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/********************************************************************************
* *
* B a s e - 6 4 E n c o d i n g / D e c o d i n g *
* *
*********************************************************************************
* Copyright (C) 2012,2022 by Jeroen van der Zijp. All Rights Reserved. *
*********************************************************************************
* 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 3 of the License, or *
* (at your option) any later version. *
* *
* 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. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/> *
********************************************************************************/
#include "xincs.h"
#include "fxver.h"
#include "fxdefs.h"
/*
Notes:
- Encode/decode binary data to or from base64 ascii.
- New implementation should be both faster and safer.
- Encode 3 bytes of source into 4 bytes to destination, allowing
binary data to be safely transmitted using only 64 safe printable letters,
numbers, and other printable ASCII symbols.
*/
using namespace FX;
/*******************************************************************************/
namespace FX {
// Encode table
static const FXchar encode[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
// Decode table
static const FXuchar decode[256]={
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 62, 128, 128, 128, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 128, 128, 128, 128, 128, 128,
128, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 128, 128, 128, 128, 128,
128, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128
};
// Encode bytes from source src to destination dst using base64.
// The encoding stops when all source bytes have been encoded or destination buffer
// is full. A pointer ptr past the last written byte is returned.
// Each 3 bytes from source is encoded as 4 bytes to destination. If source is not
// a multiple of 3 bytes, last few bytes are encoded with '='.
FXchar* fxencode64(FXchar* dst,FXchar* dstend,const FXchar* src,const FXchar* srcend){
FXchar* ptr=dst;
FXuchar c0,c1,c2;
while(ptr+3<dstend && src+2<srcend){ // Encode whole groups
c0=src[0];
c1=src[1];
c2=src[2];
ptr[0]=encode[(c0>>2)&0x3f];
ptr[1]=encode[((c0<<4)|(c1>>4))&0x3f];
ptr[2]=encode[((c1<<2)|(c2>>6))&0x3f];
ptr[3]=encode[c2&0x3f];
src+=3;
ptr+=4;
}
if(ptr+3<dstend && src<srcend){ // Encode partial group
c0=src[0];
ptr[0]=encode[(c0>>2)&0x3f];
if(src+1<srcend){
c1=src[1];
ptr[1]=encode[((c0<<4)|(c1>>4))&0x3f];
ptr[2]=encode[(c1<<2)&0x3f];
}
else{
ptr[1]=encode[(c0<<4)&0x3f];
ptr[2]='=';
}
ptr[3]='=';
ptr+=4;
}
if(ptr<dstend){ // Terminate string
ptr[0]='\0';
}
return ptr;
}
// Decode bytes from source src to destination dst using base64.
// The decoding stops when all source bytes have been decoded, a illegal byte is
// encountered, the end of the source is deteced, or when the destination buffer is
// full. A pointer ptr past the last written byte is returned.
// Each 4 bytes from source is decoded to 3 bytes to destination, except at the end
// where fewer bytes may be generated.
FXchar* fxdecode64(FXchar* dst,FXchar* dstend,const FXchar* src,const FXchar* srcend){
const FXchar* end=src;
FXchar* ptr=dst;
FXuchar c0,c1,c2,c3;
while(end<srcend && decode[(FXuchar)end[0]]!=128){
++end;
}
while(ptr+2<dstend && src+3<end){ // Decode whole group of 4
c0=src[0];
c1=src[1];
c2=src[2];
c3=src[3];
c0=decode[c0];
c1=decode[c1];
c2=decode[c2];
c3=decode[c3];
FXASSERT(c0<64 && c1<64 && c2<64 && c3<64);
ptr[0]=(c0<<2)|(c1>>4);
ptr[1]=(c1<<4)|(c2>>2);
ptr[2]=(c2<<6)|c3;
src+=4;
ptr+=3;
}
if(ptr+1<dstend && src+2<end){ // Decode partial group of 3
c0=src[0];
c1=src[1];
c2=src[2];
c0=decode[c0];
c1=decode[c1];
c2=decode[c2];
FXASSERT(c0<64 && c1<64 && c2<64);
ptr[0]=(c0<<2)|(c1>>4);
ptr[1]=(c1<<4)|(c2>>2);
ptr+=2;
}
else if(ptr<dstend && src+1<end){ // Decode partial group of 2
c0=src[0];
c1=src[1];
c0=decode[c0];
c1=decode[c1];
FXASSERT(c0<64 && c1<64);
ptr[0]=(c0<<2)|(c1>>4);
ptr+=1;
}
if(ptr<dstend){ // Terminate string
ptr[0]='\0';
}
return ptr;
}
}
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