xref: /llvm-project-15.0.7/libc/src/math/generic/sincosf.cpp (revision 75d2fcb0)

//===-- Single-precision sincos function ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "src/math/sincosf.h"
#include "math_utils.h"
#include "sincosf_utils.h"

#include "src/__support/common.h"
#include <math.h>

#include <stdint.h>

namespace __llvm_libc {

// Fast sincosf implementation. Worst-case ULP is 0.5607, maximum relative
// error is 0.5303 * 2^-23. A single-step range reduction is used for
// small values. Large inputs have their range reduced using fast integer
// arithmetic.
LLVM_LIBC_FUNCTION(void, sincosf, (float y, float *sinp, float *cosp)) {
  double x = y;
  double s;
  int n;
  const sincos_t *p = &SINCOSF_TABLE[0];

  if (abstop12(y) < abstop12(PIO4)) {
    double x2 = x * x;

    if (unlikely(abstop12(y) < abstop12(as_float(0x39800000)))) {
      if (unlikely(abstop12(y) < abstop12(as_float(0x800000))))
        // Force underflow for tiny y.
        force_eval<float>(x2);
      *sinp = y;
      *cosp = 1.0f;
      return;
    }

    sincosf_poly(x, x2, p, 0, sinp, cosp);
  } else if (abstop12(y) < abstop12(120.0f)) {
    x = reduce_fast(x, p, &n);

    // Setup the signs for sin and cos.
    s = p->sign[n & 3];

    if (n & 2)
      p = &SINCOSF_TABLE[1];

    sincosf_poly(x * s, x * x, p, n, sinp, cosp);
  } else if (likely(abstop12(y) < abstop12(INFINITY))) {
    uint32_t xi = as_uint32_bits(y);
    int sign = xi >> 31;

    x = reduce_large(xi, &n);

    // Setup signs for sin and cos - include original sign.
    s = p->sign[(n + sign) & 3];

    if ((n + sign) & 2)
      p = &SINCOSF_TABLE[1];

    sincosf_poly(x * s, x * x, p, n, sinp, cosp);
  } else {
    // Return NaN if Inf or NaN for both sin and cos.
    *sinp = *cosp = y - y;

    // Needed to set errno for +-Inf, the add is a hack to work
    // around a gcc register allocation issue: just passing y
    // affects code generation in the fast path.
    invalid(y + y);
  }
}

} // namespace __llvm_libc