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https://github.com/SEPPDROID/Digital-Research-Source-Code.git
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118 lines
2.2 KiB
C
118 lines
2.2 KiB
C
/*
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Copyright 1982
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Alcyon Corporation
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8716 Production Ave.
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San Diego, Ca. 92121
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*/
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/*char *version "@(#) etoa - jan 24, 1982"; */
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/*
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* IEEE Floating Point to Ascii String Conversion Routine :
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* IEEE Standard Single Precision Representation Floating Point
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*
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* char *
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* etoa(f,buf,prec)
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* float f;
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* char *buf;
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* int prec;
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*
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* No more than 9 decimal digits are allowed in single precision.
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* Largest positive number is 3.4 * 10^33 and the smallest positive
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* number is 1.2 * 10^-38.
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* Rely's on the fact that a long and a float are both 32 bits.
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*/
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#define BIAS 127L
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#ifndef ISIEEE
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/* if this is compiled or executed with other than ieee fp */
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float _ieeetof();
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#else
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float _efake();
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#endif
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char *
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etoa(fl,buf,prec)
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long fl; /* ieee formatted float */
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char *buf;
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int prec;
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{
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register char *bp;
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register int exp, digit;
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float f;
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prec = (prec <= 0) ? 1 : (prec <= 9) ? prec : 9;
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bp = buf;
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if(fl == 0) goto shortcut;
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if(fl == 0x7f800000) { /* positive infinity */
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strcpy(bp,"+infinity");
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return(bp);
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}
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if(fl == 0xff800000) { /* negative infinity */
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strcpy(bp,"-infinity");
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return(bp);
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}
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#ifndef ISIEEE
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f = _ieeetof(fl); /* get floating point value */
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#else
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f = _efake(fl);
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#endif
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#ifndef ISIEEE
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if (f < 0.0) { /* negative float */
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#else
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if (fl & 0x80000000) { /* negative float */
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#endif
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*bp++ = '-';
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f = -f; /* make it positive */
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}
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#ifndef ISIEEE
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if (f == 0.0) {
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#else
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if (fl == 0) {
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#endif
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shortcut:
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*bp++ = '0'; *bp++ = '.';
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while (prec--)
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*bp++ = '0';
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*bp++ = 'e'; *bp++ = '0'; *bp++ = '0'; *bp = 0;
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return(buf);
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}
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for (exp=0; f < 1.0; f = f * 10.0) /* get negative exp */
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exp--;
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for ( ; f >= 1.0; f = f / 10.0) /* 0.XXXXXXE00 * 10^exp */
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exp++;
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exp--; /* for one explicit digit */
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f = f * 10.0;
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digit = f; /* get one digit */
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f = f - digit;
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*bp++ = digit + '0';
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*bp++ = '.';
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while(prec-- > 0) { /* get prec. decimal places */
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f = f * 10.0;
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digit = f;
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f = f - digit;
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*bp++ = digit + '0';
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}
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*bp++ = 'e';
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if (exp < 0) {
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exp = -exp;
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*bp++ = '-';
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}
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*bp++ = (exp / 10) + '0';
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*bp++ = (exp % 10) + '0';
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*bp = 0;
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return(buf);
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}
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#ifdef ISIEEE
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/* if these routines are executed on a 68000 using ieee then no need to
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do a translation !!! */
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float
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_efake(lf)
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float lf;
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{
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return(lf);
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}
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#endif
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