zeek/src/modp_numtoa.c

415 lines
11 KiB
C

/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
/* vi: set expandtab shiftwidth=4 tabstop=4: */
#include "zeek/modp_numtoa.h"
#include <stdint.h>
#include <stdio.h>
#include <math.h>
#include <limits.h>
// other interesting references on num to string convesion
// http://www.jb.man.ac.uk/~slowe/cpp/itoa.html
// and http://www.ddj.com/dept/cpp/184401596?pgno=6
// Version 19-Nov-2007
// Fixed round-to-even rules to match printf
// thanks to Johannes Otepka
/**
* Powers of 10
* 10^0 to 10^9
*/
static const double _pow10[] = {1, 10, 100, 1000, 10000, 100000, 1000000,
10000000, 100000000, 1000000000};
static void strreverse(char* begin, char* end)
{
char aux;
while (end > begin)
aux = *end, *end-- = *begin, *begin++ = aux;
}
void modp_itoa10(int32_t value, char* str)
{
char* wstr=str;
// Take care of sign
unsigned int uvalue = (value < 0) ? -value : value;
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (uvalue % 10)); while(uvalue /= 10);
if (value < 0) *wstr++ = '-';
*wstr='\0';
// Reverse string
strreverse(str,wstr-1);
}
void modp_uitoa10(uint32_t value, char* str)
{
char* wstr=str;
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (value % 10)); while (value /= 10);
*wstr='\0';
// Reverse string
strreverse(str, wstr-1);
}
void modp_litoa10(int64_t value, char* str)
{
char* wstr=str;
uint64_t uvalue = (value < 0) ? (value == INT64_MIN ? (uint64_t)(INT64_MAX) + 1 : -value) : value;
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (uvalue % 10)); while(uvalue /= 10);
if (value < 0) *wstr++ = '-';
*wstr='\0';
// Reverse string
strreverse(str,wstr-1);
}
void modp_ulitoa10(uint64_t value, char* str)
{
char* wstr=str;
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (value % 10)); while (value /= 10);
*wstr='\0';
// Reverse string
strreverse(str, wstr-1);
}
void modp_dtoa(double value, char* str, int prec)
{
/* Hacky test for NaN
* under -fast-math this won't work, but then you also won't
* have correct nan values anyways. The alternative is
* to link with libmath (bad) or hack IEEE double bits (bad)
*/
if (! (value == value)) {
str[0] = 'n'; str[1] = 'a'; str[2] = 'n'; str[3] = '\0';
return;
}
/* we'll work in positive values and deal with the
negative sign issue later */
int neg = 0;
if (value < 0) {
neg = 1;
value = -value;
}
/* if input is larger than thres_max, revert to exponential */
const double thres_max = (double)(INT_MAX);
/* for very large numbers switch back to native sprintf for exponentials.
anyone want to write code to replace this? */
/*
normal printf behavior is to print EVERY whole number digit
which can be 100s of characters overflowing your buffers == bad
*/
if (value >= thres_max) {
sprintf(str, "%e", neg ? -value : value);
return;
}
double diff = 0.0;
char* wstr = str;
if (prec < 0) {
prec = 0;
} else if (prec > 9) {
/* precision of >= 10 can lead to overflow errors */
prec = 9;
}
int whole = (int) value;
double tmp = (value - whole) * _pow10[prec];
uint32_t frac = (uint32_t)(tmp);
diff = tmp - frac;
if (diff > 0.5) {
++frac;
/* handle rollover, e.g. case 0.99 with prec 1 is 1.0 */
if (frac >= _pow10[prec]) {
frac = 0;
++whole;
}
} else if (diff == 0.5 && ((frac == 0) || (frac & 1))) {
/* if halfway, round up if odd, OR
if last digit is 0. That last part is strange */
++frac;
}
if (prec == 0) {
diff = value - whole;
if (diff > 0.5) {
/* greater than 0.5, round up, e.g. 1.6 -> 2 */
++whole;
} else if (diff == 0.5 && (whole & 1)) {
/* exactly 0.5 and ODD, then round up */
/* 1.5 -> 2, but 2.5 -> 2 */
++whole;
}
} else {
int count = prec;
// now do fractional part, as an unsigned number
do {
--count;
*wstr++ = (char)(48 + (frac % 10));
} while (frac /= 10);
// add extra 0s
while (count-- > 0) *wstr++ = '0';
// add decimal
*wstr++ = '.';
}
// do whole part
// Take care of sign
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (whole % 10)); while (whole /= 10);
if (neg) {
*wstr++ = '-';
}
*wstr='\0';
strreverse(str, wstr-1);
}
// This is near identical to modp_dtoa above
// The differnce is noted below
void modp_dtoa2(double value, char* str, int prec)
{
/* Hacky test for NaN
* under -fast-math this won't work, but then you also won't
* have correct nan values anyways. The alternative is
* to link with libmath (bad) or hack IEEE double bits (bad)
*/
if (! (value == value)) {
str[0] = 'n'; str[1] = 'a'; str[2] = 'n'; str[3] = '\0';
return;
}
/* we'll work in positive values and deal with the
negative sign issue later */
int neg = 0;
if (value < 0) {
neg = 1;
value = -value;
}
/* if input is larger than thres_max, revert to exponential */
const double thres_max = (double)(INT_MAX);
/* for very large numbers switch back to native sprintf for exponentials.
anyone want to write code to replace this? */
/*
normal printf behavior is to print EVERY whole number digit
which can be 100s of characters overflowing your buffers == bad
*/
if (value >= thres_max) {
sprintf(str, "%e", neg ? -value : value);
return;
}
int count;
double diff = 0.0;
char* wstr = str;
if (prec < 0) {
prec = 0;
} else if (prec > 9) {
/* precision of >= 10 can lead to overflow errors */
prec = 9;
}
int whole = (int) value;
double tmp = (value - whole) * _pow10[prec];
uint32_t frac = (uint32_t)(tmp);
diff = tmp - frac;
if (diff > 0.5) {
++frac;
/* handle rollover, e.g. case 0.99 with prec 1 is 1.0 */
if (frac >= _pow10[prec]) {
frac = 0;
++whole;
}
} else if (diff == 0.5 && ((frac == 0) || (frac & 1))) {
/* if halfway, round up if odd, OR
if last digit is 0. That last part is strange */
++frac;
}
if (prec == 0) {
diff = value - whole;
if (diff > 0.5) {
/* greater than 0.5, round up, e.g. 1.6 -> 2 */
++whole;
} else if (diff == 0.5 && (whole & 1)) {
/* exactly 0.5 and ODD, then round up */
/* 1.5 -> 2, but 2.5 -> 2 */
++whole;
}
//vvvvvvvvvvvvvvvvvvv Diff from modp_dto2
} else if (frac) {
count = prec;
// now do fractional part, as an unsigned number
// we know it is not 0 but we can have leading zeros, these
// should be removed
while (!(frac % 10)) {
--count;
frac /= 10;
}
//^^^^^^^^^^^^^^^^^^^ Diff from modp_dto2
// now do fractional part, as an unsigned number
do {
--count;
*wstr++ = (char)(48 + (frac % 10));
} while (frac /= 10);
// add extra 0s
while (count-- > 0) *wstr++ = '0';
// add decimal
*wstr++ = '.';
}
// do whole part
// Take care of sign
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (whole % 10)); while (whole /= 10);
if (neg) {
*wstr++ = '-';
}
*wstr='\0';
strreverse(str, wstr-1);
}
// This is near identical to modp_dtoa2 above, excep that it never uses
// exponential notation and requires a buffer length.
void modp_dtoa3(double value, char* str, int n, int prec)
{
/* Hacky test for NaN
* under -fast-math this won't work, but then you also won't
* have correct nan values anyways. The alternative is
* to link with libmath (bad) or hack IEEE double bits (bad)
*/
if (! (value == value)) {
str[0] = 'n'; str[1] = 'a'; str[2] = 'n'; str[3] = '\0';
return;
}
/* we'll work in positive values and deal with the
negative sign issue later */
int neg = 0;
if (value < 0) {
neg = 1;
value = -value;
}
if (prec < 0) {
prec = 0;
} else if (prec > 9) {
/* precision of >= 10 can lead to overflow errors */
prec = 9;
}
/* if input is larger than thres_max, revert to exponential */
const double thres_max = (double)(INT_MAX);
/* for very large numbers switch back to native sprintf for exponentials.
anyone want to write code to replace this? */
/*
normal printf behavior is to print EVERY whole number digit
which can be 100s of characters overflowing your buffers == bad
*/
if (value >= thres_max) {
/* ---- Modified part, compared to modp_dtoa3. */
int i = snprintf(str, n, "%.*f", prec, neg ? -value : value);
if ( i < 0 || i >= n ) {
// Error or truncated output.
snprintf(str, n, "NAN");
return;
}
/* Remove trailing zeros. */
char* p;
for ( p = str + i - 1; p >= str && *p == '0'; --p );
if ( p >= str && *p == '.' )
--p;
*++p = '\0';
return;
/* ---- End of modified part.. */
}
int count;
double diff = 0.0;
char* wstr = str;
int whole = (int) value;
double tmp = (value - whole) * _pow10[prec];
uint32_t frac = (uint32_t)(tmp);
diff = tmp - frac;
if (diff > 0.5) {
++frac;
/* handle rollover, e.g. case 0.99 with prec 1 is 1.0 */
if (frac >= _pow10[prec]) {
frac = 0;
++whole;
}
} else if (diff == 0.5 && ((frac == 0) || (frac & 1))) {
/* if halfway, round up if odd, OR
if last digit is 0. That last part is strange */
++frac;
}
if (prec == 0) {
diff = value - whole;
if (diff > 0.5) {
/* greater than 0.5, round up, e.g. 1.6 -> 2 */
++whole;
} else if (diff == 0.5 && (whole & 1)) {
/* exactly 0.5 and ODD, then round up */
/* 1.5 -> 2, but 2.5 -> 2 */
++whole;
}
//vvvvvvvvvvvvvvvvvvv Diff from modp_dto2
} else if (frac) {
count = prec;
// now do fractional part, as an unsigned number
// we know it is not 0 but we can have leading zeros, these
// should be removed
while (!(frac % 10)) {
--count;
frac /= 10;
}
//^^^^^^^^^^^^^^^^^^^ Diff from modp_dto2
// now do fractional part, as an unsigned number
do {
--count;
*wstr++ = (char)(48 + (frac % 10));
} while (frac /= 10);
// add extra 0s
while (count-- > 0) *wstr++ = '0';
// add decimal
*wstr++ = '.';
}
// do whole part
// Take care of sign
// Conversion. Number is reversed.
do *wstr++ = (char)(48 + (whole % 10)); while (whole /= 10);
if (neg) {
*wstr++ = '-';
}
*wstr='\0';
strreverse(str, wstr-1);
}