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61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
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// Base32 implementation
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//
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// Copyright 2010 Google Inc.
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// Author: Markus Gutschke
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "base32.h"
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int base32_decode(const uint8_t* encoded, uint8_t* result, int bufSize) {
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int buffer = 0;
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int bitsLeft = 0;
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int count = 0;
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for(const uint8_t* ptr = encoded; count < bufSize && *ptr; ++ptr) {
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uint8_t ch = *ptr;
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if(ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '-') {
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continue;
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}
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buffer <<= 5;
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// Deal with commonly mistyped characters
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if(ch == '0') {
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ch = 'O';
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} else if(ch == '1') {
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ch = 'L';
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} else if(ch == '8') {
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ch = 'B';
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}
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// Look up one base32 digit
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if((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
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ch = (ch & 0x1F) - 1;
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} else if(ch >= '2' && ch <= '7') {
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ch -= '2' - 26;
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} else {
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return -1;
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}
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buffer |= ch;
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bitsLeft += 5;
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if(bitsLeft >= 8) {
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result[count++] = buffer >> (bitsLeft - 8);
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bitsLeft -= 8;
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}
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}
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if(count < bufSize) {
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result[count] = '\000';
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}
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return count;
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}
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