package main

import (
	"encoding/hex"
	"fmt"
)

func main() {
	const sample = "54747A0E4ACF4161D00D244ED341F4329E1E02"

	bs, _ := hex.DecodeString(sample)

	fmt.Println(string(decode7bit(bs)))
}

func decode7bit(bs []byte) []byte {
	bit7s := make([]byte, len(bs)*8/7)

	for i := range bit7s {
		byteStart := (i * 7) / 8
		byteEnd := ((i + 1) * 7) / 8
		bitStart := (i * 7) % 8
		bitEnd := ((i + 1) * 7) % 8

		low := (bs[byteStart] >> uint8(bitStart)) & 0x7f
		high := bs[byteEnd] << uint8(8-bitEnd) >> uint8(8-bitEnd) << uint8(7-bitEnd)

		bit7s[i] = low | high
	}

	return bit7s
}