Method encodeBlocks

qrcode.go:445–513

encodeBlocks takes the completed (terminated & padded) encoded data, splits the data into blocks (as specified by the QR Code version), applies error correction to each block, then interleaves the blocks together. The QR Code's final data sequence is returned.

()

//
// The QR Code's final data sequence is returned.
func (q *QRCode) encodeBlocks() *bitset.Bitset {
	// Split into blocks.
	type dataBlock struct {
		data          *bitset.Bitset
		ecStartOffset int
	}

	block := make([]dataBlock, q.version.numBlocks())

	start := 0
	end := 0
	blockID := 0

	for _, b := range q.version.block {
		for j := 0; j < b.numBlocks; j++ {
			start = end
			end = start + b.numDataCodewords*8

			// Apply error correction to each block.
			numErrorCodewords := b.numCodewords - b.numDataCodewords
			block[blockID].data = reedsolomon.Encode(q.data.Substr(start, end), numErrorCodewords)
			block[blockID].ecStartOffset = end - start

			blockID++
		}
	}

	// Interleave the blocks.

	result := bitset.New()

	// Combine data blocks.
	working := true
	for i := 0; working; i += 8 {
		working = false

		for j, b := range block {
			if i >= block[j].ecStartOffset {
				continue
			}

			result.Append(b.data.Substr(i, i+8))

			working = true
		}
	}

	// Combine error correction blocks.
	working = true
	for i := 0; working; i += 8 {
		working = false

		for j, b := range block {
			offset := i + block[j].ecStartOffset
			if offset >= block[j].data.Len() {
				continue
			}