From 16654d37ead1f31effb8aa76e683d2e446905ff2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Henrik=20Rydg=C3=A5rd?= Date: Sat, 10 Oct 2020 10:06:28 +0200 Subject: [PATCH] VFPU: Compute sines and cosines in double precision. Let's see if we can do without the special checks in double precision. --- Core/MIPS/MIPSVFPUUtils.h | 63 ++++++++++++++------------------------- unittest/UnitTest.cpp | 14 ++++++++- 2 files changed, 35 insertions(+), 42 deletions(-) diff --git a/Core/MIPS/MIPSVFPUUtils.h b/Core/MIPS/MIPSVFPUUtils.h index cf7c1e7426d6..e43c588a4178 100644 --- a/Core/MIPS/MIPSVFPUUtils.h +++ b/Core/MIPS/MIPSVFPUUtils.h @@ -29,67 +29,48 @@ inline int Xpose(int v) { return v^0x20; } +// Half of PI, or 90 degrees. #ifndef M_PI_2 #define M_PI_2 1.57079632679489661923 #endif -// Some games depend on exact values, but sinf() and cosf() aren't always precise. +// The VFPU uses weird angles where 4.0 represents a full circle. This makes it possible to return +// exact 1.0/-1.0 values at certain angles. We get close enough for #2921 and #12900 by computing +// things in double precision, multiplying the input by pi/2. +// +// A better solution would be to tailor some sine approximation for the 0..90 degrees range, compute +// modulo manually and mirror that around the circle. Also correctly special casing for inf/nan inputs +// and just trying to match it as closely as possible to the real PSP. +// // Stepping down to [0, 2pi) helps, but we also check common exact-result values. // TODO: cos(1) and sin(2) should be -0.0, but doing that gives wrong results (possibly from floorf.) +// Messing around with the modulo functions? try https://www.desmos.com/calculator. + inline float vfpu_sin(float angle) { - angle -= floorf(angle * 0.25f) * 4.f; - if (angle == 0.0f || angle == 2.0f) { - return 0.0f; - } else if (angle == 1.0f) { - return 1.0f; - } else if (angle == 3.0f) { - return -1.0f; - } - angle *= (float)M_PI_2; - return sinf(angle); + return (float)sin((double)angle * M_PI_2); } inline float vfpu_cos(float angle) { - angle -= floorf(angle * 0.25f) * 4.f; - if (angle == 1.0f || angle == 3.0f) { - return 0.0f; - } else if (angle == 0.0f) { - return 1.0f; - } else if (angle == 2.0f) { - return -1.0f; - } - angle *= (float)M_PI_2; - return cosf(angle); + return (float)cos((double)angle * M_PI_2); } inline float vfpu_asin(float angle) { return asinf(angle) / M_PI_2; } -inline void vfpu_sincos(float angle, float &sine, float &cosine) { - angle -= floorf(angle * 0.25f) * 4.f; - if (angle == 0.0f) { - sine = 0.0f; - cosine = 1.0f; - } else if (angle == 1.0f) { - sine = 1.0f; - cosine = 0.0f; - } else if (angle == 2.0f) { - sine = 0.0f; - cosine = -1.0f; - } else if (angle == 3.0f) { - sine = -1.0f; - cosine = 0.0f; - } else { - angle *= (float)M_PI_2; +inline void vfpu_sincos(float angle_f, float &sine, float &cosine) { + double angle = (double)angle_f * M_PI_2; #if defined(__linux__) - sincosf(angle, &sine, &cosine); + double d_sine; + double d_cosine; + sincos(angle, &d_sine, &d_cosine); + sine = (float)d_sine; + cosine = (float)d_cosine; #else - sine = sinf(angle); - cosine = cosf(angle); + sine = (float)sin(angle); + cosine = (float)cos(angle); #endif - } } inline float vfpu_clamp(float v, float min, float max) { diff --git a/unittest/UnitTest.cpp b/unittest/UnitTest.cpp index edb5939cbae7..a3109993606c 100644 --- a/unittest/UnitTest.cpp +++ b/unittest/UnitTest.cpp @@ -23,6 +23,9 @@ // // TODO: Make a test of nice unittest asserts and count successes etc. // Or just integrate with an existing testing framework. +// +// To use, set command line parameter to one or more of the tests below, or "all". +// Search for "availableTests". #include #include @@ -308,10 +311,19 @@ bool TestVFPUSinCos() { EXPECT_APPROX_EQ_FLOAT(sine, 1.0f); EXPECT_APPROX_EQ_FLOAT(cosine, 0.0f); - for (float angle = -10.0f; angle < 10.0f; angle++) { + vfpu_sincos(-1.0f, sine, cosine); + EXPECT_EQ_FLOAT(sine, -1.0f); + EXPECT_EQ_FLOAT(cosine, 0.0f); + vfpu_sincos(-2.0f, sine, cosine); + EXPECT_EQ_FLOAT(sine, 0.0f); + EXPECT_EQ_FLOAT(cosine, -1.0f); + + for (float angle = -10.0f; angle < 10.0f; angle += 0.1f) { vfpu_sincos(angle, sine, cosine); EXPECT_APPROX_EQ_FLOAT(sine, sinf(angle * M_PI_2)); EXPECT_APPROX_EQ_FLOAT(cosine, cosf(angle * M_PI_2)); + + printf("sine: %f==%f cosine: %f==%f\n", sine, sinf(angle * M_PI_2), cosine, cosf(angle * M_PI_2)); } return true; }