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      1 // Copyright 2010 Google Inc.
      2 //
      3 // This code is licensed under the same terms as WebM:
      4 //  Software License Agreement:  http://www.webmproject.org/license/software/
      5 //  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
      6 // -----------------------------------------------------------------------------
      7 //
      8 // speed-critical functions.
      9 //
     10 // Author: Skal (pascal.massimino (at) gmail.com)
     11 
     12 #include "vp8i.h"
     13 
     14 #if defined(__cplusplus) || defined(c_plusplus)
     15 extern "C" {
     16 #endif
     17 
     18 //-----------------------------------------------------------------------------
     19 // run-time tables (~4k)
     20 
     21 static uint8_t abs0[255 + 255 + 1];     // abs(i)
     22 static uint8_t abs1[255 + 255 + 1];     // abs(i)>>1
     23 static int8_t sclip1[1020 + 1020 + 1];  // clips [-1020, 1020] to [-128, 127]
     24 static int8_t sclip2[112 + 112 + 1];    // clips [-112, 112] to [-16, 15]
     25 static uint8_t clip1[255 + 510 + 1];    // clips [-255,510] to [0,255]
     26 
     27 // We declare this variable 'volatile' to prevent instruction reordering
     28 // and make sure it's set to true _last_ (so as to be thread-safe)
     29 static volatile int tables_ok = 0;
     30 
     31 void VP8DspInitTables(void) {
     32   if (!tables_ok) {
     33     int i;
     34     for (i = -255; i <= 255; ++i) {
     35       abs0[255 + i] = (i < 0) ? -i : i;
     36       abs1[255 + i] = abs0[255 + i] >> 1;
     37     }
     38     for (i = -1020; i <= 1020; ++i) {
     39       sclip1[1020 + i] = (i < -128) ? -128 : (i > 127) ? 127 : i;
     40     }
     41     for (i = -112; i <= 112; ++i) {
     42       sclip2[112 + i] = (i < -16) ? -16 : (i > 15) ? 15 : i;
     43     }
     44     for (i = -255; i <= 255 + 255; ++i) {
     45       clip1[255 + i] = (i < 0) ? 0 : (i > 255) ? 255 : i;
     46     }
     47     tables_ok = 1;
     48   }
     49 }
     50 
     51 static inline uint8_t clip_8b(int v) {
     52   return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
     53 }
     54 
     55 //-----------------------------------------------------------------------------
     56 // Transforms (Paragraph 14.4)
     57 
     58 #define STORE(x, y, v) \
     59   dst[x + y * BPS] = clip_8b(dst[x + y * BPS] + ((v) >> 3))
     60 
     61 static const int kC1 = 20091 + (1 << 16);
     62 static const int kC2 = 35468;
     63 #define MUL(a, b) (((a) * (b)) >> 16)
     64 
     65 static void TransformOne(const int16_t* in, uint8_t* dst) {
     66   int C[4 * 4], *tmp;
     67   int i;
     68   tmp = C;
     69   for (i = 0; i < 4; ++i) {    // vertical pass
     70     const int a = in[0] + in[8];    // [-4096, 4094]
     71     const int b = in[0] - in[8];    // [-4095, 4095]
     72     const int c = MUL(in[4], kC2) - MUL(in[12], kC1);   // [-3783, 3783]
     73     const int d = MUL(in[4], kC1) + MUL(in[12], kC2);   // [-3785, 3781]
     74     tmp[0] = a + d;   // [-7881, 7875]
     75     tmp[1] = b + c;   // [-7878, 7878]
     76     tmp[2] = b - c;   // [-7878, 7878]
     77     tmp[3] = a - d;   // [-7877, 7879]
     78     tmp += 4;
     79     in++;
     80   }
     81   // Each pass is expanding the dynamic range by ~3.85 (upper bound).
     82   // The exact value is (2. + (kC1 + kC2) / 65536).
     83   // After the second pass, maximum interval is [-3794, 3794], assuming
     84   // an input in [-2048, 2047] interval. We then need to add a dst value
     85   // in the [0, 255] range.
     86   // In the worst case scenario, the input to clip_8b() can be as large as
     87   // [-60713, 60968].
     88   tmp = C;
     89   for (i = 0; i < 4; ++i) {    // horizontal pass
     90     const int dc = tmp[0] + 4;
     91     const int a =  dc +  tmp[8];
     92     const int b =  dc -  tmp[8];
     93     const int c = MUL(tmp[4], kC2) - MUL(tmp[12], kC1);
     94     const int d = MUL(tmp[4], kC1) + MUL(tmp[12], kC2);
     95     STORE(0, 0, a + d);
     96     STORE(1, 0, b + c);
     97     STORE(2, 0, b - c);
     98     STORE(3, 0, a - d);
     99     tmp++;
    100     dst += BPS;
    101   }
    102 }
    103 #undef MUL
    104 
    105 static void TransformTwo(const int16_t* in, uint8_t* dst, int do_two) {
    106   TransformOne(in, dst);
    107   if (do_two) {
    108     TransformOne(in + 16, dst + 4);
    109   }
    110 }
    111 
    112 static void TransformUV(const int16_t* in, uint8_t* dst) {
    113   VP8Transform(in + 0 * 16, dst, 1);
    114   VP8Transform(in + 2 * 16, dst + 4 * BPS, 1);
    115 }
    116 
    117 static void TransformDC(const int16_t *in, uint8_t* dst) {
    118   const int DC = in[0] + 4;
    119   int i, j;
    120   for (j = 0; j < 4; ++j) {
    121     for (i = 0; i < 4; ++i) {
    122       STORE(i, j, DC);
    123     }
    124   }
    125 }
    126 
    127 static void TransformDCUV(const int16_t* in, uint8_t* dst) {
    128   if (in[0 * 16]) TransformDC(in + 0 * 16, dst);
    129   if (in[1 * 16]) TransformDC(in + 1 * 16, dst + 4);
    130   if (in[2 * 16]) TransformDC(in + 2 * 16, dst + 4 * BPS);
    131   if (in[3 * 16]) TransformDC(in + 3 * 16, dst + 4 * BPS + 4);
    132 }
    133 
    134 #undef STORE
    135 
    136 // default C implementations:
    137 VP8Idct2 VP8Transform = TransformTwo;
    138 VP8Idct VP8TransformUV = TransformUV;
    139 VP8Idct VP8TransformDC = TransformDC;
    140 VP8Idct VP8TransformDCUV = TransformDCUV;
    141 
    142 //-----------------------------------------------------------------------------
    143 // Paragraph 14.3
    144 
    145 static void TransformWHT(const int16_t* in, int16_t* out) {
    146   int tmp[16];
    147   int i;
    148   for (i = 0; i < 4; ++i) {
    149     const int a0 = in[0 + i] + in[12 + i];
    150     const int a1 = in[4 + i] + in[ 8 + i];
    151     const int a2 = in[4 + i] - in[ 8 + i];
    152     const int a3 = in[0 + i] - in[12 + i];
    153     tmp[0  + i] = a0 + a1;
    154     tmp[8  + i] = a0 - a1;
    155     tmp[4  + i] = a3 + a2;
    156     tmp[12 + i] = a3 - a2;
    157   }
    158   for (i = 0; i < 4; ++i) {
    159     const int dc = tmp[0 + i * 4] + 3;    // w/ rounder
    160     const int a0 = dc             + tmp[3 + i * 4];
    161     const int a1 = tmp[1 + i * 4] + tmp[2 + i * 4];
    162     const int a2 = tmp[1 + i * 4] - tmp[2 + i * 4];
    163     const int a3 = dc             - tmp[3 + i * 4];
    164     out[ 0] = (a0 + a1) >> 3;
    165     out[16] = (a3 + a2) >> 3;
    166     out[32] = (a0 - a1) >> 3;
    167     out[48] = (a3 - a2) >> 3;
    168     out += 64;
    169   }
    170 }
    171 
    172 void (*VP8TransformWHT)(const int16_t* in, int16_t* out) = TransformWHT;
    173 
    174 //-----------------------------------------------------------------------------
    175 // Intra predictions
    176 
    177 #define OUT(x, y) dst[(x) + (y) * BPS]
    178 
    179 static inline void TrueMotion(uint8_t *dst, int size) {
    180   const uint8_t* top = dst - BPS;
    181   const uint8_t* const clip0 = clip1 + 255 - top[-1];
    182   int y;
    183   for (y = 0; y < size; ++y) {
    184     const uint8_t* const clip = clip0 + dst[-1];
    185     int x;
    186     for (x = 0; x < size; ++x) {
    187       dst[x] = clip[top[x]];
    188     }
    189     dst += BPS;
    190   }
    191 }
    192 static void TM4(uint8_t *dst)   { TrueMotion(dst, 4); }
    193 static void TM8uv(uint8_t *dst) { TrueMotion(dst, 8); }
    194 static void TM16(uint8_t *dst)  { TrueMotion(dst, 16); }
    195 
    196 //-----------------------------------------------------------------------------
    197 // 16x16
    198 
    199 static void VE16(uint8_t *dst) {     // vertical
    200   int j;
    201   for (j = 0; j < 16; ++j) {
    202     memcpy(dst + j * BPS, dst - BPS, 16);
    203   }
    204 }
    205 
    206 static void HE16(uint8_t *dst) {     // horizontal
    207   int j;
    208   for (j = 16; j > 0; --j) {
    209     memset(dst, dst[-1], 16);
    210     dst += BPS;
    211   }
    212 }
    213 
    214 static inline void Put16(int v, uint8_t* dst) {
    215   int j;
    216   for (j = 0; j < 16; ++j) {
    217     memset(dst + j * BPS, v, 16);
    218   }
    219 }
    220 
    221 static void DC16(uint8_t *dst) {    // DC
    222   int DC = 16;
    223   int j;
    224   for (j = 0; j < 16; ++j) {
    225     DC += dst[-1 + j * BPS] + dst[j - BPS];
    226   }
    227   Put16(DC >> 5, dst);
    228 }
    229 
    230 static void DC16NoTop(uint8_t *dst) {   // DC with top samples not available
    231   int DC = 8;
    232   int j;
    233   for (j = 0; j < 16; ++j) {
    234     DC += dst[-1 + j * BPS];
    235   }
    236   Put16(DC >> 4, dst);
    237 }
    238 
    239 static void DC16NoLeft(uint8_t *dst) {  // DC with left samples not available
    240   int DC = 8;
    241   int i;
    242   for (i = 0; i < 16; ++i) {
    243     DC += dst[i - BPS];
    244   }
    245   Put16(DC >> 4, dst);
    246 }
    247 
    248 static void DC16NoTopLeft(uint8_t *dst) {  // DC with no top and left samples
    249   Put16(0x80, dst);
    250 }
    251 
    252 //-----------------------------------------------------------------------------
    253 // 4x4
    254 
    255 #define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)
    256 #define AVG2(a, b) (((a) + (b) + 1) >> 1)
    257 
    258 static void VE4(uint8_t *dst) {    // vertical
    259   const uint8_t* top = dst - BPS;
    260   const uint8_t vals[4] = {
    261     AVG3(top[-1], top[0], top[1]),
    262     AVG3(top[ 0], top[1], top[2]),
    263     AVG3(top[ 1], top[2], top[3]),
    264     AVG3(top[ 2], top[3], top[4])
    265   };
    266   int i;
    267   for (i = 0; i < 4; ++i) {
    268     memcpy(dst + i * BPS, vals, sizeof(vals));
    269   }
    270 }
    271 
    272 static void HE4(uint8_t *dst) {    // horizontal
    273   const int A = dst[-1 - BPS];
    274   const int B = dst[-1];
    275   const int C = dst[-1 + BPS];
    276   const int D = dst[-1 + 2 * BPS];
    277   const int E = dst[-1 + 3 * BPS];
    278   *(uint32_t*)(dst + 0 * BPS) = 0x01010101U * AVG3(A, B, C);
    279   *(uint32_t*)(dst + 1 * BPS) = 0x01010101U * AVG3(B, C, D);
    280   *(uint32_t*)(dst + 2 * BPS) = 0x01010101U * AVG3(C, D, E);
    281   *(uint32_t*)(dst + 3 * BPS) = 0x01010101U * AVG3(D, E, E);
    282 }
    283 
    284 static void DC4(uint8_t *dst) {   // DC
    285   uint32_t dc = 4;
    286   int i;
    287   for (i = 0; i < 4; ++i) dc += dst[i - BPS] + dst[-1 + i * BPS];
    288   dc >>= 3;
    289   for (i = 0; i < 4; ++i) memset(dst + i * BPS, dc, 4);
    290 }
    291 
    292 static void RD4(uint8_t *dst) {   // Down-right
    293   const int I = dst[-1 + 0 * BPS];
    294   const int J = dst[-1 + 1 * BPS];
    295   const int K = dst[-1 + 2 * BPS];
    296   const int L = dst[-1 + 3 * BPS];
    297   const int X = dst[-1 - BPS];
    298   const int A = dst[0 - BPS];
    299   const int B = dst[1 - BPS];
    300   const int C = dst[2 - BPS];
    301   const int D = dst[3 - BPS];
    302   OUT(0, 3)                                     = AVG3(J, K, L);
    303   OUT(0, 2) = OUT(1, 3)                         = AVG3(I, J, K);
    304   OUT(0, 1) = OUT(1, 2) = OUT(2, 3)             = AVG3(X, I, J);
    305   OUT(0, 0) = OUT(1, 1) = OUT(2, 2) = OUT(3, 3) = AVG3(A, X, I);
    306   OUT(1, 0) = OUT(2, 1) = OUT(3, 2)             = AVG3(B, A, X);
    307   OUT(2, 0) = OUT(3, 1)                         = AVG3(C, B, A);
    308   OUT(3, 0)                                     = AVG3(D, C, B);
    309 }
    310 
    311 static void LD4(uint8_t *dst) {   // Down-Left
    312   const int A = dst[0 - BPS];
    313   const int B = dst[1 - BPS];
    314   const int C = dst[2 - BPS];
    315   const int D = dst[3 - BPS];
    316   const int E = dst[4 - BPS];
    317   const int F = dst[5 - BPS];
    318   const int G = dst[6 - BPS];
    319   const int H = dst[7 - BPS];
    320   OUT(0, 0)                                     = AVG3(A, B, C);
    321   OUT(1, 0) = OUT(0, 1)                         = AVG3(B, C, D);
    322   OUT(2, 0) = OUT(1, 1) = OUT(0, 2)             = AVG3(C, D, E);
    323   OUT(3, 0) = OUT(2, 1) = OUT(1, 2) = OUT(0, 3) = AVG3(D, E, F);
    324   OUT(3, 1) = OUT(2, 2) = OUT(1, 3)             = AVG3(E, F, G);
    325   OUT(3, 2) = OUT(2, 3)                         = AVG3(F, G, H);
    326   OUT(3, 3)                                     = AVG3(G, H, H);
    327 }
    328 
    329 static void VR4(uint8_t *dst) {   // Vertical-Right
    330   const int I = dst[-1 + 0 * BPS];
    331   const int J = dst[-1 + 1 * BPS];
    332   const int K = dst[-1 + 2 * BPS];
    333   const int X = dst[-1 - BPS];
    334   const int A = dst[0 - BPS];
    335   const int B = dst[1 - BPS];
    336   const int C = dst[2 - BPS];
    337   const int D = dst[3 - BPS];
    338   OUT(0, 0) = OUT(1, 2) = AVG2(X, A);
    339   OUT(1, 0) = OUT(2, 2) = AVG2(A, B);
    340   OUT(2, 0) = OUT(3, 2) = AVG2(B, C);
    341   OUT(3, 0)             = AVG2(C, D);
    342 
    343   OUT(0, 3) =             AVG3(K, J, I);
    344   OUT(0, 2) =             AVG3(J, I, X);
    345   OUT(0, 1) = OUT(1, 3) = AVG3(I, X, A);
    346   OUT(1, 1) = OUT(2, 3) = AVG3(X, A, B);
    347   OUT(2, 1) = OUT(3, 3) = AVG3(A, B, C);
    348   OUT(3, 1) =             AVG3(B, C, D);
    349 }
    350 
    351 static void VL4(uint8_t *dst) {   // Vertical-Left
    352   const int A = dst[0 - BPS];
    353   const int B = dst[1 - BPS];
    354   const int C = dst[2 - BPS];
    355   const int D = dst[3 - BPS];
    356   const int E = dst[4 - BPS];
    357   const int F = dst[5 - BPS];
    358   const int G = dst[6 - BPS];
    359   const int H = dst[7 - BPS];
    360   OUT(0, 0) =             AVG2(A, B);
    361   OUT(1, 0) = OUT(0, 2) = AVG2(B, C);
    362   OUT(2, 0) = OUT(1, 2) = AVG2(C, D);
    363   OUT(3, 0) = OUT(2, 2) = AVG2(D, E);
    364 
    365   OUT(0, 1) =             AVG3(A, B, C);
    366   OUT(1, 1) = OUT(0, 3) = AVG3(B, C, D);
    367   OUT(2, 1) = OUT(1, 3) = AVG3(C, D, E);
    368   OUT(3, 1) = OUT(2, 3) = AVG3(D, E, F);
    369               OUT(3, 2) = AVG3(E, F, G);
    370               OUT(3, 3) = AVG3(F, G, H);
    371 }
    372 
    373 static void HU4(uint8_t *dst) {   // Horizontal-Up
    374   const int I = dst[-1 + 0 * BPS];
    375   const int J = dst[-1 + 1 * BPS];
    376   const int K = dst[-1 + 2 * BPS];
    377   const int L = dst[-1 + 3 * BPS];
    378   OUT(0, 0) =             AVG2(I, J);
    379   OUT(2, 0) = OUT(0, 1) = AVG2(J, K);
    380   OUT(2, 1) = OUT(0, 2) = AVG2(K, L);
    381   OUT(1, 0) =             AVG3(I, J, K);
    382   OUT(3, 0) = OUT(1, 1) = AVG3(J, K, L);
    383   OUT(3, 1) = OUT(1, 2) = AVG3(K, L, L);
    384   OUT(3, 2) = OUT(2, 2) =
    385     OUT(0, 3) = OUT(1, 3) = OUT(2, 3) = OUT(3, 3) = L;
    386 }
    387 
    388 static void HD4(uint8_t *dst) {  // Horizontal-Down
    389   const int I = dst[-1 + 0 * BPS];
    390   const int J = dst[-1 + 1 * BPS];
    391   const int K = dst[-1 + 2 * BPS];
    392   const int L = dst[-1 + 3 * BPS];
    393   const int X = dst[-1 - BPS];
    394   const int A = dst[0 - BPS];
    395   const int B = dst[1 - BPS];
    396   const int C = dst[2 - BPS];
    397 
    398   OUT(0, 0) = OUT(2, 1) = AVG2(I, X);
    399   OUT(0, 1) = OUT(2, 2) = AVG2(J, I);
    400   OUT(0, 2) = OUT(2, 3) = AVG2(K, J);
    401   OUT(0, 3)             = AVG2(L, K);
    402 
    403   OUT(3, 0)             = AVG3(A, B, C);
    404   OUT(2, 0)             = AVG3(X, A, B);
    405   OUT(1, 0) = OUT(3, 1) = AVG3(I, X, A);
    406   OUT(1, 1) = OUT(3, 2) = AVG3(J, I, X);
    407   OUT(1, 2) = OUT(3, 3) = AVG3(K, J, I);
    408   OUT(1, 3)             = AVG3(L, K, J);
    409 }
    410 
    411 #undef AVG3
    412 #undef AVG2
    413 
    414 //-----------------------------------------------------------------------------
    415 // Chroma
    416 
    417 static void VE8uv(uint8_t *dst) {    // vertical
    418   int j;
    419   for (j = 0; j < 8; ++j) {
    420     memcpy(dst + j * BPS, dst - BPS, 8);
    421   }
    422 }
    423 
    424 static void HE8uv(uint8_t *dst) {    // horizontal
    425   int j;
    426   for (j = 0; j < 8; ++j) {
    427     memset(dst, dst[-1], 8);
    428     dst += BPS;
    429   }
    430 }
    431 
    432 // helper for chroma-DC predictions
    433 static inline void Put8x8uv(uint64_t v, uint8_t* dst) {
    434   int j;
    435   for (j = 0; j < 8; ++j) {
    436     *(uint64_t*)(dst + j * BPS) = v;
    437   }
    438 }
    439 
    440 static void DC8uv(uint8_t *dst) {     // DC
    441   int dc0 = 8;
    442   int i;
    443   for (i = 0; i < 8; ++i) {
    444     dc0 += dst[i - BPS] + dst[-1 + i * BPS];
    445   }
    446   Put8x8uv((uint64_t)((dc0 >> 4) * 0x0101010101010101ULL), dst);
    447 }
    448 
    449 static void DC8uvNoLeft(uint8_t *dst) {   // DC with no left samples
    450   int dc0 = 4;
    451   int i;
    452   for (i = 0; i < 8; ++i) {
    453     dc0 += dst[i - BPS];
    454   }
    455   Put8x8uv((uint64_t)((dc0 >> 3) * 0x0101010101010101ULL), dst);
    456 }
    457 
    458 static void DC8uvNoTop(uint8_t *dst) {  // DC with no top samples
    459   int dc0 = 4;
    460   int i;
    461   for (i = 0; i < 8; ++i) {
    462     dc0 += dst[-1 + i * BPS];
    463   }
    464   Put8x8uv((uint64_t)((dc0 >> 3) * 0x0101010101010101ULL), dst);
    465 }
    466 
    467 static void DC8uvNoTopLeft(uint8_t *dst) {    // DC with nothing
    468   Put8x8uv(0x8080808080808080ULL, dst);
    469 }
    470 
    471 //-----------------------------------------------------------------------------
    472 // default C implementations
    473 
    474 VP8PredFunc VP8PredLuma4[NUM_BMODES] = {
    475   DC4, TM4, VE4, HE4, RD4, VR4, LD4, VL4, HD4, HU4
    476 };
    477 
    478 VP8PredFunc VP8PredLuma16[NUM_B_DC_MODES] = {
    479   DC16, TM16, VE16, HE16,
    480   DC16NoTop, DC16NoLeft, DC16NoTopLeft
    481 };
    482 
    483 VP8PredFunc VP8PredChroma8[NUM_B_DC_MODES] = {
    484   DC8uv, TM8uv, VE8uv, HE8uv,
    485   DC8uvNoTop, DC8uvNoLeft, DC8uvNoTopLeft
    486 };
    487 
    488 //-----------------------------------------------------------------------------
    489 // Edge filtering functions
    490 
    491 // 4 pixels in, 2 pixels out
    492 static inline void do_filter2(uint8_t* p, int step) {
    493   const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step];
    494   const int a = 3 * (q0 - p0) + sclip1[1020 + p1 - q1];
    495   const int a1 = sclip2[112 + ((a + 4) >> 3)];
    496   const int a2 = sclip2[112 + ((a + 3) >> 3)];
    497   p[-step] = clip1[255 + p0 + a2];
    498   p[    0] = clip1[255 + q0 - a1];
    499 }
    500 
    501 // 4 pixels in, 4 pixels out
    502 static inline void do_filter4(uint8_t* p, int step) {
    503   const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step];
    504   const int a = 3 * (q0 - p0);
    505   const int a1 = sclip2[112 + ((a + 4) >> 3)];
    506   const int a2 = sclip2[112 + ((a + 3) >> 3)];
    507   const int a3 = (a1 + 1) >> 1;
    508   p[-2*step] = clip1[255 + p1 + a3];
    509   p[-  step] = clip1[255 + p0 + a2];
    510   p[      0] = clip1[255 + q0 - a1];
    511   p[   step] = clip1[255 + q1 - a3];
    512 }
    513 
    514 // 6 pixels in, 6 pixels out
    515 static inline void do_filter6(uint8_t* p, int step) {
    516   const int p2 = p[-3*step], p1 = p[-2*step], p0 = p[-step];
    517   const int q0 = p[0], q1 = p[step], q2 = p[2*step];
    518   const int a = sclip1[1020 + 3 * (q0 - p0) + sclip1[1020 + p1 - q1]];
    519   const int a1 = (27 * a + 63) >> 7;  // eq. to ((3 * a + 7) * 9) >> 7
    520   const int a2 = (18 * a + 63) >> 7;  // eq. to ((2 * a + 7) * 9) >> 7
    521   const int a3 = (9  * a + 63) >> 7;  // eq. to ((1 * a + 7) * 9) >> 7
    522   p[-3*step] = clip1[255 + p2 + a3];
    523   p[-2*step] = clip1[255 + p1 + a2];
    524   p[-  step] = clip1[255 + p0 + a1];
    525   p[      0] = clip1[255 + q0 - a1];
    526   p[   step] = clip1[255 + q1 - a2];
    527   p[ 2*step] = clip1[255 + q2 - a3];
    528 }
    529 
    530 static inline int hev(const uint8_t* p, int step, int thresh) {
    531   const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step];
    532   return (abs0[255 + p1 - p0] > thresh) || (abs0[255 + q1 - q0] > thresh);
    533 }
    534 
    535 static inline int needs_filter(const uint8_t* p, int step, int thresh) {
    536   const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step];
    537   return (2 * abs0[255 + p0 - q0] + abs1[255 + p1 - q1]) <= thresh;
    538 }
    539 
    540 static inline int needs_filter2(const uint8_t* p, int step, int t, int it) {
    541   const int p3 = p[-4*step], p2 = p[-3*step], p1 = p[-2*step], p0 = p[-step];
    542   const int q0 = p[0], q1 = p[step], q2 = p[2*step], q3 = p[3*step];
    543   if ((2 * abs0[255 + p0 - q0] + abs1[255 + p1 - q1]) > t)
    544     return 0;
    545   return abs0[255 + p3 - p2] <= it && abs0[255 + p2 - p1] <= it &&
    546          abs0[255 + p1 - p0] <= it && abs0[255 + q3 - q2] <= it &&
    547          abs0[255 + q2 - q1] <= it && abs0[255 + q1 - q0] <= it;
    548 }
    549 
    550 //-----------------------------------------------------------------------------
    551 // Simple In-loop filtering (Paragraph 15.2)
    552 
    553 static void SimpleVFilter16(uint8_t* p, int stride, int thresh) {
    554   int i;
    555   for (i = 0; i < 16; ++i) {
    556     if (needs_filter(p + i, stride, thresh)) {
    557       do_filter2(p + i, stride);
    558     }
    559   }
    560 }
    561 
    562 static void SimpleHFilter16(uint8_t* p, int stride, int thresh) {
    563   int i;
    564   for (i = 0; i < 16; ++i) {
    565     if (needs_filter(p + i * stride, 1, thresh)) {
    566       do_filter2(p + i * stride, 1);
    567     }
    568   }
    569 }
    570 
    571 static void SimpleVFilter16i(uint8_t* p, int stride, int thresh) {
    572   int k;
    573   for (k = 3; k > 0; --k) {
    574     p += 4 * stride;
    575     SimpleVFilter16(p, stride, thresh);
    576   }
    577 }
    578 
    579 static void SimpleHFilter16i(uint8_t* p, int stride, int thresh) {
    580   int k;
    581   for (k = 3; k > 0; --k) {
    582     p += 4;
    583     SimpleHFilter16(p, stride, thresh);
    584   }
    585 }
    586 
    587 //-----------------------------------------------------------------------------
    588 // Complex In-loop filtering (Paragraph 15.3)
    589 
    590 static inline void FilterLoop26(uint8_t* p, int hstride, int vstride, int size,
    591                                 int thresh, int ithresh, int hev_thresh) {
    592   while (size-- > 0) {
    593     if (needs_filter2(p, hstride, thresh, ithresh)) {
    594       if (hev(p, hstride, hev_thresh)) {
    595         do_filter2(p, hstride);
    596       } else {
    597         do_filter6(p, hstride);
    598       }
    599     }
    600     p += vstride;
    601   }
    602 }
    603 
    604 static inline void FilterLoop24(uint8_t* p, int hstride, int vstride, int size,
    605                                 int thresh, int ithresh, int hev_thresh) {
    606   while (size-- > 0) {
    607     if (needs_filter2(p, hstride, thresh, ithresh)) {
    608       if (hev(p, hstride, hev_thresh)) {
    609         do_filter2(p, hstride);
    610       } else {
    611         do_filter4(p, hstride);
    612       }
    613     }
    614     p += vstride;
    615   }
    616 }
    617 
    618 // on macroblock edges
    619 static void VFilter16(uint8_t* p, int stride,
    620                       int thresh, int ithresh, int hev_thresh) {
    621   FilterLoop26(p, stride, 1, 16, thresh, ithresh, hev_thresh);
    622 }
    623 
    624 static void HFilter16(uint8_t* p, int stride,
    625                       int thresh, int ithresh, int hev_thresh) {
    626   FilterLoop26(p, 1, stride, 16, thresh, ithresh, hev_thresh);
    627 }
    628 
    629 // on three inner edges
    630 static void VFilter16i(uint8_t* p, int stride,
    631                        int thresh, int ithresh, int hev_thresh) {
    632   int k;
    633   for (k = 3; k > 0; --k) {
    634     p += 4 * stride;
    635     FilterLoop24(p, stride, 1, 16, thresh, ithresh, hev_thresh);
    636   }
    637 }
    638 
    639 static void HFilter16i(uint8_t* p, int stride,
    640                        int thresh, int ithresh, int hev_thresh) {
    641   int k;
    642   for (k = 3; k > 0; --k) {
    643     p += 4;
    644     FilterLoop24(p, 1, stride, 16, thresh, ithresh, hev_thresh);
    645   }
    646 }
    647 
    648 // 8-pixels wide variant, for chroma filtering
    649 static void VFilter8(uint8_t* u, uint8_t* v, int stride,
    650                      int thresh, int ithresh, int hev_thresh) {
    651   FilterLoop26(u, stride, 1, 8, thresh, ithresh, hev_thresh);
    652   FilterLoop26(v, stride, 1, 8, thresh, ithresh, hev_thresh);
    653 }
    654 
    655 static void HFilter8(uint8_t* u, uint8_t* v, int stride,
    656                      int thresh, int ithresh, int hev_thresh) {
    657   FilterLoop26(u, 1, stride, 8, thresh, ithresh, hev_thresh);
    658   FilterLoop26(v, 1, stride, 8, thresh, ithresh, hev_thresh);
    659 }
    660 
    661 static void VFilter8i(uint8_t* u, uint8_t* v, int stride,
    662                       int thresh, int ithresh, int hev_thresh) {
    663   FilterLoop24(u + 4 * stride, stride, 1, 8, thresh, ithresh, hev_thresh);
    664   FilterLoop24(v + 4 * stride, stride, 1, 8, thresh, ithresh, hev_thresh);
    665 }
    666 
    667 static void HFilter8i(uint8_t* u, uint8_t* v, int stride,
    668                       int thresh, int ithresh, int hev_thresh) {
    669   FilterLoop24(u + 4, 1, stride, 8, thresh, ithresh, hev_thresh);
    670   FilterLoop24(v + 4, 1, stride, 8, thresh, ithresh, hev_thresh);
    671 }
    672 
    673 //-----------------------------------------------------------------------------
    674 
    675 void (*VP8VFilter16)(uint8_t*, int, int, int, int) = VFilter16;
    676 void (*VP8HFilter16)(uint8_t*, int, int, int, int) = HFilter16;
    677 void (*VP8VFilter8)(uint8_t*, uint8_t*, int, int, int, int) = VFilter8;
    678 void (*VP8HFilter8)(uint8_t*, uint8_t*, int, int, int, int) = HFilter8;
    679 void (*VP8VFilter16i)(uint8_t*, int, int, int, int) = VFilter16i;
    680 void (*VP8HFilter16i)(uint8_t*, int, int, int, int) = HFilter16i;
    681 void (*VP8VFilter8i)(uint8_t*, uint8_t*, int, int, int, int) = VFilter8i;
    682 void (*VP8HFilter8i)(uint8_t*, uint8_t*, int, int, int, int) = HFilter8i;
    683 
    684 void (*VP8SimpleVFilter16)(uint8_t*, int, int) = SimpleVFilter16;
    685 void (*VP8SimpleHFilter16)(uint8_t*, int, int) = SimpleHFilter16;
    686 void (*VP8SimpleVFilter16i)(uint8_t*, int, int) = SimpleVFilter16i;
    687 void (*VP8SimpleHFilter16i)(uint8_t*, int, int) = SimpleHFilter16i;
    688 
    689 //-----------------------------------------------------------------------------
    690 // SSE2 detection.
    691 //
    692 
    693 #if defined(__pic__) && defined(__i386__)
    694 static inline void GetCPUInfo(int cpu_info[4], int info_type) {
    695   __asm__ volatile (
    696     "mov %%ebx, %%edi\n"
    697     "cpuid\n"
    698     "xchg %%edi, %%ebx\n"
    699     : "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]), "=d"(cpu_info[3])
    700     : "a"(info_type));
    701 }
    702 #elif defined(__i386__) || defined(__x86_64__)
    703 static inline void GetCPUInfo(int cpu_info[4], int info_type) {
    704   __asm__ volatile (
    705     "cpuid\n"
    706     : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]), "=d"(cpu_info[3])
    707     : "a"(info_type));
    708 }
    709 #elif defined(_MSC_VER)  // Visual C++
    710 #define GetCPUInfo __cpuid
    711 #endif
    712 
    713 #if defined(__i386__) || defined(__x86_64__) || defined(_MSC_VER)
    714 static int x86CPUInfo(CPUFeature feature) {
    715   int cpu_info[4];
    716   GetCPUInfo(cpu_info, 1);
    717   if (feature == kSSE2) {
    718     return 0 != (cpu_info[3] & 0x04000000);
    719   }
    720   if (feature == kSSE3) {
    721     return 0 != (cpu_info[2] & 0x00000001);
    722   }
    723   return 0;
    724 }
    725 VP8CPUInfo VP8DecGetCPUInfo = x86CPUInfo;
    726 #else
    727 VP8CPUInfo VP8DecGetCPUInfo = NULL;
    728 #endif
    729 
    730 //-----------------------------------------------------------------------------
    731 
    732 extern void VP8DspInitSSE2(void);
    733 
    734 void VP8DspInit(void) {
    735   // If defined, use CPUInfo() to overwrite some pointers with faster versions.
    736   if (VP8DecGetCPUInfo) {
    737     if (VP8DecGetCPUInfo(kSSE2)) {
    738 #if defined(__SSE2__) || defined(_MSC_VER)
    739       VP8DspInitSSE2();
    740 #endif
    741     }
    742     if (VP8DecGetCPUInfo(kSSE3)) {
    743       // later we'll plug some SSE3 variant here
    744     }
    745   }
    746 }
    747 
    748 #if defined(__cplusplus) || defined(c_plusplus)
    749 }    // extern "C"
    750 #endif
    751