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Small simple idct improvement for Alpha by Falk Hueffner <falk.hueffner@student.uni-tuebingen.de> 

Originally committed as revision 276 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Nick Kurshev 2002-01-21 17:46:42 +00:00
parent 5cebb24be0
commit c7997007be
1 changed files with 25 additions and 7 deletions
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30
libavcodec/simple_idct.c
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@ -104,6 +104,7 @@ static int inline idctRowCondZ (int16_t * row)
}
#ifdef ARCH_ALPHA
/* 0: all entries 0, 1: only first entry nonzero, 2: otherwise */
static int inline idctRowCondDC(int16_t *row)
{
int_fast32_t a0, a1, a2, a3, b0, b1, b2, b3;
@ -201,7 +202,7 @@ static int inline idctRowCondDC(int16_t *row)
row[6] = (a1 - b1) >> ROW_SHIFT;
row[7] = (a0 - b0) >> ROW_SHIFT;
return 1;
return 2;
}
#else /* not ARCH_ALPHA */
static int inline idctRowCondDC (int16_t * row)
@ -547,16 +548,33 @@ void simple_idct (short *block)
idctSparse2Col(block + i);
}
#elif defined(ARCH_ALPHA)
int shortcut = 1;
int rowsZero = 1; /* all rows except row 0 zero */
int rowsConstant = 1; /* all rows consist of a constant value */
for (i = 0; i < 8; i++) {
int anynonzero = idctRowCondDC(block + 8 * i);
if (i > 0 && anynonzero)
shortcut = 0;
int sparseness = idctRowCondDC(block + 8 * i);
if (i > 0 && sparseness > 0)
rowsZero = 0;
if (sparseness == 2)
rowsConstant = 0;
}
if (shortcut) {
if (rowsZero) {
idctCol2(block);
} else if (rowsConstant) {
uint64_t *lblock = (uint64_t *) block;
idctSparseCol(block);
for (i = 0; i < 8; i++) {
uint64_t v = (uint16_t) block[i * 8];
v += v << 16;
v += v << 32;
lblock[0] = v;
lblock[1] = v;
lblock += 2;
}
} else {
for (i = 0; i < 8; i++)
idctSparseCol(block + i);