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enc_sse2/TTransform: simplify abs calculation

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max(b, 0 - b) works as well as (b ^ sign) - b

Change-Id: Iad923236fd70db85ff58a64d3c8e25e4f42a525d
This commit is contained in:
James Zern 2015-05-08 19:50:16 -07:00
parent 17dbd05819
commit 929a0fdccd
1 changed files with 8 additions and 15 deletions
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23
src/dsp/enc_sse2.c
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@ -1197,21 +1197,14 @@ static int TTransform(const uint8_t* inA, const uint8_t* inB,
__m128i B_b2 = _mm_unpackhi_epi64(b2, b3);
{
// sign(b) = b >> 15 (0x0000 if positive, 0xffff if negative)
const __m128i sign_A_b0 = _mm_srai_epi16(A_b0, 15);
const __m128i sign_A_b2 = _mm_srai_epi16(A_b2, 15);
const __m128i sign_B_b0 = _mm_srai_epi16(B_b0, 15);
const __m128i sign_B_b2 = _mm_srai_epi16(B_b2, 15);
// b = abs(b) = (b ^ sign) - sign
A_b0 = _mm_xor_si128(A_b0, sign_A_b0);
A_b2 = _mm_xor_si128(A_b2, sign_A_b2);
B_b0 = _mm_xor_si128(B_b0, sign_B_b0);
B_b2 = _mm_xor_si128(B_b2, sign_B_b2);
A_b0 = _mm_sub_epi16(A_b0, sign_A_b0);
A_b2 = _mm_sub_epi16(A_b2, sign_A_b2);
B_b0 = _mm_sub_epi16(B_b0, sign_B_b0);
B_b2 = _mm_sub_epi16(B_b2, sign_B_b2);
const __m128i d0 = _mm_sub_epi16(zero, A_b0);
const __m128i d1 = _mm_sub_epi16(zero, A_b2);
const __m128i d2 = _mm_sub_epi16(zero, B_b0);
const __m128i d3 = _mm_sub_epi16(zero, B_b2);
A_b0 = _mm_max_epi16(A_b0, d0); // abs(v), 16b
A_b2 = _mm_max_epi16(A_b2, d1);
B_b0 = _mm_max_epi16(B_b0, d2);
B_b2 = _mm_max_epi16(B_b2, d3);
}
// weighted sums