From 1c316b060327c5da644fdcce0bfc3d717e62b723 Mon Sep 17 00:00:00 2001
From: Ivan Ukhov <ivan.ukhov@gmail.com>
Date: Sun, 21 Jun 2015 17:49:03 -0400
Subject: [PATCH] Remove conversion hacks

---
 benches/lib.rs |  2 +-
 src/lib.rs     | 87 +++++++-------------------------------------------
 tests/lib.rs   | 12 +++++--
 3 files changed, 22 insertions(+), 79 deletions(-)

diff --git a/benches/lib.rs b/benches/lib.rs
index e8b4dae..6c107ee 100644
--- a/benches/lib.rs
+++ b/benches/lib.rs
@@ -11,7 +11,7 @@ extern crate test;
 #[bench] fn forward_4096(bencher: &mut test::Bencher) { forward(4096, bencher); }
 
 fn forward(size: usize, bencher: &mut test::Bencher) {
-    let mut data = vec![42.0; 2 * size];
+    let mut data = vec![fft::c64(42.0, 0.0); size];
     bencher.iter(|| {
         test::black_box(fft::forward(&mut data));
     });
diff --git a/src/lib.rs b/src/lib.rs
index 20246c4..9497868 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,85 +9,20 @@
 
 extern crate complex;
 
-use complex::{Complex, c64};
-use std::slice;
-
-/// A means of obtaining a slice of mutable complex numbers.
-pub trait AsMutComplex<'l> {
-    type Complex: Complex + 'l;
-
-    fn as_mut_complex(self) -> &'l mut [Self::Complex];
-}
-
-macro_rules! implement(
-    ($complex:ty) => (
-        impl<'l> AsMutComplex<'l> for &'l mut [$complex] {
-            type Complex = $complex;
-
-            #[inline(always)]
-            fn as_mut_complex(self) -> &'l mut [Self::Complex] {
-                self
-            }
-        }
-
-        impl<'l> AsMutComplex<'l> for &'l mut Vec<$complex> {
-            type Complex = $complex;
-
-            #[inline]
-            fn as_mut_complex(self) -> &'l mut [Self::Complex] {
-                <&mut [$complex]>::as_mut_complex(&mut *self)
-            }
-        }
-    );
-);
-
-implement!(c64);
-
-macro_rules! implement(
-    ($complex:ty, $real:ty) => (
-        impl<'l> AsMutComplex<'l> for &'l mut [$real] {
-            type Complex = $complex;
-
-            /// Treat the slice as a collection of pairs of real and imaginary
-            /// parts and reinterpret it as a slice of complex numbers.
-            ///
-            /// ## Panics
-            ///
-            /// The function panics if the number of elements is not even.
-            #[inline]
-            fn as_mut_complex(self) -> &'l mut [Self::Complex] {
-                unsafe {
-                    let length = self.len();
-                    assert!(length % 2 == 0, "the number of elements should be even");
-                    slice::from_raw_parts_mut(self.as_mut_ptr() as *mut _, length / 2)
-                }
-            }
-        }
-
-        impl<'l> AsMutComplex<'l> for &'l mut Vec<$real> {
-            type Complex = $complex;
-
-            #[inline]
-            fn as_mut_complex(self) -> &'l mut [Self::Complex] {
-                <&mut [$real]>::as_mut_complex(&mut *self)
-            }
-        }
-    );
-);
-
-implement!(c64, f64);
+pub use complex::c64;
 
 /// Perform the Fourier transform.
 ///
 /// The number of points should be a power of two.
-pub fn forward<'l, T>(data: T) where T: AsMutComplex<'l, Complex=c64> {
-    let data = data.as_mut_complex();
-
+///
+/// ## Panics
+///
+/// The function panics if the number of points is not a power of two.
+pub fn forward(data: &mut [c64]) {
     let n = data.len();
     if n < 1 || n & (n - 1) != 0 {
         panic!("expected the number of points to be a power of two");
     }
-
     rearrange(data, n);
     perform(data, n, false);
 }
@@ -95,14 +30,15 @@ pub fn forward<'l, T>(data: T) where T: AsMutComplex<'l, Complex=c64> {
 /// Perform the inverse Fourier transform.
 ///
 /// The number of points should be a power of two.
-pub fn inverse<'l, T>(data: T, scaling: bool) where T: AsMutComplex<'l, Complex=c64> {
-    let data = data.as_mut_complex();
-
+///
+/// ## Panics
+///
+/// The function panics if the number of points is not a power of two.
+pub fn inverse(data: &mut [c64], scaling: bool) {
     let n = data.len();
     if n < 1 || n & (n - 1) != 0 {
         panic!("expected the number of points to be a power of two");
     }
-
     rearrange(data, n);
     perform(data, n, true);
     if scaling {
@@ -131,7 +67,6 @@ fn perform(data: &mut [c64], n: usize, inverse: bool) {
     use std::f64::consts::PI;
 
     let pi = if inverse { PI } else { -PI };
-
     let mut step = 1;
     while step < n {
         let jump = step << 1;
diff --git a/tests/lib.rs b/tests/lib.rs
index 8feee60..5920722 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -6,13 +6,21 @@ mod fixtures;
 #[test]
 fn forward() {
     let mut data = fixtures::TIME_DATA.to_vec();
-    fft::forward(&mut data);
+    fft::forward(reinterpret(&mut data));
     assert::close(&data, &fixtures::FREQUENCY_DATA[..], 1e-14);
 }
 
 #[test]
 fn inverse() {
     let mut data = fixtures::FREQUENCY_DATA.to_vec();
-    fft::inverse(&mut data, true);
+    fft::inverse(reinterpret(&mut data), true);
     assert::close(&data, &fixtures::TIME_DATA[..], 1e-14);
 }
+
+fn reinterpret<'l>(slice: &'l mut [f64]) -> &'l mut [fft::c64] {
+    unsafe {
+        let length = slice.len();
+        assert!(length % 2 == 0, "the number of elements should be even");
+        std::slice::from_raw_parts_mut(slice.as_mut_ptr() as *mut _, length / 2)
+    }
+}