ref: ad26dc48a6dc05da02f96e5f1e7b82de58ff5b2c
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; }