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-rw-r--r--src/core/SkHalf.h63
-rw-r--r--src/core/SkXfermodeU64.cpp25
-rw-r--r--tests/Float16Test.cpp35
3 files changed, 23 insertions, 100 deletions
diff --git a/src/core/SkHalf.h b/src/core/SkHalf.h
index baf86fda3b..7e41c6ff0c 100644
--- a/src/core/SkHalf.h
+++ b/src/core/SkHalf.h
@@ -8,7 +8,6 @@
#ifndef SkHalf_DEFINED
#define SkHalf_DEFINED
-#include "SkNx.h"
#include "SkTypes.h"
// 16-bit floating point value
@@ -24,66 +23,4 @@ typedef uint16_t SkHalf;
float SkHalfToFloat(SkHalf h);
SkHalf SkFloatToHalf(float f);
-// Convert between half and single precision floating point, but pull any dirty
-// trick we can to make it faster as long as it's correct enough for values in [0,1].
-static inline Sk4f SkHalfToFloat_01(uint64_t);
-static inline uint64_t SkFloatToHalf_01(const Sk4f&);
-
-// ~~~~~~~~~~~ impl ~~~~~~~~~~~~~~ //
-
-// Like the serial versions in SkHalf.cpp, these are based on
-// https://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
-
-// TODO: NEON versions
-static inline Sk4f SkHalfToFloat_01(uint64_t hs) {
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
- // Load our 16-bit floats into the bottom 16 bits of each 32-bit lane, with zeroes on top.
- __m128i h = _mm_unpacklo_epi16(_mm_loadl_epi64((const __m128i*)&hs), _mm_setzero_si128());
-
- // Fork into two paths, depending on whether the 16-bit float is denormalized.
- __m128 is_denorm = _mm_castsi128_ps(_mm_cmplt_epi32(h, _mm_set1_epi32(0x0400)));
-
- // TODO: figure out, explain
- const __m128 half = _mm_set1_ps(0.5f);
- __m128 denorm = _mm_sub_ps(_mm_or_ps(_mm_castsi128_ps(h), half), half);
-
- // If we're normalized, just shift ourselves so the exponent/mantissa dividing line
- // is correct, then re-bias the exponent from 15 to 127.
- __m128 norm = _mm_castsi128_ps(_mm_add_epi32(_mm_slli_epi32(h, 13),
- _mm_set1_epi32((127-15) << 23)));
-
- return _mm_or_ps(_mm_and_ps (is_denorm, denorm),
- _mm_andnot_ps(is_denorm, norm));
-#else
- float fs[4];
- for (int i = 0; i < 4; i++) {
- fs[i] = SkHalfToFloat(hs >> (i*16));
- }
- return Sk4f::Load(fs);
-#endif
-}
-
-static inline uint64_t SkFloatToHalf_01(const Sk4f& fs) {
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
- // Scale our floats down by a tiny power of 2 to pull up our mantissa bits,
- // then shift back down to 16-bit float layout. This doesn't round, so can be 1 bit small.
- // TODO: understand better. Why this scale factor?
- const __m128 scale = _mm_castsi128_ps(_mm_set1_epi32(15 << 23));
- __m128i h = _mm_srli_epi32(_mm_castps_si128(_mm_mul_ps(fs.fVec, scale)), 13);
-
- uint64_t r;
- _mm_storel_epi64((__m128i*)&r, _mm_packs_epi32(h,h));
- return r;
-#else
- SkHalf hs[4];
- for (int i = 0; i < 4; i++) {
- hs[i] = SkFloatToHalf(fs[i]);
- }
- return (uint64_t)hs[3] << 48
- | (uint64_t)hs[2] << 32
- | (uint64_t)hs[1] << 16
- | (uint64_t)hs[0] << 0;
-#endif
-}
-
#endif
diff --git a/src/core/SkXfermodeU64.cpp b/src/core/SkXfermodeU64.cpp
index 6de5f1b09f..6435e6a2e2 100644
--- a/src/core/SkXfermodeU64.cpp
+++ b/src/core/SkXfermodeU64.cpp
@@ -46,15 +46,36 @@ static uint64_t store_to_u16(const Sk4f& x4) {
return value;
}
+static Sk4f load_from_f16(uint64_t value) {
+ const uint16_t* u16 = reinterpret_cast<const uint16_t*>(&value);
+ float f4[4];
+ for (int i = 0; i < 4; ++i) {
+ f4[i] = SkHalfToFloat(u16[i]);
+ }
+ return Sk4f::Load(f4);
+}
+
+static uint64_t store_to_f16(const Sk4f& x4) {
+ uint64_t value;
+ uint16_t* u16 = reinterpret_cast<uint16_t*>(&value);
+
+ float f4[4];
+ x4.store(f4);
+ for (int i = 0; i < 4; ++i) {
+ u16[i] = SkFloatToHalf(f4[i]);
+ }
+ return value;
+}
+
// Returns dst in its "natural" bias (either unit-float or 16bit int)
//
template <DstType D> Sk4f load_from_dst(uint64_t dst) {
- return (D == kU16_Dst) ? load_from_u16(dst) : SkHalfToFloat_01(dst);
+ return (D == kU16_Dst) ? load_from_u16(dst) : load_from_f16(dst);
}
// Assumes x4 is already in the "natural" bias (either unit-float or 16bit int)
template <DstType D> uint64_t store_to_dst(const Sk4f& x4) {
- return (D == kU16_Dst) ? store_to_u16(x4) : SkFloatToHalf_01(x4);
+ return (D == kU16_Dst) ? store_to_u16(x4) : store_to_f16(x4);
}
///////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/tests/Float16Test.cpp b/tests/Float16Test.cpp
index f96d904567..f437268c79 100644
--- a/tests/Float16Test.cpp
+++ b/tests/Float16Test.cpp
@@ -10,7 +10,6 @@
#include "SkHalf.h"
#include "SkOpts.h"
#include "SkPixmap.h"
-#include "SkRandom.h"
static bool eq_within_half_float(float a, float b) {
const float kTolerance = 1.0f / (1 << (8 + 10));
@@ -65,37 +64,3 @@ DEF_TEST(float_to_half, reporter) {
SkOpts::half_to_float(fscratch, hs, 7);
REPORTER_ASSERT(reporter, 0 == memcmp(fscratch, fs, sizeof(fs)));
}
-
-DEF_TEST(HalfToFloat_01, r) {
- for (uint16_t h = 0; h < 0x8000; h++) {
- float f = SkHalfToFloat(h);
- if (f >= 0 && f <= 1) {
- REPORTER_ASSERT(r, SkHalfToFloat_01(h)[0] == f);
- REPORTER_ASSERT(r, SkFloatToHalf_01(SkHalfToFloat_01(h)) == h);
- }
- }
-}
-
-DEF_TEST(FloatToHalf_01, r) {
-#if 0
- for (uint32_t bits = 0; bits < 0x80000000; bits++) {
-#else
- SkRandom rand;
- for (int i = 0; i < 1000000; i++) {
- uint32_t bits = rand.nextU();
-#endif
- float f;
- memcpy(&f, &bits, 4);
- if (f >= 0 && f <= 1) {
- uint16_t h1 = (uint16_t)SkFloatToHalf_01(Sk4f(f,0,0,0)),
- h2 = SkFloatToHalf(f);
- bool ok = (h1 == h2 || h1 == h2-1);
- REPORTER_ASSERT(r, ok);
- if (!ok) {
- SkDebugf("%08x (%d) -> %04x (%d), want %04x (%d)\n",
- bits, bits>>23, h1, h1>>10, h2, h2>>10);
- break;
- }
- }
- }
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-11 04:59:03 +0000