raze-gles/tools/re2c/src/util/u32lim.h

#ifndef _RE2C_UTIL_U32LIM_
#define _RE2C_UTIL_U32LIM_

#include "src/util/c99_stdint.h"

// uint32_t truncated to LIMIT
// any overflow (either result of a binary operation
// or conversion from another type) results in LIMIT
// LIMIT is a fixpoint
template<uint32_t LIMIT>
class u32lim_t
{
	uint32_t value;
	explicit u32lim_t (uint32_t x)
		: value (x < LIMIT ? x : LIMIT)
	{}
	explicit u32lim_t (uint64_t x)
		: value (x < LIMIT ? static_cast<uint32_t> (x) : LIMIT)
	{}

public:
	// implicit conversion is forbidden, because
	// operands should be converted before operation:
	//     uint32_t x, y; ... u32lim_t z = x + y;
	// will result in 32-bit addition and may overflow
	// Don't export overloaded constructors: it breaks OS X builds
	// ('size_t' causes resolution ambiguity)
	static u32lim_t from32 (uint32_t x) { return u32lim_t(x); }
	static u32lim_t from64 (uint64_t x) { return u32lim_t(x); }

	static u32lim_t limit ()
	{
		return u32lim_t (LIMIT);
	}

	uint32_t uint32 () const
	{
		return value;
	}

	bool overflow () const
	{
		return value == LIMIT;
	}

	friend u32lim_t operator + (u32lim_t x, u32lim_t y)
	{
		const uint64_t z
			= static_cast<uint64_t> (x.value)
			+ static_cast<uint64_t> (y.value);
		return z < LIMIT
			? u32lim_t (z)
			: u32lim_t (LIMIT);
	}

	friend u32lim_t operator * (u32lim_t x, u32lim_t y)
	{
		const uint64_t z
			= static_cast<uint64_t> (x.value)
			* static_cast<uint64_t> (y.value);
		return z < LIMIT
			? u32lim_t (z)
			: u32lim_t (LIMIT);
	}

	friend bool operator < (u32lim_t x, u32lim_t y)
	{
		return x.value < y.value;
	}
};

#endif // _RE2C_UTIL_U32LIM_