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 16 bits
9 // (fix8_16), then widen those to 8-bit-in-32-bits (fix8_32), and finally convert those to floats.
10
11 // round() and roundClamp() do the opposite, working from floats to 8-bit-in-32-bit,
12 // to 8-bit-in-16-bit, back down to 8-bit components.
13 // _mm_packus_epi16() gives us clamping for free while narrowing.
14
SkPMFloat(SkPMColor c)15 inline SkPMFloat::SkPMFloat(SkPMColor c) {
16 SkPMColorAssert(c);
17 __m128i fix8 = _mm_set_epi32(0,0,0,c),
18 fix8_16 = _mm_unpacklo_epi8 (fix8, _mm_setzero_si128()),
19 fix8_32 = _mm_unpacklo_epi16(fix8_16, _mm_setzero_si128());
20 fVec = _mm_cvtepi32_ps(fix8_32);
21 SkASSERT(this->isValid());
22 }
23
round()24 inline SkPMColor SkPMFloat::round() const {
25 return this->roundClamp(); // Haven't beaten this yet.
26 }
27
roundClamp()28 inline SkPMColor SkPMFloat::roundClamp() const {
29 // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
30 __m128i fix8_32 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), fVec)),
31 fix8_16 = _mm_packus_epi16(fix8_32, fix8_32),
32 fix8 = _mm_packus_epi16(fix8_16, fix8_16);
33 SkPMColor c = _mm_cvtsi128_si32(fix8);
34 SkPMColorAssert(c);
35 return c;
36 }
37
trunc()38 inline SkPMColor SkPMFloat::trunc() const {
39 // Basically, same as roundClamp(), but no rounding.
40 __m128i fix8_32 = _mm_cvttps_epi32(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.
61 RoundClampTo4PMColors(a,b,c,d, colors);
62 }
63
RoundClampTo4PMColors(const SkPMFloat & a,const SkPMFloat & b,const SkPMFloat & c,const SkPMFloat & d,SkPMColor colors[4])64 inline void SkPMFloat::RoundClampTo4PMColors(
65 const SkPMFloat& a, const SkPMFloat& b, const SkPMFloat&c, const SkPMFloat& d,
66 SkPMColor colors[4]) {
67 // Same as _SSSE3.h's. We use 3 _mm_packus_epi16() where the naive loop uses 8.
68 // We don't use _mm_cvtps_epi32, because we want precise control over how 0.5 rounds (up).
69 __m128i c0 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), a.fVec)),
70 c1 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), b.fVec)),
71 c2 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), c.fVec)),
72 c3 = _mm_cvttps_epi32(_mm_add_ps(_mm_set1_ps(0.5f), d.fVec));
73 __m128i c3210 = _mm_packus_epi16(_mm_packus_epi16(c0, c1),
74 _mm_packus_epi16(c2, c3));
75 _mm_storeu_si128((__m128i*)colors, c3210);
76 SkPMColorAssert(colors[0]);
77 SkPMColorAssert(colors[1]);
78 SkPMColorAssert(colors[2]);
79 SkPMColorAssert(colors[3]);
80 }
81