libwebp/src/dec/dsp_sse2.c

// Copyright 2011 Google Inc.
//
// This code is licensed under the same terms as WebM:
//  Software License Agreement:  http://www.webmproject.org/license/software/
//  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// SSE2 version of dsp functions and loop filtering.
//
// Author: somnath@google.com (Somnath Banerjee)
//         cduvivier@google.com (Christian Duvivier)

#if defined(__SSE2__) || defined(_MSC_VER)

#include <emmintrin.h>
#include "vp8i.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

//-----------------------------------------------------------------------------
// Transforms (Paragraph 14.4)

static void TransformSSE2(const int16_t* in, uint8_t* dst) {
  // This implementation makes use of 16-bit fixed point versions of two
  // multiply constants:
  //    K1 = sqrt(2) * cos (pi/8) ~= 85627 / 2^16
  //    K2 = sqrt(2) * sin (pi/8) ~= 35468 / 2^16
  //
  // To be able to use signed 16-bit integers, we use the following trick to
  // have constants within range:
  // - Associated constants are obtained by subtracting the 16-bit fixed point
  //   version of one:
  //      k = K - (1 << 16)  =>  K = k + (1 << 16)
  //      K1 = 85267  =>  k1 =  20091
  //      K2 = 35468  =>  k2 = -30068
  // - The multiplication of a variable by a constant become the sum of the
  //   variable and the multiplication of that variable by the associated
  //   constant:
  //      (x * K) >> 16 = (x * (k + (1 << 16))) >> 16 = ((x * k ) >> 16) + x
  const __m128i k1 = _mm_set1_epi16(20091);
  const __m128i k2 = _mm_set1_epi16(-30068);
  __m128i T0, T1, T2, T3;

  // Load the transform coefficients. The second half of the vectors will just
  // contain random value we'll never use nor store.
  __m128i in0, in1, in2, in3;
  {
    in0 = _mm_loadl_epi64((__m128i*)&in[0]);
    in1 = _mm_loadl_epi64((__m128i*)&in[4]);
    in2 = _mm_loadl_epi64((__m128i*)&in[8]);
    in3 = _mm_loadl_epi64((__m128i*)&in[12]);
    // a00 a10 a20 a30   x x x x
    // a01 a11 a21 a31   x x x x
    // a02 a12 a22 a32   x x x x
    // a03 a13 a23 a33   x x x x
  }

  // Vertical pass and subsequent transpose.
  {
    // First pass, c and d calculations are longer because of the "trick"
    // multiplications.
    const __m128i a = _mm_add_epi16(in0, in2);
    const __m128i b = _mm_sub_epi16(in0, in2);
    // c = MUL(in1, K2) - MUL(in3, K1) = MUL(in1, k2) - MUL(in3, k1) + in1 - in3
    const __m128i c1 = _mm_mulhi_epi16(in1, k2);
    const __m128i c2 = _mm_mulhi_epi16(in3, k1);
    const __m128i c3 = _mm_sub_epi16(in1, in3);
    const __m128i c4 = _mm_sub_epi16(c1, c2);
    const __m128i c = _mm_add_epi16(c3, c4);
    // d = MUL(in1, K1) + MUL(in3, K2) = MUL(in1, k1) + MUL(in3, k2) + in1 + in3
    const __m128i d1 = _mm_mulhi_epi16(in1, k1);
    const __m128i d2 = _mm_mulhi_epi16(in3, k2);
    const __m128i d3 = _mm_add_epi16(in1, in3);
    const __m128i d4 = _mm_add_epi16(d1, d2);
    const __m128i d = _mm_add_epi16(d3, d4);

    // Second pass.
    const __m128i tmp0 = _mm_add_epi16(a, d);
    const __m128i tmp1 = _mm_add_epi16(b, c);
    const __m128i tmp2 = _mm_sub_epi16(b, c);
    const __m128i tmp3 = _mm_sub_epi16(a, d);

    // Transpose the two 4x4.
    // a00 a01 a02 a03   b00 b01 b02 b03
    // a10 a11 a12 a13   b10 b11 b12 b13
    // a20 a21 a22 a23   b20 b21 b22 b23
    // a30 a31 a32 a33   b30 b31 b32 b33
    const __m128i transpose0_0 = _mm_unpacklo_epi16(tmp0, tmp1);
    const __m128i transpose0_1 = _mm_unpacklo_epi16(tmp2, tmp3);
    const __m128i transpose0_2 = _mm_unpackhi_epi16(tmp0, tmp1);
    const __m128i transpose0_3 = _mm_unpackhi_epi16(tmp2, tmp3);
    // a00 a10 a01 a11   a02 a12 a03 a13
    // a20 a30 a21 a31   a22 a32 a23 a33
    // b00 b10 b01 b11   b02 b12 b03 b13
    // b20 b30 b21 b31   b22 b32 b23 b33
    const __m128i transpose1_0 = _mm_unpacklo_epi32(transpose0_0, transpose0_1);
    const __m128i transpose1_1 = _mm_unpacklo_epi32(transpose0_2, transpose0_3);
    const __m128i transpose1_2 = _mm_unpackhi_epi32(transpose0_0, transpose0_1);
    const __m128i transpose1_3 = _mm_unpackhi_epi32(transpose0_2, transpose0_3);
    // a00 a10 a20 a30 a01 a11 a21 a31
    // b00 b10 b20 b30 b01 b11 b21 b31
    // a02 a12 a22 a32 a03 a13 a23 a33
    // b02 b12 a22 b32 b03 b13 b23 b33
    T0 = _mm_unpacklo_epi64(transpose1_0, transpose1_1);
    T1 = _mm_unpackhi_epi64(transpose1_0, transpose1_1);
    T2 = _mm_unpacklo_epi64(transpose1_2, transpose1_3);
    T3 = _mm_unpackhi_epi64(transpose1_2, transpose1_3);
    // a00 a10 a20 a30   b00 b10 b20 b30
    // a01 a11 a21 a31   b01 b11 b21 b31
    // a02 a12 a22 a32   b02 b12 b22 b32
    // a03 a13 a23 a33   b03 b13 b23 b33
  }

  // Horizontal pass and subsequent transpose.
  {
    // First pass, c and d calculations are longer because of the "trick"
    // multiplications.
    const __m128i four = _mm_set1_epi16(4);
    const __m128i dc = _mm_add_epi16(T0, four);
    const __m128i a =  _mm_add_epi16(dc, T2);
    const __m128i b =  _mm_sub_epi16(dc, T2);
    // c = MUL(T1, K2) - MUL(T3, K1) = MUL(T1, k2) - MUL(T3, k1) + T1 - T3
    const __m128i c1 = _mm_mulhi_epi16(T1, k2);
    const __m128i c2 = _mm_mulhi_epi16(T3, k1);
    const __m128i c3 = _mm_sub_epi16(T1, T3);
    const __m128i c4 = _mm_sub_epi16(c1, c2);
    const __m128i c = _mm_add_epi16(c3, c4);
    // d = MUL(T1, K1) + MUL(T3, K2) = MUL(T1, k1) + MUL(T3, k2) + T1 + T3
    const __m128i d1 = _mm_mulhi_epi16(T1, k1);
    const __m128i d2 = _mm_mulhi_epi16(T3, k2);
    const __m128i d3 = _mm_add_epi16(T1, T3);
    const __m128i d4 = _mm_add_epi16(d1, d2);
    const __m128i d = _mm_add_epi16(d3, d4);

    // Second pass.
    const __m128i tmp0 = _mm_add_epi16(a, d);
    const __m128i tmp1 = _mm_add_epi16(b, c);
    const __m128i tmp2 = _mm_sub_epi16(b, c);
    const __m128i tmp3 = _mm_sub_epi16(a, d);
    const __m128i shifted0 = _mm_srai_epi16(tmp0, 3);
    const __m128i shifted1 = _mm_srai_epi16(tmp1, 3);
    const __m128i shifted2 = _mm_srai_epi16(tmp2, 3);
    const __m128i shifted3 = _mm_srai_epi16(tmp3, 3);

    // Transpose the two 4x4.
    // a00 a01 a02 a03   b00 b01 b02 b03
    // a10 a11 a12 a13   b10 b11 b12 b13
    // a20 a21 a22 a23   b20 b21 b22 b23
    // a30 a31 a32 a33   b30 b31 b32 b33
    const __m128i transpose0_0 = _mm_unpacklo_epi16(shifted0, shifted1);
    const __m128i transpose0_1 = _mm_unpacklo_epi16(shifted2, shifted3);
    const __m128i transpose0_2 = _mm_unpackhi_epi16(shifted0, shifted1);
    const __m128i transpose0_3 = _mm_unpackhi_epi16(shifted2, shifted3);
    // a00 a10 a01 a11   a02 a12 a03 a13
    // a20 a30 a21 a31   a22 a32 a23 a33
    // b00 b10 b01 b11   b02 b12 b03 b13
    // b20 b30 b21 b31   b22 b32 b23 b33
    const __m128i transpose1_0 = _mm_unpacklo_epi32(transpose0_0, transpose0_1);
    const __m128i transpose1_1 = _mm_unpacklo_epi32(transpose0_2, transpose0_3);
    const __m128i transpose1_2 = _mm_unpackhi_epi32(transpose0_0, transpose0_1);
    const __m128i transpose1_3 = _mm_unpackhi_epi32(transpose0_2, transpose0_3);
    // a00 a10 a20 a30 a01 a11 a21 a31
    // b00 b10 b20 b30 b01 b11 b21 b31
    // a02 a12 a22 a32 a03 a13 a23 a33
    // b02 b12 a22 b32 b03 b13 b23 b33
    T0 = _mm_unpacklo_epi64(transpose1_0, transpose1_1);
    T1 = _mm_unpackhi_epi64(transpose1_0, transpose1_1);
    T2 = _mm_unpacklo_epi64(transpose1_2, transpose1_3);
    T3 = _mm_unpackhi_epi64(transpose1_2, transpose1_3);
    // a00 a10 a20 a30   b00 b10 b20 b30
    // a01 a11 a21 a31   b01 b11 b21 b31
    // a02 a12 a22 a32   b02 b12 b22 b32
    // a03 a13 a23 a33   b03 b13 b23 b33
  }

  // Add inverse transform to 'dst' and store.
  {
    const __m128i zero = _mm_set1_epi16(0);
    // Load the reference(s).
    __m128i dst0 = _mm_cvtsi32_si128(*(int*)&dst[0 * BPS]);
    __m128i dst1 = _mm_cvtsi32_si128(*(int*)&dst[1 * BPS]);
    __m128i dst2 = _mm_cvtsi32_si128(*(int*)&dst[2 * BPS]);
    __m128i dst3 = _mm_cvtsi32_si128(*(int*)&dst[3 * BPS]);
    // Convert to 16b.
    dst0 = _mm_unpacklo_epi8(dst0, zero);
    dst1 = _mm_unpacklo_epi8(dst1, zero);
    dst2 = _mm_unpacklo_epi8(dst2, zero);
    dst3 = _mm_unpacklo_epi8(dst3, zero);
    // Add the inverse transform(s).
    dst0 = _mm_add_epi16(dst0, T0);
    dst1 = _mm_add_epi16(dst1, T1);
    dst2 = _mm_add_epi16(dst2, T2);
    dst3 = _mm_add_epi16(dst3, T3);
    // Unsigned saturate to 8b.
    dst0 = _mm_packus_epi16(dst0, dst0);
    dst1 = _mm_packus_epi16(dst1, dst1);
    dst2 = _mm_packus_epi16(dst2, dst2);
    dst3 = _mm_packus_epi16(dst3, dst3);
    // Store the results, four bytes/pixels per line.
    *((int32_t *)&dst[0 * BPS]) = _mm_cvtsi128_si32(dst0);
    *((int32_t *)&dst[1 * BPS]) = _mm_cvtsi128_si32(dst1);
    *((int32_t *)&dst[2 * BPS]) = _mm_cvtsi128_si32(dst2);
    *((int32_t *)&dst[3 * BPS]) = _mm_cvtsi128_si32(dst3);
  }
}

//-----------------------------------------------------------------------------
// Loop Filter (Paragraph 15)

// Compute abs(p - q) = subs(p - q) OR subs(q - p)
#define MM_ABS(p, q)  _mm_or_si128(                                     \
  _mm_subs_epu8(*(q), *(p)),                                            \
  _mm_subs_epu8(*(p), *(q)))

// Shift each byte of "a" by N bits while preserving by the sign bit.
//
// It first shifts the lower bytes of the words and then the upper bytes and
// then merges the results together.
#define SIGNED_SHIFT_N(a, N) {                                          \
  __m128i t = a;                                                        \
  t = _mm_slli_epi16(t, 8);                                             \
  t = _mm_srai_epi16(t, N);                                             \
  t = _mm_srli_epi16(t, 8);                                             \
                                                                        \
  a = _mm_srai_epi16(a, N + 8);                                         \
  a = _mm_slli_epi16(a, 8);                                             \
                                                                        \
  a = _mm_or_si128(t, a);                                               \
}


static void NeedsFilter(const __m128i* p1, const __m128i* p0, const __m128i* q0,
                        const __m128i* q1, int thresh, __m128i *mask) {
  __m128i t1, t2;

  t1 = MM_ABS(p1, q1);               // abs(p1 - q1)
  t2 = _mm_set1_epi8(0xFE);
  t1 = _mm_and_si128(t1, t2);        // set lsb of each byte to zero
  t1 = _mm_srli_epi16(t1, 1);        // abs(p1 - q1) / 2

  t2 = MM_ABS(p0, q0);
  t2 = _mm_adds_epu8(t2, t2);        // abs(p0 - q0) * 2
  t2 = _mm_adds_epu8(t2, t1);        // abs(p0 - q0) * 2 + abs(p1 - q1) / 2

  t1 = _mm_set1_epi8(thresh);
  t2 = _mm_subs_epu8(t2, t1);  // abs(p0 - q0) * 2 + abs(p1 - q1) / 2 > thresh
  *mask = _mm_cmpeq_epi8(t2, _mm_setzero_si128());
}

//-----------------------------------------------------------------------------
// Edge filtering functions

// Applies filter on p0 and q0
static void DoFilter2(const __m128i* p1, __m128i* p0, __m128i* q0,
                      const __m128i* q1, int thresh) {
  __m128i t1, t2, mask;
  const __m128i sign_bit = _mm_set1_epi8(0x80);
  NeedsFilter(p1, p0, q0, q1, thresh, &mask);

  // convert to signed values
  *p0 = _mm_xor_si128(*p0, sign_bit);
  *q0 = _mm_xor_si128(*q0, sign_bit);
  t1 = _mm_xor_si128(*p1, sign_bit);
  t2 = _mm_xor_si128(*q1, sign_bit);

  t1 = _mm_subs_epi8(t1, t2);        // p1 - q1
  t2 = _mm_subs_epi8(*q0, *p0);      // q0 - p0
  t1 = _mm_adds_epi8(t1, t2);        // p1 - q1 + 1 * (q0 - p0)
  t1 = _mm_adds_epi8(t1, t2);        // p1 - q1 + 2 * (q0 - p0)
  t1 = _mm_adds_epi8(t1, t2);        // p1 - q1 + 3 * (q0 - p0)
  t1 = _mm_and_si128(t1, mask);      // mask filter values we don't care about

  // Do +4 side
  t2 = _mm_set1_epi8(4);
  t2 = _mm_adds_epi8(t2, t1);        // 3 * (q0 - p0) + (p1 - q1) + 4
  SIGNED_SHIFT_N(t2, 3);             // t2 >> 3
  *q0 = _mm_subs_epi8(*q0, t2);      // q0 -= a

  // Now do +3 side
  t2 = _mm_set1_epi8(3);
  t2 = _mm_adds_epi8(t2, t1);        // +3 instead of +4
  SIGNED_SHIFT_N(t2, 3);             // t2 >> 3
  *p0 = _mm_adds_epi8(*p0, t2);      // p0 += b

  // unoffset
  *p0 = _mm_xor_si128(*p0, sign_bit);
  *q0 = _mm_xor_si128(*q0, sign_bit);
}

// Reads 8 rows across a vertical edge.
//
// TODO(somnath): Investigate _mm_shuffle* also see if it can be broken into
// two Load4x4() to avoid code duplication.
static void Load8x4(const uint8_t* b, int stride, __m128i* p, __m128i* q) {
  __m128i t1, t2;

  // Load 0th, 1st, 4th and 5th rows
  __m128i r0 =  _mm_cvtsi32_si128(*((int*)&b[0 * stride]));  // 03 02 01 00
  __m128i r1 =  _mm_cvtsi32_si128(*((int*)&b[1 * stride]));  // 13 12 11 10
  __m128i r4 =  _mm_cvtsi32_si128(*((int*)&b[4 * stride]));  // 43 42 41 40
  __m128i r5 =  _mm_cvtsi32_si128(*((int*)&b[5 * stride]));  // 53 52 51 50

  r0 = _mm_unpacklo_epi32(r0, r4);               // 43 42 41 40 03 02 01 00
  r1 = _mm_unpacklo_epi32(r1, r5);               // 53 52 51 50 13 12 11 10

  // t1 = 53 43 52 42 51 41 50 40 13 03 12 02 11 01 10 00
  t1 = _mm_unpacklo_epi8(r0, r1);

  // Load 2nd, 3rd, 6th and 7th rows
  r0 =  _mm_cvtsi32_si128(*((int*)&b[2 * stride]));          // 23 22 21 22
  r1 =  _mm_cvtsi32_si128(*((int*)&b[3 * stride]));          // 33 32 31 30
  r4 =  _mm_cvtsi32_si128(*((int*)&b[6 * stride]));          // 63 62 61 60
  r5 =  _mm_cvtsi32_si128(*((int*)&b[7 * stride]));          // 73 72 71 70

  r0 = _mm_unpacklo_epi32(r0, r4);               // 63 62 61 60 23 22 21 20
  r1 = _mm_unpacklo_epi32(r1, r5);               // 73 72 71 70 33 32 31 30

  // t2 = 73 63 72 62 71 61 70 60 33 23 32 22 31 21 30 20
  t2 = _mm_unpacklo_epi8(r0, r1);

  // t1 = 33 23 13 03 32 22 12 02 31 21 11 01 30 20 10 00
  // t2 = 73 63 53 43 72 62 52 42 71 61 51 41 70 60 50 40
  r0 = t1;
  t1 = _mm_unpacklo_epi16(t1, t2);
  t2 = _mm_unpackhi_epi16(r0, t2);

  // *p = 71 61 51 41 31 21 11 01 70 60 50 40 30 20 10 00
  // *q = 73 63 53 43 33 23 13 03 72 62 52 42 32 22 12 02
  *p = _mm_unpacklo_epi32(t1, t2);
  *q = _mm_unpackhi_epi32(t1, t2);
}

static inline void Store4x4(__m128i* x, uint8_t* dst, int stride) {
  int i;
  for (i = 0; i < 4; ++i, dst += stride) {
    *((int32_t*)dst) = _mm_cvtsi128_si32(*x);
    *x = _mm_srli_si128(*x, 4);
  }
}

//-----------------------------------------------------------------------------
// Simple In-loop filtering (Paragraph 15.2)

static void SimpleVFilter16SSE2(uint8_t* p, int stride, int thresh) {
  // Load
  __m128i p1 = _mm_loadu_si128((__m128i*)&p[-2 * stride]);
  __m128i p0 = _mm_loadu_si128((__m128i*)&p[-stride]);
  __m128i q0 = _mm_loadu_si128((__m128i*)&p[0]);
  __m128i q1 = _mm_loadu_si128((__m128i*)&p[stride]);

  DoFilter2(&p1, &p0, &q0, &q1, thresh);

  // Store
  _mm_storeu_si128((__m128i*)&p[-stride], p0);
  _mm_storeu_si128((__m128i*)p, q0);
}

static void SimpleHFilter16SSE2(uint8_t* p, int stride, int thresh) {
  __m128i t1, t2;
  __m128i p1, p0, q0, q1;
  // Assume the pixels around the edge (|) are numbered as follows
  //                00 01 | 02 03
  //                10 11 | 12 13
  //                 ...  |  ...
  //                e0 e1 | e2 e3
  //                f0 f1 | f2 f3
  p -= 2;  // beginning of the first segment

  // Load
  // p1 = 71 61 51 41 31 21 11 01 70 60 50 40 30 20 10 00
  // q0 = 73 63 53 43 33 23 13 03 72 62 52 42 32 22 12 02
  // p0 = f1 e1 d1 c1 b1 a1 91 81 f0 e0 d0 c0 b0 a0 90 80
  // q1 = f3 e3 d3 c3 b3 a3 93 83 f2 e2 d2 c2 b2 a2 92 82
  Load8x4(p, stride, &p1, &q0);
  Load8x4(p + 8 * stride, stride, &p0, &q1);

  t1 = p1;
  t2 = q0;
  // p1 = f0 e0 d0 c0 b0 a0 90 80 70 60 50 40 30 20 10 00
  // p0 = f1 e1 d1 c1 b1 a1 91 81 71 61 51 41 31 21 11 01
  // q0 = f2 e2 d2 c2 b2 a2 92 82 72 62 52 42 32 22 12 02
  // q1 = f3 e3 d3 c3 b3 a3 93 83 73 63 53 43 33 23 13 03
  p1 = _mm_unpacklo_epi64(p1, p0);
  p0 = _mm_unpackhi_epi64(t1, p0);
  q0 = _mm_unpacklo_epi64(q0, q1);
  q1 = _mm_unpackhi_epi64(t2, q1);

  // Filter
  DoFilter2(&p1, &p0, &q0, &q1, thresh);
  t1 = p0;
  t2 = q0;

  // Transpose back to write out
  // p0 = 71 70 61 60 51 50 41 40 31 30 21 20 11 10 01 00
  // p1 = f1 f0 e1 e0 d1 d0 c1 c0 b1 b0 a1 a0 91 90 81 80
  // q0 = 73 72 63 62 53 52 43 42 33 32 23 22 13 12 03 02
  // q1 = f3 f2 e3 e2 d3 d2 c3 c2 b3 b2 a3 a2 93 92 83 82
  p0 = _mm_unpacklo_epi8(p1, t1);
  p1 = _mm_unpackhi_epi8(p1, t1);
  q0 = _mm_unpacklo_epi8(t2, q1);
  q1 = _mm_unpackhi_epi8(t2, q1);

  t1 = p0;
  t2 = p1;
  // p0 = 33 32 31 30 23 22 21 20 13 12 11 10 03 02 01 00
  // q0 = 73 72 71 70 63 62 61 60 53 52 51 50 43 42 41 40
  // p1 = b3 b2 b1 b0 a3 a2 a1 a0 93 92 91 90 83 82 81 80
  // q1 = f3 f2 f1 f0 e3 e2 e1 e0 d3 d2 d1 d0 c3 c2 c1 c0
  p0 = _mm_unpacklo_epi16(p0, q0);
  q0 = _mm_unpackhi_epi16(t1, q0);
  p1 = _mm_unpacklo_epi16(p1, q1);
  q1 = _mm_unpackhi_epi16(t2, q1);

  // Store
  Store4x4(&p0, p, stride);
  p += 4 * stride;
  Store4x4(&q0, p, stride);
  p += 4 * stride;
  Store4x4(&p1, p, stride);
  p += 4 * stride;
  Store4x4(&q1, p, stride);
}

static void SimpleVFilter16iSSE2(uint8_t* p, int stride, int thresh) {
  int k;
  for (k = 3; k > 0; --k) {
    p += 4 * stride;
    SimpleVFilter16SSE2(p, stride, thresh);
  }
}

static void SimpleHFilter16iSSE2(uint8_t* p, int stride, int thresh) {
  int k;
  for (k = 3; k > 0; --k) {
    p += 4;
    SimpleHFilter16SSE2(p, stride, thresh);
  }
}

extern void VP8DspInitSSE2(void);

void VP8DspInitSSE2(void) {
  VP8Transform = TransformSSE2;

  VP8SimpleVFilter16 = SimpleVFilter16SSE2;
  VP8SimpleHFilter16 = SimpleHFilter16SSE2;
  VP8SimpleVFilter16i = SimpleVFilter16iSSE2;
  VP8SimpleHFilter16i = SimpleHFilter16iSSE2;
}

#if defined(__cplusplus) || defined(c_plusplus)
}    // extern "C"
#endif

#endif   //__SSE2__ || _MSC_VER