git.sr.ht/~pingoo/stdx@v0.0.0-20240218134121-094174641f6e/barcode/qr/numeric.go (about)

     1  package qr
     2  
     3  import (
     4  	"errors"
     5  	"fmt"
     6  	"strconv"
     7  
     8  	"git.sr.ht/~pingoo/stdx/barcode/utils"
     9  )
    10  
    11  func encodeNumeric(content string, ecl ErrorCorrectionLevel) (*utils.BitList, *versionInfo, error) {
    12  	contentBitCount := (len(content) / 3) * 10
    13  	switch len(content) % 3 {
    14  	case 1:
    15  		contentBitCount += 4
    16  	case 2:
    17  		contentBitCount += 7
    18  	}
    19  	vi := findSmallestVersionInfo(ecl, numericMode, contentBitCount)
    20  	if vi == nil {
    21  		return nil, nil, errors.New("To much data to encode")
    22  	}
    23  	res := new(utils.BitList)
    24  	res.AddBits(int(numericMode), 4)
    25  	res.AddBits(len(content), vi.charCountBits(numericMode))
    26  
    27  	for pos := 0; pos < len(content); pos += 3 {
    28  		var curStr string
    29  		if pos+3 <= len(content) {
    30  			curStr = content[pos : pos+3]
    31  		} else {
    32  			curStr = content[pos:]
    33  		}
    34  
    35  		i, err := strconv.Atoi(curStr)
    36  		if err != nil || i < 0 {
    37  			return nil, nil, fmt.Errorf("\"%s\" can not be encoded as %s", content, Numeric)
    38  		}
    39  		var bitCnt byte
    40  		switch len(curStr) % 3 {
    41  		case 0:
    42  			bitCnt = 10
    43  		case 1:
    44  			bitCnt = 4
    45  			break
    46  		case 2:
    47  			bitCnt = 7
    48  			break
    49  		}
    50  
    51  		res.AddBits(i, bitCnt)
    52  	}
    53  
    54  	addPaddingAndTerminator(res, vi)
    55  	return res, vi, nil
    56  }