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libavutil: add saturating addition functions

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Fixed-point audio codecs often use saturating arithmetic, and
special instructions for these operations are common.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard 2012-08-11 01:15:19 +01:00
parent 17c11cef9f
commit 6c4975eaaf
2 changed files with 45 additions and 0 deletions
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15
libavutil/arm/intmath.h
View File

@ -83,6 +83,21 @@ static av_always_inline av_const unsigned av_clip_uintp2_arm(int a, int p)
return x;
}
#define av_sat_add32 av_sat_add32_arm
static av_always_inline int av_sat_add32_arm(int a, int b)
{
int r;
__asm__ ("qadd %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
return r;
}
#define av_sat_dadd32 av_sat_dadd32_arm
static av_always_inline int av_sat_dadd32_arm(int a, int b)
{
int r;
__asm__ ("qdadd %0, %1, %2" : "=r"(r) : "r"(a), "r"(b));
return r;
}
#else /* HAVE_ARMV6 */

30
libavutil/common.h
View File

@ -181,6 +181,30 @@ static av_always_inline av_const unsigned av_clip_uintp2_c(int a, int p)
else return a;
}
/**
* Add two signed 32-bit values with saturation.
*
* @param a one value
* @param b another value
* @return sum with signed saturation
*/
static av_always_inline int av_sat_add32_c(int a, int b)
{
return av_clipl_int32((int64_t)a + b);
}
/**
* Add a doubled value to another value with saturation at both stages.
*
* @param a first value
* @param b value doubled and added to a
* @return sum 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));
}
/**
* Clip a float value into the amin-amax range.
* @param a value to clip
@ -387,6 +411,12 @@ static av_always_inline av_const int av_popcount64_c(uint64_t x)
#ifndef av_clip_uintp2
# define av_clip_uintp2 av_clip_uintp2_c
#endif
#ifndef av_sat_add32
# define av_sat_add32 av_sat_add32_c
#endif
#ifndef av_sat_dadd32
# define av_sat_dadd32 av_sat_dadd32_c
#endif
#ifndef av_clipf
# define av_clipf av_clipf_c
#endif