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| /*
| Ported to JavaScript by Lazar Laszlo 2011
|
| lazarsoft@gmail.com, www.lazarsoft.info
|
| */
|
| /*
| *
| * Copyright 2007 ZXing authors
| *
| * Licensed under the Apache License, Version 2.0 (the "License");
| * you may not use this file except in compliance with the License.
| * You may obtain a copy of the License at
| *
| * http://www.apache.org/licenses/LICENSE-2.0
| *
| * Unless required by applicable law or agreed to in writing, software
| * distributed under the License is distributed on an "AS IS" BASIS,
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
| * See the License for the specific language governing permissions and
| * limitations under the License.
| */
|
| import {URShift} from './qrcode';
| import ErrorCorrectionLevel from './errorlevel';
|
| var FORMAT_INFO_MASK_QR = 0x5412;
| var FORMAT_INFO_DECODE_LOOKUP = [
| [0x5412, 0x00],
| [0x5125, 0x01],
| [0x5E7C, 0x02],
| [0x5B4B, 0x03],
| [0x45F9, 0x04],
| [0x40CE, 0x05],
| [0x4F97, 0x06],
| [0x4AA0, 0x07],
| [0x77C4, 0x08],
| [0x72F3, 0x09],
| [0x7DAA, 0x0A],
| [0x789D, 0x0B],
| [0x662F, 0x0C],
| [0x6318, 0x0D],
| [0x6C41, 0x0E],
| [0x6976, 0x0F],
| [0x1689, 0x10],
| [0x13BE, 0x11],
| [0x1CE7, 0x12],
| [0x19D0, 0x13],
| [0x0762, 0x14],
| [0x0255, 0x15],
| [0x0D0C, 0x16],
| [0x083B, 0x17],
| [0x355F, 0x18],
| [0x3068, 0x19],
| [0x3F31, 0x1A],
| [0x3A06, 0x1B],
| [0x24B4, 0x1C],
| [0x2183, 0x1D],
| [0x2EDA, 0x1E],
| [0x2BED, 0x1F],
| ];
| var BITS_SET_IN_HALF_BYTE = [0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4];
|
|
| export default function FormatInformation(formatInfo) {
| this.errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
| this.dataMask = (formatInfo & 0x07);
| }
|
| FormatInformation.prototype.GetHashCode = function() {
| return (this.errorCorrectionLevel.ordinal() << 3) | this.dataMask;
| };
|
| FormatInformation.prototype.Equals = function(o) {
| var other = o;
| return this.errorCorrectionLevel == other.errorCorrectionLevel && this.dataMask == other.dataMask;
| };
|
| FormatInformation.numBitsDiffering = function(a, b) {
| a ^= b; // a now has a 1 bit exactly where its bit differs with b's
| // Count bits set quickly with a series of lookups:
| return BITS_SET_IN_HALF_BYTE[a & 0x0F] + BITS_SET_IN_HALF_BYTE[(URShift(a, 4) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 8) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 12) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 16) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 20) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 24) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 28) & 0x0F)];
| };
|
| FormatInformation.decodeFormatInformation = function(maskedFormatInfo) {
| var formatInfo = FormatInformation.doDecodeFormatInformation(maskedFormatInfo);
| if (formatInfo != null) {
| return formatInfo;
| }
| // Should return null, but, some QR codes apparently
| // do not mask this info. Try again by actually masking the pattern
| // first
| return FormatInformation.doDecodeFormatInformation(maskedFormatInfo ^ FORMAT_INFO_MASK_QR);
| };
| FormatInformation.doDecodeFormatInformation = function(maskedFormatInfo) {
| // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
| var bestDifference = 0xffffffff;
| var bestFormatInfo = 0;
| for (var i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
| var decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
| var targetInfo = decodeInfo[0];
| if (targetInfo == maskedFormatInfo) {
| // Found an exact match
| return new FormatInformation(decodeInfo[1]);
| }
| var bitsDifference = this.numBitsDiffering(maskedFormatInfo, targetInfo);
| if (bitsDifference < bestDifference) {
| bestFormatInfo = decodeInfo[1];
| bestDifference = bitsDifference;
| }
| }
| // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
| // differing means we found a match
| if (bestDifference <= 3) {
| return new FormatInformation(bestFormatInfo);
| }
| return null;
| };
|
|
