base64: Rewrite base64_decode() and add some tests
parent
5651ba5342
commit
f6cf724571
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@ -15,36 +15,53 @@ const (
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)
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pub fn decode(data string) string {
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p := data.cstr()
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len := data.len
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mut pad := 0
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if len > 0 && (len % 4 != 0 || p[len - 1] == `=`) {
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pad = 1
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}
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L := ((len + 3) / 4 - pad) * 4
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str_len := L / 4 * 3 + pad
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mut str := malloc(str_len + 2)
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mut j := 0
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for i := 0; i < L; i = i+4 {
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n := (Index[p[i]] << 18) | (Index[p[i + 1]] << 12) |
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(Index[p[i + 2]] << 6) | (Index[p[i + 3]])
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str[j] = n >> 16
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j++
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str[j] = n >> 8 & 0xff
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j++
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str[j] = n & 0xff
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j++
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}
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if pad > 0 {
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mut nn := (Index[p[L]] << 18) | (Index[p[L + 1]] << 12)
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str[str_len - 1] = nn >> 16
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if len > L + 2 && p[L + 2] != `=` {
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nn = nn | (Index[p[L + 2]] << 6)
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str[str_len] = nn >> 8 & 0xff
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mut padding := 0
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if data.ends_with('=') {
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if data.ends_with('==') {
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padding = 2
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} else {
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padding = 1
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}
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}
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str[str_len + 1] = `\0`
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return tos(str, str_len+1)
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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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mut i := 0
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mut j := 0
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mut str := malloc(output_length)
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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[int(data[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[int(data[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[int(data[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[int(data[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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str[j] = decoded_bytes >> 16
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str[j+1] = (decoded_bytes >> 8) & 0xff
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str[j+2] = (decoded_bytes >> 0) & 0xff
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j += 3
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}
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return tos(str, output_length)
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}
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const (
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@ -3,5 +3,14 @@ import base64
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fn test_decode() {
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assert base64.decode('TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=')
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== 'Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.'
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// Test for incorrect padding.
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assert base64.decode('aGk') == 'hi'
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assert base64.decode('aGk=') == 'hi'
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assert base64.decode('aGk==') == 'hi'
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}
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fn test_encode() {
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assert base64.encode('Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.')
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== 'TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4='
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}
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