Add stable likely/unlikely to utils module

src/lib.rs

@@ -5,6 +5,7 @@ mod encode;
 mod error;
 mod header;
 mod pixel;
+mod utils;
 
 pub mod canonical;
 

src/utils.rs

@@ -0,0 +1,23 @@
+#[inline(always)]
+#[allow(unused)]
+pub const fn likely(b: bool) -> bool {
+    // borrowed from `likely_stable` crate
+    #[allow(clippy::needless_bool)]
+    if (1i32).checked_div(if b { 1 } else { 0 }).is_some() {
+        true
+    } else {
+        false
+    }
+}
+
+#[inline(always)]
+#[allow(unused)]
+pub const fn unlikely(b: bool) -> bool {
+    // borrowed from `likely_stable` crate
+    #[allow(clippy::needless_bool)]
+    if (1i32).checked_div(if b { 0 } else { 1 }).is_none() {
+        true
+    } else {
+        false
+    }
+}