1 /*
2 * Copyright 2015 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 // For SkPMFloat(SkPMColor), we widen our 8 bit components (fix8) to 8-bit components in 32 bits
9 // (fix8_32), then convert those to floats.
10
11 // round() does the opposite, working from floats to 8-bit-in-32-bits, then back to packed 8 bit.
12
13 // roundClamp() is the same as _SSE2: floats to 8-in-32, to 8-in-16, to packed 8 bit, with
14 // _mm_packus_epi16() both clamping and narrowing.
15
SkPMFloat(SkPMColor c)16 inline SkPMFloat::SkPMFloat(SkPMColor c) {
17 SkPMColorAssert(c);
18 const int _ = 255; // _ means to zero that byte.
19 __m128i fix8 = _mm_set_epi32(0,0,0,c),
20 fix8_32 = _mm_shuffle_epi8(fix8, _mm_set_epi8(_,_,_,3, _,_,_,2, _,_,_,1, _,_,_,0));
21 fVec = _mm_cvtepi32_ps(fix8_32);
22 SkASSERT(this->isValid());
23 }
24
trunc()25 inline SkPMColor SkPMFloat::trunc() const {
26 const int _ = 255; // _ means to zero that byte.
27 __m128i fix8_32 = _mm_cvttps_epi32(fVec),
28 fix8 = _mm_shuffle_epi8(fix8_32, _mm_set_epi8(_,_,_,_, _,_,_,_, _,_,_,_, 12,8,4,0));
29 SkPMColor c = _mm_cvtsi128_si32(fix8);
30 SkPMColorAssert(c);
31 return c;
32 }
33
round()34 inline SkPMColor SkPMFloat::round() const {
35 return SkPMFloat(Sk4f(0.5f) + *this).trunc();
36 }
37
roundClamp()38 inline SkPMColor SkPMFloat::roundClamp() const {
39 // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
40 __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fVec)),
41 fix8_16 = _mm_packus_epi16(fix8_32, fix8_32),
42 fix8 = _mm_packus_epi16(fix8_16, fix8_16);
43 SkPMColor c = _mm_cvtsi128_si32(fix8);
44 SkPMColorAssert(c);
45 return c;
46 }
47
From4PMColors(const SkPMColor colors[4],SkPMFloat * a,SkPMFloat * b,SkPMFloat * c,SkPMFloat * d)48 inline void SkPMFloat::From4PMColors(const SkPMColor colors[4],
49 SkPMFloat* a, SkPMFloat* b, SkPMFloat* c, SkPMFloat* d) {
50 // Haven't beaten this yet.
51 *a = FromPMColor(colors[0]);
52 *b = FromPMColor(colors[1]);
53 *c = FromPMColor(colors[2]);
54 *d = FromPMColor(colors[3]);
55 }
56
RoundTo4PMColors(const SkPMFloat & a,const SkPMFloat & b,const SkPMFloat & c,const SkPMFloat & d,SkPMColor colors[4])57 inline void SkPMFloat::RoundTo4PMColors(
58 const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
59 SkPMColor colors[4]) {
60 // Haven't beaten this yet. Still faster than RoundClampTo4PMColors?
61 colors[0] = a.round();
62 colors[1] = b.round();
63 colors[2] = c.round();
64 colors[3] = d.round();
65 }
66
RoundClampTo4PMColors(const SkPMFloat & a,const SkPMFloat & b,const SkPMFloat & c,const SkPMFloat & d,SkPMColor colors[4])67 inline void SkPMFloat::RoundClampTo4PMColors(
68 const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
69 SkPMColor colors[4]) {
70 // Same as _SSE2.h's. We use 3 _mm_packus_epi16() where the naive loop uses 8.
71 // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
72 __m128i c0 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), a.fVec)),
73 c1 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), b.fVec)),
74 c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fVec)),
75 c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fVec));
76 __m128i c3210 = _mm_packus_epi16(_mm_packus_epi16(c0, c1),
77 _mm_packus_epi16(c2, c3));
78 _mm_storeu_si128((__m128i*)colors, c3210);
79 SkPMColorAssert(colors[0]);
80 SkPMColorAssert(colors[1]);
81 SkPMColorAssert(colors[2]);
82 SkPMColorAssert(colors[3]);
83 }
84