SkPMFloat::trunc()

src/opts/SkPMFloat_SSSE3.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.
  */
 
 inline SkPMFloat& SkPMFloat::operator=(const SkPMFloat& that) {
     fColors = that.fColors;
     return *this;
 }
 
 // For SkPMFloat(SkPMColor), we widen our 8 bit components (fix8) to 8-bit components in 32 bits
 // (fix8_32), then convert those to floats.
 
 // get() does the opposite, working from floats to 8-bit-in-32-bits, then back to packed 8 bit.
 
 // clamped() is the same as _SSE2: floats to 8-in-32, to 8-in-16, to packed 8 bit, with
 // _mm_packus_epi16() both clamping and narrowing.
 
 inline SkPMFloat::SkPMFloat(SkPMColor c) {
     SkPMColorAssert(c);
     const int _ = 255;  // _ means to zero that byte.
     __m128i fix8    = _mm_set_epi32(0,0,0,c),
             fix8_32 = _mm_shuffle_epi8(fix8, _mm_set_epi8(_,_,_,3, _,_,_,2, _,_,_,1, _,_,_,0));
     fColors = _mm_cvtepi32_ps(fix8_32);
     SkASSERT(this->isValid());
 }
 
-inline SkPMColor SkPMFloat::get() const {
-    SkASSERT(this->isValid());
+inline SkPMColor SkPMFloat::trunc() const {
     const int _ = 255;  // _ means to zero that byte.
-    // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
-    __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fColors)),
+    __m128i fix8_32 = _mm_cvttps_epi32(fColors),
             fix8    = _mm_shuffle_epi8(fix8_32, _mm_set_epi8(_,_,_,_, _,_,_,_, _,_,_,_, 12,8,4,0));
     SkPMColor c = _mm_cvtsi128_si32(fix8);
     SkPMColorAssert(c);
     return c;
 }
 
+inline SkPMColor SkPMFloat::get() const {
+    SkASSERT(this->isValid());
+    return SkPMFloat(Sk4f(0.5f) + *this).trunc();
+}
+
 inline SkPMColor SkPMFloat::clamped() const {
     // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
     __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fColors)),
             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;
 }
 
@@ skipping 26 matching lines @@
             c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fColors)),
             c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fColors));
     __m128i c3210 = _mm_packus_epi16(_mm_packus_epi16(c0, c1),
                                      _mm_packus_epi16(c2, c3));
     _mm_storeu_si128((__m128i*)colors, c3210);
     SkPMColorAssert(colors[0]);
     SkPMColorAssert(colors[1]);
     SkPMColorAssert(colors[2]);
     SkPMColorAssert(colors[3]);
 }