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libavutil: Add saturating subtraction functions

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Add av_sat_sub32 and av_sat_dsub32 as the subtraction analogues to
av_sat_add32/av_sat_dadd32.

Also clarify the formulas for dadd32/dsub32.

Signed-off-by: Andrew D'Addesio <modchipv12@gmail.com>
This commit is contained in:
Andrew D'Addesio 2017-12-02 11:36:24 -06:00 committed by Rostislav Pehlivanov
parent b73304f79e
commit 9b45bcf713
3 changed files with 48 additions and 2 deletions
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16
libavutil/arm/intmath.h
View File

@ -94,6 +94,22 @@ static av_always_inline int av_sat_dadd32_arm(int a, int b)
return r;
}
#define av_sat_sub32 av_sat_sub32_arm
static av_always_inline int av_sat_sub32_arm(int a, int b)
{
int r;
__asm__ ("qsub %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
return r;
}
#define av_sat_dsub32 av_sat_dsub32_arm
static av_always_inline int av_sat_dsub32_arm(int a, int b)
{
int r;
__asm__ ("qdsub %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
return r;
}
#endif /* HAVE_ARMV6_INLINE */
#if HAVE_ASM_MOD_Q

32
libavutil/common.h
View File

@ -260,13 +260,37 @@ static av_always_inline int av_sat_add32_c(int a, int b)
*
* @param a first value
* @param b value doubled and added to a
* @return sum with signed saturation
* @return sum sat(a + sat(2*b)) with signed saturation
*/
static av_always_inline int av_sat_dadd32_c(int a, int b)
{
return av_sat_add32(a, av_sat_add32(b, b));
}
/**
* Subtract two signed 32-bit values with saturation.
*
* @param a one value
* @param b another value
* @return difference with signed saturation
*/
static av_always_inline int av_sat_sub32_c(int a, int b)
{
return av_clipl_int32((int64_t)a - b);
}
/**
* Subtract a doubled value from another value with saturation at both stages.
*
* @param a first value
* @param b value doubled and subtracted from a
* @return difference sat(a - sat(2*b)) with signed saturation
*/
static av_always_inline int av_sat_dsub32_c(int a, int b)
{
return av_sat_sub32(a, av_sat_add32(b, b));
}
/**
* Clip a float value into the amin-amax range.
* @param a value to clip
@ -513,6 +537,12 @@ static av_always_inline av_const int av_parity_c(uint32_t v)
#ifndef av_sat_dadd32
# define av_sat_dadd32 av_sat_dadd32_c
#endif
#ifndef av_sat_sub32
# define av_sat_sub32 av_sat_sub32_c
#endif
#ifndef av_sat_dsub32
# define av_sat_dsub32 av_sat_dsub32_c
#endif
#ifndef av_clipf
# define av_clipf av_clipf_c
#endif

2
libavutil/version.h
View File

@ -79,7 +79,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 56
#define LIBAVUTIL_VERSION_MINOR 4
#define LIBAVUTIL_VERSION_MINOR 5
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \