Fixing SSE2 byte interleaving path to work with short runs

AcademySoftwareFoundation · Sep 8, 2014 · da28ad8 · da28ad8
1 parent 699b4a6
commit da28ad8
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Showing 2 changed files with 66 additions and 22 deletions.
diff --git a/OpenEXR/IlmImf/ImfDwaCompressorSimd.h b/OpenEXR/IlmImf/ImfDwaCompressorSimd.h
@@ -334,34 +334,37 @@ interleaveByte2 (char *dst, char *src0, char *src1, int numBytes)
         // use aligned loads
         //
 
-        for (int x = 0; x < 8; ++x)
+        for (int x = 0; x < std::min (numBytes, 8); ++x)
         {
             dst[2 * x]     = src0[x];
             dst[2 * x + 1] = src1[x];
         }
 
-        dst_epi8  = (__m128i*)&dst[16];
-        src0_epi8 = (__m128i*)&src0[8];
-        src1_epi8 = (__m128i*)&src1[8];
-        sseWidth  =  (numBytes - 8) / 16;
-
-        for (int x=0; x<sseWidth; ++x)
+        if (numBytes > 8) 
         {
-            _mm_stream_si128 (&dst_epi8[2 * x],
-                              _mm_unpacklo_epi8 (src0_epi8[x], src1_epi8[x]));
+            dst_epi8  = (__m128i*)&dst[16];
+            src0_epi8 = (__m128i*)&src0[8];
+            src1_epi8 = (__m128i*)&src1[8];
+            sseWidth  =  (numBytes - 8) / 16;
 
-            _mm_stream_si128 (&dst_epi8[2 * x + 1],
-                              _mm_unpackhi_epi8 (src0_epi8[x], src1_epi8[x]));
-        }
+            for (int x=0; x<sseWidth; ++x)
+            {
+                _mm_stream_si128 (&dst_epi8[2 * x],
+                                  _mm_unpacklo_epi8 (src0_epi8[x], src1_epi8[x]));
 
-        //
-        // Then do run the leftovers one at a time
-        //
+                _mm_stream_si128 (&dst_epi8[2 * x + 1],
+                                  _mm_unpackhi_epi8 (src0_epi8[x], src1_epi8[x]));
+            }
 
-        for (int x = 16 * sseWidth + 8; x < numBytes; ++x)
-        {
-            dst[2 * x]     = src0[x];
-            dst[2 * x + 1] = src1[x];
+            //
+            // Then do run the leftovers one at a time
+            //
+
+            for (int x = 16 * sseWidth + 8; x < numBytes; ++x)
+            {
+                dst[2 * x]     = src0[x];
+                dst[2 * x + 1] = src1[x];
+            }
         }
     }
     else

diff --git a/OpenEXR/IlmImfTest/testDwaCompressorSimd.cpp b/OpenEXR/IlmImfTest/testDwaCompressorSimd.cpp
@@ -171,8 +171,9 @@ testCsc()
 void
 testInterleave()
 {
-    const int bufferLen = 100000;
-    const int numIter   = 10000;
+    const int bufferLen     = 100000;
+    const int randomNumIter = 10000;
+    const int lengthNumIter = 128;
     Rand48    rand48(0);
     char     *srcA    = new char[bufferLen];
     char     *srcB    = new char[bufferLen];
@@ -189,7 +190,7 @@ testInterleave()
         dst[2*i+1] = srcB[i];
     }
 
-    for (int iter=0; iter<numIter; ++iter)
+    for (int iter=0; iter<randomNumIter; ++iter)
     {
         memset(test, 0, 2*bufferLen);
 
@@ -203,6 +204,46 @@ testInterleave()
         }
     }
 
+    //
+    // Test increasing length buffers, with varying alignment
+    // on all the buffers.
+    //
+    for (int len=1; len<lengthNumIter; ++len) 
+    {
+        for (int offset=0; offset<16*16*16; ++offset) 
+        {
+            int offsetA    =  offset        % 16;
+            int offsetB    = (offset /  16) % 16;
+            int offsetTest = (offset / 256) % 16;
+
+            memset(srcA, 255, bufferLen);
+            memset(srcB, 255, bufferLen);
+            memset(dst,  0,   2*bufferLen);
+            memset(test, 0,   2*bufferLen);
+
+            char *a   = srcA + offsetA;
+            char *b   = srcB + offsetB;
+            char *out = test + offsetTest;
+
+            for (int i=0; i<len; ++i) 
+            {
+                a[i] = (char)rand48.nextf(0.0, 255.0);
+                b[i] = (char)rand48.nextf(0.0, 255.0);
+
+                dst[2*i]   = a[i];
+                dst[2*i+1] = b[i];
+            }
+
+            interleaveByte2(out, a, b, len);
+
+            for (int i=0; i<2*len+8; ++i) 
+            {
+                assert( dst[2*i]   == out[2*i] );
+                assert( dst[2*i+1] == out[2*i+1] );
+            }
+        }
+    }
+
     delete[] srcA;
     delete[] srcB;
     delete[] dst;