Reading Large Bytes in Reverse Line Order [Golang]

main.go

// https://go.dev/play/p/qKDFxiJQAfF
package main

import (
	"fmt"
)

func main() {
	someBytes := []byte(`Lorem ipsum dolor sit amet,
consectetur adipiscing elit.
Sed in mattis leo. Integer eu
tortor ut libero aliquet
dignissim. Etiam nisi metus,
consectetur eu luctus vel,
malesuada id arcu.

Integer egestas velit a velit
sollicitudin venenatis.
In volutpat nunc posuere
ex lobortis maximus.
Vivamus fringilla lacinia
nisi nec hendrerit. Duis
ipsum tortor, congue ut est
eu, volutpat pharetra orci.



`)
	fmt.Println(string(ReverseByte(someBytes, 15)))
}

func ReverseByte(fileByte []byte, maxLine int) []byte {
	// This is a byte "code" for NewLine or "\n"
	nl := byte(10)

	var reverseFileByte []byte
	var lineLen, lineWritten int

	byteIndex := len(fileByte) - 1
	for lineWritten < maxLine {
		if fileByte[byteIndex] == nl {
			currentLine := make([]byte, lineLen)
			byteLineIndex := byteIndex
			var currentLineIndex int
			for currentLineIndex < lineLen {
				currentLine[currentLineIndex] = fileByte[byteLineIndex]
				byteLineIndex++
				currentLineIndex++
			}
			reverseFileByte = append(reverseFileByte, currentLine...)
			lineLen = 0
			lineWritten++
		}
		lineLen++
		byteIndex--
	}
	return reverseFileByte
}