fplib comparisons between floats and doubles

ARM Compiler toolchain v5.02 for µVision Using ARM C and C++ Libraries and Floating-Point Support

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Table 18 describes routines to perform comparisons between floating-point numbers. See Notes on floating-point comparison routines for more information as indicated in the Notes column.

Table 18. Floating-point comparison routines

Function	Argument types	Return type	Condition tested	Notes
`_fcmpeq`	2 float	Flags, EQ/NE	x equal to y	a
`_fcmpge`	2 float	Flags, HS/LO	x greater than or equal to y	a, b
`_fcmple`	2 float	Flags, HI/LS	x less than or equal to y	a, b
`_feq`	2 float	Boolean	x equal to y	-
`_fneq`	2 float	Boolean	x not equal to y	-
`_fgeq`	2 float	Boolean	x greater than or equal to y	b
`_fgr`	2 float	Boolean	x greater than y	b
`_fleq`	2 float	Boolean	x less than or equal to y	b
`_fls`	2 float	Boolean	x less than y	b
`_dcmpeq`	2 double	Flags, EQ/NE	x equal to y	a
`_dcmpge`	2 double	Flags, HS/LO	x greater than or equal to y	a, b
`_dcmple`	2 double	Flags, HI/LS	x less than or equal to y	a, b
`_deq`	2 double	Boolean	x equal to y	-
`_dneq`	2 double	Boolean	x not equal to y	-
`_dgeq`	2 double	Boolean	x greater than or equal to y	b
`_dgr`	2 double	Boolean	x greater than y	b
`_dleq`	2 double	Boolean	x less than or equal to y	b
`_dls`	2 double	Boolean	x less than y	b
`_fcmp4`	2 float	Flags, VFP	x less than or equal to y	c
`_fcmp4e`	2 float	Flags, VFP	x less than or equal to y	b, c
`_fdcmp4`	float, double	Flags, VFP	x less than or equal to y	c
`_fdcmp4e`	float, double	Flags, VFP	x less than or equal to y	b, c
`_dcmp4`	2 double	Flags, VFP	x less than or equal to y	c
`_dcmp4e`	2 double	Flags, VFP	x less than or equal to y	b, c
`_dfcmp4`	double, float	Flags, VFP	x less than or equal to y	c
`_dfcmp4e`	double, float	Flags, VFP	x less than or equal to y	b, c

a: Returns results in the ARM condition flags. This is efficient in assembly language, because you can directly follow a call to the function with a conditional instruction, but it means there is no way to use this function from C. This function is not declared in rt_fp.h.
b: Causes an Invalid Operation exception if either argument is a NaN, even a quiet NaN. Other functions only cause Invalid Operation if an argument is an SNaN. QNaNs return not equal when compared to anything, including other QNaNs (so comparing a QNaN to the same QNaN still returns not equal).
c: Returns VFP-type status flags in the CPSR. Also returns VFP-type status flags in the top four bits of r0, meaning that it is possible to use this function from C. This function is declared in rt_fp.h.