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cencode.c
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cencode.c
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/****************************************************************************************************************************
cencoder.c - c source to a base64 decoding algorithm implementation
EthernetWebServer is a library for the Ethernet shields to run WebServer
Based on and modified from ESP8266 https://github.com/esp8266/Arduino/releases
Built by Khoi Hoang https://github.com/khoih-prog/EthernetWebServer
Licensed under MIT license
Original author:
@file Esp8266WebServer.h
@author Ivan Grokhotkov
*****************************************************************************************************************************/
#if !( defined(ESP32) || defined(ESP8266) )
#include "cencode.h"
const int CHARS_PER_LINE = 72;
void base64_init_encodestate(base64_encodestate* state_in)
{
state_in->step = step_A;
state_in->result = 0;
state_in->stepcount = 0;
}
char base64_encode_value(char value_in)
{
static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
if (value_in > 63)
return '=';
return encoding[(unsigned int)value_in];
}
int base64_encode_block(const char* plaintext_in, int length_in, char* code_out, base64_encodestate* state_in)
{
const char* plainchar = plaintext_in;
const char* const plaintextend = plaintext_in + length_in;
char* codechar = code_out;
char result;
char fragment;
result = state_in->result;
switch (state_in->step)
{
while (1)
{
case step_A:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_A;
return codechar - code_out;
}
fragment = *plainchar++;
result = (fragment & 0x0fc) >> 2;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x003) << 4;
// fall through
case step_B:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_B;
return codechar - code_out;
}
fragment = *plainchar++;
result |= (fragment & 0x0f0) >> 4;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x00f) << 2;
// fall through
case step_C:
if (plainchar == plaintextend)
{
state_in->result = result;
state_in->step = step_C;
return codechar - code_out;
}
fragment = *plainchar++;
result |= (fragment & 0x0c0) >> 6;
*codechar++ = base64_encode_value(result);
result = (fragment & 0x03f) >> 0;
*codechar++ = base64_encode_value(result);
++(state_in->stepcount);
if (state_in->stepcount == CHARS_PER_LINE / 4)
{
*codechar++ = '\n';
state_in->stepcount = 0;
}
// fall through
}
}
/* control should not reach here */
return codechar - code_out;
}
int base64_encode_blockend(char* code_out, base64_encodestate* state_in)
{
char* codechar = code_out;
switch (state_in->step)
{
case step_B:
*codechar++ = base64_encode_value(state_in->result);
*codechar++ = '=';
*codechar++ = '=';
break;
case step_C:
*codechar++ = base64_encode_value(state_in->result);
*codechar++ = '=';
break;
case step_A:
break;
}
*codechar = 0x00;
return codechar - code_out;
}
int base64_encode_chars(const char* plaintext_in, int length_in, char* code_out)
{
base64_encodestate _state;
base64_init_encodestate(&_state);
int len = base64_encode_block(plaintext_in, length_in, code_out, &_state);
return len + base64_encode_blockend((code_out + len), &_state);
}
#endif