diff options
Diffstat (limited to 'libc/src/math/generic/exp10m1f16.cpp')
| -rw-r--r-- | libc/src/math/generic/exp10m1f16.cpp | 158 |
1 files changed, 2 insertions, 156 deletions
diff --git a/libc/src/math/generic/exp10m1f16.cpp b/libc/src/math/generic/exp10m1f16.cpp index 6c2fdbe..8a3c4ab 100644 --- a/libc/src/math/generic/exp10m1f16.cpp +++ b/libc/src/math/generic/exp10m1f16.cpp @@ -7,166 +7,12 @@ //===----------------------------------------------------------------------===// #include "src/math/exp10m1f16.h" -#include "hdr/errno_macros.h" -#include "hdr/fenv_macros.h" -#include "src/__support/FPUtil/FEnvImpl.h" -#include "src/__support/FPUtil/FPBits.h" -#include "src/__support/FPUtil/PolyEval.h" -#include "src/__support/FPUtil/cast.h" -#include "src/__support/FPUtil/except_value_utils.h" -#include "src/__support/FPUtil/multiply_add.h" -#include "src/__support/FPUtil/rounding_mode.h" -#include "src/__support/common.h" -#include "src/__support/macros/config.h" -#include "src/__support/macros/optimization.h" -#include "src/__support/macros/properties/cpu_features.h" -#include "src/__support/math/exp10f16_utils.h" +#include "src/__support/math/exp10m1f16.h" namespace LIBC_NAMESPACE_DECL { -#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS -static constexpr fputil::ExceptValues<float16, 3> EXP10M1F16_EXCEPTS_LO = {{ - // (input, RZ output, RU offset, RD offset, RN offset) - // x = 0x1.5c4p-4, exp10m1f16(x) = 0x1.bacp-3 (RZ) - {0x2d71U, 0x32ebU, 1U, 0U, 0U}, - // x = -0x1.5ep-13, exp10m1f16(x) = -0x1.92cp-12 (RZ) - {0x8978U, 0x8e4bU, 0U, 1U, 0U}, - // x = -0x1.e2p-10, exp10m1f16(x) = -0x1.14cp-8 (RZ) - {0x9788U, 0x9c53U, 0U, 1U, 0U}, -}}; - -#ifdef LIBC_TARGET_CPU_HAS_FMA_FLOAT -static constexpr size_t N_EXP10M1F16_EXCEPTS_HI = 3; -#else -static constexpr size_t N_EXP10M1F16_EXCEPTS_HI = 6; -#endif - -static constexpr fputil::ExceptValues<float16, N_EXP10M1F16_EXCEPTS_HI> - EXP10M1F16_EXCEPTS_HI = {{ - // (input, RZ output, RU offset, RD offset, RN offset) - // x = 0x1.8f4p-2, exp10m1f16(x) = 0x1.744p+0 (RZ) - {0x363dU, 0x3dd1U, 1U, 0U, 0U}, - // x = 0x1.95cp-2, exp10m1f16(x) = 0x1.7d8p+0 (RZ) - {0x3657U, 0x3df6U, 1U, 0U, 0U}, - // x = 0x1.d04p-2, exp10m1f16(x) = 0x1.d7p+0 (RZ) - {0x3741U, 0x3f5cU, 1U, 0U, 1U}, -#ifndef LIBC_TARGET_CPU_HAS_FMA_FLOAT - // x = 0x1.0cp+1, exp10m1f16(x) = 0x1.ec4p+6 (RZ) - {0x4030U, 0x57b1U, 1U, 0U, 1U}, - // x = 0x1.1b8p+1, exp10m1f16(x) = 0x1.45cp+7 (RZ) - {0x406eU, 0x5917U, 1U, 0U, 1U}, - // x = 0x1.2f4p+2, exp10m1f16(x) = 0x1.ab8p+15 (RZ) - {0x44bdU, 0x7aaeU, 1U, 0U, 1U}, -#endif - }}; -#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS - LLVM_LIBC_FUNCTION(float16, exp10m1f16, (float16 x)) { - using FPBits = fputil::FPBits<float16>; - FPBits x_bits(x); - - uint16_t x_u = x_bits.uintval(); - uint16_t x_abs = x_u & 0x7fffU; - - // When |x| <= 2^(-3), or |x| >= 11 * log10(2), or x is NaN. - if (LIBC_UNLIKELY(x_abs <= 0x3000U || x_abs >= 0x429fU)) { - // exp10m1(NaN) = NaN - if (x_bits.is_nan()) { - if (x_bits.is_signaling_nan()) { - fputil::raise_except_if_required(FE_INVALID); - return FPBits::quiet_nan().get_val(); - } - - return x; - } - - // When x >= 16 * log10(2). - if (x_u >= 0x44d1U && x_bits.is_pos()) { - // exp10m1(+inf) = +inf - if (x_bits.is_inf()) - return FPBits::inf().get_val(); - - switch (fputil::quick_get_round()) { - case FE_TONEAREST: - case FE_UPWARD: - fputil::set_errno_if_required(ERANGE); - fputil::raise_except_if_required(FE_OVERFLOW | FE_INEXACT); - return FPBits::inf().get_val(); - default: - return FPBits::max_normal().get_val(); - } - } - - // When x < -11 * log10(2). - if (x_u > 0xc29fU) { - // exp10m1(-inf) = -1 - if (x_bits.is_inf()) - return FPBits::one(Sign::NEG).get_val(); - - // When x >= -0x1.ce4p+1, round(10^x - 1, HP, RN) = -0x1.ffcp-1. - if (x_u <= 0xc339U) { - return fputil::round_result_slightly_down( - fputil::cast<float16>(-0x1.ffcp-1)); - } - - // When x < -0x1.ce4p+1, round(10^x - 1, HP, RN) = -1. - switch (fputil::quick_get_round()) { - case FE_TONEAREST: - case FE_DOWNWARD: - return FPBits::one(Sign::NEG).get_val(); - default: - return fputil::cast<float16>(-0x1.ffcp-1); - } - } - - // When |x| <= 2^(-3). - if (x_abs <= 0x3000U) { - if (LIBC_UNLIKELY(x_abs == 0)) - return x; - -#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS - if (auto r = EXP10M1F16_EXCEPTS_LO.lookup(x_u); - LIBC_UNLIKELY(r.has_value())) - return r.value(); -#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS - - float xf = x; - // Degree-5 minimax polynomial generated by Sollya with the following - // commands: - // > display = hexadecimal; - // > P = fpminimax((10^x - 1)/x, 4, [|SG...|], [-2^-3, 2^-3]); - // > x * P; - return fputil::cast<float16>( - xf * fputil::polyeval(xf, 0x1.26bb1cp+1f, 0x1.5351c8p+1f, - 0x1.04704p+1f, 0x1.2ce084p+0f, 0x1.14a6bep-1f)); - } - } - - // When x is 1, 2, or 3. These are hard-to-round cases with exact results. - // 10^4 - 1 = 9'999 is not exactly representable as a float16, but luckily the - // polynomial approximation gives the correct result for x = 4 in all - // rounding modes. - if (LIBC_UNLIKELY((x_u & ~(0x3c00U | 0x4000U | 0x4200U | 0x4400U)) == 0)) { - switch (x_u) { - case 0x3c00U: // x = 1.0f16 - return fputil::cast<float16>(9.0); - case 0x4000U: // x = 2.0f16 - return fputil::cast<float16>(99.0); - case 0x4200U: // x = 3.0f16 - return fputil::cast<float16>(999.0); - } - } - -#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS - if (auto r = EXP10M1F16_EXCEPTS_HI.lookup(x_u); LIBC_UNLIKELY(r.has_value())) - return r.value(); -#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS - - // exp10(x) = exp2((hi + mid) * log2(10)) * exp10(lo) - auto [exp2_hi_mid, exp10_lo] = exp10_range_reduction(x); - // exp10m1(x) = exp2((hi + mid) * log2(lo)) * exp10(lo) - 1 - return fputil::cast<float16>( - fputil::multiply_add(exp2_hi_mid, exp10_lo, -1.0f)); + return math::exp10m1f16(x); } } // namespace LIBC_NAMESPACE_DECL |