inline half log1p()

in include/half.hpp [3167:3202]

• 36 lines of code
• 12 McCabe index (conditional complexity)

	inline half log1p(half arg)
	{
	#if defined(HALF_ARITHMETIC_TYPE) && HALF_ENABLE_CPP11_CMATH
		return half(detail::binary, detail::float2half<half::round_style>(std::log1p(detail::half2float<detail::internal_t>(arg.data_))));
	#else
		if(arg.data_ >= 0xBC00)
			return half(detail::binary, (arg.data_==0xBC00) ? detail::pole(0x8000) : (arg.data_<=0xFC00) ? detail::invalid() : detail::signal(arg.data_));
		int abs = arg.data_ & 0x7FFF, exp = -15;
		if(!abs || abs >= 0x7C00)
			return (abs>0x7C00) ? half(detail::binary, detail::signal(arg.data_)) : arg;
		for(; abs<0x400; abs<<=1,--exp) ;
		exp += abs >> 10;
		detail::uint32 m = static_cast<detail::uint32>((abs&0x3FF)|0x400) << 20;
		if(arg.data_ & 0x8000)
		{
			m = 0x40000000 - (m>>-exp);
			for(exp=0; m<0x40000000; m<<=1,--exp) ;
		}
		else
		{
			if(exp < 0)
			{
				m = 0x40000000 + (m>>-exp);
				exp = 0;
			}
			else
			{
				m += 0x40000000 >> exp;
				int i = m >> 31;
				m >>= i;
				exp += i;
			}
		}
		return half(detail::binary, detail::log2_post<half::round_style,0xB8AA3B2A>(detail::log2(m), exp, 17));
	#endif
	}