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All zero coeff skip in IDCT 32x32

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When all coefficients are zeros, skip the corresponding 1-D inverse
transform. This practice has been used in the SSE2 implementation of
inverse 32x32 DCT. This commit imports this algorithm into the C code.

Change-Id: I0f58bfcb183a569fab85d524d5d9cf8ae8653f86
This commit is contained in:
Jingning Han 2013-10-08 09:06:08 -07:00
parent 2ae93a776b
commit 6594ca8897
1 changed files with 14 additions and 1 deletions
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15
vp9/common/vp9_idct.c
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@ -1253,7 +1253,20 @@ void vp9_short_idct32x32_add_c(int16_t *input, uint8_t *dest, int dest_stride) {
// Rows
for (i = 0; i < 32; ++i) {
idct32_1d(input, outptr);
int16_t zero_coeff[16];
for (j = 0; j < 16; ++j)
zero_coeff[j] = input[2 * j] | input[2 * j + 1];
for (j = 0; j < 8; ++j)
zero_coeff[j] = zero_coeff[2 * j] | zero_coeff[2 * j + 1];
for (j = 0; j < 4; ++j)
zero_coeff[j] = zero_coeff[2 * j] | zero_coeff[2 * j + 1];
for (j = 0; j < 2; ++j)
zero_coeff[j] = zero_coeff[2 * j] | zero_coeff[2 * j + 1];
if (zero_coeff[0] | zero_coeff[1])
idct32_1d(input, outptr);
else
vpx_memset(outptr, 0, sizeof(int16_t) * 32);
input += 32;
outptr += 32;
}