encoding: document all of the `encoding.base64` module (#8276)
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@ -1,44 +1,34 @@
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// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module base64
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const (
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index = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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62, 63, 62, 62, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
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17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 63, 0, 26, 27, 28, 29,
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30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
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47, 48, 49, 50, 51]!
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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,
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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,
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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,
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13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 63, 0, 26, 27, 28, 29,
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30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51]!
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ending_table = [0, 2, 1]!
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enc_table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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enc_table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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)
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/*
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decode - expects a base64 encoded string. Returns its decoded version.
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@param data - the encoded input string.
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@return the decoded version of the input string data.
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NB: if you need to decode many strings repeatedly, take a look at decode_in_buffer too.
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*/
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// decode decodes the base64 encoded `string` value passed in `data`.
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// Please note: If you need to decode many strings repeatedly, take a look at `decode_in_buffer`.
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// Example: assert base64.decode('ViBpbiBiYXNlIDY0') == 'V in base 64'
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pub fn decode(data string) string {
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size := data.len * 3 / 4
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if size <= 0 {
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return ''
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}
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buffer := malloc(size)
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return tos(buffer, decode_in_buffer(data, buffer) )
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return tos(buffer, decode_in_buffer(data, buffer))
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}
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/*
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decode - expects a string. Returns its base64 encoded version.
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@param data - the input string.
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@return the base64 encoded version of the input string.
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NB: base64 encoding returns a string that is ~ 4/3 larger than the input.
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NB: if you need to encode many strings repeatedly, take a look at encode_in_buffer too.
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*/
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// encode encodes the `string` value passed in `data` to base64.
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// Please note: base64 encoding returns a `string` that is ~ 4/3 larger than the input.
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// Please note: If you need to encode many strings repeatedly, take a look at `encode_in_buffer`.
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// Example: assert base64.encode('V in base 64') == 'ViBpbiBiYXNlIDY0'
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pub fn encode(data string) string {
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size := 4 * ((data.len + 2) / 3)
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if size <= 0 {
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@ -48,34 +38,33 @@ pub fn encode(data string) string {
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return tos(buffer, encode_in_buffer(data, buffer))
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}
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// decode decodes base64url string to string
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// decode_url returns a decoded URL `string` version of
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// the a base64 url encoded `string` passed in `data`.
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pub fn decode_url(data string) string {
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mut result := data.replace('-', '+') // 62nd char of encoding
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result = data.replace('_', '/') // 63rd char of encoding
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match result.len % 4 { // Pad with trailing '='s
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2 { result += "==" } // 2 pad chars
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3 { result += "=" } // 1 pad char
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else { } // no padding
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2 { result += '==' } // 2 pad chars
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3 { result += '=' } // 1 pad char
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else {} // no padding
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}
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return base64.decode(data)
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return decode(data)
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}
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// encode encodes given string to base64url string
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// encode_url returns a base64 URL encoded `string` version
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// of the value passed in `data`.
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pub fn encode_url(data string) string {
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mut result := base64.encode(data)
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mut result := encode(data)
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// 62nd char of encoding, 63rd char of encoding, remove any trailing '='s
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result = result.replace_each(['+', '-', '/', '_', '=', ''])
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return result
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}
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/*
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decode_in_buffer - expects a string reference, and a buffer in which to store its decoded version.
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@param data - a reference/pointer to the input string that will be decoded.
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@param buffer - a reference/pointer to the buffer that will hold the result.
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The buffer should be large enough (i.e. 3/4 of the data.len, or larger) to hold the decoded data.
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@return the actual size of the decoded data in the buffer.
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NB: this function does NOT allocate new memory, and is suitable for handling very large strings.
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*/
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// decode_in_buffer decodes the base64 encoded `string` reference passed in `data` into `buffer`.
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// decode_in_buffer returns the size of the decoded data in the buffer.
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// Please note: The `buffer` should be large enough (i.e. 3/4 of the data.len, or larger)
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// to hold the decoded data.
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// Please note: This function does NOT allocate new memory, and is thus suitable for handling very large strings.
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pub fn decode_in_buffer(data &string, buffer byteptr) int {
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mut padding := 0
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if data.ends_with('=') {
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@ -85,7 +74,7 @@ pub fn decode_in_buffer(data &string, buffer byteptr) int {
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padding = 1
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}
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}
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//input_length is the length of meaningful data
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// input_length is the length of meaningful data
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input_length := data.len - padding
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output_length := input_length * 3 / 4
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@ -93,52 +82,47 @@ pub fn decode_in_buffer(data &string, buffer byteptr) int {
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mut j := 0
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mut b := &byte(0)
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mut d := &byte(0)
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unsafe{
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unsafe {
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d = byteptr(data.str)
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b = byteptr(buffer)
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}
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for i < input_length {
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mut char_a := 0
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mut char_b := 0
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mut char_c := 0
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mut char_d := 0
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if i < input_length {
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char_a = index[unsafe {d[i]}]
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char_a = index[unsafe { d[i] }]
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i++
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}
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if i < input_length {
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char_b = index[unsafe {d[i]}]
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char_b = index[unsafe { d[i] }]
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i++
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}
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if i < input_length {
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char_c = index[unsafe {d[i]}]
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char_c = index[unsafe { d[i] }]
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i++
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}
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if i < input_length {
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char_d = index[unsafe {d[i]}]
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char_d = index[unsafe { d[i] }]
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i++
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}
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decoded_bytes := (char_a << 18) | (char_b << 12) | (char_c << 6) | (char_d << 0)
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unsafe {
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b[j] = byte(decoded_bytes >> 16)
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b[j+1] = byte((decoded_bytes >> 8) & 0xff)
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b[j+2] = byte((decoded_bytes >> 0) & 0xff)
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b[j] = byte(decoded_bytes >> 16)
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b[j + 1] = byte((decoded_bytes >> 8) & 0xff)
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b[j + 2] = byte((decoded_bytes >> 0) & 0xff)
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}
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j += 3
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}
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return output_length
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}
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/*
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encode_in_buffer - expects a string reference, and a buffer in which to store its base64 encoded version.
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@param data - a reference/pointer to the input string.
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@param buffer - a reference/pointer to the buffer that will hold the result.
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The buffer should be large enough (i.e. 4/3 of the data.len, or larger) to hold the encoded data.
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@return the actual size of the encoded data in the buffer.
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NB: this function does NOT allocate new memory, and is suitable for handling very large strings.
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*/
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// encode_in_buffer base64 encodes the `string` reference passed in `data` into `buffer`.
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// encode_in_buffer returns the size of the encoded data in the buffer.
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// Please note: The buffer should be large enough (i.e. 4/3 of the data.len, or larger) to hold the encoded data.
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// Please note: The function does NOT allocate new memory, and is suitable for handling very large strings.
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pub fn encode_in_buffer(data &string, buffer byteptr) int {
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input_length := data.len
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output_length := 4 * ((input_length + 2) / 3)
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@ -146,40 +130,39 @@ pub fn encode_in_buffer(data &string, buffer byteptr) int {
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mut i := 0
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mut j := 0
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mut d := byteptr(0)
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mut b := byteptr(0)
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mut d := byteptr(0)
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mut b := byteptr(0)
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mut etable := byteptr(0)
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unsafe{
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unsafe {
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d = data.str
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b = buffer
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etable = enc_table.str
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}
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for i < input_length {
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mut octet_a := 0
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mut octet_b := 0
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mut octet_c := 0
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if i < input_length {
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octet_a = int(unsafe {d[i]})
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octet_a = int(unsafe { d[i] })
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i++
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}
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if i < input_length {
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octet_b = int(unsafe {d[i]})
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octet_b = int(unsafe { d[i] })
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i++
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}
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if i < input_length {
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octet_c = int(unsafe {d[i]})
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octet_c = int(unsafe { d[i] })
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i++
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}
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triple := ((octet_a << 0x10) + (octet_b << 0x08) + octet_c)
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unsafe {
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b[j] = etable[ (triple >> 3 * 6) & 63 ] // 63 is 0x3F
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b[j+1] = etable[ (triple >> 2 * 6) & 63 ]
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b[j+2] = etable[ (triple >> 1 * 6) & 63 ]
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b[j+3] = etable[ (triple >> 0 * 6) & 63 ]
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b[j] = etable[(triple >> 3 * 6) & 63] // 63 is 0x3F
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b[j + 1] = etable[(triple >> 2 * 6) & 63]
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b[j + 2] = etable[(triple >> 1 * 6) & 63]
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b[j + 3] = etable[(triple >> 0 * 6) & 63]
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}
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j += 4
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}
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