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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
// For SkPMFloat(SkPMColor), we widen our 8 bit components (fix8) to 8-bit components in 16 bits
// (fix8_16), then widen those to 8-bit-in-32-bits (fix8_32), and finally convert those to floats.
// round() and roundClamp() do the opposite, working from floats to 8-bit-in-32-bit,
// to 8-bit-in-16-bit, back down to 8-bit components.
// _mm_packus_epi16() gives us clamping for free while narrowing.
inline SkPMFloat::SkPMFloat(SkPMColor c) {
SkPMColorAssert(c);
__m128i fix8 = _mm_set_epi32(0,0,0,c),
fix8_16 = _mm_unpacklo_epi8 (fix8, _mm_setzero_si128()),
fix8_32 = _mm_unpacklo_epi16(fix8_16, _mm_setzero_si128());
fVec = _mm_cvtepi32_ps(fix8_32);
SkASSERT(this->isValid());
}
inline SkPMColor SkPMFloat::round() const {
return this->roundClamp(); // Haven't beaten this yet.
}
inline SkPMColor SkPMFloat::roundClamp() 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), fVec)),
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 SkPMColor SkPMFloat::trunc() const {
// Basically, same as roundClamp(), but no rounding.
__m128i fix8_32 = _mm_cvttps_epi32(fVec),
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 void SkPMFloat::From4PMColors(const SkPMColor colors[4],
SkPMFloat* a, SkPMFloat* b, SkPMFloat* c, SkPMFloat* d) {
// Haven't beaten this yet.
*a = FromPMColor(colors[0]);
*b = FromPMColor(colors[1]);
*c = FromPMColor(colors[2]);
*d = FromPMColor(colors[3]);
}
inline void SkPMFloat::RoundTo4PMColors(
const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
SkPMColor colors[4]) {
// Haven't beaten this yet.
RoundClampTo4PMColors(a,b,c,d, colors);
}
inline void SkPMFloat::RoundClampTo4PMColors(
const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
SkPMColor colors[4]) {
// Same as _SSSE3.h's. We use 3 _mm_packus_epi16() where the naive loop uses 8.
// We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
__m128i c0 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), a.fVec)),
c1 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), b.fVec)),
c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fVec)),
c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fVec));
__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]);
}
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