1 package aztec
2
3 import (
4 "github.com/boombuler/barcode/utils"
5 )
6
7 func bitsToWords(stuffedBits *utils.BitList, wordSize int, wordCount int) []int {
8 message := make([]int, wordCount)
9
10 for i := 0; i < wordCount; i++ {
11 value := 0
12 for j := 0; j < wordSize; j++ {
13 if stuffedBits.GetBit(i*wordSize + j) {
14 value |= (1 << uint(wordSize-j-1))
15 }
16 }
17 message[i] = value
18 }
19 return message
20 }
21
22 func generateCheckWords(bits *utils.BitList, totalBits, wordSize int) *utils.BitList {
23 rs := utils.NewReedSolomonEncoder(getGF(wordSize))
24
25
26 messageWordCount := bits.Len() / wordSize
27 totalWordCount := totalBits / wordSize
28 eccWordCount := totalWordCount - messageWordCount
29
30 messageWords := bitsToWords(bits, wordSize, messageWordCount)
31 eccWords := rs.Encode(messageWords, eccWordCount)
32 startPad := totalBits % wordSize
33
34 messageBits := new(utils.BitList)
35 messageBits.AddBits(0, byte(startPad))
36
37 for _, messageWord := range messageWords {
38 messageBits.AddBits(messageWord, byte(wordSize))
39 }
40 for _, eccWord := range eccWords {
41 messageBits.AddBits(eccWord, byte(wordSize))
42 }
43 return messageBits
44 }
45
46 func getGF(wordSize int) *utils.GaloisField {
47 switch wordSize {
48 case 4:
49 return utils.NewGaloisField(0x13, 16, 1)
50 case 6:
51 return utils.NewGaloisField(0x43, 64, 1)
52 case 8:
53 return utils.NewGaloisField(0x012D, 256, 1)
54 case 10:
55 return utils.NewGaloisField(0x409, 1024, 1)
56 case 12:
57 return utils.NewGaloisField(0x1069, 4096, 1)
58 default:
59 return nil
60 }
61 }
62
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