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- /*
- * 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 <u.h>
- #include <libc.h>
- #include <float.h>
- #include <ctype.h>
- #include "fmtdef.h"
- enum
- {
- FDIGIT = 30,
- 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,
- };
- #undef pow10
- #define pow10(x) fmtpow10(x)
- 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
- xdtoa(Fmt *fmt, char *s2, double f)
- {
- char s1[NSIGNIF+10];
- double g, h;
- int e, d, i, n;
- int c1, c2, c3, c4, ucase, sign, chr, prec;
- prec = FDEFLT;
- if(fmt->flags & FmtPrec)
- prec = fmt->prec;
- if(prec > FDIGIT)
- prec = FDIGIT;
- if(__isNaN(f)) {
- strcpy(s2, "NaN");
- return;
- }
- if(__isInf(f, 1)) {
- strcpy(s2, "+Inf");
- return;
- }
- if(__isInf(f, -1)) {
- strcpy(s2, "-Inf");
- return;
- }
- sign = 0;
- if(f < 0) {
- f = -f;
- sign++;
- }
- ucase = 0;
- chr = fmt->r;
- if(isupper(chr)) {
- ucase = 1;
- chr = tolower(chr);
- }
- e = 0;
- g = f;
- if(g != 0) {
- frexp(f, &e);
- e = 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 = 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;
- if(c2 >= NSIGNIF-2) {
- strcpy(s2, s1);
- d = e;
- s1[NSIGNIF-2] = '0';
- s1[NSIGNIF-1] = '0';
- sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
- g = strtod(s1, nil);
- if(g == f)
- goto found;
- if(xadd(s1, NSIGNIF-3, 1)) {
- e++;
- sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
- }
- g = strtod(s1, nil);
- if(g == f)
- goto found;
- strcpy(s1, s2);
- e = d;
- }
- /*
- * convert back so s1 gets exact answer
- */
- for(;;) {
- sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
- g = strtod(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:
- /*
- * sign
- */
- d = 0;
- i = 0;
- if(sign)
- s2[d++] = '-';
- else if(fmt->flags & FmtSign)
- s2[d++] = '+';
- else if(fmt->flags & FmtSpace)
- s2[d++] = ' ';
- /*
- * 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:
- if(xadd(s1, c2, 5))
- e++;
- break;
- case 'g':
- /*
- * decide on 'e' of 'f' style convers
- */
- if(xadd(s1, c2, 5))
- e++;
- if(e >= -5 && e <= prec) {
- c1 = -e - 1;
- c4 = prec - e;
- chr = 'h'; // flag for 'f' style
- }
- break;
- case 'f':
- if(xadd(s1, c2+e, 5))
- e++;
- c1 = -e;
- if(c1 > prec)
- c1 = c2;
- 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;
- }
- /*
- * copy digits
- */
- while(c1 > 0) {
- if(c1+c2+c3 == c4)
- s2[d++] = '.';
- s2[d++] = '0';
- c1--;
- }
- while(c2 > 0) {
- if(c2+c3 == c4)
- s2[d++] = '.';
- s2[d++] = s1[i++];
- c2--;
- }
- while(c3 > 0) {
- if(c3 == c4)
- s2[d++] = '.';
- s2[d++] = '0';
- c3--;
- }
- /*
- * strip trailing '0' on g conv
- */
- if(fmt->flags & FmtSharp) {
- if(0 == c4)
- s2[d++] = '.';
- } else
- if(chr == 'g' || chr == 'h') {
- for(n=d-1; n>=0; n--)
- if(s2[n] != '0')
- break;
- for(i=n; i>=0; i--)
- if(s2[i] == '.') {
- d = n;
- if(i != n)
- d++;
- break;
- }
- }
- if(chr == 'e' || chr == 'g') {
- if(ucase)
- s2[d++] = 'E';
- else
- s2[d++] = 'e';
- c1 = e;
- if(c1 < 0) {
- s2[d++] = '-';
- c1 = -c1;
- } else
- s2[d++] = '+';
- if(c1 >= 100) {
- s2[d++] = c1/100 + '0';
- c1 = c1%100;
- }
- s2[d++] = c1/10 + '0';
- s2[d++] = c1%10 + '0';
- }
- s2[d] = 0;
- }
- static int
- floatfmt(Fmt *fmt, double f)
- {
- char s[341]; /* precision+exponent+sign+'.'+null */
- xdtoa(fmt, s, f);
- fmt->flags &= FmtWidth|FmtLeft;
- __fmtcpy(fmt, s, strlen(s), strlen(s));
- return 0;
- }
- int
- __efgfmt(Fmt *f)
- {
- double d;
- d = va_arg(f->args, double);
- return floatfmt(f, d);
- }
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