Xfermode: SSE2 implementation of softlight_modeproc

src/opts/SkMath_opts_SSE2.h

+/*
+ * Copyright 2014 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkMath_opts_SSE2_DEFINED
+#define SkMath_opts_SSE2_DEFINED
+
+#include <emmintrin.h>
+
+// Portable version of SkSqrtBits is in SkMath.cpp.
+static inline __m128i SkSqrtBits_SSE2(const __m128i& x, int count) {
+    __m128i root =  _mm_setzero_si128();
+    __m128i remHi = _mm_setzero_si128();
+    __m128i remLo = x;
+    __m128i one128 = _mm_set1_epi32(1);
+
+    do {
+        root = _mm_slli_epi32(root, 1);
+
+        remHi = _mm_or_si128(_mm_slli_epi32(remHi, 2),
+                             _mm_srli_epi32(remLo, 30));
+        remLo = _mm_slli_epi32(remLo, 2);
+
+        __m128i testDiv = _mm_slli_epi32(root, 1);
+        testDiv = _mm_add_epi32(testDiv, _mm_set1_epi32(1));
+
+        __m128i cmp = _mm_cmplt_epi32(remHi, testDiv);
+        __m128i remHi1 = _mm_and_si128(cmp, remHi);
+        __m128i root1 = _mm_and_si128(cmp, root);
+        __m128i remHi2 = _mm_andnot_si128(cmp, _mm_sub_epi32(remHi, testDiv));
+        __m128i root2 = _mm_andnot_si128(cmp, _mm_add_epi32(root, one128));
+
+        remHi = _mm_or_si128(remHi1, remHi2);
+        root = _mm_or_si128(root1, root2);
+    } while (--count >= 0);
+
+    return root;
+}
+
+#endif // SkMath_opts_SSE2_DEFINED