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//! Common math utils
use super::errors::NumberOutOfRange;
macro_rules! floating_fixed_convert {
($f_to_q:ident, $q_to_f:ident, $unsigned_bin_typ:ty, $signed_bin_typ:ty, $float_ty:ty, $offset:literal, $min_positive:literal) => {
/// convert float point to fixed point format
pub fn $f_to_q(value: $float_ty) -> Result<$unsigned_bin_typ, NumberOutOfRange> {
const MIN_POSITIVE: $float_ty = <$float_ty>::from_bits($min_positive);
if value < -1.0 {
return Err(NumberOutOfRange::BelowLowerBound)
}
if value > 1.0 {
return Err(NumberOutOfRange::AboveUpperBound)
}
let value = if 1.0 - MIN_POSITIVE < value && value <= 1.0 {
// make a exception for value between (1.0^{-x} , 1.0] float point,
// convert it to max representable value of q1.x format
(1.0 as $float_ty) - MIN_POSITIVE
} else {
value
};
// It's necessary to cast the float value to signed integer, before convert it to a unsigned value.
// Since value from register is actually a "signed value", a "as" cast will keep original binary format but mark it as a unsigned value for register writing.
// see https://doc.rust-lang.org/reference/expressions/operator-expr.html#numeric-cast
Ok((value * ((1 as $unsigned_bin_typ << $offset) as $float_ty)) as $signed_bin_typ as $unsigned_bin_typ)
}
#[inline(always)]
/// convert fixed point to float point format
pub fn $q_to_f(value: $unsigned_bin_typ) -> $float_ty {
// It's necessary to cast the unsigned integer to signed integer, before convert it to a float value.
// Since value from register is actually a "signed value", a "as" cast will keep original binary format but mark it as a signed value.
// see https://doc.rust-lang.org/reference/expressions/operator-expr.html#numeric-cast
(value as $signed_bin_typ as $float_ty) / ((1 as $unsigned_bin_typ << $offset) as $float_ty)
}
};
}
floating_fixed_convert!(
f64_to_q1_31,
q1_31_to_f64,
u32,
i32,
f64,
31,
0x3E00_0000_0000_0000u64 // binary form of 1f64^(-31)
);
floating_fixed_convert!(
f32_to_q1_15,
q1_15_to_f32,
u16,
i16,
f32,
15,
0x3800_0000u32 // binary form of 1f32^(-15)
);
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