From 081c5ac2e6133998ae3a13ebb58fa5bab99f1114 Mon Sep 17 00:00:00 2001
From: Sebastian <sebastian@sebastians-site.de>
Date: Sun, 16 Jul 2023 20:00:55 +0200
Subject: [PATCH] Improved errors

---
 Cargo.lock                                    | 21 +++++++++++++++++++
 firls-rs-macros/examples/filter_real_macro.rs |  2 +-
 firls-rs/Cargo.toml                           |  1 +
 firls-rs/src/error.rs                         | 13 ++++++++++++
 firls-rs/src/lib.rs                           | 20 +++++++++++++++---
 5 files changed, 53 insertions(+), 4 deletions(-)
 create mode 100644 firls-rs/src/error.rs

diff --git a/Cargo.lock b/Cargo.lock
index b606bc4..4e10c2d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -39,6 +39,7 @@ version = "0.1.0"
 dependencies = [
  "nalgebra",
  "num",
+ "thiserror",
 ]
 
 [[package]]
@@ -228,6 +229,26 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a35fc5b8971143ca348fa6df4f024d4d55264f3468c71ad1c2f365b0a4d58c42"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "463fe12d7993d3b327787537ce8dd4dfa058de32fc2b195ef3cde03dc4771e8f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.23",
+]
+
 [[package]]
 name = "typenum"
 version = "1.16.0"
diff --git a/firls-rs-macros/examples/filter_real_macro.rs b/firls-rs-macros/examples/filter_real_macro.rs
index 47756b1..8a13bf1 100644
--- a/firls-rs-macros/examples/filter_real_macro.rs
+++ b/firls-rs-macros/examples/filter_real_macro.rs
@@ -3,7 +3,7 @@ use firls_rs_macros::firls_real;
 const COEFFS: [f32; 13] = firls_real!(
     13,
     8000.0,
-    [(0.0, 1.0), (1900.0, 1.0), (3000.0, 0.0), (7000.0, 0.0)]
+    [(0.0, 1.0), (1900.0, 1.0), (3000.0, 0.0), (4000.0, 0.0)]
 );
 
 fn main() {
diff --git a/firls-rs/Cargo.toml b/firls-rs/Cargo.toml
index 7b3df16..2049adc 100644
--- a/firls-rs/Cargo.toml
+++ b/firls-rs/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2021"
 [dependencies]
 nalgebra = "0.32.2"
 num = "0.4.0"
+thiserror = "1.0.43"
diff --git a/firls-rs/src/error.rs b/firls-rs/src/error.rs
new file mode 100644
index 0000000..054c605
--- /dev/null
+++ b/firls-rs/src/error.rs
@@ -0,0 +1,13 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum FirLSError {
+    #[error("Filter length should be odd. Filter length {0} is even.")]
+    EvenFilterLen(usize),
+    #[error("Frequency response points should be above 0Hz. {0}Hz is below.")]
+    ResponseFreqBelowZero(f32),
+    #[error(
+        "Frequency response points should be below the nyquist frequency. {0}Hz is above {1}Hz"
+    )]
+    ResponseFreqAboveNyquist(f32, f32),
+}
diff --git a/firls-rs/src/lib.rs b/firls-rs/src/lib.rs
index 1accd5d..5c4fa9d 100644
--- a/firls-rs/src/lib.rs
+++ b/firls-rs/src/lib.rs
@@ -1,9 +1,24 @@
 use nalgebra::base::{DMatrix, DVector};
 use num::complex::Complex;
 
-pub fn firls(lenght: usize, f_samp: f32, points: &Vec<(f32, f32)>) -> Result<Vec<f32>, &str> {
+mod error;
+use error::FirLSError;
+
+pub fn firls(
+    lenght: usize,
+    f_samp: f32,
+    points: &Vec<(f32, f32)>,
+) -> Result<Vec<f32>, error::FirLSError> {
     if lenght % 2 != 1 {
-        return Result::Err("Filter should have an odd length");
+        return Result::Err(FirLSError::EvenFilterLen(lenght));
+    }
+    for (freq, _) in points.iter() {
+        if *freq > f_samp / 2.0 {
+            return Result::Err(FirLSError::ResponseFreqAboveNyquist(*freq, f_samp / 2.0));
+        }
+        if *freq < 0.0 {
+            return Result::Err(FirLSError::ResponseFreqBelowZero(*freq));
+        }
     }
 
     let half_lenght = lenght / 2 + 1;
@@ -49,7 +64,6 @@ fn generate_frequency_response(
 
     for step in 0..num_points {
         let step_freq = step as f32 * step_size;
-
         response[step] = interpolate_between_points(step_freq, &points)
     }