/* ********************************************************************** * Copyright (C) 1997-2001, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * * File DIGITLST.CPP * * Modification History: * * Date Name Description * 03/21/97 clhuang Converted from java. * 03/21/97 clhuang Implemented with new APIs. * 03/27/97 helena Updated to pass the simple test after code review. * 03/31/97 aliu Moved isLONG_MIN to here, and fixed it. * 04/15/97 aliu Changed MAX_COUNT to DBL_DIG. Changed Digit to char. * Reworked representation by replacing fDecimalAt * with fExponent. * 04/16/97 aliu Rewrote set() and getDouble() to use sprintf/atof * to do digit conversion. * 09/09/97 aliu Modified for exponential notation support. * 08/02/98 stephen Added nearest/even rounding * Fixed bug in fitsIntoLong ****************************************************************************** */ #include "unicode/putil.h" #include "digitlst.h" #include <stdlib.h> #include <limits.h> #include <string.h> #include <stdio.h> // *************************************************************************** // class DigitList // This class handles the transcoding between numeric values and strings of // characters. Only handles as non-negative numbers. // *************************************************************************** /** * This is the zero digit. Array elements fDigits[i] have values from * kZero to kZero + 9. Typically, this is '0'. */ #define kZero '0' static char gDecimal = 0; /* Only for 32 bit numbers. Ignore the negative sign. */ static const char LONG_MIN_REP[] = "2147483648"; enum { LONG_MIN_REP_LENGTH = sizeof(LONG_MIN_REP) - 1 //Ignore the NULL at the end }; U_NAMESPACE_BEGIN // ------------------------------------- // default constructor DigitList::DigitList() { clear(); } // ------------------------------------- DigitList::~DigitList() { } // ------------------------------------- // copy constructor DigitList::DigitList(const DigitList &other) { fDigits = fDecimalDigits + 1; // skip the decimal *this = other; } // ------------------------------------- // assignment operator DigitList& DigitList::operator=(const DigitList& other) { if (this != &other) { fDecimalAt = other.fDecimalAt; fCount = other.fCount; fIsPositive = other.fIsPositive; strncpy(fDigits, other.fDigits, fCount); } return *this; } // ------------------------------------- UBool DigitList::operator==(const DigitList& that) const { return ((this == &that) || (fDecimalAt == that.fDecimalAt && fCount == that.fCount && fIsPositive == that.fIsPositive && strncmp(fDigits, that.fDigits, fCount) == 0)); } // ------------------------------------- // Resets the digit list; sets all the digits to zero. void DigitList::clear() { fDigits = fDecimalDigits + 1; // skip the decimal fDecimalAt = 0; fCount = 0; fIsPositive = TRUE; // Don't bother initializing fDigits because fCount is 0. } // ------------------------------------- /** * Formats a number into a base 10 string representation, and NULL terminates it. * @param number The number to format * @param outputStr The string to output to * @param outputLen The maximum number of characters to put into outputStr * (including NULL). * @return the number of digits written, not including the sign. */ static int32_t formatBase10(int32_t number, char *outputStr, int32_t outputLen) { char buffer[MAX_DIGITS + 1]; int32_t bufferLen; if (outputLen > MAX_DIGITS) { outputLen = MAX_DIGITS; // Ignore NULL } else if (outputLen < 3) { return 0; // Not enough room } bufferLen = outputLen; if (number < 0) { // Negative numbers are slightly larger than a postive buffer[bufferLen--] = (char)(-(number % 10) + kZero); number /= -10; *(outputStr++) = '-'; } else { *(outputStr++) = '+'; // allow +0 } while (bufferLen >= 0 && number) { // Output the number buffer[bufferLen--] = (char)(number % 10 + kZero); number /= 10; } outputLen -= bufferLen++; while (bufferLen <= MAX_DIGITS) { // Copy the number to output *(outputStr++) = buffer[bufferLen++]; } *outputStr = 0; // NULL terminate. return outputLen; } /** * Currently, getDouble() depends on atof() to do its conversion. * * WARNING!! * This is an extremely costly function. ~1/2 of the conversion time * can be linked to this function. */ double DigitList::getDouble() { double value; if (fCount == 0) { value = 0.0; } else { if (!gDecimal) { char rep[MAX_DIGITS]; // For machines that decide to change the decimal on you, // and try to be too smart with localization. // This normally should be just a '.'. sprintf(rep, "%+1.1f", 1.0); gDecimal = rep[2]; } *fDecimalDigits = gDecimal; *(fDigits+fCount) = 'e'; // add an e after the digits. formatBase10(fDecimalAt, fDigits + fCount + 1, // skip the 'e' MAX_DEC_DIGITS - fCount - 3); // skip the 'e' and '.' value = atof(fDecimalDigits); } return fIsPositive ? value : -value; } // ------------------------------------- /** * Make sure that fitsIntoLong() is called before calling this function. */ int32_t DigitList::getLong() { if (fCount == fDecimalAt) { int32_t value; fDigits[fCount] = 0; // NULL terminate // This conversion is bad on 64-bit platforms when we want to // be able to return a 64-bit number [grhoten] *fDecimalDigits = fIsPositive ? '+' : '-'; value = (int32_t)atol(fDecimalDigits); return value; } else { // This is 100% accurate in c++ because if we are representing // an integral value, we suffer nothing in the conversion to // double. If we are to support 64-bit longs later, getLong() // must be rewritten. [LIU] return (int32_t)getDouble(); } } /** * Return true if the number represented by this object can fit into * a long. */ UBool DigitList::fitsIntoLong(UBool ignoreNegativeZero) { // Figure out if the result will fit in a long. We have to // first look for nonzero digits after the decimal point; // then check the size. If the digit count is 18 or less, then // the value can definitely be represented as a long. If it is 19 // then it may be too large. // Trim trailing zeros after the decimal point. This does not change // the represented value. while (fCount > fDecimalAt && fCount > 0 && fDigits[fCount - 1] == kZero) --fCount; if (fCount == 0) { // Positive zero fits into a long, but negative zero can only // be represented as a double. - bug 4162852 return fIsPositive || ignoreNegativeZero; } // initializeLONG_MIN_REP(); // If the digit list represents a double or this number is too // big for a long. if (fDecimalAt < fCount || fDecimalAt > LONG_MIN_REP_LENGTH) return FALSE; // If number is small enough to fit in a long if (fDecimalAt < LONG_MIN_REP_LENGTH) return TRUE; // At this point we have fDecimalAt == fCount, and fCount == LONG_MIN_REP_LENGTH. // The number will overflow if it is larger than LONG_MAX // or smaller than LONG_MIN. for (int32_t i=0; i<fCount; ++i) { char dig = fDigits[i], max = LONG_MIN_REP[i]; if (dig > max) return FALSE; if (dig < max) return TRUE; } // At this point the first count digits match. If fDecimalAt is less // than count, then the remaining digits are zero, and we return true. if (fCount < fDecimalAt) return TRUE; // Now we have a representation of Long.MIN_VALUE, without the leading // negative sign. If this represents a positive value, then it does // not fit; otherwise it fits. return !fIsPositive; } // ------------------------------------- /** * @param maximumDigits The maximum digits to be generated. If zero, * there is no maximum -- generate all digits. */ void DigitList::set(int32_t source, int32_t maximumDigits) { fCount = fDecimalAt = formatBase10(source, fDecimalDigits, MAX_DIGITS); fIsPositive = (*fDecimalDigits == '+'); // Don't copy trailing zeros while (fCount > 1 && fDigits[fCount - 1] == kZero) --fCount; if(maximumDigits > 0) round(maximumDigits); } /** * Set the digit list to a representation of the given double value. * This method supports both fixed-point and exponential notation. * @param source Value to be converted; must not be Inf, -Inf, Nan, * or a value <= 0. * @param maximumDigits The most fractional or total digits which should * be converted. If total digits, and the value is zero, then * there is no maximum -- generate all digits. * @param fixedPoint If true, then maximumDigits is the maximum * fractional digits to be converted. If false, total digits. */ void DigitList::set(double source, int32_t maximumDigits, UBool fixedPoint) { // for now, simple implementation; later, do proper IEEE stuff char rep[MAX_DIGITS + 8]; // Extra space for '+', '.', e+NNN, and '\0' (actually +8 is enough) char *digitPtr = fDigits; char *repPtr = rep + 2; // +2 to skip the sign and decimal int32_t exponent = 0; fIsPositive = !uprv_isNegative(source); // Allow +0 and -0 // Generate a representation of the form /[+-][0-9]+e[+-][0-9]+/ sprintf(rep, "%+1.*e", MAX_DIGITS - 1, source); fDecimalAt = 0; rep[2] = rep[1]; // remove decimal while (*repPtr == kZero) { repPtr++; fDecimalAt--; // account for leading zeros } while (*repPtr != 'e') { *(digitPtr++) = *(repPtr++); } fCount = MAX_DIGITS + fDecimalAt; // Parse an exponent of the form /[eE][+-][0-9]+/ UBool negExp = (*(++repPtr) == '-'); while (*(++repPtr) != 0) { exponent = 10*exponent + *repPtr - kZero; } if (negExp) { exponent = -exponent; } fDecimalAt += exponent + 1; // +1 for decimal removal // The negative of the exponent represents the number of leading // zeros between the decimal and the first non-zero digit, for // a value < 0.1 (e.g., for 0.00123, -decimalAt == 2). If this // is more than the maximum fraction digits, then we have an underflow // for the printed representation. if (fixedPoint && -fDecimalAt >= maximumDigits) { // If we round 0.0009 to 3 fractional digits, then we have to // create a new one digit in the least significant location. if (-fDecimalAt == maximumDigits && shouldRoundUp(0)) { fCount = 1; ++fDecimalAt; fDigits[0] = (char)'1'; } else { // Handle an underflow to zero when we round something like // 0.0009 to 2 fractional digits. fCount = 0; } return; } // Eliminate digits beyond maximum digits to be displayed. // Round up if appropriate. Do NOT round in the special // case where maximumDigits == 0 and fixedPoint is FALSE. if (fixedPoint || (0 < maximumDigits && maximumDigits < fCount)) { round(fixedPoint ? (maximumDigits + fDecimalAt) : maximumDigits); } else { // Eliminate trailing zeros. while (fCount > 1 && fDigits[fCount - 1] == kZero) --fCount; } } // ------------------------------------- /** * Round the representation to the given number of digits. * @param maximumDigits The maximum number of digits to be shown. * Upon return, count will be less than or equal to maximumDigits. */ void DigitList::round(int32_t maximumDigits) { // Eliminate digits beyond maximum digits to be displayed. // Round up if appropriate. if (maximumDigits >= 0 && maximumDigits < fCount) { if (shouldRoundUp(maximumDigits)) { // Rounding up involved incrementing digits from LSD to MSD. // In most cases this is simple, but in a worst case situation // (9999..99) we have to adjust the decimalAt value. while (--maximumDigits >= 0 && ++fDigits[maximumDigits] > '9') ; if (maximumDigits < 0) { // We have all 9's, so we increment to a single digit // of one and adjust the exponent. fDigits[0] = (char) '1'; ++fDecimalAt; maximumDigits = 1; // Adjust the count } else { ++maximumDigits; // Increment for use as count } } fCount = maximumDigits; } // Eliminate trailing zeros. while (fCount > 1 && fDigits[fCount-1] == kZero) { --fCount; } } /** * Return true if truncating the representation to the given number * of digits will result in an increment to the last digit. This * method implements half-even rounding, the default rounding mode. * [bnf] * @param maximumDigits the number of digits to keep, from 0 to * <code>count-1</code>. If 0, then all digits are rounded away, and * this method returns true if a one should be generated (e.g., formatting * 0.09 with "#.#"). * @return true if digit <code>maximumDigits-1</code> should be * incremented */ UBool DigitList::shouldRoundUp(int32_t maximumDigits) { // Implement IEEE half-even rounding if (fDigits[maximumDigits] == '5' ) { for (int i=maximumDigits+1; i<fCount; ++i) { if (fDigits[i] != kZero) { return TRUE; } } return maximumDigits > 0 && (fDigits[maximumDigits-1] % 2 != 0); } return (fDigits[maximumDigits] > '5'); } // ------------------------------------- // In the Java implementation, we need a separate set(long) because 64-bit longs // have too much precision to fit into a 64-bit double. In C++, longs can just // be passed to set(double) as long as they are 32 bits in size. We currently // don't implement 64-bit longs in C++, although the code below would work for // that with slight modifications. [LIU] /* void DigitList::set(long source) { // handle the special case of zero using a standard exponent of 0. // mathematically, the exponent can be any value. if (source == 0) { fcount = 0; fDecimalAt = 0; return; } // we don't accept negative numbers, with the exception of long_min. // long_min is treated specially by being represented as long_max+1, // which is actually an impossible signed long value, so there is no // ambiguity. we do this for convenience, so digitlist can easily // represent the digits of a long. bool islongmin = (source == long_min); if (islongmin) { source = -(source + 1); // that is, long_max islongmin = true; } sprintf(fdigits, "%d", source); // now we need to compute the exponent. it's easy in this case; it's // just the same as the count. e.g., 0.123 * 10^3 = 123. fcount = strlen(fdigits); fDecimalAt = fcount; // here's how we represent long_max + 1. note that we always know // that the last digit of long_max will not be 9, because long_max // is of the form (2^n)-1. if (islongmin) ++fdigits[fcount-1]; // finally, we trim off trailing zeros. we don't alter fDecimalAt, // so this has no effect on the represented value. we know the first // digit is non-zero (see code above), so we only have to check down // to fdigits[1]. while (fcount > 1 && fdigits[fcount-1] == kzero) --fcount; } */ /** * Return true if this object represents the value zero. Anything with * no digits, or all zero digits, is zero, regardless of fDecimalAt. */ UBool DigitList::isZero() const { for (int32_t i=0; i<fCount; ++i) if (fDigits[i] != kZero) return FALSE; return TRUE; } /** * We represent LONG_MIN internally as LONG_MAX + 1. This is actually an impossible * value, for positive long integers, so we are safe in doing so. */ /* // This code is unused. UBool DigitList::isLONG_MIN() const { // initializeLONG_MIN_REP(); if (fCount != LONG_MIN_REP_LENGTH) return FALSE; for (int32_t i = 0; i < LONG_MIN_REP_LENGTH; ++i) { if (fDigits[i] != LONG_MIN_REP[i+1]) return FALSE; } return TRUE; } */ // Initialize the LONG_MIN representation buffer. Note that LONG_MIN // is stored as LONG_MAX+1 (LONG_MIN without the negative sign). /*void DigitList::initializeLONG_MIN_REP() { if (LONG_MIN_REP_LENGTH == 0) { char buf[LONG_DIGITS]; sprintf(buf, "%d", INT32_MIN); LONG_MIN_REP_LENGTH = strlen(buf) - 1; // assert(LONG_MIN_REP_LENGTH == LONG_DIGITS); for (int32_t i=1; i<=LONG_MIN_REP_LENGTH; ++i) LONG_MIN_REP[i-1] = buf[i]; } }*/ U_NAMESPACE_END //eof