jpegr: fix float to float_16 bug
Bug: b/264715926
Change-Id: I7d78b87f971916503ef84b056f4fc8db8720d2fe
diff --git a/libs/jpegrecoverymap/include/jpegrecoverymap/recoverymapmath.h b/libs/jpegrecoverymap/include/jpegrecoverymap/recoverymapmath.h
index 67d2a6a..0aef9b9 100644
--- a/libs/jpegrecoverymap/include/jpegrecoverymap/recoverymapmath.h
+++ b/libs/jpegrecoverymap/include/jpegrecoverymap/recoverymapmath.h
@@ -116,11 +116,17 @@
}
inline uint16_t floatToHalf(float f) {
- uint32_t x = *((uint32_t*)&f);
- uint16_t h = ((x >> 16) & 0x8000)
- | ((((x & 0x7f800000) - 0x38000000) >> 13) & 0x7c00)
- | ((x >> 13) & 0x03ff);
- return h;
+ // round-to-nearest-even: add last bit after truncated mantissa
+ const uint32_t b = *((uint32_t*)&f) + 0x00001000;
+
+ const uint32_t e = (b & 0x7F800000) >> 23; // exponent
+ const uint32_t m = b & 0x007FFFFF; // mantissa
+
+ // sign : normalized : denormalized : saturate
+ return (b & 0x80000000) >> 16
+ | (e > 112) * ((((e - 112) << 10) & 0x7C00) | m >> 13)
+ | ((e < 113) & (e > 101)) * ((((0x007FF000 + m) >> (125 - e)) + 1) >> 1)
+ | (e > 143) * 0x7FFF;
}
constexpr size_t kRecoveryFactorPrecision = 10;
diff --git a/libs/jpegrecoverymap/tests/recoverymapmath_test.cpp b/libs/jpegrecoverymap/tests/recoverymapmath_test.cpp
index 5ef79e9..2369a7e 100644
--- a/libs/jpegrecoverymap/tests/recoverymapmath_test.cpp
+++ b/libs/jpegrecoverymap/tests/recoverymapmath_test.cpp
@@ -952,6 +952,27 @@
| static_cast<uint32_t>(0.3f * static_cast<float>(0x3ff)) << 20);
}
+TEST_F(RecoveryMapMathTest, ColorToRgbaF16) {
+ EXPECT_EQ(colorToRgbaF16(RgbBlack()), ((uint64_t) 0x3C00) << 48);
+ EXPECT_EQ(colorToRgbaF16(RgbWhite()), 0x3C003C003C003C00);
+ EXPECT_EQ(colorToRgbaF16(RgbRed()), (((uint64_t) 0x3C00) << 48) | ((uint64_t) 0x3C00));
+ EXPECT_EQ(colorToRgbaF16(RgbGreen()), (((uint64_t) 0x3C00) << 48) | (((uint64_t) 0x3C00) << 16));
+ EXPECT_EQ(colorToRgbaF16(RgbBlue()), (((uint64_t) 0x3C00) << 48) | (((uint64_t) 0x3C00) << 32));
+
+ Color e_gamma = {{{ 0.1f, 0.2f, 0.3f }}};
+ EXPECT_EQ(colorToRgbaF16(e_gamma), 0x3C0034CD32662E66);
+}
+
+TEST_F(RecoveryMapMathTest, Float32ToFloat16) {
+ EXPECT_EQ(floatToHalf(0.1f), 0x2E66);
+ EXPECT_EQ(floatToHalf(0.0f), 0x0);
+ EXPECT_EQ(floatToHalf(1.0f), 0x3C00);
+ EXPECT_EQ(floatToHalf(-1.0f), 0xBC00);
+ EXPECT_EQ(floatToHalf(0x1.fffffep127f), 0x7FFF); // float max
+ EXPECT_EQ(floatToHalf(-0x1.fffffep127f), 0xFFFF); // float min
+ EXPECT_EQ(floatToHalf(0x1.0p-126f), 0x0); // float zero
+}
+
TEST_F(RecoveryMapMathTest, GenerateMapLuminanceSrgb) {
EXPECT_FLOAT_EQ(SrgbYuvToLuminance(YuvBlack(), srgbLuminance),
0.0f);