Improve performance and specialise maths ops

Author: bushrat011899

src/lib.rs

@@ -78,7 +78,7 @@ use alloc::{vec, vec::Vec};
 use core::cmp::{max, min};
 
 mod math;
-use crate::math::{abs, clamp, round};
+use crate::math::{abs, clamp_round};
 
 const CHANNELS: usize = 4;
 
@@ -398,10 +398,10 @@ impl NeuQuant {
     /// initializes the color map
     fn build_colormap(&mut self) {
         for i in 0usize..self.netsize {
-            self.colormap[i].b = clamp(round(self.network[i].b) as i32);
-            self.colormap[i].g = clamp(round(self.network[i].g) as i32);
-            self.colormap[i].r = clamp(round(self.network[i].r) as i32);
-            self.colormap[i].a = clamp(round(self.network[i].a) as i32);
+            self.colormap[i].b = clamp_round(self.network[i].b);
+            self.colormap[i].g = clamp_round(self.network[i].g);
+            self.colormap[i].r = clamp_round(self.network[i].r);
+            self.colormap[i].a = clamp_round(self.network[i].a);
         }
     }
 

src/math.rs

@@ -1,52 +1,21 @@
 #[inline]
-pub(crate) fn clamp(a: i32) -> i32 {
-    if a < 0 {
-        0
-    } else if a > 255 {
-        255
-    } else {
+pub(crate) fn abs(a: f64) -> f64 {
+    if a.is_sign_positive() {
         a
-    }
-}
-
-#[inline]
-fn fract(a: f64) -> f64 {
-    if a == 0.0 {
-        0.
+    } else if a.is_sign_negative() {
+        -a
     } else {
-        a % 1.
+        core::f64::NAN
     }
 }
 
 #[inline]
-pub(crate) fn round(a: f64) -> f64 {
-    let one = 1.0;
-    let h = 0.5;
-    let f = fract(a);
-    if f.is_nan() || f == 0.0 {
-        a
-    } else if a > 0. {
-        if f < h {
-            a - f
-        } else {
-            a - f + one
-        }
-    } else if -f < h {
-        a - f
+pub(crate) fn clamp_round(a: f64) -> i32 {
+    if a < 0. {
+        0
+    } else if a > 255. {
+        255
     } else {
-        a - f - one
-    }
-}
-
-#[inline]
-pub(crate) fn abs(a: f64) -> f64 {
-    if a.is_sign_positive() {
-        return a;
+        (a + 0.5) as i32
     }
-
-    if a.is_sign_negative() {
-        return -a;
-    }
-
-    core::f64::NAN
 }