本文仅作为测试时做的笔记,以备自己回忆用
- 1.base64.c与base64.h若不放在.ino同目录下编译不通过,可能并没按标准c++写;
- 2.编码时原文的长度要-1,否则与在线工具的结果不同,用其结果解码发现后面多一个空格,可能和数组末尾结束符\0有关;
- 3.以下例程在NodeMCU下编译通过 IDE版本1.8.9;
源文下载地址:
http://www.lab-z.com/wp-content/uploads/2016/04/arduino-base64-master.zip
#include "Base64.h"
/*
与 https://1024tools.com/base64 中用UTF-8编码 对比相同 注意编码不同结果也会不同
*/
void setup()
{
// start serial port at 9600 bps:
Serial.begin(115200);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
Serial.println("Base64 example");
// encoding
char input[] = "Hello world 好";//结果为 SGVsbG8gd29ybGQg5aW9
int inputLen = sizeof(input)-1;//测试时不-1不对 推测与数组末尾结束符\0有关 解码回来后面多个空格
int encodedLen = base64_enc_len(inputLen);
char encoded[encodedLen];
Serial.print(input); Serial.print(" = ");
// note input is consumed in this step: it will be empty afterwards
base64_encode(encoded, input, inputLen); //编码
Serial.println(encoded);
// decoding
char input2[] = "Zm9vYmFy";//结果为 foobar
int input2Len = sizeof(input2);
int decodedLen = base64_dec_len(input2, input2Len);
char decoded[decodedLen];
base64_decode(decoded, input2, input2Len);//解码
Serial.print(input2); Serial.print(" = "); Serial.println(decoded);
}
void loop(){ }
base64.h:
/*
* Copyright (c) 2013 Adam Rudd.
* See LICENSE for more information
*/
#ifndef _BASE64_H
#define _BASE64_H
/* b64_alphabet:
* Description: Base64 alphabet table, a mapping between integers
* and base64 digits
* Notes: This is an extern here but is defined in Base64.c
*/
extern const char b64_alphabet[];
/* base64_encode:
* Description:
* Encode a string of characters as base64
* Parameters:
* output: the output buffer for the encoding, stores the encoded string
* input: the input buffer for the encoding, stores the binary to be encoded
* inputLen: the length of the input buffer, in bytes
* Return value:
* Returns the length of the encoded string
* Requirements:
* 1. output must not be null or empty
* 2. input must not be null
* 3. inputLen must be greater than or equal to 0
*/
int base64_encode(char *output, char *input, int inputLen);
/* base64_decode:
* Description:
* Decode a base64 encoded string into bytes
* Parameters:
* output: the output buffer for the decoding,
* stores the decoded binary
* input: the input buffer for the decoding,
* stores the base64 string to be decoded
* inputLen: the length of the input buffer, in bytes
* Return value:
* Returns the length of the decoded string
* Requirements:
* 1. output must not be null or empty
* 2. input must not be null
* 3. inputLen must be greater than or equal to 0
*/
int base64_decode(char *output, char *input, int inputLen);
/* base64_enc_len:
* Description:
* Returns the length of a base64 encoded string whose decoded
* form is inputLen bytes long
* Parameters:
* inputLen: the length of the decoded string
* Return value:
* The length of a base64 encoded string whose decoded form
* is inputLen bytes long
* Requirements:
* None
*/
int base64_enc_len(int inputLen);
/* base64_dec_len:
* Description:
* Returns the length of the decoded form of a
* base64 encoded string
* Parameters:
* input: the base64 encoded string to be measured
* inputLen: the length of the base64 encoded string
* Return value:
* Returns the length of the decoded form of a
* base64 encoded string
* Requirements:
* 1. input must not be null
* 2. input must be greater than or equal to zero
*/
int base64_dec_len(char *input, int inputLen);
#endif // _BASE64_H
base64.cpp
#include "Base64.h"
#include <avr/pgmspace.h>
const char PROGMEM b64_alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
/* 'Private' declarations */
inline void a3_to_a4(unsigned char * a4, unsigned char * a3);
inline void a4_to_a3(unsigned char * a3, unsigned char * a4);
inline unsigned char b64_lookup(char c);
int base64_encode(char *output, char *input, int inputLen) {
int i = 0, j = 0;
int encLen = 0;
unsigned char a3[3];
unsigned char a4[4];
while(inputLen--) {
a3[i++] = *(input++);
if(i == 3) {
a3_to_a4(a4, a3);
for(i = 0; i < 4; i++) {
output[encLen++] = pgm_read_byte(&b64_alphabet[a4[i]]);
}
i = 0;
}
}
if(i) {
for(j = i; j < 3; j++) {
a3[j] = '\0';
}
a3_to_a4(a4, a3);
for(j = 0; j < i + 1; j++) {
output[encLen++] = pgm_read_byte(&b64_alphabet[a4[j]]);
}
while((i++ < 3)) {
output[encLen++] = '=';
}
}
output[encLen] = '\0';
return encLen;
}
int base64_decode(char * output, char * input, int inputLen) {
int i = 0, j = 0;
int decLen = 0;
unsigned char a3[3];
unsigned char a4[4];
while (inputLen--) {
if(*input == '=') {
break;
}
a4[i++] = *(input++);
if (i == 4) {
for (i = 0; i <4; i++) {
a4[i] = b64_lookup(a4[i]);
}
a4_to_a3(a3,a4);
for (i = 0; i < 3; i++) {
output[decLen++] = a3[i];
}
i = 0;
}
}
if (i) {
for (j = i; j < 4; j++) {
a4[j] = '\0';
}
for (j = 0; j <4; j++) {
a4[j] = b64_lookup(a4[j]);
}
a4_to_a3(a3,a4);
for (j = 0; j < i - 1; j++) {
output[decLen++] = a3[j];
}
}
output[decLen] = '\0';
return decLen;
}
int base64_enc_len(int plainLen) {
int n = plainLen;
return (n + 2 - ((n + 2) % 3)) / 3 * 4;
}
int base64_dec_len(char * input, int inputLen) {
int i = 0;
int numEq = 0;
for(i = inputLen - 1; input[i] == '='; i--) {
numEq++;
}
return ((6 * inputLen) / 8) - numEq;
}
inline void a3_to_a4(unsigned char * a4, unsigned char * a3) {
a4[0] = (a3[0] & 0xfc) >> 2;
a4[1] = ((a3[0] & 0x03) << 4) + ((a3[1] & 0xf0) >> 4);
a4[2] = ((a3[1] & 0x0f) << 2) + ((a3[2] & 0xc0) >> 6);
a4[3] = (a3[2] & 0x3f);
}
inline void a4_to_a3(unsigned char * a3, unsigned char * a4) {
a3[0] = (a4[0] << 2) + ((a4[1] & 0x30) >> 4);
a3[1] = ((a4[1] & 0xf) << 4) + ((a4[2] & 0x3c) >> 2);
a3[2] = ((a4[2] & 0x3) << 6) + a4[3];
}
inline unsigned char b64_lookup(char c) {
if(c >='A' && c <='Z') return c - 'A';
if(c >='a' && c <='z') return c - 71;
if(c >='0' && c <='9') return c + 4;
if(c == '+') return 62;
if(c == '/') return 63;
return -1;
}
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