ref: f35d5ee5b036b7b4fa59b1839f52fca15b7f99f9
dir: /sys/src/ape/lib/fmt/fltfmt.c/
/*
* The authors of this software are Rob Pike and Ken Thompson.
* Copyright (c) 2002 by Lucent Technologies.
* Permission to use, copy, modify, and distribute this software for any
* purpose without fee is hereby granted, provided that this entire notice
* is included in all copies of any software which is or includes a copy
* or modification of this software and in all copies of the supporting
* documentation for such software.
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
*/
#include <stdio.h>
#include <math.h>
#include <float.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <stdarg.h>
#include "fmt.h"
#include "fmtdef.h"
#include "nan.h"
enum
{
FDEFLT = 6,
NSIGNIF = 17
};
/*
* first few powers of 10, enough for about 1/2 of the
* total space for doubles.
*/
static double pows10[] =
{
1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29,
1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39,
1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49,
1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59,
1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79,
1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89,
1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99,
1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
};
static double
pow10(int n)
{
double d;
int neg;
neg = 0;
if(n < 0){
if(n < DBL_MIN_10_EXP){
return 0.;
}
neg = 1;
n = -n;
}else if(n > DBL_MAX_10_EXP){
return HUGE_VAL;
}
if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
d = pows10[n];
else{
d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
for(;;){
n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
d *= pows10[n];
break;
}
d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
}
}
if(neg){
return 1./d;
}
return d;
}
static int
xadd(char *a, int n, int v)
{
char *b;
int c;
if(n < 0 || n >= NSIGNIF)
return 0;
for(b = a+n; b >= a; b--) {
c = *b + v;
if(c <= '9') {
*b = c;
return 0;
}
*b = '0';
v = 1;
}
*a = '1'; /* overflow adding */
return 1;
}
static int
xsub(char *a, int n, int v)
{
char *b;
int c;
for(b = a+n; b >= a; b--) {
c = *b - v;
if(c >= '0') {
*b = c;
return 0;
}
*b = '9';
v = 1;
}
*a = '9'; /* underflow subtracting */
return 1;
}
static void
xaddexp(char *p, int e)
{
char se[9];
int i;
*p++ = 'e';
if(e < 0) {
*p++ = '-';
e = -e;
}
i = 0;
while(e) {
se[i++] = e % 10 + '0';
e /= 10;
}
if(i == 0) {
*p++ = '0';
} else {
while(i > 0)
*p++ = se[--i];
}
*p++ = '\0';
}
static char*
xdodtoa(char *s1, double f, int chr, int prec, int *decpt, int *rsign)
{
char s2[NSIGNIF+10];
double g, h;
int e, d, i;
int c2, sign, oerr;
if(chr == 'F')
chr = 'f';
if(prec > NSIGNIF)
prec = NSIGNIF;
if(prec < 0)
prec = 0;
if(__isNaN(f)) {
*decpt = 9999;
*rsign = 0;
strcpy(s1, "nan");
return &s1[3];
}
sign = 0;
if(f < 0) {
f = -f;
sign++;
}
*rsign = sign;
if(__isInf(f, 1) || __isInf(f, -1)) {
*decpt = 9999;
strcpy(s1, "inf");
return &s1[3];
}
e = 0;
g = f;
if(g != 0) {
frexp(f, &e);
e = (int)(e * .301029995664);
if(e >= -150 && e <= +150) {
d = 0;
h = f;
} else {
d = e/2;
h = f * pow10(-d);
}
g = h * pow10(d-e);
while(g < 1) {
e--;
g = h * pow10(d-e);
}
while(g >= 10) {
e++;
g = h * pow10(d-e);
}
}
/*
* convert NSIGNIF digits and convert
* back to get accuracy.
*/
for(i=0; i<NSIGNIF; i++) {
d = (int)g;
s1[i] = d + '0';
g = (g - d) * 10;
}
s1[i] = 0;
/*
* try decimal rounding to eliminate 9s
*/
c2 = prec + 1;
if(chr == 'f')
c2 += e;
oerr = errno;
if(c2 >= NSIGNIF-2) {
strcpy(s2, s1);
d = e;
s1[NSIGNIF-2] = '0';
s1[NSIGNIF-1] = '0';
xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
g = fmtstrtod(s1, nil);
if(g == f)
goto found;
if(xadd(s1, NSIGNIF-3, 1)) {
e++;
xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
}
g = fmtstrtod(s1, nil);
if(g == f)
goto found;
strcpy(s1, s2);
e = d;
}
/*
* convert back so s1 gets exact answer
*/
for(d = 0; d < 10; d++) {
xaddexp(s1+NSIGNIF, e-NSIGNIF+1);
g = fmtstrtod(s1, nil);
if(f > g) {
if(xadd(s1, NSIGNIF-1, 1))
e--;
continue;
}
if(f < g) {
if(xsub(s1, NSIGNIF-1, 1))
e++;
continue;
}
break;
}
found:
errno = oerr;
/*
* sign
*/
d = 0;
i = 0;
/*
* round & adjust 'f' digits
*/
c2 = prec + 1;
if(chr == 'f'){
if(xadd(s1, c2+e, 5))
e++;
c2 += e;
if(c2 < 0){
c2 = 0;
e = -prec - 1;
}
}else{
if(xadd(s1, c2, 5))
e++;
}
if(c2 > NSIGNIF){
c2 = NSIGNIF;
}
*decpt = e + 1;
/*
* terminate the converted digits
*/
s1[c2] = '\0';
return &s1[c2];
}
/*
* this function works like the standard dtoa, if you want it.
*/
#if 0
static char*
__dtoa(double f, int mode, int ndigits, int *decpt, int *rsign, char **rve)
{
static char s2[NSIGNIF + 10];
char *es;
int chr, prec;
switch(mode) {
/* like 'e' */
case 2:
case 4:
case 6:
case 8:
chr = 'e';
break;
/* like 'g' */
case 0:
case 1:
default:
chr = 'g';
break;
/* like 'f' */
case 3:
case 5:
case 7:
case 9:
chr = 'f';
break;
}
if(chr != 'f' && ndigits){
ndigits--;
}
prec = ndigits;
if(prec > NSIGNIF)
prec = NSIGNIF;
if(ndigits == 0)
prec = NSIGNIF;
es = xdodtoa(s2, f, chr, prec, decpt, rsign);
/*
* strip trailing 0
*/
for(; es > s2 + 1; es--){
if(es[-1] != '0'){
break;
}
}
*es = '\0';
if(rve != NULL)
*rve = es;
return s2;
}
#endif
static int
fmtzdotpad(Fmt *f, int n, int pt)
{
char *t, *s;
int i;
Rune *rt, *rs;
if(f->runes){
rt = (Rune*)f->to;
rs = (Rune*)f->stop;
for(i = 0; i < n; i++){
if(i == pt){
FMTRCHAR(f, rt, rs, '.');
}
FMTRCHAR(f, rt, rs, '0');
}
f->nfmt += rt - (Rune*)f->to;
f->to = rt;
}else{
t = (char*)f->to;
s = (char*)f->stop;
for(i = 0; i < n; i++){
if(i == pt){
FMTCHAR(f, t, s, '.');
}
FMTCHAR(f, t, s, '0');
}
f->nfmt += t - (char *)f->to;
f->to = t;
}
return 0;
}
int
__efgfmt(Fmt *fmt)
{
double f;
char s1[NSIGNIF+10];
int e, d, n;
int c1, c2, c3, c4, ucase, sign, chr, prec, fl;
f = va_arg(fmt->args, double);
prec = FDEFLT;
fl = fmt->flags;
fmt->flags = 0;
if(fl & FmtPrec)
prec = fmt->prec;
chr = fmt->r;
ucase = 0;
if(chr == 'E'){
chr = 'e';
ucase = 1;
}else if(chr == 'F'){
chr = 'f';
ucase = 1;
}else if(chr == 'G'){
chr = 'g';
ucase = 1;
}
if(prec > 0 && chr == 'g')
prec--;
if(prec < 0)
prec = 0;
xdodtoa(s1, f, chr, prec, &e, &sign);
e--;
if(*s1 == 'i' || *s1 == 'n'){
if(ucase){
if(*s1 == 'i'){
strcpy(s1, "INF");
}else{
strcpy(s1, "NAN");
}
}
fmt->flags = fl & (FmtWidth|FmtLeft);
return __fmtcpy(fmt, (const void*)s1, 3, 3);
}
/*
* copy into final place
* c1 digits of leading '0'
* c2 digits from conversion
* c3 digits of trailing '0'
* c4 digits after '.'
*/
c1 = 0;
c2 = prec + 1;
c3 = 0;
c4 = prec;
switch(chr) {
default:
chr = 'e';
break;
case 'g':
/*
* decide on 'e' of 'f' style convers
*/
if(e >= -4 && e <= prec) {
c1 = -e;
c4 = prec - e;
chr = 'h'; /* flag for 'f' style */
}
break;
case 'f':
c1 = -e;
if(c1 > prec)
c1 = prec + 1;
c2 += e;
break;
}
/*
* clean up c1 c2 and c3
*/
if(c1 < 0)
c1 = 0;
if(c2 < 0)
c2 = 0;
if(c2 > NSIGNIF) {
c3 = c2-NSIGNIF;
c2 = NSIGNIF;
}
/*
* trim trailing zeros for %g
*/
if(!(fl & FmtSharp)
&& (chr == 'g' || chr == 'h')){
if(c4 >= c3){
c4 -= c3;
c3 = 0;
}else{
c3 -= c4;
c4 = 0;
}
while(c4 && c2 > 1 && s1[c2 - 1] == '0'){
c4--;
c2--;
}
}
/*
* calculate the total length
*/
n = c1 + c2 + c3;
if(sign || (fl & (FmtSign|FmtSpace)))
n++;
if(c4 || (fl & FmtSharp)){
n++;
}
if(chr == 'e' || chr == 'g'){
n += 4;
if(e >= 100)
n++;
}
/*
* pad to width if right justified
*/
if((fl & (FmtWidth|FmtLeft)) == FmtWidth && n < fmt->width){
if(fl & FmtZero){
c1 += fmt->width - n;
}else{
if(__fmtpad(fmt, fmt->width - n) < 0){
return -1;
}
}
}
/*
* sign
*/
d = 0;
if(sign)
d = '-';
else if(fl & FmtSign)
d = '+';
else if(fl & FmtSpace)
d = ' ';
if(d && fmtrune(fmt, d) < 0){
return -1;
}
/*
* copy digits
*/
c4 = c1 + c2 + c3 - c4;
if(c1 > 0){
if(fmtzdotpad(fmt, c1, c4) < 0){
return -1;
}
c4 -= c1;
}
d = 0;
if(c4 >= 0 && c4 < c2){
if(__fmtcpy(fmt, s1, c4, c4) < 0 || fmtrune(fmt, '.') < 0)
return -1;
d = c4;
c2 -= c4;
c4 = -1;
}
if(__fmtcpy(fmt, (const void*)(s1 + d), c2, c2) < 0){
return -1;
}
c4 -= c2;
if(c3 > 0){
if(fmtzdotpad(fmt, c3, c4) < 0){
return -1;
}
c4 -= c3;
}
/*
* strip trailing '0' on g conv
*/
if((fl & FmtSharp) && c4 == 0 && fmtrune(fmt, '.') < 0){
return -1;
}
if(chr == 'e' || chr == 'g') {
d = 0;
if(ucase)
s1[d++] = 'E';
else
s1[d++] = 'e';
c1 = e;
if(c1 < 0) {
s1[d++] = '-';
c1 = -c1;
} else
s1[d++] = '+';
if(c1 >= 100) {
s1[d++] = c1/100 + '0';
c1 = c1%100;
}
s1[d++] = c1/10 + '0';
s1[d++] = c1%10 + '0';
if(__fmtcpy(fmt, s1, d, d) < 0){
return -1;
}
}
if((fl & (FmtWidth|FmtLeft)) == (FmtWidth|FmtLeft) && n < fmt->width){
if(__fmtpad(fmt, fmt->width - n) < 0){
return -1;
}
}
return 0;
}