1 package qr
2
3 import (
4 "errors"
5 "fmt"
6 "strings"
7
8 "github.com/boombuler/barcode/utils"
9 )
10
11 const charSet string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"
12
13 func stringToAlphaIdx(content string) <-chan int {
14 result := make(chan int)
15 go func() {
16 for _, r := range content {
17 idx := strings.IndexRune(charSet, r)
18 result <- idx
19 if idx < 0 {
20 break
21 }
22 }
23 close(result)
24 }()
25
26 return result
27 }
28
29 func encodeAlphaNumeric(content string, ecl ErrorCorrectionLevel) (*utils.BitList, *versionInfo, error) {
30
31 contentLenIsOdd := len(content)%2 == 1
32 contentBitCount := (len(content) / 2) * 11
33 if contentLenIsOdd {
34 contentBitCount += 6
35 }
36 vi := findSmallestVersionInfo(ecl, alphaNumericMode, contentBitCount)
37 if vi == nil {
38 return nil, nil, errors.New("To much data to encode")
39 }
40
41 res := new(utils.BitList)
42 res.AddBits(int(alphaNumericMode), 4)
43 res.AddBits(len(content), vi.charCountBits(alphaNumericMode))
44
45 encoder := stringToAlphaIdx(content)
46
47 for idx := 0; idx < len(content)/2; idx++ {
48 c1 := <-encoder
49 c2 := <-encoder
50 if c1 < 0 || c2 < 0 {
51 return nil, nil, fmt.Errorf("\"%s\" can not be encoded as %s", content, AlphaNumeric)
52 }
53 res.AddBits(c1*45+c2, 11)
54 }
55 if contentLenIsOdd {
56 c := <-encoder
57 if c < 0 {
58 return nil, nil, fmt.Errorf("\"%s\" can not be encoded as %s", content, AlphaNumeric)
59 }
60 res.AddBits(c, 6)
61 }
62
63 addPaddingAndTerminator(res, vi)
64
65 return res, vi, nil
66 }
67
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