mirror of
https://github.com/odin-lang/Odin.git
synced 2026-10-09 14:22:18 -04:00
Ihor Antonov
2109ba8fbd
core:encoding/base64 currently decodes leniently: it infers padding from the last one or two bytes, accepts missing/extra/interior padding, and does not check the trailing padding bits required by RFC 4648 Section 3.5. Go exposes canonical decoding as `Encoding.Strict()`; Odin has no equivalent, so downstream ports (e.g. age) have to reimplement base64 from scratch. This adds opt-in strict decoding through a `Decode_Options` bit set. Existing calls and behavior are unchanged.
486 lines
11 KiB
Odin
486 lines
11 KiB
Odin
/*
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`Base64` encoding and decoding.
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A secondary param can be used to supply a custom alphabet to `encode` and a matching decoding table to `decode`.
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If none is supplied it just uses the standard Base64 alphabet.
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In case your specific version does not use padding, you may
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truncate it from the encoded output.
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By default `decode` is lenient, accepting padded and unpadded input and not
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checking the trailing padding bits. Decode options can enable strict
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(RFC 4648 section 3.5) canonical decoding: `{.Strict}` requires correct
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padding and zero trailing bits, while `{.Strict, .No_Padding}` accepts only
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canonical unpadded input.
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*/
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package encoding_base64
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import "base:intrinsics"
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import "base:runtime"
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import "core:io"
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@(rodata)
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ENC_TABLE := [64]byte {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/',
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}
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// Encoding table for Base64url variant
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@(rodata)
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ENC_URL_TABLE := [64]byte {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '-', '_',
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}
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PADDING :: '='
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@(rodata)
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DEC_TABLE := [256]i8 {
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, 62, -1, -1, -1, 63,
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52, 53, 54, 55, 56, 57, 58, 59,
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60, 61, -1, -1, -1, -1, -1, -1,
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-1, 0, 1, 2, 3, 4, 5, 6,
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7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22,
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23, 24, 25, -1, -1, -1, -1, -1,
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-1, 26, 27, 28, 29, 30, 31, 32,
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33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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}
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// Decoding table for Base64url variant
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@(rodata)
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DEC_URL_TABLE := [256]i8 {
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, 62, -1, -1,
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52, 53, 54, 55, 56, 57, 58, 59,
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60, 61, -1, -1, -1, -1, -1, -1,
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-1, 0, 1, 2, 3, 4, 5, 6,
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7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22,
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23, 24, 25, -1, -1, -1, -1, 63,
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-1, 26, 27, 28, 29, 30, 31, 32,
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33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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}
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Error :: union #shared_nil {
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runtime.Allocator_Error,
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io.Error,
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Decode_Error,
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}
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Decode_Error :: enum {
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None,
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Invalid_Character,
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Invalid_Padding,
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Non_Canonical,
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}
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// Decode_Option selects optional validation performed by the decode routines.
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Decode_Option :: enum {
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// Strict requires canonical input as described in RFC 4648 section 3.5:
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// trailing padding bits must be zero, padding must be exact, and padding
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// characters may only appear at the end.
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Strict,
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// No_Padding rejects the padding character, requiring unpadded input.
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No_Padding,
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}
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// Decode_Options is a set of Decode_Option values.
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Decode_Options :: bit_set[Decode_Option; u8]
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encode :: proc(data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) -> (encoded: string, err: runtime.Allocator_Error) #optional_allocator_error {
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out_length := encoded_len(data)
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if out_length == 0 {
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return
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}
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out := make([]byte, out_length, allocator) or_return
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_, ioerr := encode_impl(out, data, ENC_TBL)
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assert(ioerr == nil, "encode should not IO error")
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assert(len(out) == out_length, "buffer resized, `encoded_len` was wrong")
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encoded = transmute(string)(out)
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return
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}
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encode_into_buf :: proc(dst, data: []byte, ENC_TBL := ENC_TABLE) -> (encoded: []byte, err: Error) {
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out_length := encoded_len(data)
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if out_length == 0 {
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return
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}
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return encode_impl(dst, data, ENC_TBL)
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}
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encode_into :: proc(w: io.Writer, data: []byte, ENC_TBL := ENC_TABLE) -> io.Error {
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_, err := encode_impl(w, data, ENC_TBL)
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return err
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}
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@(private)
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encode_impl :: proc(dst: $T, data: []byte, ENC_TBL := ENC_TABLE) -> ([]byte, io.Error) where T == io.Writer || T == []byte {
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length := len(data)
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when T == []byte {
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out_length := encoded_len(data)
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if len(dst) < out_length {
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return nil, io.Error.Short_Buffer
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}
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buf := dst
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} else {
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if length == 0 {
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return nil, nil
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}
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buf: [4]byte
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}
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c0, c1, c2, block: int
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for i := 0; i < length; i += 3 {
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#no_bounds_check {
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c0, c1, c2 = int(data[i]), -1, -1
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if i + 1 < length { c1 = int(data[i + 1]) }
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if i + 2 < length { c2 = int(data[i + 2]) }
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block = (c0 << 16) | (max(c1, 0) << 8) | max(c2, 0)
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buf[0] = ENC_TBL[block >> 18 & 63]
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buf[1] = ENC_TBL[block >> 12 & 63]
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buf[2] = c1 == -1 ? PADDING : ENC_TBL[block >> 6 & 63]
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buf[3] = c2 == -1 ? PADDING : ENC_TBL[block & 63]
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when T == []byte {
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buf = buf[4:]
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}
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}
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when T == io.Writer {
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if _, err := io.write_full(dst, buf[:]); err != nil {
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return nil, err
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}
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}
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}
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when T == io.Writer {
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return nil, nil
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} else {
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return dst[:out_length], nil
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}
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}
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encoded_len :: proc(data: []byte) -> int {
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length := len(data)
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if length == 0 {
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return 0
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}
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return ((4 * length / 3) + 3) &~ 3
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}
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@(private)
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validate_strict_decode :: proc(data: string, dec_tbl: [256]i8, options: Decode_Options) -> Decode_Error {
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if options == {} {
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return .None
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}
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n := len(data)
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if n == 0 {
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return .None
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}
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si := n
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pad: int
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if .No_Padding in options {
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for i in 0 ..< n {
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if data[i] == PADDING {
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return .Invalid_Padding
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}
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}
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} else {
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for si > 0 && data[si - 1] == PADDING {
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si -= 1
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pad += 1
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}
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if pad > 2 {
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return .Invalid_Padding
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}
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for j in 0 ..< si {
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if data[j] == PADDING {
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return .Invalid_Padding
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}
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}
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}
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rem := si % 4
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if .No_Padding in options && rem == 1 {
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return .Invalid_Padding
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}
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if .Strict in options {
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if .No_Padding not_in options {
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if n % 4 != 0 {
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return .Invalid_Padding
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}
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switch rem {
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case 0:
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if pad != 0 {
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return .Invalid_Padding
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}
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case 2:
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if pad != 2 {
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return .Invalid_Padding
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}
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case 3:
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if pad != 1 {
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return .Invalid_Padding
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}
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case:
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return .Invalid_Padding
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}
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}
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switch rem {
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case 2:
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c := dec_tbl[data[si - 1]]
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if c < 0 {
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return .Invalid_Character
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}
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if (c & 0x0f) != 0 {
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return .Non_Canonical
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}
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case 3:
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c := dec_tbl[data[si - 1]]
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if c < 0 {
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return .Invalid_Character
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}
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if (c & 0x03) != 0 {
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return .Non_Canonical
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}
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}
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}
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return .None
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}
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decode :: proc(data: string, DEC_TBL := DEC_TABLE, dst: []byte = nil, allocator := context.allocator, options := Decode_Options{}) -> (decoded: []byte, err: Error) {
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if derr := validate_strict_decode(data, DEC_TBL, options); derr != .None {
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return nil, derr
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}
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out_length := decoded_len(data)
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if out_length == 0 {
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return nil, nil
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}
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buf: []byte
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if buf, err = make([]byte, out_length, allocator); err != nil {
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return
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}
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decoded, err = decode_impl(buf, data, DEC_TBL)
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if err != nil {
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delete(buf, allocator)
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}
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assert(err != nil || len(decoded) == out_length, "buffer unexpectedly resized, `decoded_len` was wrong")
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return
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}
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decode_into_buf :: proc(dst: []byte, data: string, DEC_TBL := DEC_TABLE, options := Decode_Options{}) -> (decoded: []byte, err: Error) {
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if derr := validate_strict_decode(data, DEC_TBL, options); derr != .None {
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return nil, derr
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}
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out_length := decoded_len(data)
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if out_length == 0 {
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return
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}
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return decode_impl(dst, data, DEC_TBL)
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}
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decode_into :: proc(w: io.Writer, data: string, DEC_TBL := DEC_TABLE, options := Decode_Options{}) -> Error {
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if derr := validate_strict_decode(data, DEC_TBL, options); derr != .None {
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return derr
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}
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_, err := decode_impl(w, data, DEC_TBL)
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return err
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}
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@(private)
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decode_impl :: proc(dst: $T, data: string, DEC_TBL := DEC_TABLE) -> ([]byte, Error) where T == io.Writer || T == []byte {
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length := decoded_len(data)
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when T == []byte {
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if len(dst) < length {
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return nil, io.Error.Short_Buffer
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}
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off: int
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} else {
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if length == 0 {
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return nil, nil
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}
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buf: [3]byte
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}
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c0, c1, c2, c3: int
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d0, d1, d2, d3: i8
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b0, b1, b2: int
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i, j: int
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for ; j + 3 <= length; i, j = i + 4, j + 3 {
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#no_bounds_check {
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d0 = DEC_TBL[data[i]]
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d1 = DEC_TBL[data[i + 1]]
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d2 = DEC_TBL[data[i + 2]]
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d3 = DEC_TBL[data[i + 3]]
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if intrinsics.unlikely((d0 | d1 | d2 | d3) & ~i8(0x3f) != 0) {
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return nil, Decode_Error.Invalid_Character
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}
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c0, c1, c2, c3 = int(d0), int(d1), int(d2), int(d3)
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b0 = (c0 << 2) | (c1 >> 4)
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b1 = (c1 << 4) | (c2 >> 2)
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b2 = (c2 << 6) | c3
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when T == []byte {
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dst[off+0] = byte(b0)
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dst[off+1] = byte(b1)
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dst[off+2] = byte(b2)
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off += 3
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} else {
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buf[0] = byte(b0)
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buf[1] = byte(b1)
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buf[2] = byte(b2)
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}
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}
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when T == io.Writer {
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if _, err := io.write_full(dst, buf[:]); err != .None {
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return nil, err
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}
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}
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}
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rest := length - j
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if rest > 0 {
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#no_bounds_check {
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// Note: decoded_len handles removing padding.
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d0 = DEC_TBL[data[i]]
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d1 = DEC_TBL[data[i + 1]]
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if d2 = 0; rest == 2 {
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d2 = DEC_TBL[data[i + 2]]
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}
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if intrinsics.unlikely((d0 | d1 | d2) & ~i8(0x3f) != 0) {
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return nil, Decode_Error.Invalid_Character
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}
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c0, c1, c2 = int(d0), int(d1), int(d2)
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b0 = (c0 << 2) | (c1 >> 4)
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b1 = (c1 << 4) | (c2 >> 2)
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when T == []byte {
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switch rest {
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case 2:
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dst[off+1] = byte(b1)
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fallthrough
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case 1:
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dst[off] = byte(b0)
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}
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} else {
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buf[0] = byte(b0)
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buf[1] = byte(b1)
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}
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}
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when T == io.Writer {
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if _, err := io.write_full(dst, buf[:rest]); err != .None {
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return nil, err
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}
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}
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}
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when T == io.Writer {
|
|
return nil, nil
|
|
} else {
|
|
return dst[:length], nil
|
|
}
|
|
}
|
|
|
|
decoded_len :: proc(data: string) -> int {
|
|
length := len(data)
|
|
if length == 0 {
|
|
return 0
|
|
}
|
|
|
|
padding: int
|
|
if data[length - 1] == PADDING {
|
|
if length > 1 && data[length - 2] == PADDING {
|
|
padding = 2
|
|
} else {
|
|
padding = 1
|
|
}
|
|
}
|
|
|
|
return ((length * 6) >> 3) - padding
|
|
}
|