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codecrypt
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base64: simplify debase64ing a bit

This commit is contained in:
Mirek Kratochvil 2017-07-10 11:17:34 +02:00
parent be8c3faa55
commit cc9b6b5858
1 changed files with 16 additions and 86 deletions
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102
src/base64.cpp
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@ -20,12 +20,14 @@
#include "base64.h"
static const unsigned char b64str[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static int b64d[256];
static bool b64d_init = false;
void base64_encode (const std::string& in, std::string&out, int cols)
{
//note: it could be b64str[64], but we'd need -fpermissive
static const unsigned char b64str[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
unsigned int acc = 0;
int accbits = 0, idx = 0, idxmax = in.length(), col = 0;
out.clear();
@ -52,80 +54,12 @@ void base64_encode (const std::string& in, std::string&out, int cols)
}
}
static void init_dec_str (unsigned char s[256])
static void init_b64d ()
{
for (int i = 0; i < 256; ++i) s[i] = -1;
s['A'] = 0;
s['B'] = 1;
s['C'] = 2;
s['D'] = 3;
s['E'] = 4;
s['F'] = 5;
s['G'] = 6;
s['H'] = 7;
s['I'] = 8;
s['J'] = 9;
s['K'] = 10;
s['L'] = 11;
s['M'] = 12;
s['N'] = 13;
s['O'] = 14;
s['P'] = 15;
s['Q'] = 16;
s['R'] = 17;
s['S'] = 18;
s['T'] = 19;
s['U'] = 20;
s['V'] = 21;
s['W'] = 22;
s['X'] = 23;
s['Y'] = 24;
s['Z'] = 25;
s['a'] = 26;
s['b'] = 27;
s['c'] = 28;
s['d'] = 29;
s['e'] = 30;
s['f'] = 31;
s['g'] = 32;
s['h'] = 33;
s['i'] = 34;
s['j'] = 35;
s['k'] = 36;
s['l'] = 37;
s['m'] = 38;
s['n'] = 39;
s['o'] = 40;
s['p'] = 41;
s['q'] = 42;
s['r'] = 43;
s['s'] = 44;
s['t'] = 45;
s['u'] = 46;
s['v'] = 47;
s['w'] = 48;
s['x'] = 49;
s['y'] = 50;
s['z'] = 51;
s['0'] = 52;
s['1'] = 53;
s['2'] = 54;
s['3'] = 55;
s['4'] = 56;
s['5'] = 57;
s['6'] = 58;
s['7'] = 59;
s['8'] = 60;
s['9'] = 61;
s['+'] = 62;
s['/'] = 63;
if (b64d_init) return;
for (int i = 0; i < 256; ++i) b64d[i] = -1;
for (int i = 0; i < 64; ++i) b64d[b64str[i]] = i;
b64d_init = true;
}
static inline bool is_white (unsigned char c)
@ -147,7 +81,7 @@ static void eat_white (const std::string&in, int&idx, int idxmax)
for (; (idx < idxmax) && is_white (in[idx]); ++idx);
}
static bool eat_4 (const std::string&in, int&idx, int idxmax, unsigned char*a)
static bool eat_4 (const std::string&in, int&idx, int idxmax, int a[4])
{
for (int i = 0; i < 4; ++i) {
eat_white (in, idx, idxmax);
@ -161,13 +95,7 @@ static bool eat_4 (const std::string&in, int&idx, int idxmax, unsigned char*a)
bool base64_decode (const std::string& in, std::string&out)
{
static unsigned char b64d[256];
static bool b64d_init = false;
if (!b64d_init) {
init_dec_str (b64d);
b64d_init = true;
}
init_b64d();
int idx = 0, idxmax = in.length();
@ -175,10 +103,12 @@ bool base64_decode (const std::string& in, std::string&out)
out.reserve (3 * in.length() / 4);
//start parsing
unsigned char c[4];
int c[4];
while (eat_4 (in, idx, idxmax, c)) {
for (int i = 0; i < 4; ++i)
for (int i = 0; i < 4; ++i) {
if (c[i] < 0 || c[i] >= 256) return false;
c[i] = b64d[c[i]]; // '=' gets converted to -1
}
//consistency checks
if ( (c[0] == -1) || (c[1] == -1)) return false;