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JFBase64.m
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JFBase64.m
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//
// JFBase64.m
// JFCommon
//
// Created by Jason Fuerstenberg on 11/01/08.
// Copyright 2011 Jason Fuerstenberg. All rights reserved.
//
// 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 "JFBase64.h"
#define ArrayLength(x) (sizeof(x)/sizeof(*(x)))
static char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static char decodingTable[128];
@implementation JFBase64
+ (void) initialize {
if (self == [JFBase64 class]) {
memset(decodingTable, 0, ArrayLength(decodingTable));
for (NSInteger i = 0; i < ArrayLength(encodingTable); i++) {
decodingTable[encodingTable[i]] = i;
}
}
}
+ (NSString *) encode: (const uint8_t *) input length: (NSInteger) length {
NSMutableData *data = [NSMutableData dataWithLength: ((length + 2) / 3) * 4];
uint8_t *output = (uint8_t*) data.mutableBytes;
for (NSInteger i = 0; i < length; i += 3) {
NSInteger value = 0;
for (NSInteger j = i; j < (i + 3); j++) {
value <<= 8;
if (j < length) {
value |= (0xFF & input[j]);
}
}
NSInteger index = (i / 3) * 4;
output[index + 0] = encodingTable[(value >> 18) & 0x3F];
output[index + 1] = encodingTable[(value >> 12) & 0x3F];
output[index + 2] = (i + 1) < length ? encodingTable[(value >> 6) & 0x3F] : '=';
output[index + 3] = (i + 2) < length ? encodingTable[(value >> 0) & 0x3F] : '=';
}
#if __has_feature(objc_arc)
return [[NSString alloc] initWithData: data
encoding: NSASCIIStringEncoding];
#else
return [[[NSString alloc] initWithData: data
encoding: NSASCIIStringEncoding] autorelease];
#endif
}
+ (NSString*) encode: (NSData *) rawBytes {
return [self encode: (const uint8_t*) rawBytes.bytes
length: rawBytes.length];
}
+ (NSData *) decode: (const char *) string length: (NSInteger) inputLength {
if ((string == NULL) || (inputLength % 4 != 0)) {
return nil;
}
while (inputLength > 0 && string[inputLength - 1] == '=') {
inputLength--;
}
NSInteger outputLength = inputLength * 3 / 4;
NSMutableData *data = [NSMutableData dataWithLength: outputLength];
uint8_t* output = data.mutableBytes;
NSInteger inputPoint = 0;
NSInteger outputPoint = 0;
while (inputPoint < inputLength) {
char i0 = string[inputPoint++];
char i1 = string[inputPoint++];
char i2 = inputPoint < inputLength ? string[inputPoint++] : 'A'; /* 'A' will decode to \0 */
char i3 = inputPoint < inputLength ? string[inputPoint++] : 'A';
output[outputPoint++] = (decodingTable[i0] << 2) | (decodingTable[i1] >> 4);
if (outputPoint < outputLength) {
output[outputPoint++] = ((decodingTable[i1] & 0xf) << 4) | (decodingTable[i2] >> 2);
}
if (outputPoint < outputLength) {
output[outputPoint++] = ((decodingTable[i2] & 0x3) << 6) | decodingTable[i3];
}
}
return data;
}
+ (NSData *) decode: (NSString *) string {
return [self decode: [string cStringUsingEncoding: NSASCIIStringEncoding]
length: string.length];
}
@end