lib.h File Reference

#include <cmath>
#include <limits>
#include <stdexcept>

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Functions
template<typename T >
T	DivideRoundUp (T dividend, T divisor)
bool	feq (double d1, double d2, double epsilon=0.00001)
	are the given floats nearly "equal"? More...
bool	feqf (float f1, float f2, float epsilon=0.001f)
bool	IsSimilarMagnitude (double d1, double d2, const double relativeErrorTolerance=0.05)
u32	u64_hi (u64 x)
u32	u64_lo (u64 x)
	return upper 32-bits More...
u16	u32_hi (u32 x)
	return lower 32-bits More...
u16	u32_lo (u32 x)
	return upper 16-bits More...
u64	u64_from_u32 (u32 hi, u32 lo)
	return lower 16-bits More...
u32	u32_from_u16 (u16 hi, u16 lo)
	assemble u64 from u32 More...
template<typename T >
u8	u8_from_larger (T x)
	assemble u32 from u16 More...
template<typename T >
u16	u16_from_larger (T x)
template<typename T >
u32	u32_from_larger (T x)
u8	u8_from_double (double in)
	convert double to u8; verifies number is in range. More...
u16	u16_from_double (double in)
	convert double to u16; verifies number is in range. More...

Function Documentation

DivideRoundUp()

template<typename T >

T DivideRoundUp	(	T	dividend,
		T	divisor
	)

low-level aka "lib"

this codebase was grown from modules shared between several projects, i.e. my personal library; hence the name "lib". it has been expanded to fit the needs of 0ad - in particular, resource loading.

owing to the dual-use situation, the 0ad coding conventions are not met; also, major changes are ill-advised because they may break other projects.

design goals

• fast and low-overhead, including startup time
• portable: must run on Win32, Mac OS X and Linux
• reusable across projects, i.e. no dependency on a central 'manager' that ties modules together.

scope

• POSIX definitions
• resource management
• debugging tools (including memory tracker)
• low-level helper functions, e.g. ADTs, endian conversion and timing
• platform-dependent system/feature detection

feq()

bool feq ( double  d1, double  d2, double  epsilon = 0.00001  )

inline

are the given floats nearly "equal"?

Returns

whether the numbers are within "epsilon" of each other.

notes:

• the epsilon magic number varies with the magnitude of the inputs. we use a sane default, but don't use this routine for very large/small comparands.
• floating-point numbers don't magically lose precision. addition, subtraction and multiplication results are precise up to the mantissa's least-significant bit. only division, sqrt, sin/cos and other transcendental operations introduce error.

feqf()

bool feqf ( float  f1, float  f2, float  epsilon = 0.001f  )

inline

IsSimilarMagnitude()

bool IsSimilarMagnitude ( double  d1, double  d2, const double  relativeErrorTolerance = 0.05  )

inline

u16_from_double()

u16 u16_from_double

(

double

in

)

convert double to u16; verifies number is in range.

u16_from_larger()

template<typename T >

u16 u16_from_larger

(

T

x

)

u32_from_larger()

template<typename T >

u32 u32_from_larger

(

T

x

)

u32_from_u16()

u32 u32_from_u16	(	u16	hi,
		u16	lo
	)

assemble u64 from u32

u32_hi()

u16 u32_hi

(

u32

x

)

return lower 32-bits

u32_lo()

u16 u32_lo

(

u32

x

)

return upper 16-bits

u64_from_u32()

u64 u64_from_u32	(	u32	hi,
		u32	lo
	)

return lower 16-bits

u64_hi()

u32 u64_hi

(

u64

x

)

u64_lo()

u32 u64_lo

(

u64

x

)

return upper 32-bits

u8_from_double()

u8 u8_from_double

(

double

in

)

convert double to u8; verifies number is in range.

u8_from_larger()

template<typename T >

u8 u8_from_larger

(

T

x

)

assemble u32 from u16