Improves findContours using SSE _mm_movemask_epi8 to find next contour point.…

Improves findContours using SSE _mm_movemask_epi8 to find next contour point. Cleaned up code a little bit

modules/imgproc/src/contours.cpp

@@ -50,6 +50,21 @@
 static const CvPoint icvCodeDeltas[8] =
     { CvPoint(1, 0), CvPoint(1, -1), CvPoint(0, -1), CvPoint(-1, -1), CvPoint(-1, 0), CvPoint(-1, 1), CvPoint(0, 1), CvPoint(1, 1) };
 
+inline unsigned int trailingZeros(unsigned int value) {
+#if defined(_MSC_VER)
+    return _tzcnt_u32(value);
+#elif defined(_GCC)
+    return __builtin_ctz(value);
+#elif defined(__INTEL_COMPILER)
+    //return _bit_scan_reverse(value);
+#else
+    static const int MultiplyDeBruijnBitPosition[32] = {
+        0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
+        31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9 };
+    return MultiplyDeBruijnBitPosition[((uint32_t)((value & -value) * 0x077CB531U)) >> 27];
+#endif
+}
+
 CV_IMPL void
 cvStartReadChainPoints( CvChain * chain, CvChainPtReader * reader )
 {
@@ -527,10 +542,8 @@ icvFetchContour( schar                  *ptr,
     {
         s = (s - 1) & 7;
         i1 = i0 + deltas[s];
-        if( *i1 != 0 )
-            break;
     }
-    while( s != s_end );
+    while( *i1 == 0 && s != s_end );
 
     if( s == s_end )            /* single pixel domain */
     {
@@ -631,10 +644,8 @@ icvTraceContour( schar *ptr, int step, schar *stop_ptr, int is_hole )
     {
         s = (s - 1) & 7;
         i1 = i0 + deltas[s];
-        if( *i1 != 0 )
-            break;
     }
-    while( s != s_end );
+    while( *i1 == 0 && s != s_end );
 
     i3 = i0;
 
@@ -644,7 +655,6 @@ icvTraceContour( schar *ptr, int step, schar *stop_ptr, int is_hole )
         /* follow border */
         for( ;; )
         {
-            s_end = s;
 
             for( ;; )
             {
@@ -702,10 +712,8 @@ icvFetchContourEx( schar*               ptr,
     {
         s = (s - 1) & 7;
         i1 = i0 + deltas[s];
-        if( *i1 != 0 )
-            break;
     }
-    while( s != s_end );
+    while( *i1 == 0 && s != s_end );
 
     if( s == s_end )            /* single pixel domain */
     {
@@ -817,10 +825,8 @@ icvTraceContour_32s( int *ptr, int step, int *stop_ptr, int is_hole )
     {
         s = (s - 1) & 7;
         i1 = i0 + deltas[s];
-        if( (*i1 & value_mask) == ccomp_val )
-            break;
     }
-    while( s != s_end );
+    while( (*i1 & value_mask) != ccomp_val && s != s_end );
 
     i3 = i0;
 
@@ -892,10 +898,8 @@ icvFetchContourEx_32s( int*                 ptr,
     {
         s = (s - 1) & 7;
         i1 = i0 + deltas[s];
-        if( (*i1 & value_mask) == ccomp_val )
-            break;
     }
-    while( s != s_end );
+    while( (*i1 & value_mask) != ccomp_val && s != s_end );
 
     if( s == s_end )            /* single pixel domain */
     {
@@ -990,6 +994,11 @@ cvFindNextContour( CvContourScanner scanner )
 {
     if( !scanner )
         CV_Error( CV_StsNullPtr, "" );
+
+#if CV_SSE2
+    bool haveSSE2 = cv::checkHardwareSupport(CPU_SSE2);
+#endif
+
     icvEndProcessContour( scanner );
 
     /* initialize local state */
@@ -1034,13 +1043,60 @@ cvFindNextContour( CvContourScanner scanner )
             }
             else
             {
+#if CV_SSE2
+                if ((p = img[x]) != prev) {
+                    goto _next_contour;
+                } else if (haveSSE2) {
+
+                    __m128i v_prev = _mm_set1_epi8(prev);
+                    int v_size = width - 32;
+
+                    for (; x <= v_size; x += 32) {
+                        __m128i v_p1 = _mm_loadu_si128((__m128i*)(img + x));
+                        __m128i v_p2 = _mm_loadu_si128((__m128i*)(img + x + 16));
+
+                        __m128i v_cmp1 = _mm_cmpeq_epi8(v_p1, v_prev);
+                        __m128i v_cmp2 = _mm_cmpeq_epi8(v_p2, v_prev);
+
+                        unsigned int mask1 = _mm_movemask_epi8(v_cmp1);
+                        unsigned int mask2 = _mm_movemask_epi8(v_cmp2);
+
+                        mask1 ^= 0x0000ffff;
+                        mask2 ^= 0x0000ffff;
+
+                        if (mask1) {
+                            p = img[(x += trailingZeros(mask1))];
+                            goto _next_contour;
+                        }
+
+                        if (mask2) {
+                            p = img[(x += trailingZeros(mask2 << 16))];
+                            goto _next_contour;
+                        }
+                    }
+
+                    if(x <= width - 16) {
+                        __m128i v_p = _mm_loadu_si128((__m128i*)(img + x));
+
+                        unsigned int mask = _mm_movemask_epi8(_mm_cmpeq_epi8(v_p, v_prev)) ^ 0x0000ffff;
+
+                        if (mask) {
+                            p = img[(x += trailingZeros(mask))];
+                            goto _next_contour;
+                        }
+                        x += 16;
+                    }
+                }
+#endif
                 for( ; x < width && (p = img[x]) == prev; x++ )
                     ;
             }
 
             if( x >= width )
                 break;
-
+#if CV_SSE2
+        _next_contour:
+#endif
             {
                 _CvContourInfo *par_info = 0;
                 _CvContourInfo *l_cinfo = 0;
@@ -1275,7 +1331,7 @@ cvEndFindContours( CvContourScanner * _scanner )
 #define ICV_SINGLE                  0
 #define ICV_CONNECTING_ABOVE        1
 #define ICV_CONNECTING_BELOW        -1
-#define ICV_IS_COMPONENT_POINT(val) ((val) != 0)
+//#define ICV_IS_COMPONENT_POINT(val) ((val) != 0)
 
 #define CV_GET_WRITTEN_ELEM( writer ) ((writer).ptr - (writer).seq->elem_size)
 
@@ -1287,6 +1343,108 @@ typedef  struct CvLinkedRunPoint
 }
 CvLinkedRunPoint;
 
+#if CV_SSE2
+inline int findStartContourPoint(uchar *src_data, CvSize img_size, int j, bool haveSSE2) {
+#else
+inline int findStartContourPoint(uchar *src_data, CvSize img_size, int j) {
+#endif
+#if CV_SSE2
+    if (haveSSE2) {
+        __m128i sseZero = _mm_setzero_si128();
+        int sizeSse = img_size.width - 32;
+
+        for (; j <= sizeSse; j += 32) {
+            __m128i sseP1 = _mm_loadu_si128((__m128i*)(src_data + j));
+            __m128i sseP2 = _mm_loadu_si128((__m128i*)(src_data + j + 16));
+
+            __m128i sseCmp1 = _mm_cmpeq_epi8(sseP1, sseZero);
+            __m128i sseCmp2 = _mm_cmpeq_epi8(sseP2, sseZero);
+
+            unsigned int mask1 = _mm_movemask_epi8(sseCmp1);
+            unsigned int mask2 = _mm_movemask_epi8(sseCmp2);
+
+            mask1 ^= 0x0000ffff;
+            mask2 ^= 0x0000ffff;
+
+            if (mask1) {
+                j += trailingZeros(mask1);
+                return j;
+            }
+
+            if (mask2) {
+                j += trailingZeros(mask2 << 16);
+                return j;
+            }
+        }
+
+        if (j <= img_size.width - 16) {
+            __m128i sseP = _mm_loadu_si128((__m128i*)(src_data + j));
+
+            unsigned int mask = _mm_movemask_epi8(_mm_cmpeq_epi8(sseP, sseZero)) ^ 0x0000ffff;
+
+            if (mask) {
+                j += trailingZeros(mask);
+                return j;
+            }
+            j += 16;
+        }
+    }
+#endif
+    for (; j < img_size.width && !src_data[j]; ++j)
+        ;
+    return j;
+}
+
+#if CV_SSE2
+inline int findEndContourPoint(uchar *src_data, CvSize img_size, int j, bool haveSSE2) {
+#else
+inline int findEndContourPoint(uchar *src_data, CvSize img_size, int j) {
+#endif
+#if CV_SSE2
+    if (!src_data[j]) {
+        return j;
+    } else if (haveSSE2) {
+        __m128i sseZero = _mm_setzero_si128();
+        int sizeSse = img_size.width - 32;
+
+        for (; j <= sizeSse; j += 32) {
+            __m128i sseP1 = _mm_loadu_si128((__m128i*)(src_data + j));
+            __m128i sseP2 = _mm_loadu_si128((__m128i*)(src_data + j + 16));
+
+            __m128i sseCmp1 = _mm_cmpeq_epi8(sseP1, sseZero);
+            __m128i sseCmp2 = _mm_cmpeq_epi8(sseP2, sseZero);
+
+            unsigned int mask1 = _mm_movemask_epi8(sseCmp1);
+            unsigned int mask2 = _mm_movemask_epi8(sseCmp2);
+
+            if (mask1) {
+                j += trailingZeros(mask1);
+                return j;
+            }
+
+            if (mask2) {
+                j += trailingZeros(mask2 << 16);
+                return j;
+            }
+        }
+
+        if (j <= img_size.width - 16) {
+            __m128i sseP = _mm_loadu_si128((__m128i*)(src_data + j));
+
+            unsigned int mask = _mm_movemask_epi8(_mm_cmpeq_epi8(sseP, sseZero));
+
+            if (mask) {
+                j += trailingZeros(mask);
+                return j;
+            }
+            j += 16;
+        }
+    }
+#endif
+    for (; j < img_size.width && src_data[j]; ++j)
+        ;
+    return j;
+}
 
 static int
 icvFindContoursInInterval( const CvArr* src,
@@ -1339,7 +1497,9 @@ icvFindContoursInInterval( const CvArr* src,
 
     if( contourHeaderSize < (int)sizeof(CvContour))
         CV_Error( CV_StsBadSize, "Contour header size must be >= sizeof(CvContour)" );
-
+#if CV_SSE2
+    bool haveSSE2 = cv::checkHardwareSupport(CPU_SSE2);
+#endif
     storage00.reset(cvCreateChildMemStorage(storage));
     storage01.reset(cvCreateChildMemStorage(storage));
 
@@ -1372,8 +1532,11 @@ icvFindContoursInInterval( const CvArr* src,
     tmp_prev = upper_line;
     for( j = 0; j < img_size.width; )
     {
-        for( ; j < img_size.width && !ICV_IS_COMPONENT_POINT(src_data[j]); j++ )
-            ;
+#if CV_SSE2
+        j = findStartContourPoint(src_data, img_size, j, haveSSE2);
+#else
+        j = findStartContourPoint(src_data, img_size, j);
+#endif
         if( j == img_size.width )
             break;
 
@@ -1381,10 +1544,11 @@ icvFindContoursInInterval( const CvArr* src,
         CV_WRITE_SEQ_ELEM( tmp, writer );
         tmp_prev->next = (CvLinkedRunPoint*)CV_GET_WRITTEN_ELEM( writer );
         tmp_prev = tmp_prev->next;
-
-        for( ; j < img_size.width && ICV_IS_COMPONENT_POINT(src_data[j]); j++ )
-            ;
-
+#if CV_SSE2
+        j = findEndContourPoint(src_data, img_size, j, haveSSE2);
+#else
+        j = findEndContourPoint(src_data, img_size, j);
+#endif
         tmp.pt.x = j-1;
         CV_WRITE_SEQ_ELEM( tmp, writer );
         tmp_prev->next = (CvLinkedRunPoint*)CV_GET_WRITTEN_ELEM( writer );
@@ -1407,18 +1571,22 @@ icvFindContoursInInterval( const CvArr* src,
         all_total = runs->total;
         for( j = 0; j < img_size.width; )
         {
-            for( ; j < img_size.width && !ICV_IS_COMPONENT_POINT(src_data[j]); j++ )
-                ;
+#if CV_SSE2
+            j = findStartContourPoint(src_data, img_size, j, haveSSE2);
+#else
+            j = findStartContourPoint(src_data, img_size, j);
+#endif
             if( j == img_size.width ) break;
 
             tmp.pt.x = j;
             CV_WRITE_SEQ_ELEM( tmp, writer );
             tmp_prev->next = (CvLinkedRunPoint*)CV_GET_WRITTEN_ELEM( writer );
             tmp_prev = tmp_prev->next;
-
-            for( ; j < img_size.width && ICV_IS_COMPONENT_POINT(src_data[j]); j++ )
-                ;
-
+#if CV_SSE2
+            j = findEndContourPoint(src_data, img_size, j, haveSSE2);
+#else
+            j = findEndContourPoint(src_data, img_size, j);
+#endif
             tmp.pt.x = j-1;
             CV_WRITE_SEQ_ELEM( tmp, writer );
             tmp_prev = tmp_prev->next = (CvLinkedRunPoint*)CV_GET_WRITTEN_ELEM( writer );