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Merge branch 'base64-optimize'

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Daniel Eklöf 2020-11-29 11:17:50 +01:00
commit 0beed9fcf6
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1 changed files with 27 additions and 32 deletions
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59
base64.c
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@ -11,21 +11,28 @@
#define LOG_ENABLE_DBG 0
#include "log.h"
enum {
P = 0, // Padding byte (=)
I = 128, // Invalid byte ([^A-Za-z0-9+/=])
};
static const uint8_t reverse_lookup[256] = {
['A'] = 0, ['B'] = 1, ['C'] = 2, ['D'] = 3, ['E'] = 4, ['F'] = 5, ['G'] = 6,
['H'] = 7, ['I'] = 8, ['J'] = 9, ['K'] = 10, ['L'] = 11, ['M'] = 12, ['N'] = 13,
['O'] = 14, ['P'] = 15, ['Q'] = 16, ['R'] = 17, ['S'] = 18, ['T'] = 19, ['U'] = 20,
['V'] = 21, ['W'] = 22, ['X'] = 23, ['Y'] = 24, ['Z'] = 25,
['a'] = 26, ['b'] = 27, ['c'] = 28, ['d'] = 29, ['e'] = 30, ['f'] = 31, ['g'] = 32,
['h'] = 33, ['i'] = 34, ['j'] = 35, ['k'] = 36, ['l'] = 37, ['m'] = 38, ['n'] = 39,
['o'] = 40, ['p'] = 41, ['q'] = 42, ['r'] = 43, ['s'] = 44, ['t'] = 45, ['u'] = 46,
['v'] = 47, ['w'] = 48, ['x'] = 49, ['y'] = 50, ['z'] = 51,
['0'] = 52, ['1'] = 53, ['2'] = 54, ['3'] = 55, ['4'] = 56, ['5'] = 57,
['6'] = 58, ['7'] = 59, ['8'] = 60, ['9'] = 61,
['+'] = 62, ['/'] = 63,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, 62, I, I, I, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, I, I, I, P, I, I,
I, 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, I, I, I, I, I,
I, 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, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I,
I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I
};
static const char lookup[64] = {
@ -37,18 +44,11 @@ static const char lookup[64] = {
'+', '/',
};
static inline bool
is_valid(unsigned char c)
{
return reverse_lookup[c] != 0 || c == 'A' || c == '=';
}
char *
base64_decode(const char *s)
{
const size_t len = strlen(s);
if (len % 4 != 0) {
if (unlikely(len % 4 != 0)) {
errno = EINVAL;
return NULL;
}
@ -58,22 +58,17 @@ base64_decode(const char *s)
return NULL;
for (size_t i = 0, o = 0; i < len; i += 4, o += 3) {
unsigned char c0 = s[i + 0];
unsigned char c1 = s[i + 1];
unsigned char c2 = s[i + 2];
unsigned char c3 = s[i + 3];
unsigned a = reverse_lookup[(unsigned char)s[i + 0]];
unsigned b = reverse_lookup[(unsigned char)s[i + 1]];
unsigned c = reverse_lookup[(unsigned char)s[i + 2]];
unsigned d = reverse_lookup[(unsigned char)s[i + 3]];
if (!is_valid(c0) || !is_valid(c1) || !is_valid(c2) || !is_valid(c3)) {
if (unlikely((a | b | c | d) & I)) {
free(ret);
errno = EINVAL;
return NULL;
}
unsigned a = reverse_lookup[c0];
unsigned b = reverse_lookup[c1];
unsigned c = reverse_lookup[c2];
unsigned d = reverse_lookup[c3];
uint32_t v = a << 18 | b << 12 | c << 6 | d << 0;
char x = (v >> 16) & 0xff;
char y = (v >> 8) & 0xff;