376 lines
6.2 KiB
C
376 lines
6.2 KiB
C
#include <u.h>
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#include <libc.h>
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#include <float.h>
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#include <ctype.h>
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#include "fmtdef.h"
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enum
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{
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FDIGIT = 30,
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FDEFLT = 6,
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NSIGNIF = 17
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};
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/*
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* first few powers of 10, enough for about 1/2 of the
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* total space for doubles.
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*/
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static double pows10[] =
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{
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1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
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1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
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1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29,
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1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39,
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1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49,
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1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59,
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1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
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1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79,
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1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89,
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1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99,
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1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
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1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
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1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
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1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
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1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
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1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
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};
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#undef pow10
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#define pow10(x) fmtpow10(x)
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static double
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pow10(int n)
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{
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double d;
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int neg;
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neg = 0;
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if(n < 0){
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if(n < DBL_MIN_10_EXP){
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return 0.;
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}
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neg = 1;
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n = -n;
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}else if(n > DBL_MAX_10_EXP){
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return HUGE_VAL;
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}
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if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
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d = pows10[n];
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else{
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d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
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for(;;){
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n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
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if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
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d *= pows10[n];
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break;
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}
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d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
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}
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}
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if(neg){
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return 1./d;
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}
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return d;
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}
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static int
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xadd(char *a, int n, int v)
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{
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char *b;
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int c;
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if(n < 0 || n >= NSIGNIF)
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return 0;
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for(b = a+n; b >= a; b--) {
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c = *b + v;
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if(c <= '9') {
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*b = c;
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return 0;
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}
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*b = '0';
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v = 1;
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}
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*a = '1'; /* overflow adding */
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return 1;
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}
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static int
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xsub(char *a, int n, int v)
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{
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char *b;
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int c;
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for(b = a+n; b >= a; b--) {
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c = *b - v;
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if(c >= '0') {
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*b = c;
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return 0;
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}
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*b = '9';
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v = 1;
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}
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*a = '9'; /* underflow subtracting */
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return 1;
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}
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static void
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xdtoa(Fmt *fmt, char *s2, double f)
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{
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char s1[NSIGNIF+10];
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double g, h;
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int e, d, i, n;
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int c1, c2, c3, c4, ucase, sign, chr, prec;
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prec = FDEFLT;
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if(fmt->flags & FmtPrec)
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prec = fmt->prec;
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if(prec > FDIGIT)
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prec = FDIGIT;
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if(__isNaN(f)) {
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strcpy(s2, "NaN");
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return;
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}
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if(__isInf(f, 1)) {
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strcpy(s2, "+Inf");
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return;
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}
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if(__isInf(f, -1)) {
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strcpy(s2, "-Inf");
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return;
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}
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sign = 0;
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if(f < 0) {
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f = -f;
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sign++;
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}
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ucase = 0;
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chr = fmt->r;
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if(isupper(chr)) {
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ucase = 1;
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chr = tolower(chr);
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}
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e = 0;
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g = f;
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if(g != 0) {
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frexp(f, &e);
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e = e * .301029995664;
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if(e >= -150 && e <= +150) {
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d = 0;
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h = f;
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} else {
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d = e/2;
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h = f * pow10(-d);
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}
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g = h * pow10(d-e);
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while(g < 1) {
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e--;
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g = h * pow10(d-e);
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}
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while(g >= 10) {
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e++;
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g = h * pow10(d-e);
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}
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}
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/*
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* convert NSIGNIF digits and convert
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* back to get accuracy.
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*/
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for(i=0; i<NSIGNIF; i++) {
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d = g;
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s1[i] = d + '0';
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g = (g - d) * 10;
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}
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s1[i] = 0;
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/*
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* try decimal rounding to eliminate 9s
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*/
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c2 = prec + 1;
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if(chr == 'f')
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c2 += e;
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if(c2 >= NSIGNIF-2) {
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strcpy(s2, s1);
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d = e;
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s1[NSIGNIF-2] = '0';
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s1[NSIGNIF-1] = '0';
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sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
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g = strtod(s1, nil);
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if(g == f)
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goto found;
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if(xadd(s1, NSIGNIF-3, 1)) {
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e++;
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sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
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}
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g = strtod(s1, nil);
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if(g == f)
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goto found;
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strcpy(s1, s2);
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e = d;
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}
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/*
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* convert back so s1 gets exact answer
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*/
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for(;;) {
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sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
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g = strtod(s1, nil);
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if(f > g) {
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if(xadd(s1, NSIGNIF-1, 1))
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e--;
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continue;
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}
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if(f < g) {
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if(xsub(s1, NSIGNIF-1, 1))
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e++;
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continue;
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}
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break;
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}
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found:
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/*
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* sign
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*/
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d = 0;
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i = 0;
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if(sign)
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s2[d++] = '-';
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else if(fmt->flags & FmtSign)
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s2[d++] = '+';
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else if(fmt->flags & FmtSpace)
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s2[d++] = ' ';
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/*
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* copy into final place
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* c1 digits of leading '0'
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* c2 digits from conversion
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* c3 digits of trailing '0'
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* c4 digits after '.'
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*/
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c1 = 0;
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c2 = prec + 1;
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c3 = 0;
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c4 = prec;
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switch(chr) {
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default:
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if(xadd(s1, c2, 5))
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e++;
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break;
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case 'g':
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/*
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* decide on 'e' of 'f' style convers
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*/
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if(xadd(s1, c2, 5))
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e++;
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if(e >= -5 && e <= prec) {
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c1 = -e - 1;
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c4 = prec - e;
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chr = 'h'; // flag for 'f' style
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}
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break;
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case 'f':
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if(xadd(s1, c2+e, 5))
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e++;
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c1 = -e;
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if(c1 > prec)
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c1 = c2;
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c2 += e;
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break;
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}
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/*
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* clean up c1 c2 and c3
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*/
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if(c1 < 0)
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c1 = 0;
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if(c2 < 0)
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c2 = 0;
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if(c2 > NSIGNIF) {
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c3 = c2-NSIGNIF;
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c2 = NSIGNIF;
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}
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/*
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* copy digits
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*/
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while(c1 > 0) {
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if(c1+c2+c3 == c4)
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s2[d++] = '.';
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s2[d++] = '0';
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c1--;
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}
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while(c2 > 0) {
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if(c2+c3 == c4)
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s2[d++] = '.';
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s2[d++] = s1[i++];
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c2--;
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}
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while(c3 > 0) {
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if(c3 == c4)
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s2[d++] = '.';
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s2[d++] = '0';
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c3--;
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}
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/*
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* strip trailing '0' on g conv
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*/
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if(fmt->flags & FmtSharp) {
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if(0 == c4)
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s2[d++] = '.';
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} else
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if(chr == 'g' || chr == 'h') {
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for(n=d-1; n>=0; n--)
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if(s2[n] != '0')
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break;
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for(i=n; i>=0; i--)
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if(s2[i] == '.') {
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d = n;
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if(i != n)
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d++;
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break;
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}
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}
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if(chr == 'e' || chr == 'g') {
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if(ucase)
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s2[d++] = 'E';
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else
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s2[d++] = 'e';
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c1 = e;
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if(c1 < 0) {
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s2[d++] = '-';
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c1 = -c1;
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} else
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s2[d++] = '+';
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if(c1 >= 100) {
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s2[d++] = c1/100 + '0';
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c1 = c1%100;
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}
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s2[d++] = c1/10 + '0';
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s2[d++] = c1%10 + '0';
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}
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s2[d] = 0;
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}
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static int
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floatfmt(Fmt *fmt, double f)
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{
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char s[341]; /* precision+exponent+sign+'.'+null */
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xdtoa(fmt, s, f);
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fmt->flags &= FmtWidth|FmtLeft;
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__fmtcpy(fmt, s, strlen(s), strlen(s));
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return 0;
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}
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int
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__efgfmt(Fmt *f)
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{
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double d;
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d = va_arg(f->args, double);
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return floatfmt(f, d);
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}
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