// Base32 implementation
//
// Copyright 2010 Google Inc.
// Author: Markus Gutschke
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <string.h>

#include "base32.h"

int base32_decode(const uint8_t *encoded, uint8_t *result, int bufSize) {
 int buffer = 0;
 int bitsLeft = 0;
 int count = 0;
 for (const uint8_t *ptr = encoded; count < bufSize && *ptr; ++ptr) {
 uint8_t ch = *ptr;
 if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '-') {
 continue;
 }
 buffer <<= 5;

 // Deal with commonly mistyped characters
 if (ch == '0') {
 ch = 'O';
 } else if (ch == '1') {
 ch = 'L';
 } else if (ch == '8') {
 ch = 'B';
 }

 // Look up one base32 digit
 if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')) {
 ch = (ch & 0x1F) - 1;
 } else if (ch >= '2' && ch <= '7') {
 ch -= '2' - 26;
 } else {
 return -1;
 }

 buffer |= ch;
 bitsLeft += 5;
 if (bitsLeft >= 8) {
 result[count++] = buffer >> (bitsLeft - 8);
 bitsLeft -= 8;
 }
 }
 if (count < bufSize) {
 result[count] = '000円';
 }
 return count;
}

int base32_encode(const uint8_t *data, int length, uint8_t *result,
 int bufSize) {
 if (length < 0 || length > (1 << 28)) {
 return -1;
 }
 int count = 0;
 if (length > 0) {
 int buffer = data[0];
 int next = 1;
 int bitsLeft = 8;
 while (count < bufSize && (bitsLeft > 0 || next < length)) {
 if (bitsLeft < 5) {
 if (next < length) {
 buffer <<= 8;
 buffer |= data[next++] & 0xFF;
 bitsLeft += 8;
 } else {
 int pad = 5 - bitsLeft;
 buffer <<= pad;
 bitsLeft += pad;
 }
 }
 int index = 0x1F & (buffer >> (bitsLeft - 5));
 bitsLeft -= 5;
 result[count++] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"[index];
 }
 }
 if (count < bufSize) {
 result[count] = '000円';
 }
 return count;
}