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Optimized single-precision floating point functions.
Optimized single-precision floating point functions.
An application can take control of the floating point routines used in the application over and above what is provided by the compiler, by depending on the pico_float library. A user might want to do this
The pico_float library comes in three main flavors:
pico_float_none
- all floating point operations cause a panic - no single-precision floating point code is includedpico_float_compiler
- no custom functions are provided; all single-precision floating point is handled by the C compiler/librarypico_float_pico
- the smallest and fastest available for the platform, along with additional functionality (e.g. fixed point conversions) which are detailed belowThe user can control which version they want (e.g. pico_float_xxx by either setting the CMake global variable PICO_DEFAULT_FLOAT_IMPL=xxx
, or by using the CMake function pico_set_float_implementation(<TARGET> xxx)
. Note that in the absence of either, pico_float_pico is used by default.
On RP2040, pico_float_pico
uses optimized hand coded implementations from the bootrom and the SDK for both basic single-precision floating point operations and floating point math library functions. These implementations are generally faster and smaller than those provided by the C compiler/library, though they don't support all the features of a fully compliant floating point implementation; they are however usually fine for the majority of cases
On Arm, (replacement) optimized implementations are provided for the following compiler built-ins and math library functions when using _pico
variants of pico_float
:
basic arithmetic: (except pico_float_pico_vfp
)
__aeabi_fadd, __aeabi_fdiv, __aeabi_fmul, __aeabi_frsub, __aeabi_fsub
comparison: (except pico_float_pico_vfp
)
__aeabi_cfcmpeq, __aeabi_cfrcmple, __aeabi_cfcmple, __aeabi_fcmpeq, __aeabi_fcmplt, __aeabi_fcmple, __aeabi_fcmpge, __aeabi_fcmpgt, __aeabi_fcmpun
(u)int32 <-> float: (except pico_float_pico_vfp
)
__aeabi_i2f, __aeabi_ui2f, __aeabi_f2iz, __aeabi_f2uiz
(u)int64 <-> float: (except pico_float_pico_vfp
)
__aeabi_l2f, __aeabi_ul2f, __aeabi_f2lz, __aeabi_f2ulz
float -> double: (except pico_float_pico_vfp
)
__aeabi_f2d
basic trigonometric:
sqrtf, cosf, sinf, tanf, atan2f, expf, logf
trigonometric and scientific
ldexpf, copysignf, truncf, floorf, ceilf, roundf, asinf, acosf, atanf, sinhf, coshf, tanhf, asinhf, acoshf, atanhf, exp2f, log2f, exp10f, log10f, powf, hypotf, cbrtf, fmodf, dremf, remainderf, remquof, expm1f, log1pf, fmaf
GNU exetnsions:
powintf, sincosf
On Arm, the following additional optimized functions are also provided (when using _pico
variants of pico_float
):
(u)int -> float (round to nearest):
int2float, uint2float, int642float, uint642float
note: on pico_float_pico_vfp
the 32-bit functions are also provided as C macros since they map to inline VFP code
(u)float -> int (round towards zero):
float2int_z, float2uint_z, float2int64_z, float2uint64_z
note: on pico_float_pico_vfp
the 32-bit functions are also provided as C macros since they map to inline VFP code
(u)float -> int (round towards -infinity):
float2int, float2uint, float2int64, float2uint64
(u)fix -> float (round to nearest):
fix2float, ufix2float, fix642float, ufix642float
float -> (u)fix (round towards zero):
float2fix_z, float2ufix_z, float2fix64_z, float2ufix64_z
note: on pico_float_pico_vfp
the 32-bit functions are also provided as C macros since they can map to inline VFP code when the number of fractional bits is a compile time constant between 1 and 32
float -> (u)fix (round towards -infinity):
float2fix, float2ufix, float2fix64, float2ufix64
note: on pico_float_pico_vfp
the 32-bit functions are also provided as C macros since they can map to inline VFP code when the number of fractional bits is a compile time constant between 1 and 32
Even faster versions of divide and square-root functions that do not round correctly: (pico_float_pico_dcp
only)
fdiv_fast, sqrtf_fast