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ac3enc: Add x86-optimized function to speed up log2_tab().

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AC3DSPContext.ac3_max_msb_abs_int16() finds the maximum MSB of the absolute
value of each element in an array of int16_t.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This commit is contained in:
Justin Ruggles 2011-02-13 14:49:50 -05:00 committed by Ronald S. Bultje
parent 1a973feb45
commit fbb6b49dab
5 changed files with 103 additions and 8 deletions
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9
libavcodec/ac3dsp.c
View File

@ -42,9 +42,18 @@ static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
}
}
static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
{
int i, v = 0;
for (i = 0; i < len; i++)
v |= abs(src[i]);
return v;
}
av_cold void ff_ac3dsp_init(AC3DSPContext *c)
{
c->ac3_exponent_min = ac3_exponent_min_c;
c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
if (HAVE_MMX)
ff_ac3dsp_init_x86(c);

11
libavcodec/ac3dsp.h
View File

@ -35,6 +35,17 @@ typedef struct AC3DSPContext {
* @param nb_coefs number of frequency coefficients.
*/
void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
/**
* Calculate the maximum MSB of the absolute value of each element in an
* array of int16_t.
* @param src input array
* constraints: align 16. values must be in range [-32767,32767]
* @param len number of values in the array
* constraints: multiple of 16 greater than 0
* @return a value with the same MSB as max(abs(src[]))
*/
int (*ac3_max_msb_abs_int16)(const int16_t *src, int len);
} AC3DSPContext;
void ff_ac3dsp_init (AC3DSPContext *c);

11
libavcodec/ac3enc_fixed.c
View File

@ -270,14 +270,9 @@ static void apply_window(DSPContext *dsp, int16_t *output, const int16_t *input,
* @param n number of values in the array
* @return log2(max(abs(tab[])))
*/
static int log2_tab(int16_t *tab, int n)
static int log2_tab(AC3EncodeContext *s, int16_t *src, int len)
{
int i, v;
v = 0;
for (i = 0; i < n; i++)
v |= abs(tab[i]);
int v = s->ac3dsp.ac3_max_msb_abs_int16(src, len);
return av_log2(v);
}
@ -308,7 +303,7 @@ static void lshift_tab(int16_t *tab, int n, unsigned int lshift)
*/
static int normalize_samples(AC3EncodeContext *s)
{
int v = 14 - log2_tab(s->windowed_samples, AC3_WINDOW_SIZE);
int v = 14 - log2_tab(s, s->windowed_samples, AC3_WINDOW_SIZE);
lshift_tab(s->windowed_samples, AC3_WINDOW_SIZE, v);
return v - 9;
}

69
libavcodec/x86/ac3dsp.asm
View File

@ -65,3 +65,72 @@ AC3_EXPONENT_MIN sse2
%endif
%undef PMINUB
%undef LOOP_ALIGN
;-----------------------------------------------------------------------------
; int ff_ac3_max_msb_abs_int16(const int16_t *src, int len)
;
; This function uses 2 different methods to calculate a valid result.
; 1) logical 'or' of abs of each element
; This is used for ssse3 because of the pabsw instruction.
; It is also used for mmx because of the lack of min/max instructions.
; 2) calculate min/max for the array, then or(abs(min),abs(max))
; This is used for mmxext and sse2 because they have pminsw/pmaxsw.
;-----------------------------------------------------------------------------
%macro AC3_MAX_MSB_ABS_INT16 2
cglobal ac3_max_msb_abs_int16_%1, 2,2,5, src, len
pxor m2, m2
pxor m3, m3
.loop:
%ifidn %2, min_max
mova m0, [srcq]
mova m1, [srcq+mmsize]
pminsw m2, m0
pminsw m2, m1
pmaxsw m3, m0
pmaxsw m3, m1
%else ; or_abs
%ifidn %1, mmx
mova m0, [srcq]
mova m1, [srcq+mmsize]
ABS2 m0, m1, m3, m4
%else ; ssse3
; using memory args is faster for ssse3
pabsw m0, [srcq]
pabsw m1, [srcq+mmsize]
%endif
por m2, m0
por m2, m1
%endif
add srcq, mmsize*2
sub lend, mmsize
ja .loop
%ifidn %2, min_max
ABS2 m2, m3, m0, m1
por m2, m3
%endif
%ifidn mmsize, 16
mova m0, m2
punpckhqdq m0, m0
por m2, m0
%endif
PSHUFLW m0, m2, 0xe
por m2, m0
PSHUFLW m0, m2, 0x1
por m2, m0
movd eax, m2
and eax, 0xFFFF
RET
%endmacro
INIT_MMX
%define ABS2 ABS2_MMX
%define PSHUFLW pshufw
AC3_MAX_MSB_ABS_INT16 mmx, or_abs
%define ABS2 ABS2_MMX2
AC3_MAX_MSB_ABS_INT16 mmxext, min_max
INIT_XMM
%define PSHUFLW pshuflw
AC3_MAX_MSB_ABS_INT16 sse2, min_max
%define ABS2 ABS2_SSSE3
AC3_MAX_MSB_ABS_INT16 ssse3, or_abs

11
libavcodec/x86/ac3dsp_mmx.c
View File

@ -27,6 +27,11 @@ extern void ff_ac3_exponent_min_mmx (uint8_t *exp, int num_reuse_blocks, int n
extern void ff_ac3_exponent_min_mmxext(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
extern void ff_ac3_exponent_min_sse2 (uint8_t *exp, int num_reuse_blocks, int nb_coefs);
extern int ff_ac3_max_msb_abs_int16_mmx (const int16_t *src, int len);
extern int ff_ac3_max_msb_abs_int16_mmxext(const int16_t *src, int len);
extern int ff_ac3_max_msb_abs_int16_sse2 (const int16_t *src, int len);
extern int ff_ac3_max_msb_abs_int16_ssse3 (const int16_t *src, int len);
av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c)
{
int mm_flags = av_get_cpu_flags();
@ -34,12 +39,18 @@ av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c)
#if HAVE_YASM
if (mm_flags & AV_CPU_FLAG_MMX) {
c->ac3_exponent_min = ff_ac3_exponent_min_mmx;
c->ac3_max_msb_abs_int16 = ff_ac3_max_msb_abs_int16_mmx;
}
if (mm_flags & AV_CPU_FLAG_MMX2 && HAVE_MMX2) {
c->ac3_exponent_min = ff_ac3_exponent_min_mmxext;
c->ac3_max_msb_abs_int16 = ff_ac3_max_msb_abs_int16_mmxext;
}
if (mm_flags & AV_CPU_FLAG_SSE2 && HAVE_SSE) {
c->ac3_exponent_min = ff_ac3_exponent_min_sse2;
c->ac3_max_msb_abs_int16 = ff_ac3_max_msb_abs_int16_sse2;
}
if (mm_flags & AV_CPU_FLAG_SSSE3 && HAVE_SSSE3) {
c->ac3_max_msb_abs_int16 = ff_ac3_max_msb_abs_int16_ssse3;
}
#endif
}