAY(ff_h264_cabac_tables)
-    );
-#endif
-
-    __asm__ volatile(
-        "3:                                     \n\t"
-
-        BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
-                             "%5", "%q5", "%k0", "%b0",
-                             "%c11(%6)", "%c12(%6)",
-                             AV_STRINGIFY(H264_NORM_SHIFT_OFFSET),
-                             AV_STRINGIFY(H264_LPS_RANGE_OFFSET),
-                             AV_STRINGIFY(H264_MLPS_STATE_OFFSET),
-                             "%13")
-
-        "test $1, %4                            \n\t"
-        " jz 4f                                 \n\t"
-        "add  %10, %1                           \n\t"
-
-        BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
-                             "%5", "%q5", "%k0", "%b0",
-                             "%c11(%6)", "%c12(%6)",
-                             AV_STRINGIFY(H264_NORM_SHIFT_OFFSET),
-                             AV_STRINGIFY(H264_LPS_RANGE_OFFSET),
-                             AV_STRINGIFY(H264_MLPS_STATE_OFFSET),
-                             "%13")
-
-        "sub  %10, %1                           \n\t"
-        "mov  %2, %0                            \n\t"
-        "movl %7, %%ecx                         \n\t"
-        "add  %1, %%"FF_REG_c"                  \n\t"
-        "movl %%ecx, (%0)                       \n\t"
-
-        "test $1, %4                            \n\t"
-        " jnz 5f                                \n\t"
-
-        "add"FF_OPSIZE"  $4, %2                 \n\t"
-
-        "4:                                     \n\t"
-        "add  $1, %1                            \n\t"
-        "cmp  %8, %1                            \n\t"
-        " jb 3b                                 \n\t"
-        "mov  %2, %0                            \n\t"
-        "movl %7, %%ecx                         \n\t"
-        "add  %1, %%"FF_REG_c"                  \n\t"
-        "movl %%ecx, (%0)                       \n\t"
-        "5:                                     \n\t"
-        "add  %9, %k0                           \n\t"
-        "shr $2, %k0                            \n\t"
-        : "=&q"(coeff_count), "+r"(significant_coeff_ctx_base), "+m"(index),
-          "+&r"(c->low), "=&r"(bit), "+&r"(c->range)
-        : "r"(c), "m"(minusstart), "m"(end), "m"(minusindex), "m"(last_off),
-          "i"(offsetof(CABACContext, bytestream)),
-          "i"(offsetof(CABACContext, bytestream_end))
-          TABLES_ARG
-        : "%"FF_REG_c, "memory"
-    );
-    return coeff_count;
-}
-
-#define decode_significance_8x8 decode_significance_8x8_x86
-static int decode_significance_8x8_x86(CABACContext *c,
-                                       uint8_t *significant_coeff_ctx_base,
-                                       int *index, uint8_t *last_coeff_ctx_base, const uint8_t *sig_off){
-    int minusindex= 4-(intptr_t)index;
-    int bit;
-    x86_reg coeff_count;
-    x86_reg last=0;
-    x86_reg state;
-
-#ifdef BROKEN_RELOCATIONS
-    void *tables;
-
-    __asm__ volatile(
-        "lea    "MANGLE(ff_h264_cabac_tables)", %0      \n\t"
-        : "=&r"(tables)
-        : NAMED_CONSTRAINTS_ARRAY(ff_h264_cabac_tables)
-    );
-#endif
-
-    __asm__ volatile(
-        "mov %1, %6                             \n\t"
-        "3:                                     \n\t"
-
-        "mov %10, %0                            \n\t"
-        "movzb (%0, %6), %6                     \n\t"
-        "add %9, %6                             \n\t"
-
-        BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
-                             "%5", "%q5", "%k0", "%b0",
-                             "%c12(%7)", "%c13(%7)",
-                             AV_STRINGIFY(H264_NORM_SHIFT_OFFSET),
-                             AV_STRINGIFY(H264_LPS_RANGE_OFFSET),
-                             AV_STRINGIFY(H264_MLPS_STATE_OFFSET),
-                             "%15")
-
-        "mov %1, %6                             \n\t"
-        "test $1, %4                            \n\t"
-        " jz 4f                                 \n\t"
-
-#ifdef BROKEN_RELOCATIONS
-        "movzb %c14(%15, %q6), %6\n\t"
-#else
-        "movzb "MANGLE(ff_h264_cabac_tables)"+%c14(%6), %6\n\t"
-#endif
-        "add %11, %6                            \n\t"
-
-        BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
-                             "%5", "%q5", "%k0", "%b0",
-                             "%c12(%7)", "%c13(%7)",
-                             AV_STRINGIFY(H264_NORM_SHIFT_OFFSET),
-                             AV_STRINGIFY(H264_LPS_RANGE_OFFSET),
-                             AV_STRINGIFY(H264_MLPS_STATE_OFFSET),
-                             "%15")
-
-        "mov %2, %0                             \n\t"
-        "mov %1, %6                             \n\t"
-        "mov %k6, (%0)                          \n\t"
-
-        "test $1, %4                            \n\t"
-        " jnz 5f                                \n\t"
-
-        "add"FF_OPSIZE"  $4, %2                 \n\t"
-
-        "4:                                     \n\t"
-        "add $1, %6                             \n\t"
-        "mov %6, %1                             \n\t"
-        "cmp $63, %6                            \n\t"
-        " jb 3b                                 \n\t"
-        "mov %2, %0                             \n\t"
-        "mov %k6, (%0)                          \n\t"
-        "5:                                     \n\t"
-        "addl %8, %k0                           \n\t"
-        "shr $2, %k0                            \n\t"
-        : "=&q"(coeff_count), "+"REG64(last), "+"REG64(index), "+&r"(c->low),
-          "=&r"(bit), "+&r"(c->range), "=&r"(state)
-        : "r"(c), "m"(minusindex), "m"(significant_coeff_ctx_base),
-          REG64(sig_off), REG64(last_coeff_ctx_base),
-          "i"(offsetof(CABACContext, bytestream)),
-          "i"(offsetof(CABACContext, bytestream_end)),
-          "i"(H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET) TABLES_ARG
-        : "%"FF_REG_c, "memory"
-    );
-    return coeff_count;
-}
-#endif /* HAVE_7REGS && BROKEN_COMPILER */
-
-#endif /* HAVE_INLINE_ASM */
diff --git a/libavcodec/x86/h264_cabac.h b/libavcodec/x86/h264_cabac.h
new file mode 100644
index 0000000000..bbbe875320
--- /dev/null
+++ b/libavcodec/x86/h264_cabac.h
@@ -0,0 +1,40 @@
+/*
+;* x86-optimized H.264 CABAC decoding (non-SIMD)
+ *
+ * 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_X86_H264_CABAC_H
+#define AVCODEC_X86_H264_CABAC_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "libavcodec/cabac.h"
+
+int ff_h264_decode_significance_x86(CABACContext *c, size_t max_coeff,
+                                    uint8_t *significant_coeff_ctx_base,
+                                    int *index, ptrdiff_t last_off);
+int ff_h264_decode_significance_8x8_x86(CABACContext *c,
+                                        uint8_t *significant_coeff_ctx_base,
+                                        int *index, uint8_t *last_coeff_ctx_base,
+                                        const uint8_t *sig_off);
+
+#define decode_significance     ff_h264_decode_significance_x86
+#define decode_significance_8x8 ff_h264_decode_significance_8x8_x86
+
+#endif // AVCODEC_X86_H264_CABAC_H