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/*
* 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>
// Because no _mm_div_epi32() in SSE2, we use float division to emulate.
// When using this function, make sure a and b don't exceed float's precision.
static inline __m128i shim_mm_div_epi32(const __m128i& a, const __m128i& b) {
__m128 x = _mm_cvtepi32_ps(a);
__m128 y = _mm_cvtepi32_ps(b);
return _mm_cvttps_epi32(_mm_div_ps(x, y));
}
// 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
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