144 lines
3.2 KiB
C++
144 lines
3.2 KiB
C++
/*
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Copyright (C) 2016 Arturo Guadalupi. All right reserved.
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This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
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*/
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#include <Arduino.h>
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#include "base64_wrapper.h"
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#if (defined(__AVR__))
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#include <avr/pgmspace.h>
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#else
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#include <pgmspace.h>
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#endif
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const char PROGMEM _Base64AlphabetTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789+/";
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int Base64Class::encode(char *output, char *input, int inputLength) {
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int i = 0, j = 0;
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int encodedLength = 0;
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unsigned char A3[3];
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unsigned char A4[4];
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while(inputLength--) {
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A3[i++] = *(input++);
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if(i == 3) {
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fromA3ToA4(A4, A3);
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for(i = 0; i < 4; i++) {
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output[encodedLength++] = pgm_read_byte(&_Base64AlphabetTable[A4[i]]);
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}
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i = 0;
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}
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}
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if(i) {
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for(j = i; j < 3; j++) {
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A3[j] = '\0';
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}
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fromA3ToA4(A4, A3);
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for(j = 0; j < i + 1; j++) {
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output[encodedLength++] = pgm_read_byte(&_Base64AlphabetTable[A4[j]]);
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}
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while((i++ < 3)) {
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output[encodedLength++] = '=';
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}
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}
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output[encodedLength] = '\0';
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return encodedLength;
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}
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int Base64Class::decode(char * output, char * input, int inputLength) {
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int i = 0, j = 0;
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int decodedLength = 0;
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unsigned char A3[3];
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unsigned char A4[4];
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while (inputLength--) {
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if(*input == '=') {
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break;
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}
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A4[i++] = *(input++);
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if (i == 4) {
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for (i = 0; i <4; i++) {
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A4[i] = lookupTable(A4[i]);
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}
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fromA4ToA3(A3,A4);
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for (i = 0; i < 3; i++) {
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output[decodedLength++] = A3[i];
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}
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i = 0;
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}
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}
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if (i) {
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for (j = i; j < 4; j++) {
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A4[j] = '\0';
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}
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for (j = 0; j <4; j++) {
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A4[j] = lookupTable(A4[j]);
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}
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fromA4ToA3(A3,A4);
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for (j = 0; j < i - 1; j++) {
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output[decodedLength++] = A3[j];
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}
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}
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output[decodedLength] = '\0';
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return decodedLength;
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}
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int Base64Class::encodedLength(int plainLength) {
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int n = plainLength;
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return (n + 2 - ((n + 2) % 3)) / 3 * 4;
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}
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int Base64Class::decodedLength(char * input, int inputLength) {
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int i = 0;
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int numEq = 0;
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for(i = inputLength - 1; input[i] == '='; i--) {
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numEq++;
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}
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return ((6 * inputLength) / 8) - numEq;
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}
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//Private utility functions
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inline void Base64Class::fromA3ToA4(unsigned char * A4, unsigned char * A3) {
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A4[0] = (A3[0] & 0xfc) >> 2;
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A4[1] = ((A3[0] & 0x03) << 4) + ((A3[1] & 0xf0) >> 4);
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A4[2] = ((A3[1] & 0x0f) << 2) + ((A3[2] & 0xc0) >> 6);
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A4[3] = (A3[2] & 0x3f);
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}
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inline void Base64Class::fromA4ToA3(unsigned char * A3, unsigned char * A4) {
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A3[0] = (A4[0] << 2) + ((A4[1] & 0x30) >> 4);
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A3[1] = ((A4[1] & 0xf) << 4) + ((A4[2] & 0x3c) >> 2);
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A3[2] = ((A4[2] & 0x3) << 6) + A4[3];
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}
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inline unsigned char Base64Class::lookupTable(char c) {
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if(c >='A' && c <='Z') return c - 'A';
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if(c >='a' && c <='z') return c - 71;
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if(c >='0' && c <='9') return c + 4;
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if(c == '+') return 62;
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if(c == '/') return 63;
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return -1;
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}
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Base64Class Base64;
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