/* ecvt, fcvt -- convert floating-point numbers to ascii -*- C -*- */ /* Copyright (c) 2009 Ian Piumarta * * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the 'Software'), to * deal in the Software without restriction, including without limitation the * rights to use, copy, modify, merge, publish, distribute, and/or sell copies * of the Software, and to permit persons to whom the Software is furnished to * do so, provided that the above copyright notice(s) and this permission * notice appear in all copies of the Software. Inclusion of the above * copyright notice(s) and this permission notice in supporting documentation * would be appreciated but is not required. * * THE SOFTWARE IS PROVIDED 'AS IS'. USE ENTIRELY AT YOUR OWN RISK. */ /* This file provides replacements for the functions ecvt() and fcvt() that * were recently deprecated in POSIX. The interface and behaviour is identical * to the functions that they replace (and faster too, at least on my machine). * They have been tested on 32- and 64-bit machines of both orientations. * * For details on the use of these functions, see your ecvt(3) manual page. If * you don't have one handy, there might still be one available here: * http://opengroup.org/onlinepubs/007908799/xsh/ecvt.html */ #include #include #include #include static char *convert(double value, int ndigit, int *decpt, int *sign, int fflag) { static char *buf= 0; static int bufsize= 0; union { uint64_t l; double f; } x; x.f= value; int exp2= (0x7ff & (x.l >> 52)) -1023; uint64_t mant= x.l & 0x000fffffffffffffULL; if ((*sign= x.l >> 63)) value= -value; if (exp2 == 0x400) { *decpt= 0; return mant ? "nan" : "inf"; } int exp10= (value == 0) ? !fflag : (int)ceil(log10(value)); if (exp10 < -307) exp10= -307; /* otherwise overflow in pow() */ value *= pow(10.0, -exp10); if (value) { while (value < 0.1) { value *= 10; --exp10; } while (value >= 1.0) { value /= 10; ++exp10; } } assert(value == 0 || (0.1 <= value && value < 1.0)); if (fflag) { if (ndigit + exp10 < 0) { *decpt= -ndigit; return ""; } ndigit += exp10; } *decpt= exp10; if (bufsize < ndigit + 2) { bufsize= ndigit + 2; buf= buf ? realloc(buf, bufsize) : malloc(bufsize); } int ptr= 1; #if 0 /* slow and safe (and dreadfully boring) */ while (ptr <= ndigit) { double i; value= modf(value * 10, &i); buf[ptr++]= '0' + (int)i; } if (value >= 0.5) while (--ptr && ++buf[ptr] > '9') buf[ptr]= '0'; #else /* faster */ x.f= value; exp2= (0x7ff & (x.l >> 52)) -1023; assert(value == 0 || (-4 <= exp2 && exp2 <= -1)); mant= x.l & 0x000fffffffffffffULL; if (exp2 == -1023) ++exp2; else mant |= 0x0010000000000000ULL; mant <<= (exp2 + 4); /* 56-bit denormalised signifier */ while (ptr <= ndigit) { mant &= 0x00ffffffffffffffULL; /* mod 1.0 */ mant= (mant << 1) + (mant << 3); buf[ptr++]= '0' + (mant >> 56); } if (mant & 0x0080000000000000ULL) /* 1/2 << 56 */ while (--ptr && ++buf[ptr] > '9') buf[ptr]= '0'; #endif if (ptr) { buf[ndigit + 1]= 0; return buf + 1; } if (fflag) { ++ndigit; ++*decpt; } buf[0]= '1'; buf[ndigit]= 0; return buf; } char *e_cvt(double value, int ndigit, int *decpt, int *sign) { return convert(value, ndigit, decpt, sign, 0); } char *f_cvt(double value, int ndigit, int *decpt, int *sign) { return convert(value, ndigit, decpt, sign, 1); } /* ---------------------------------------------------------------- */ #if defined(TEST_FCVT) #include #include #include int mod10cmp16(char *a, char *b) { int i= 0; while (a[i] == b[i]) if (!a[i]) return 0; else ++i; if (a[i] == b[i] + 1) { while (b[i + 1] == '9' || b[i + 1] == '.') ++i; if (b[i + 1] >= '5') ++i; } else if (b[i] == a[i] + 1) { while (a[i + 1] == '9' || a[i + 1] == '.') ++i; if (a[i + 1] >= '5') ++i; } if ((i >= 15) || (!a[i + 1] && !b[i + 1])) return 0; printf("%d <%s>\n", i, a + i); printf("%d <%s>\n", i, b + i); return 1; } int main(int argc, char **argv) { if (argc > 1) { while (argc > 1) { --argc; ++argv; double d= atof(*argv); printf("%.3f %.20f\n", d, d); int decpt, sign; char *cvtbuf; cvtbuf= ecvt(d, 3, &decpt, &sign); printf("e \t%d\t%d\t<%s>\n", sign, decpt, cvtbuf); cvtbuf= e_cvt(d, 3, &decpt, &sign); printf("e_\t%d\t%d\t<%s>\n", sign, decpt, cvtbuf); cvtbuf= fcvt(d, 3, &decpt, &sign); printf("f \t%d\t%d\t<%s>\n", sign, decpt, cvtbuf); cvtbuf= f_cvt(d, 3, &decpt, &sign); printf("f_\t%d\t%d\t<%s>\n", sign, decpt, cvtbuf); } } else { # define METHOD 1 srandom(getpid()); int i; for (i= 0; i < 100000; ++i) { if (i % 1000 == 0) { printf(" %d\r", i); fflush(stdout); } union { uint32_t l[2]; double f; } x; x.l[0]= random() ^ (random() << 16); x.l[1]= random() ^ (random() << 16); int ossign, osdecpt, mysign, mydecpt; char *osbuf, *mybuf; osbuf= ecvt(x.f, 9, &osdecpt, &ossign); switch (METHOD) { case 0: mybuf= ecvt(x.f, 9, &mydecpt, &mysign); break; case 1: mybuf= e_cvt(x.f, 9, &mydecpt, &mysign); break; } if (ossign != mysign || osdecpt != mydecpt || strcmp(osbuf, mybuf)) { printf("ECVT %08x%08x %.10f\n", x.l[0], x.l[1], x.f); printf("%d\t%d\t<%s>\n", ossign, osdecpt, osbuf); printf("%d\t%d\t<%s>\n", mysign, mydecpt, mybuf); printf("fail\n"); fflush(stdout); abort(); } osbuf= fcvt(x.f, 9, &osdecpt, &ossign); switch (METHOD) { case 0: mybuf= fcvt(x.f, 9, &mydecpt, &mysign); break; case 1: mybuf= f_cvt(x.f, 9, &mydecpt, &mysign); break; } if (ossign != mysign || osdecpt != mydecpt || mod10cmp16(osbuf, mybuf)) { printf("FCVT %08x%08x %.10f\n", x.l[0], x.l[1], x.f); printf("%d\t%d\t<%s>\n", ossign, osdecpt, osbuf); printf("%d\t%d\t<%s>\n", mysign, mydecpt, mybuf); printf("fail\n"); fflush(stdout); abort(); } } printf(" %d\nok\n", i); } return 0; } #endif /* defined(TEST_FCVT) */