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optimize fast_quantizer c version

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As the zbin and rounding constants are normalized, rounding effectively
does the zbinning, therefore the zbin operation can be removed. In
addition, the memset on the two arrays are no longer necessary.

Change-Id: If39c353c42d7e052296cb65322e5218810b5cc4c
This commit is contained in:
Yaowu Xu 2010-10-06 13:28:36 -07:00
parent 7be093ea4d
commit d338d14c6b
1 changed files with 7 additions and 16 deletions
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23
vp8/encoder/quantize.c
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@ -125,38 +125,29 @@ void vp8_fast_quantize_b_c(BLOCK *b, BLOCKD *d)
int zbin;
int x, y, z, sz;
short *coeff_ptr = &b->coeff[0];
short *zbin_ptr = &b->zbin[0][0];
short *round_ptr = &b->round[0][0];
short *quant_ptr = &b->quant[0][0];
short *qcoeff_ptr = d->qcoeff;
short *dqcoeff_ptr = d->dqcoeff;
short *dequant_ptr = &d->dequant[0][0];
vpx_memset(qcoeff_ptr, 0, 32);
vpx_memset(dqcoeff_ptr, 0, 32);
eob = -1;
for (i = 0; i < 16; i++)
{
rc = vp8_default_zig_zag1d[i];
z = coeff_ptr[rc];
zbin = zbin_ptr[rc] ;
sz = (z >> 31); // sign of z
x = (z ^ sz) - sz; // x = abs(z)
if (x >= zbin)
{
y = ((x + round_ptr[rc]) * quant_ptr[rc]) >> 16; // quantize (x)
x = (y ^ sz) - sz; // get the sign back
qcoeff_ptr[rc] = x; // write to destination
dqcoeff_ptr[rc] = x * dequant_ptr[rc]; // dequantized value
y = ((x + round_ptr[rc]) * quant_ptr[rc]) >> 16; // quantize (x)
x = (y ^ sz) - sz; // get the sign back
qcoeff_ptr[rc] = x; // write to destination
dqcoeff_ptr[rc] = x * dequant_ptr[rc]; // dequantized value
if (y)
{
eob = i; // last nonzero coeffs
}
if (y)
{
eob = i; // last nonzero coeffs
}
}
d->eob = eob + 1;