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// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Original code by Matt McCutchen, see the LICENSE file.
#include "BigUnsignedInABase.hh"
BigUnsignedInABase::BigUnsignedInABase(const Digit *d, Index l, Base base)
: NumberlikeArray<Digit>(d, l), base(base) {
// Check the base
if (base < 2)
abort();
// Validate the digits.
for (Index i = 0; i < l; i++)
if (blk[i] >= base)
abort();
// Eliminate any leading zeros we may have been passed.
zapLeadingZeros();
}
namespace {
unsigned int bitLen(unsigned int x) {
unsigned int len = 0;
while (x > 0) {
x >>= 1;
len++;
}
return len;
}
unsigned int ceilingDiv(unsigned int a, unsigned int b) {
return (a + b - 1) / b;
}
}
BigUnsignedInABase::BigUnsignedInABase(const BigUnsigned &x, Base base) {
// Check the base
if (base < 2)
abort();
this->base = base;
// Get an upper bound on how much space we need
int maxBitLenOfX = x.getLength() * BigUnsigned::N;
int minBitsPerDigit = bitLen(base) - 1;
int maxDigitLenOfX = ceilingDiv(maxBitLenOfX, minBitsPerDigit);
len = maxDigitLenOfX; // Another change to comply with `staying in bounds'.
allocate(len); // Get the space
BigUnsigned x2(x), buBase(base);
Index digitNum = 0;
while (!x2.isZero()) {
// Get last digit. This is like `lastDigit = x2 % buBase, x2 /= buBase'.
BigUnsigned lastDigit(x2);
lastDigit.divideWithRemainder(buBase, x2);
// Save the digit.
blk[digitNum] = lastDigit.toUnsignedShort();
// Move on. We can't run out of room: we figured it out above.
digitNum++;
}
// Save the actual length.
len = digitNum;
}
BigUnsignedInABase::operator BigUnsigned() const {
BigUnsigned ans(0), buBase(base), temp;
Index digitNum = len;
while (digitNum > 0) {
digitNum--;
temp.multiply(ans, buBase);
ans.add(temp, BigUnsigned(blk[digitNum]));
}
return ans;
}
BigUnsignedInABase::BigUnsignedInABase(const std::string &s, Base base) {
// Check the base.
if (base > 36)
abort();
// Save the base.
// This pattern is seldom seen in C++, but the analogous ``this.'' is common in Java.
this->base = base;
// `s.length()' is a `size_t', while `len' is a `NumberlikeArray::Index',
// also known as an `unsigned int'. Some compilers warn without this cast.
len = Index(s.length());
allocate(len);
Index digitNum, symbolNumInString;
for (digitNum = 0; digitNum < len; digitNum++) {
symbolNumInString = len - 1 - digitNum;
char theSymbol = s[symbolNumInString];
if (theSymbol >= '0' && theSymbol <= '9')
blk[digitNum] = theSymbol - '0';
else if (theSymbol >= 'A' && theSymbol <= 'Z')
blk[digitNum] = theSymbol - 'A' + 10;
else if (theSymbol >= 'a' && theSymbol <= 'z')
blk[digitNum] = theSymbol - 'a' + 10;
else
abort();
if (blk[digitNum] >= base)
abort();
}
zapLeadingZeros();
}
BigUnsignedInABase::operator std::string() const {
if (base > 36)
abort();
if (len == 0)
return std::string("0");
// Some compilers don't have push_back, so use a char * buffer instead.
char *s = new char[len + 1];
s[len] = '\0';
Index digitNum, symbolNumInString;
for (symbolNumInString = 0; symbolNumInString < len; symbolNumInString++) {
digitNum = len - 1 - symbolNumInString;
Digit theDigit = blk[digitNum];
if (theDigit < 10)
s[symbolNumInString] = char('0' + theDigit);
else
s[symbolNumInString] = char('A' + theDigit - 10);
}
std::string s2(s);
delete [] s;
return s2;
}
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