llvm/compiler-rt/lib/builtins/fp_div_impl.inc

//===-- fp_div_impl.inc - Floating point division -----------------*- C -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements soft-float division with the IEEE-754 default
// rounding (to nearest, ties to even).
//
//===----------------------------------------------------------------------===//

#include "fp_lib.h"

// The __divXf3__ function implements Newton-Raphson floating point division.
// It uses 3 iterations for float32, 4 for float64 and 5 for float128,
// respectively. Due to number of significant bits being roughly doubled
// every iteration, the two modes are supported: N full-width iterations (as
// it is done for float32 by default) and (N-1) half-width iteration plus one
// final full-width iteration. It is expected that half-width integer
// operations (w.r.t rep_t size) can be performed faster for some hardware but
// they require error estimations to be computed separately due to larger
// computational errors caused by truncating intermediate results.

// Half the bit-size of rep_t
#define HW …
// rep_t-sized bitmask with lower half of bits set to ones
#define loMask …

#if NUMBER_OF_FULL_ITERATIONS < 1
#error At least one full iteration is required
#endif

static __inline fp_t __divXf3__(fp_t a, fp_t b) { … }