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avcodec/cabac: support UNCHECKED_BITSTREAM_READER = 0

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Fixes overreads in HEVC
Fixes Ticket3070
Also fixed remaining issues from Ticket3075 and Ticket3076

Some lines of code taken from  0c5f839693da2276c2da23400f67a67be4ea0af1:libavcodec/x86/cabac.h
and                            0c5f839693da2276c2da23400f67a67be4ea0af1:libavcodec/cabac_functions.h

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
pull/45/head
Michael Niedermayer 11 years ago
parent 7c8b65f688
commit fa6fa2162b
2 changed files with 31 additions and 2 deletions
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  1. 10
      libavcodec/cabac_functions.h
  2. 23
      libavcodec/x86/cabac.h

10
libavcodec/cabac_functions.h
Unescape View File

@ -49,7 +49,10 @@ static void refill(CABACContext *c){
c->low+= c->bytestream[0]<<1;
#endif
c->low -= CABAC_MASK;
c->bytestream += CABAC_BITS / 8;
#if !UNCHECKED_BITSTREAM_READER
if (c->bytestream < c->bytestream_end)
#endif
c->bytestream += CABAC_BITS / 8;
}
static inline void renorm_cabac_decoder_once(CABACContext *c){
@ -76,7 +79,10 @@ static void refill2(CABACContext *c){
#endif
c->low += x<<i;
c->bytestream += CABAC_BITS/8;
#if !UNCHECKED_BITSTREAM_READER
if (c->bytestream < c->bytestream_end)
#endif
c->bytestream += CABAC_BITS/8;
}
static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){

23
libavcodec/x86/cabac.h
Unescape View File

@ -36,6 +36,18 @@
#if HAVE_INLINE_ASM
#ifndef UNCHECKED_BITSTREAM_READER
#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
#endif
#if UNCHECKED_BITSTREAM_READER
#define END_CHECK(end) ""
#else
#define END_CHECK(end) \
"cmp "end" , %%"REG_c" \n\t"\
"jge 1f \n\t"
#endif
#ifdef BROKEN_RELOCATIONS
#define TABLES_ARG , "r"(tables)
@ -80,7 +92,9 @@
"test "lowword" , "lowword" \n\t"\
"jnz 2f \n\t"\
"mov "byte" , %%"REG_c" \n\t"\
END_CHECK(end)\
"add"OPSIZE" $2 , "byte" \n\t"\
"1: \n\t"\
"movzwl (%%"REG_c") , "tmp" \n\t"\
"lea -1("low") , %%ecx \n\t"\
"xor "low" , %%ecx \n\t"\
@ -139,7 +153,9 @@
"test "lowword" , "lowword" \n\t"\
" jnz 2f \n\t"\
"mov "byte" , %%"REG_c" \n\t"\
END_CHECK(end)\
"add"OPSIZE" $2 , "byte" \n\t"\
"1: \n\t"\
"movzwl (%%"REG_c") , "tmp" \n\t"\
"lea -1("low") , %%ecx \n\t"\
"xor "low" , %%ecx \n\t"\
@ -214,9 +230,16 @@ static av_always_inline int get_cabac_bypass_sign_x86(CABACContext *c, int val)
"movzwl (%1), %%edx \n\t"
"bswap %%edx \n\t"
"shrl $15, %%edx \n\t"
#if UNCHECKED_BITSTREAM_READER
"add $2, %1 \n\t"
"addl %%edx, %%eax \n\t"
"mov %1, %c4(%2) \n\t"
#else
"addl %%edx, %%eax \n\t"
"cmp %c5(%2), %1 \n\t"
"jge 1f \n\t"
"add"OPSIZE" $2, %c4(%2) \n\t"
#endif
"1: \n\t"
"movl %%eax, %c3(%2) \n\t"

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