63 lines
1.1 KiB
C
63 lines
1.1 KiB
C
/* $Header$ */
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#ifndef NOFLOAT
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extern char *ecvt();
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#define NDIGINEXP(exp) (((exp) >= 100 || (exp) <= -100) ? 3 : 2)
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char *
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gcvt(value, ndigit, buf)
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double value;
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char *buf;
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register int ndigit;
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{
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int sign, dp;
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register char *s1, *s2;
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register int i;
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s1 = ecvt(value, ndigit, &dp, &sign);
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s2 = buf;
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if (sign) *s2++ = '-';
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for (i = ndigit - 1; i > 0 && s1[i] == '0'; i--) ndigit--;
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if (dp - ndigit > NDIGINEXP(dp) + 2 || dp < -NDIGINEXP(dp) - 1) {
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/* Use E format, otherwise we need too many '0''s */
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dp--;
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*s2++ = *s1++;
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*s2++ = '.';
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while (--ndigit > 0) *s2++ = *s1++;
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*s2++ = 'e';
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if (dp < 0) {
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*s2++ = '-';
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dp = -dp;
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}
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else *s2++ = '+';
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s2 += NDIGINEXP(dp);
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*s2 = 0;
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for (i = NDIGINEXP(dp); i > 0; i--) {
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*--s2 = dp % 10 + '0';
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dp /= 10;
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}
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return buf;
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}
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if (dp <= 0) {
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if (*s1 != '0') {
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/* otherwise the whole number is 0 */
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*s2++ = '.';
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}
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while (dp < 0) {
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dp++;
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*s2++ = '0';
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}
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}
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for (i = 1; i <= ndigit; i++) {
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*s2++ = *s1++;
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if (i == dp) *s2++ = '.';
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}
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if (i <= dp) {
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while (i++ <= dp) *s2++ = '0';
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*s2++ = '.';
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}
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if (s2[-1]=='.') s2--;
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*s2 = '\0';
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return buf;
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}
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#endif
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