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avutil/common: assert that bit position in av_zero_extend is valid 

Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
James Almer 2024-06-11 13:44:37 -03:00
parent 39c90d6466
commit 4b57ea8fc7
2 changed files with 17 additions and 2 deletions
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5
libavutil/common.h
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@ -286,11 +286,14 @@ static av_always_inline av_const unsigned av_clip_uintp2_c(int a, int p)
/**
* Clear high bits from an unsigned integer starting with specific bit position
* @param a value to clip
* @param p bit position to clip at
* @param p bit position to clip at. Must be between 0 and 31.
* @return clipped value
*/
static av_always_inline av_const unsigned av_zero_extend_c(unsigned a, unsigned p)
{
#if defined(HAVE_AV_CONFIG_H) && defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
if (p > 31) abort();
#endif
return a & ((1U << p) - 1);
}

14
libavutil/x86/intmath.h
View File

@ -82,7 +82,16 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
#if defined(__BMI2__)
#if AV_GCC_VERSION_AT_LEAST(5,1)
#if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
#define av_zero_extend av_zero_extend_bmi2
static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
{
if (p > 31) abort();
return __builtin_ia32_bzhi_si(a, p);
}
#else
#define av_zero_extend __builtin_ia32_bzhi_si
#endif
#elif HAVE_INLINE_ASM
/* GCC releases before 5.1.0 have a broken bzhi builtin, so for those we
* implement it using inline assembly
@ -90,8 +99,11 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
#define av_zero_extend av_zero_extend_bmi2
static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
{
#if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
if (p > 31) abort();
#endif
if (av_builtin_constant_p(p))
return a & ((1 << p) - 1);
return a & ((1U << p) - 1);
else {
unsigned x;
__asm__ ("bzhi %2, %1, %0 \n\t" : "=r"(x) : "rm"(a), "r"(p));