diff options
author | jfons <joan.fonssanchez@gmail.com> | 2021-05-20 12:49:33 +0200 |
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committer | jfons <joan.fonssanchez@gmail.com> | 2021-05-21 17:00:24 +0200 |
commit | 767e374dced69b45db0afb30ca2ccf0bbbeef672 (patch) | |
tree | a712cecc2c8cc2c6d6ecdc4a50020d423ddb4c0c /thirdparty/embree/common/math/transcendental.h | |
parent | 42b6602f1d4b108cecb94b94c0d2b645acaebd4f (diff) |
Upgrade Embree to the latest official release.
Since Embree v3.13.0 supports AARCH64, switch back to the
official repo instead of using Embree-aarch64.
`thirdparty/embree/patches/godot-changes.patch` should now contain
an accurate diff of the changes done to the library.
Diffstat (limited to 'thirdparty/embree/common/math/transcendental.h')
-rw-r--r-- | thirdparty/embree/common/math/transcendental.h | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/thirdparty/embree/common/math/transcendental.h b/thirdparty/embree/common/math/transcendental.h new file mode 100644 index 0000000000..fd16c26e81 --- /dev/null +++ b/thirdparty/embree/common/math/transcendental.h @@ -0,0 +1,525 @@ +// Copyright 2009-2021 Intel Corporation +// SPDX-License-Identifier: Apache-2.0 + +#pragma once + +// Transcendental functions from "ispc": https://github.com/ispc/ispc/ +// Most of the transcendental implementations in ispc code come from +// Solomon Boulos's "syrah": https://github.com/boulos/syrah/ + +#include "../simd/simd.h" + +namespace embree +{ + +namespace fastapprox +{ + +template <typename T> +__forceinline T sin(const T &v) +{ + static const float piOverTwoVec = 1.57079637050628662109375; + static const float twoOverPiVec = 0.636619746685028076171875; + auto scaled = v * twoOverPiVec; + auto kReal = floor(scaled); + auto k = toInt(kReal); + + // Reduced range version of x + auto x = v - kReal * piOverTwoVec; + auto kMod4 = k & 3; + auto sinUseCos = (kMod4 == 1 | kMod4 == 3); + auto flipSign = (kMod4 > 1); + + // These coefficients are from sollya with fpminimax(sin(x)/x, [|0, 2, + // 4, 6, 8, 10|], [|single...|], [0;Pi/2]); + static const float sinC2 = -0.16666667163372039794921875; + static const float sinC4 = +8.333347737789154052734375e-3; + static const float sinC6 = -1.9842604524455964565277099609375e-4; + static const float sinC8 = +2.760012648650445044040679931640625e-6; + static const float sinC10 = -2.50293279435709337121807038784027099609375e-8; + + static const float cosC2 = -0.5; + static const float cosC4 = +4.166664183139801025390625e-2; + static const float cosC6 = -1.388833043165504932403564453125e-3; + static const float cosC8 = +2.47562347794882953166961669921875e-5; + static const float cosC10 = -2.59630184018533327616751194000244140625e-7; + + auto outside = select(sinUseCos, 1., x); + auto c2 = select(sinUseCos, T(cosC2), T(sinC2)); + auto c4 = select(sinUseCos, T(cosC4), T(sinC4)); + auto c6 = select(sinUseCos, T(cosC6), T(sinC6)); + auto c8 = select(sinUseCos, T(cosC8), T(sinC8)); + auto c10 = select(sinUseCos, T(cosC10), T(sinC10)); + + auto x2 = x * x; + auto formula = x2 * c10 + c8; + formula = x2 * formula + c6; + formula = x2 * formula + c4; + formula = x2 * formula + c2; + formula = x2 * formula + 1.; + formula *= outside; + + formula = select(flipSign, -formula, formula); + return formula; +} + +template <typename T> +__forceinline T cos(const T &v) +{ + static const float piOverTwoVec = 1.57079637050628662109375; + static const float twoOverPiVec = 0.636619746685028076171875; + auto scaled = v * twoOverPiVec; + auto kReal = floor(scaled); + auto k = toInt(kReal); + + // Reduced range version of x + auto x = v - kReal * piOverTwoVec; + + auto kMod4 = k & 3; + auto cosUseCos = (kMod4 == 0 | kMod4 == 2); + auto flipSign = (kMod4 == 1 | kMod4 == 2); + + const float sinC2 = -0.16666667163372039794921875; + const float sinC4 = +8.333347737789154052734375e-3; + const float sinC6 = -1.9842604524455964565277099609375e-4; + const float sinC8 = +2.760012648650445044040679931640625e-6; + const float sinC10 = -2.50293279435709337121807038784027099609375e-8; + + const float cosC2 = -0.5; + const float cosC4 = +4.166664183139801025390625e-2; + const float cosC6 = -1.388833043165504932403564453125e-3; + const float cosC8 = +2.47562347794882953166961669921875e-5; + const float cosC10 = -2.59630184018533327616751194000244140625e-7; + + auto outside = select(cosUseCos, 1., x); + auto c2 = select(cosUseCos, T(cosC2), T(sinC2)); + auto c4 = select(cosUseCos, T(cosC4), T(sinC4)); + auto c6 = select(cosUseCos, T(cosC6), T(sinC6)); + auto c8 = select(cosUseCos, T(cosC8), T(sinC8)); + auto c10 = select(cosUseCos, T(cosC10), T(sinC10)); + + auto x2 = x * x; + auto formula = x2 * c10 + c8; + formula = x2 * formula + c6; + formula = x2 * formula + c4; + formula = x2 * formula + c2; + formula = x2 * formula + 1.; + formula *= outside; + + formula = select(flipSign, -formula, formula); + return formula; +} + +template <typename T> +__forceinline void sincos(const T &v, T &sinResult, T &cosResult) +{ + const float piOverTwoVec = 1.57079637050628662109375; + const float twoOverPiVec = 0.636619746685028076171875; + auto scaled = v * twoOverPiVec; + auto kReal = floor(scaled); + auto k = toInt(kReal); + + // Reduced range version of x + auto x = v - kReal * piOverTwoVec; + auto kMod4 = k & 3; + auto cosUseCos = ((kMod4 == 0) | (kMod4 == 2)); + auto sinUseCos = ((kMod4 == 1) | (kMod4 == 3)); + auto sinFlipSign = (kMod4 > 1); + auto cosFlipSign = ((kMod4 == 1) | (kMod4 == 2)); + + const float oneVec = +1.; + const float sinC2 = -0.16666667163372039794921875; + const float sinC4 = +8.333347737789154052734375e-3; + const float sinC6 = -1.9842604524455964565277099609375e-4; + const float sinC8 = +2.760012648650445044040679931640625e-6; + const float sinC10 = -2.50293279435709337121807038784027099609375e-8; + + const float cosC2 = -0.5; + const float cosC4 = +4.166664183139801025390625e-2; + const float cosC6 = -1.388833043165504932403564453125e-3; + const float cosC8 = +2.47562347794882953166961669921875e-5; + const float cosC10 = -2.59630184018533327616751194000244140625e-7; + + auto x2 = x * x; + + auto sinFormula = x2 * sinC10 + sinC8; + auto cosFormula = x2 * cosC10 + cosC8; + sinFormula = x2 * sinFormula + sinC6; + cosFormula = x2 * cosFormula + cosC6; + + sinFormula = x2 * sinFormula + sinC4; + cosFormula = x2 * cosFormula + cosC4; + + sinFormula = x2 * sinFormula + sinC2; + cosFormula = x2 * cosFormula + cosC2; + + sinFormula = x2 * sinFormula + oneVec; + cosFormula = x2 * cosFormula + oneVec; + + sinFormula *= x; + + sinResult = select(sinUseCos, cosFormula, sinFormula); + cosResult = select(cosUseCos, cosFormula, sinFormula); + + sinResult = select(sinFlipSign, -sinResult, sinResult); + cosResult = select(cosFlipSign, -cosResult, cosResult); +} + +template <typename T> +__forceinline T tan(const T &v) +{ + const float piOverFourVec = 0.785398185253143310546875; + const float fourOverPiVec = 1.27323949337005615234375; + + auto xLt0 = v < 0.; + auto y = select(xLt0, -v, v); + auto scaled = y * fourOverPiVec; + + auto kReal = floor(scaled); + auto k = toInt(kReal); + + auto x = y - kReal * piOverFourVec; + + // If k & 1, x -= Pi/4 + auto needOffset = (k & 1) != 0; + x = select(needOffset, x - piOverFourVec, x); + + // If k & 3 == (0 or 3) let z = tan_In...(y) otherwise z = -cot_In0To... + auto kMod4 = k & 3; + auto useCotan = (kMod4 == 1) | (kMod4 == 2); + + const float oneVec = 1.0; + + const float tanC2 = +0.33333075046539306640625; + const float tanC4 = +0.13339905440807342529296875; + const float tanC6 = +5.3348250687122344970703125e-2; + const float tanC8 = +2.46033705770969390869140625e-2; + const float tanC10 = +2.892402000725269317626953125e-3; + const float tanC12 = +9.500005282461643218994140625e-3; + + const float cotC2 = -0.3333333432674407958984375; + const float cotC4 = -2.222204394638538360595703125e-2; + const float cotC6 = -2.11752182804048061370849609375e-3; + const float cotC8 = -2.0846328698098659515380859375e-4; + const float cotC10 = -2.548247357481159269809722900390625e-5; + const float cotC12 = -3.5257363606433500535786151885986328125e-7; + + auto x2 = x * x; + T z; + if (any(useCotan)) + { + auto cotVal = x2 * cotC12 + cotC10; + cotVal = x2 * cotVal + cotC8; + cotVal = x2 * cotVal + cotC6; + cotVal = x2 * cotVal + cotC4; + cotVal = x2 * cotVal + cotC2; + cotVal = x2 * cotVal + oneVec; + // The equation is for x * cot(x) but we need -x * cot(x) for the tan part. + cotVal /= -x; + z = cotVal; + } + auto useTan = !useCotan; + if (any(useTan)) + { + auto tanVal = x2 * tanC12 + tanC10; + tanVal = x2 * tanVal + tanC8; + tanVal = x2 * tanVal + tanC6; + tanVal = x2 * tanVal + tanC4; + tanVal = x2 * tanVal + tanC2; + tanVal = x2 * tanVal + oneVec; + // Equation was for tan(x)/x + tanVal *= x; + z = select(useTan, tanVal, z); + } + return select(xLt0, -z, z); +} + +template <typename T> +__forceinline T asin(const T &x0) +{ + auto isneg = (x0 < 0.f); + auto x = abs(x0); + auto isnan = (x > 1.f); + + // sollya + // fpminimax(((asin(x)-pi/2)/-sqrt(1-x)), [|0,1,2,3,4,5|],[|single...|], + // [1e-20;.9999999999999999]); + // avg error: 1.1105439e-06, max error 1.3187528e-06 + auto v = 1.57079517841339111328125f + + x * (-0.21450997889041900634765625f + + x * (8.78556668758392333984375e-2f + + x * (-4.489909112453460693359375e-2f + + x * (1.928029954433441162109375e-2f + + x * (-4.3095736764371395111083984375e-3f))))); + + v *= -sqrt(1.f - x); + v = v + 1.57079637050628662109375f; + + v = select(v < 0.f, T(0.f), v); + v = select(isneg, -v, v); + v = select(isnan, T(cast_i2f(0x7fc00000)), v); + + return v; +} + +template <typename T> +__forceinline T acos(const T &v) +{ + return 1.57079637050628662109375f - asin(v); +} + +template <typename T> +__forceinline T atan(const T &v) +{ + const float piOverTwoVec = 1.57079637050628662109375; + // atan(-x) = -atan(x) (so flip from negative to positive first) + // If x > 1 -> atan(x) = Pi/2 - atan(1/x) + auto xNeg = v < 0.f; + auto xFlipped = select(xNeg, -v, v); + + auto xGt1 = xFlipped > 1.; + auto x = select(xGt1, rcpSafe(xFlipped), xFlipped); + + // These coefficients approximate atan(x)/x + const float atanC0 = +0.99999988079071044921875; + const float atanC2 = -0.3333191573619842529296875; + const float atanC4 = +0.199689209461212158203125; + const float atanC6 = -0.14015688002109527587890625; + const float atanC8 = +9.905083477497100830078125e-2; + const float atanC10 = -5.93664981424808502197265625e-2; + const float atanC12 = +2.417283318936824798583984375e-2; + const float atanC14 = -4.6721356920897960662841796875e-3; + + auto x2 = x * x; + auto result = x2 * atanC14 + atanC12; + result = x2 * result + atanC10; + result = x2 * result + atanC8; + result = x2 * result + atanC6; + result = x2 * result + atanC4; + result = x2 * result + atanC2; + result = x2 * result + atanC0; + result *= x; + + result = select(xGt1, piOverTwoVec - result, result); + result = select(xNeg, -result, result); + return result; +} + +template <typename T> +__forceinline T atan2(const T &y, const T &x) +{ + const float piVec = 3.1415926536; + // atan2(y, x) = + // + // atan2(y > 0, x = +-0) -> Pi/2 + // atan2(y < 0, x = +-0) -> -Pi/2 + // atan2(y = +-0, x < +0) -> +-Pi + // atan2(y = +-0, x >= +0) -> +-0 + // + // atan2(y >= 0, x < 0) -> Pi + atan(y/x) + // atan2(y < 0, x < 0) -> -Pi + atan(y/x) + // atan2(y, x > 0) -> atan(y/x) + // + // and then a bunch of code for dealing with infinities. + auto yOverX = y * rcpSafe(x); + auto atanArg = atan(yOverX); + auto xLt0 = x < 0.f; + auto yLt0 = y < 0.f; + auto offset = select(xLt0, + select(yLt0, T(-piVec), T(piVec)), 0.f); + return offset + atanArg; +} + +template <typename T> +__forceinline T exp(const T &v) +{ + const float ln2Part1 = 0.6931457519; + const float ln2Part2 = 1.4286067653e-6; + const float oneOverLn2 = 1.44269502162933349609375; + + auto scaled = v * oneOverLn2; + auto kReal = floor(scaled); + auto k = toInt(kReal); + + // Reduced range version of x + auto x = v - kReal * ln2Part1; + x -= kReal * ln2Part2; + + // These coefficients are for e^x in [0, ln(2)] + const float one = 1.; + const float c2 = 0.4999999105930328369140625; + const float c3 = 0.166668415069580078125; + const float c4 = 4.16539050638675689697265625e-2; + const float c5 = 8.378830738365650177001953125e-3; + const float c6 = 1.304379315115511417388916015625e-3; + const float c7 = 2.7555381529964506626129150390625e-4; + + auto result = x * c7 + c6; + result = x * result + c5; + result = x * result + c4; + result = x * result + c3; + result = x * result + c2; + result = x * result + one; + result = x * result + one; + + // Compute 2^k (should differ for float and double, but I'll avoid + // it for now and just do floats) + const int fpbias = 127; + auto biasedN = k + fpbias; + auto overflow = kReal > fpbias; + // Minimum exponent is -126, so if k is <= -127 (k + 127 <= 0) + // we've got underflow. -127 * ln(2) -> -88.02. So the most + // negative float input that doesn't result in zero is like -88. + auto underflow = kReal <= -fpbias; + const int infBits = 0x7f800000; + biasedN <<= 23; + // Reinterpret this thing as float + auto twoToTheN = asFloat(biasedN); + // Handle both doubles and floats (hopefully eliding the copy for float) + auto elemtype2n = twoToTheN; + result *= elemtype2n; + result = select(overflow, cast_i2f(infBits), result); + result = select(underflow, 0., result); + return result; +} + +// Range reduction for logarithms takes log(x) -> log(2^n * y) -> n +// * log(2) + log(y) where y is the reduced range (usually in [1/2, 1)). +template <typename T, typename R> +__forceinline void __rangeReduceLog(const T &input, + T &reduced, + R &exponent) +{ + auto intVersion = asInt(input); + // single precision = SEEE EEEE EMMM MMMM MMMM MMMM MMMM MMMM + // exponent mask = 0111 1111 1000 0000 0000 0000 0000 0000 + // 0x7 0xF 0x8 0x0 0x0 0x0 0x0 0x0 + // non-exponent = 1000 0000 0111 1111 1111 1111 1111 1111 + // = 0x8 0x0 0x7 0xF 0xF 0xF 0xF 0xF + + //const int exponentMask(0x7F800000) + static const int nonexponentMask = 0x807FFFFF; + + // We want the reduced version to have an exponent of -1 which is + // -1 + 127 after biasing or 126 + static const int exponentNeg1 = (126l << 23); + // NOTE(boulos): We don't need to mask anything out since we know + // the sign bit has to be 0. If it's 1, we need to return infinity/nan + // anyway (log(x), x = +-0 -> infinity, x < 0 -> NaN). + auto biasedExponent = intVersion >> 23; // This number is [0, 255] but it means [-127, 128] + + auto offsetExponent = biasedExponent + 1; // Treat the number as if it were 2^{e+1} * (1.m)/2 + exponent = offsetExponent - 127; // get the real value + + // Blend the offset_exponent with the original input (do this in + // int for now, until I decide if float can have & and ¬) + auto blended = (intVersion & nonexponentMask) | (exponentNeg1); + reduced = asFloat(blended); +} + +template <typename T> struct ExponentType { }; +template <int N> struct ExponentType<vfloat_impl<N>> { typedef vint<N> Ty; }; +template <> struct ExponentType<float> { typedef int Ty; }; + +template <typename T> +__forceinline T log(const T &v) +{ + T reduced; + typename ExponentType<T>::Ty exponent; + + const int nanBits = 0x7fc00000; + const int negInfBits = 0xFF800000; + const float nan = cast_i2f(nanBits); + const float negInf = cast_i2f(negInfBits); + auto useNan = v < 0.; + auto useInf = v == 0.; + auto exceptional = useNan | useInf; + const float one = 1.0; + + auto patched = select(exceptional, one, v); + __rangeReduceLog(patched, reduced, exponent); + + const float ln2 = 0.693147182464599609375; + + auto x1 = one - reduced; + const float c1 = +0.50000095367431640625; + const float c2 = +0.33326041698455810546875; + const float c3 = +0.2519190013408660888671875; + const float c4 = +0.17541764676570892333984375; + const float c5 = +0.3424419462680816650390625; + const float c6 = -0.599632322788238525390625; + const float c7 = +1.98442304134368896484375; + const float c8 = -2.4899270534515380859375; + const float c9 = +1.7491014003753662109375; + + auto result = x1 * c9 + c8; + result = x1 * result + c7; + result = x1 * result + c6; + result = x1 * result + c5; + result = x1 * result + c4; + result = x1 * result + c3; + result = x1 * result + c2; + result = x1 * result + c1; + result = x1 * result + one; + + // Equation was for -(ln(red)/(1-red)) + result *= -x1; + result += toFloat(exponent) * ln2; + + return select(exceptional, + select(useNan, T(nan), T(negInf)), + result); +} + +template <typename T> +__forceinline T pow(const T &x, const T &y) +{ + auto x1 = abs(x); + auto z = exp(y * log(x1)); + + // Handle special cases + const float twoOver23 = 8388608.0f; + auto yInt = y == round(y); + auto yOddInt = select(yInt, asInt(abs(y) + twoOver23) << 31, 0); // set sign bit + + // x == 0 + z = select(x == 0.0f, + select(y < 0.0f, T(inf) | signmsk(x), + select(y == 0.0f, T(1.0f), asFloat(yOddInt) & x)), z); + + // x < 0 + auto xNegative = x < 0.0f; + if (any(xNegative)) + { + auto z1 = z | asFloat(yOddInt); + z1 = select(yInt, z1, std::numeric_limits<float>::quiet_NaN()); + z = select(xNegative, z1, z); + } + + auto xFinite = isfinite(x); + auto yFinite = isfinite(y); + if (all(xFinite & yFinite)) + return z; + + // x finite and y infinite + z = select(andn(xFinite, yFinite), + select(x1 == 1.0f, 1.0f, + select((x1 > 1.0f) ^ (y < 0.0f), inf, T(0.0f))), z); + + // x infinite + z = select(xFinite, z, + select(y == 0.0f, 1.0f, + select(y < 0.0f, T(0.0f), inf) | (asFloat(yOddInt) & x))); + + return z; +} + +template <typename T> +__forceinline T pow(const T &x, float y) +{ + return pow(x, T(y)); +} + +} // namespace fastapprox + +} // namespace embree |