From 0f4442b1241164624a1a6e33505d694622caa6b6 Mon Sep 17 00:00:00 2001
From: Astro <astro@spaceboyz.net>
Date: Wed, 18 Mar 2020 21:56:52 +0100
Subject: [PATCH] switch pid+steinhart_hart parameters from f32 to f64

---
 src/ad7172/mod.rs     | 12 ++----------
 src/command_parser.rs | 11 ++++++-----
 src/pid.rs            | 32 ++++++++++++++++----------------
 src/steinhart_hart.rs | 10 +++++-----
 4 files changed, 29 insertions(+), 36 deletions(-)

diff --git a/src/ad7172/mod.rs b/src/ad7172/mod.rs
index 067ec0e..43d3e2f 100644
--- a/src/ad7172/mod.rs
+++ b/src/ad7172/mod.rs
@@ -1,4 +1,5 @@
 use core::fmt;
+use lexical_core::Float;
 use stm32f4xx_hal::{
     time::{MegaHertz, U32Ext},
     spi,
@@ -146,18 +147,9 @@ impl PostFilter {
     ];
 
     pub fn closest(rate: f32) -> Option<Self> {
-        /// (x - y).abs()
-        fn d(x: f32, y: f32) -> f32 {
-            if x >= y {
-                x - y
-            } else {
-                y - x
-            }
-        }
-
         let mut best: Option<(f32, Self)> = None;
         for value in Self::VALID_VALUES {
-            let error = d(rate, value.output_rate().unwrap());
+            let error = (rate - value.output_rate().unwrap()).abs();
             let better = best
                 .map(|(best_error, _)| error < best_error)
                 .unwrap_or(true);
diff --git a/src/command_parser.rs b/src/command_parser.rs
index ea901b7..4366ad3 100644
--- a/src/command_parser.rs
+++ b/src/command_parser.rs
@@ -123,12 +123,12 @@ pub enum Command {
     Pid {
         channel: usize,
         parameter: PidParameter,
-        value: f32,
+        value: f64,
     },
     SteinhartHart {
         channel: usize,
         parameter: ShParameter,
-        value: f32,
+        value: f64,
     },
     PostFilter {
         channel: usize,
@@ -158,12 +158,12 @@ fn unsigned(input: &[u8]) -> IResult<&[u8], Result<u16, Error>> {
         })
 }
 
-fn float(input: &[u8]) -> IResult<&[u8], Result<f32, Error>> {
+fn float(input: &[u8]) -> IResult<&[u8], Result<f64, Error>> {
     let (input, sign) = opt(is_a("-"))(input)?;
     let negative = sign.is_some();
     let (input, digits) = take_while1(|c| is_digit(c) || c == '.' as u8)(input)?;
     let result = lexical::parse(digits)
-        .map(|result: f32| if negative { -result } else { result })
+        .map(|result: f64| if negative { -result } else { result })
         .map_err(|e| e.into());
     Ok((input, result))
 }
@@ -357,7 +357,8 @@ fn postfilter(input: &[u8]) -> IResult<&[u8], Result<Command, Error>> {
                 let (input, rate) = float(input)?;
                 let result = rate
                     .map(|rate| Command::PostFilter {
-                        channel, rate,
+                        channel,
+                        rate: rate as f32,
                     });
                 Ok((input, result))
             }
diff --git a/src/pid.rs b/src/pid.rs
index ecf858e..efdd730 100644
--- a/src/pid.rs
+++ b/src/pid.rs
@@ -1,20 +1,20 @@
 #[derive(Clone, Copy)]
 pub struct Parameters {
-    pub kp: f32,
-    pub ki: f32,
-    pub kd: f32,
-    pub output_min: f32,
-    pub output_max: f32,
-    pub integral_min: f32,
-    pub integral_max: f32
+    pub kp: f64,
+    pub ki: f64,
+    pub kd: f64,
+    pub output_min: f64,
+    pub output_max: f64,
+    pub integral_min: f64,
+    pub integral_max: f64
 }
 
 #[derive(Clone)]
 pub struct Controller {
     parameters: Parameters,
-    target: f32,
-    integral: f32,
-    last_input: Option<f32>
+    target: f64,
+    integral: f64,
+    last_input: Option<f64>
 }
 
 impl Controller {
@@ -27,7 +27,7 @@ impl Controller {
         }
     }
 
-    pub fn update(&mut self, input: f32) -> f32 {
+    pub fn update(&mut self, input: f64) -> f64 {
         let error = self.target - input;
 
         let p = self.parameters.kp * error;
@@ -57,11 +57,11 @@ impl Controller {
         output
     }
 
-    pub fn get_target(&self) -> f32 {
+    pub fn get_target(&self) -> f64 {
         self.target
     }
 
-    pub fn set_target(&mut self, target: f32) {
+    pub fn set_target(&mut self, target: f64) {
         self.target = target;
     }
 
@@ -96,9 +96,9 @@ mod test {
 
     #[test]
     fn test_controller() {
-        const DEFAULT: f32 = 0.0;
-        const TARGET: f32 = 1234.56;
-        const ERROR: f32 = 0.01;
+        const DEFAULT: f64 = 0.0;
+        const TARGET: f64 = 1234.56;
+        const ERROR: f64 = 0.01;
         const DELAY: usize = 10;
 
         let mut pid = Controller::new(PARAMETERS.clone());
diff --git a/src/steinhart_hart.rs b/src/steinhart_hart.rs
index a585775..5a2444f 100644
--- a/src/steinhart_hart.rs
+++ b/src/steinhart_hart.rs
@@ -3,14 +3,14 @@ use lexical_core::Float;
 /// Steinhart-Hart equation parameters
 #[derive(Clone, Debug)]
 pub struct Parameters {
-    pub a: f32,
-    pub b: f32,
-    pub c: f32,
+    pub a: f64,
+    pub b: f64,
+    pub c: f64,
     /// Parallel resistance
     ///
     /// Not truly part of the equation but required to calculate
     /// resistance from voltage.
-    pub parallel_r: f32,
+    pub parallel_r: f64,
 }
 
 impl Parameters {
@@ -19,7 +19,7 @@ impl Parameters {
     /// Result unit: Kelvin
     ///
     /// TODO: verify
-    pub fn get_temperature(&self, voltage: f32) -> f32 {
+    pub fn get_temperature(&self, voltage: f64) -> f64 {
         let r = self.parallel_r * voltage;
         let ln_r = r.abs().ln();
         let inv_temp = self.a +