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#include <stdlib.h>
/*
base64.c - by Joe DF (joedf@ahkscript.org)
Released under the MIT License
Revision: 00:06 2014-09-22
Thank you for inspiration:
http://www.codeproject.com/Tips/813146/Fast-base-functions-for-encode-decode
*/
unsigned int b64_int(unsigned int ch);
unsigned int b64e_size(unsigned int in_size);
unsigned int b64d_size(unsigned int in_size);
unsigned int b64_encode(const unsigned int* in, unsigned int in_len, unsigned char* out);
unsigned int b64_decode(const unsigned char* in, unsigned int in_len, unsigned int* out);
//Base64 char table - used internally for encoding
unsigned char b64_chr[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
//Base64 char table functions - used internally for decoding
unsigned int b64_int(unsigned int ch) {
// ASCII to base64_int
// 65-90 Upper Case >> 0-25
// 97-122 Lower Case >> 26-51
// 48-57 Numbers >> 52-61
// 43 Plus (+) >> 62
// 47 Slash (/) >> 63
// 61 Equal (=) >> 64~
if (ch==43)
return 62;
if (ch==47)
return 63;
if (ch==61)
return 64;
if ((ch>47) && (ch<58))
return ch + 4;
if ((ch>64) && (ch<91))
return ch - 'A';
if ((ch>96) && (ch<123))
return (ch - 'a') + 26;
return 0;
}
// in_size : the number bytes to be encoded.
// Returns the recommended memory size to be allocated for the output buffer excluding the null byte
unsigned int b64e_size(unsigned int in_size) {
// size equals 4*floor((1/3)*(in_size+2));
int i, j = 0;
for (i=0;i<in_size;i++) {
if (i % 3 == 0)
j += 1;
}
return (4*j);
}
// in_size : the number bytes to be decoded.
// Returns the recommended memory size to be allocated for the output buffer excluding the null byte
unsigned int b64d_size(unsigned int in_size) {
return ((3*in_size)/4);
}
// in : buffer of "raw" binary to be encoded.
// in_len : number of bytes to be encoded.
// out : pointer to buffer with enough memory, user is responsible for memory allocation, receives null-terminated string
// returns size of output including null byte
unsigned int b64_encode(const unsigned int* in, unsigned int in_len, unsigned char* out) {
unsigned int i=0, j=0, k=0, s[3];
for (i=0;i<in_len;i++) {
s[j++]=*(in+i);
if (j==3) {
out[k+0] = b64_chr[ s[0]>>2 ];
out[k+1] = b64_chr[ ((s[0]&0x03)<<4)+((s[1]&0xF0)>>4) ];
out[k+2] = b64_chr[ ((s[1]&0x0F)<<2)+((s[2]&0xC0)>>6) ];
out[k+3] = b64_chr[ s[2]&0x3F ];
j=0; k+=4;
}
}
if (j) {
if (j==1)
s[1] = 0;
out[k+0] = b64_chr[ s[0]>>2 ];
out[k+1] = b64_chr[ ((s[0]&0x03)<<4)+((s[1]&0xF0)>>4) ];
if (j==2)
out[k+2] = b64_chr[ ((s[1]&0x0F)<<2) ];
else
out[k+2] = '=';
out[k+3] = '=';
k+=4;
}
out[k] = '\0';
return k;
}
// in : buffer of base64 string to be decoded.
// in_len : number of bytes to be decoded.
// out : pointer to buffer with enough memory, user is responsible for memory allocation, receives "raw" binary
// returns size of output excluding null byte
unsigned int b64_decode(const unsigned char* in, unsigned int in_len, unsigned int* out) {
unsigned int i=0, j=0, k=0, s[4];
for (i=0;i<in_len;i++) {
s[j++]=b64_int(*(in+i));
if (j==4) {
out[k+0] = (s[0]<<2)+((s[1]&0x30)>>4);
if (s[2]!=64) {
out[k+1] = ((s[1]&0x0F)<<4)+((s[2]&0x3C)>>2);
if ((s[3]!=64)) {
out[k+2] = ((s[2]&0x03)<<6)+(s[3]); k+=3;
} else {
k+=2;
}
} else {
k+=1;
}
j=0;
}
}
return k;
}
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