pounder_test/dsp/src/complex.rs

141 lines
4.0 KiB
Rust

pub use num::Complex;
use super::{atan2, cossin};
/// Complex extension trait offering DSP (fast, good accuracy) functionality.
pub trait ComplexExt<T, U> {
fn from_angle(angle: T) -> Self;
fn abs_sqr(&self) -> U;
fn log2(&self) -> T;
fn arg(&self) -> T;
fn saturating_add(&self, other: Self) -> Self;
fn saturating_sub(&self, other: Self) -> Self;
}
impl ComplexExt<i32, u32> for Complex<i32> {
/// Return a Complex on the unit circle given an angle.
///
/// Example:
///
/// ```
/// use dsp::{Complex, ComplexExt};
/// Complex::<i32>::from_angle(0);
/// Complex::<i32>::from_angle(1 << 30); // pi/2
/// Complex::<i32>::from_angle(-1 << 30); // -pi/2
/// ```
fn from_angle(angle: i32) -> Self {
let (c, s) = cossin(angle);
Self::new(c, s)
}
/// Return the absolute square (the squared magnitude).
///
/// Note: Normalization is `1 << 32`, i.e. U0.32.
///
/// Note(panic): This will panic for `Complex(i32::MIN, i32::MIN)`
///
/// Example:
///
/// ```
/// use dsp::{Complex, ComplexExt};
/// assert_eq!(Complex::new(i32::MIN, 0).abs_sqr(), 1 << 31);
/// assert_eq!(Complex::new(i32::MAX, i32::MAX).abs_sqr(), u32::MAX - 3);
/// ```
fn abs_sqr(&self) -> u32 {
(((self.re as i64) * (self.re as i64)
+ (self.im as i64) * (self.im as i64))
>> 31) as u32
}
/// log2(power) re full scale approximation
///
/// TODO: scale up, interpolate
///
/// Panic:
/// This will panic for `Complex(i32::MIN, i32::MIN)`
///
/// Example:
///
/// ```
/// use dsp::{Complex, ComplexExt};
/// assert_eq!(Complex::new(i32::MAX, i32::MAX).log2(), -1);
/// assert_eq!(Complex::new(i32::MAX, 0).log2(), -2);
/// assert_eq!(Complex::new(1, 0).log2(), -63);
/// assert_eq!(Complex::new(0, 0).log2(), -64);
/// ```
fn log2(&self) -> i32 {
let a = (self.re as i64) * (self.re as i64)
+ (self.im as i64) * (self.im as i64);
-(a.leading_zeros() as i32)
}
/// Return the angle.
///
/// Note: Normalization is `1 << 31 == pi`.
///
/// Example:
///
/// ```
/// use dsp::{Complex, ComplexExt};
/// assert_eq!(Complex::new(1, 0).arg(), 0);
/// assert_eq!(Complex::new(-i32::MAX, 1).arg(), i32::MAX);
/// assert_eq!(Complex::new(-i32::MAX, -1).arg(), -i32::MAX);
/// assert_eq!(Complex::new(0, -1).arg(), -i32::MAX >> 1);
/// assert_eq!(Complex::new(0, 1).arg(), (i32::MAX >> 1) + 1);
/// assert_eq!(Complex::new(1, 1).arg(), (i32::MAX >> 2) + 1);
/// ```
fn arg(&self) -> i32 {
atan2(self.im, self.re)
}
fn saturating_add(&self, other: Self) -> Self {
Self::new(
self.re.saturating_add(other.re),
self.im.saturating_add(other.im),
)
}
fn saturating_sub(&self, other: Self) -> Self {
Self::new(
self.re.saturating_sub(other.re),
self.im.saturating_sub(other.im),
)
}
}
/// Full scale fixed point multiplication.
pub trait MulScaled<T> {
fn mul_scaled(self, other: T) -> Self;
}
impl MulScaled<Complex<i32>> for Complex<i32> {
fn mul_scaled(self, other: Self) -> Self {
let a = self.re as i64;
let b = self.im as i64;
let c = other.re as i64;
let d = other.im as i64;
Complex {
re: ((a * c - b * d + (1 << 30)) >> 31) as i32,
im: ((b * c + a * d + (1 << 30)) >> 31) as i32,
}
}
}
impl MulScaled<i32> for Complex<i32> {
fn mul_scaled(self, other: i32) -> Self {
Complex {
re: ((other as i64 * self.re as i64 + (1 << 30)) >> 31) as i32,
im: ((other as i64 * self.im as i64 + (1 << 30)) >> 31) as i32,
}
}
}
impl MulScaled<i16> for Complex<i32> {
fn mul_scaled(self, other: i16) -> Self {
Complex {
re: (other as i32 * (self.re >> 16) + (1 << 14)) >> 15,
im: (other as i32 * (self.im >> 16) + (1 << 14)) >> 15,
}
}
}