From 012fe52b6fa121d1d9e116cbefe9109e6c2359ec Mon Sep 17 00:00:00 2001
From: Mykhailo Lohachov <ml.logachevsky@gmail.com>
Date: Sun, 25 Feb 2024 02:06:52 +0900
Subject: [PATCH] internal/atlas: use bit manipulation for function power of 2
 -like functions (#2915)

Closes #2914
---
 internal/atlas/image.go     | 7 ++-----
 internal/packing/packing.go | 8 +-------
 2 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/internal/atlas/image.go b/internal/atlas/image.go
index 5bccc45bd..270063794 100644
--- a/internal/atlas/image.go
+++ b/internal/atlas/image.go
@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"image"
 	"math"
+	"math/bits"
 	"runtime"
 	"sync"
 
@@ -885,11 +886,7 @@ func floorPowerOf2(x int) int {
 	if x <= 0 {
 		return 0
 	}
-	p2 := 1
-	for p2*2 <= x {
-		p2 *= 2
-	}
-	return p2
+	return 1 << (bits.Len(uint(x)) - 1)
 }
 
 func BeginFrame(graphicsDriver graphicsdriver.Graphics) error {
diff --git a/internal/packing/packing.go b/internal/packing/packing.go
index 1d9a5f36f..f656fc55e 100644
--- a/internal/packing/packing.go
+++ b/internal/packing/packing.go
@@ -32,13 +32,7 @@ func isPositivePowerOf2(x int) bool {
 	if x <= 0 {
 		return false
 	}
-	for x > 1 {
-		if x/2*2 != x {
-			return false
-		}
-		x /= 2
-	}
-	return true
+	return x&(x-1) == 0
 }
 
 func NewPage(initWidth, initHeight int, maxSize int) *Page {