Move float<->byte conversions into Sk4f.

src/opts/SkPMFloat_sse.h

-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-namespace {  // See SkPMFloat.h
-
-inline SkPMFloat::SkPMFloat(SkPMColor c) {
-    SkPMColorAssert(c);
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSSE3
-    const char _ = ~0;  // Zero these bytes.
-    __m128i fix8    = _mm_cvtsi32_si128((int)c),
-            fix8_32 = _mm_shuffle_epi8(fix8, _mm_setr_epi8(0,_,_,_, 1,_,_,_, 2,_,_,_, 3,_,_,_));
-#else
-    __m128i fix8    = _mm_cvtsi32_si128((int)c),
-            fix8_16 = _mm_unpacklo_epi8 (fix8,    _mm_setzero_si128()),
-            fix8_32 = _mm_unpacklo_epi16(fix8_16, _mm_setzero_si128());
-#endif
-    fVec = _mm_mul_ps(_mm_cvtepi32_ps(fix8_32), _mm_set1_ps(1.0f / 255));
-    SkASSERT(this->isValid());
-}
-
-inline SkPMColor SkPMFloat::round() const {
-    // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
-    __m128 scaled = _mm_mul_ps(_mm_set1_ps(255), fVec);
-    __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), scaled)),
-            fix8_16 = _mm_packus_epi16(fix8_32, fix8_32),
-            fix8    = _mm_packus_epi16(fix8_16, fix8_16);
-    SkPMColor c = _mm_cvtsi128_si32(fix8);
-    SkPMColorAssert(c);
-    return c;
-}
-
-inline Sk4f SkPMFloat::alphas() const {
-    static_assert(SK_A32_SHIFT == 24, "");
-    return _mm_shuffle_ps(fVec, fVec, 0xff);  // Read as 11 11 11 11, copying lane 3 to all lanes.
-}
-
-inline SkPMFloat SkPMFloat::FromOpaqueColor(SkColor c) {
-    SkASSERT(SkColorGetA(c) == 0xFF);
-    __m128i fix8 = _mm_cvtsi32_si128((int)c);
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSSE3
-    const char _ = ~0;  // Zero these bytes.
-    __m128i fix8_32 = _mm_shuffle_epi8(fix8,
-    #if defined(SK_PMCOLOR_IS_BGRA)
-            _mm_setr_epi8(0,_,_,_, 1,_,_,_, 2,_,_,_, 3,_,_,_)
-    #else
-            _mm_setr_epi8(2,_,_,_, 1,_,_,_, 0,_,_,_, 3,_,_,_)
-    #endif
-    );
-#else
-    __m128i fix8_16 = _mm_unpacklo_epi8 (fix8   , _mm_setzero_si128()),
-            fix8_32 = _mm_unpacklo_epi16(fix8_16, _mm_setzero_si128());
-    #if defined(SK_PMCOLOR_IS_RGBA)
-        fix8_32 = _mm_shuffle_epi32(fix8_32, 0xC6);  // C6 == 11 00 01 10, i.e swap lanes 0 and 2.
-    #endif
-#endif
-    SkPMFloat pmf = Sk4f(_mm_mul_ps(_mm_cvtepi32_ps(fix8_32), _mm_set1_ps(1.0f/255)));
-    SkASSERT(pmf.isValid());
-    return pmf;
-}
-
-}  // namespace