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improve RFX DWT algorithm

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merge multiple loops into the one loop for vertical DWT inverse
This commit is contained in:
Vladyslav Hordiienko
2020-05-06 12:36:44 +03:00
committed by akallabeth
parent 15245c2abd
commit f79bb517c1
1 changed files with 18 additions and 17 deletions
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35
libfreerdp/codec/rfx_dwt.c
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@@ -87,26 +87,27 @@ void rfx_dwt_2d_decode_block(INT16* buffer, INT16* idwt, int subband_width)
/* Inverse DWT in vertical direction, results are stored in original buffer. */
for (x = 0; x < total_width; x++)
{
/* Even coefficients */
for (n = 0; n < subband_width; n++)
l = idwt + x;
h = idwt + x + subband_width * total_width;
dst = buffer + x;
*dst = *l - ((*h * 2 + 1) >> 1);
for (n = 1; n < subband_width; n++)
{
y = n << 1;
dst = buffer + y * total_width + x;
l = idwt + n * total_width + x;
h = l + subband_width * total_width;
dst[0] = *l - (((n > 0 ? *(h - total_width) : *h) + (*h) + 1) >> 1);
l += total_width;
h += total_width;
/* Even coefficients */
dst[2 * total_width] = *l - ((*(h - total_width) + *h + 1) >> 1);
/* Odd coefficients */
dst[total_width] = (*(h - total_width) << 1) + ((*dst + dst[2 * total_width]) >> 1);
dst += 2 * total_width;
}
/* Odd coefficients */
for (n = 0; n < subband_width; n++)
{
y = n << 1;
dst = buffer + y * total_width + x;
l = idwt + n * total_width + x;
h = l + subband_width * total_width;
dst[total_width] =
(*h << 1) + ((dst[0] + dst[n < subband_width - 1 ? 2 * total_width : 0]) >> 1);
}
dst[total_width] = (*h << 1) + ((*dst * 2) >> 1);
}
}