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/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#include "cmBase32.h"
// -- Static functions
static const unsigned char Base32EncodeTable[33] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
inline unsigned char Base32EncodeChar(int schar)
{
return Base32EncodeTable[schar];
}
static void Base32Encode5(const unsigned char src[5], char dst[8])
{
// [0]:5 bits
dst[0] = Base32EncodeChar((src[0] >> 3) & 0x1F);
// [0]:3 bits + [1]:2 bits
dst[1] = Base32EncodeChar(((src[0] << 2) & 0x1C) + ((src[1] >> 6) & 0x03));
// [1]:5 bits
dst[2] = Base32EncodeChar((src[1] >> 1) & 0x1F);
// [1]:1 bit + [2]:4 bits
dst[3] = Base32EncodeChar(((src[1] << 4) & 0x10) + ((src[2] >> 4) & 0x0F));
// [2]:4 bits + [3]:1 bit
dst[4] = Base32EncodeChar(((src[2] << 1) & 0x1E) + ((src[3] >> 7) & 0x01));
// [3]:5 bits
dst[5] = Base32EncodeChar((src[3] >> 2) & 0x1F);
// [3]:2 bits + [4]:3 bit
dst[6] = Base32EncodeChar(((src[3] << 3) & 0x18) + ((src[4] >> 5) & 0x07));
// [4]:5 bits
dst[7] = Base32EncodeChar((src[4] << 0) & 0x1F);
}
// -- Class methods
cmBase32Encoder::cmBase32Encoder() = default;
std::string cmBase32Encoder::encodeString(const unsigned char* input,
size_t len, bool padding)
{
std::string res;
static const size_t blockSize = 5;
static const size_t bufferSize = 8;
char buffer[bufferSize];
const unsigned char* end = input + len;
while ((input + blockSize) <= end) {
Base32Encode5(input, buffer);
res.append(buffer, bufferSize);
input += blockSize;
}
size_t remain = static_cast<size_t>(end - input);
if (remain != 0) {
// Temporary source buffer filled up with 0s
unsigned char extended[blockSize];
for (size_t ii = 0; ii != remain; ++ii) {
extended[ii] = input[ii];
}
for (size_t ii = remain; ii != blockSize; ++ii) {
extended[ii] = 0;
}
Base32Encode5(extended, buffer);
size_t numPad(0);
switch (remain) {
case 1:
numPad = 6;
break;
case 2:
numPad = 4;
break;
case 3:
numPad = 3;
break;
case 4:
numPad = 1;
break;
default:
break;
}
res.append(buffer, bufferSize - numPad);
if (padding) {
for (size_t ii = 0; ii != numPad; ++ii) {
res.push_back(paddingChar);
}
}
}
return res;
}
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