113 lines
2.5 KiB
V
113 lines
2.5 KiB
V
// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
|
|
// Use of this source code is governed by an MIT license
|
|
// that can be found in the LICENSE file.
|
|
|
|
module base64
|
|
|
|
const (
|
|
Index = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
62, 63, 62, 62, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0,
|
|
0, 0, 0, 0, 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, 0, 0, 0, 0, 63, 0, 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]
|
|
)
|
|
|
|
pub fn decode(data string) string {
|
|
mut padding := 0
|
|
if data.ends_with('=') {
|
|
if data.ends_with('==') {
|
|
padding = 2
|
|
} else {
|
|
padding = 1
|
|
}
|
|
}
|
|
//input_length is the length of meaningful data
|
|
input_length := data.len - padding
|
|
output_length := input_length * 3 / 4
|
|
|
|
mut i := 0
|
|
mut j := 0
|
|
mut str := malloc(output_length)
|
|
|
|
for i < input_length {
|
|
mut char_a := 0
|
|
mut char_b := 0
|
|
mut char_c := 0
|
|
mut char_d := 0
|
|
|
|
if i < input_length {
|
|
char_a = Index[int(data[i])]
|
|
i++
|
|
}
|
|
if i < input_length {
|
|
char_b = Index[int(data[i])]
|
|
i++
|
|
}
|
|
if i < input_length {
|
|
char_c = Index[int(data[i])]
|
|
i++
|
|
}
|
|
if i < input_length {
|
|
char_d = Index[int(data[i])]
|
|
i++
|
|
}
|
|
|
|
decoded_bytes := (char_a << 18) | (char_b << 12) | (char_c << 6) | (char_d << 0)
|
|
str[j] = decoded_bytes >> 16
|
|
str[j+1] = (decoded_bytes >> 8) & 0xff
|
|
str[j+2] = (decoded_bytes >> 0) & 0xff
|
|
|
|
j += 3
|
|
}
|
|
return tos(str, output_length)
|
|
}
|
|
|
|
const (
|
|
EncodingTable = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
|
|
)
|
|
|
|
pub fn encode(data string) string {
|
|
input_length := data.len
|
|
output_length := 4 * ((input_length + 2) / 3)
|
|
|
|
mut i := 0
|
|
mut j := 0
|
|
mut str := malloc(output_length)
|
|
|
|
for i < input_length {
|
|
mut octet_a := 0
|
|
mut octet_b := 0
|
|
mut octet_c := 0
|
|
|
|
if i < input_length {
|
|
octet_a = int(data[i])
|
|
i++
|
|
}
|
|
if i < input_length {
|
|
octet_b = int(data[i])
|
|
i++
|
|
}
|
|
if i < input_length {
|
|
octet_c = int(data[i])
|
|
i++
|
|
}
|
|
|
|
triple := ((octet_a << 0x10) + (octet_b << 0x08) + octet_c)
|
|
|
|
str[j+0] = EncodingTable[(triple >> 3 * 6) & 63] // 63 is 0x3F
|
|
str[j+1] = EncodingTable[(triple >> 2 * 6) & 63]
|
|
str[j+2] = EncodingTable[(triple >> 1 * 6) & 63]
|
|
str[j+3] = EncodingTable[(triple >> 0 * 6) & 63]
|
|
j += 4
|
|
}
|
|
|
|
mod_table := [0, 2, 1]
|
|
for i = 0; i < mod_table[input_length % 3]; i++ {
|
|
str[output_length - 1 - i] = `=`
|
|
}
|
|
|
|
return tos(str, output_length)
|
|
}
|