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