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Faster base64 (#63)

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Cool kids on the Internet use two tables to do base64. That looks cool.
We should get it.
This commit is contained in:
Mingye Wang authored and GitHub committed 2020-02-16 22:42:48 +08:00
1 parent b0b2546d93
commit 0e7ba4e401
2 files changed
+37 -16
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src/misc.cpp
+34 -15
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@@ -243,23 +243,37 @@ std::string base64_encode(const std::string &string_to_encode)
}
std::string base64_decode(const std::string &encoded_string)
std::string base64_decode(const std::string &encoded_string, bool accept_urlsafe)
{
int in_len = encoded_string.size();
int i = 0;
int j = 0;
int in_ = 0;
string_size in_len = encoded_string.size();
string_size i = 0;
string_size in_ = 0;
unsigned char char_array_4[4], char_array_3[3];
static unsigned char dtable[256], itable[256], table_ready = 0;
std::string ret;
while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_]))
// Should not need thread_local with the flag...
if (!table_ready) {
// No memset needed for static/TLS
for (string_size k = 0; k < base64_chars.length(); k++) {
dtable[base64_chars[k]] = k; // decode (find)
itable[base64_chars[k]] = 1; // is_base64
}
// Add urlsafe table
dtable['-'] = dtable['+']; itable['-'] = 2;
dtable['_'] = dtable['/']; itable['_'] = 2;
table_ready = 1;
}
while (in_len-- && (encoded_string[in_] != '=') &&
(accept_urlsafe ? itable[encoded_string[in_]] : (itable[encoded_string[in_]] == 1)))
{
char_array_4[i++] = encoded_string[in_];
in_++;
if (i ==4)
if (i == 4)
{
for (i = 0; i <4; i++)
char_array_4[i] = base64_chars.find(char_array_4[i]);
for (string_size j = 0; j < 4; j++)
char_array_4[j] = dtable[char_array_4[j]];
char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
@@ -273,17 +287,17 @@ std::string base64_decode(const std::string &encoded_string)
if (i)
{
for (j = i; j <4; j++)
for (string_size j = i; j <4; j++)
char_array_4[j] = 0;
for (j = 0; j <4; j++)
char_array_4[j] = base64_chars.find(char_array_4[j]);
for (string_size j = 0; j <4; j++)
char_array_4[j] = dtable[char_array_4[j]];
char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
for (j = 0; (j < i - 1); j++)
for (string_size j = 0; (j < i - 1); j++)
ret += char_array_3[j];
}
@@ -621,14 +635,19 @@ std::string urlsafe_base64_reverse(const std::string &encoded_string)
return replace_all_distinct(replace_all_distinct(encoded_string, "-", "+"), "_", "/");
}
std::string urlsafe_base64(const std::string &encoded_string)
{
return replace_all_distinct(replace_all_distinct(replace_all_distinct(encoded_string, "+", "-"), "/", "_"), "=", "");
}
std::string urlsafe_base64_decode(const std::string &encoded_string)
{
return base64_decode(urlsafe_base64_reverse(encoded_string));
return base64_decode(encoded_string, true);
}
std::string urlsafe_base64_encode(const std::string &string_to_encode)
{
return replace_all_distinct(replace_all_distinct(replace_all_distinct(base64_encode(string_to_encode), "+", "-"), "/", "_"), "=", "");
return urlsafe_base64(base64_encode(string_to_encode));
}
std::string getMD5(const std::string &data)