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91 lines
1.8 KiB
C
91 lines
1.8 KiB
C
/*
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* Etoa routine with rounding
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*/
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#include <portab.h>
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BYTE *etoa(x,str,prec)
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FLOAT x; /* Arg to convert */
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BYTE *str; /* -> Output area */
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WORD prec; /* # digits right of dp */
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{
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REG WORD ie,i,k,ndig; /* Temps */
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BYTE *savstr; /* Copy of str to return*/
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DOUBLE y; /* Temp for rounding */
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savstr = str; /* Preserve for later */
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ndig = (prec <= 0) ? 1 : ((prec > 22) ? 23 : prec+1);
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ie = 0;
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if(x < 0) /* Fix for negative */
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{
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*str++ = '-';
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x = -x; /* Negate */
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}
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/*
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* Check for infinity. Normalization will loop on infinity.
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*/
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if(x > 9.223371e18) x = 9.223371e18;
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/*
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* Normalize x to the range 0.0 <= x < 10.0
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*/
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if(x > 0.0)
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{
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while (x < 1.0)
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{
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x *= 10.0;
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ie--;
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}
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}
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while(x >= 10.0)
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{
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x /= 10.0;
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ie++;
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}
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/*
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* Now round.
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*/
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for(y=i=1; i < ndig; i++)
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y = y / 10.0; /* Compute round amount */
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x += (y / 2.0); /* Round by 1/2 lsb */
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if(x >= 10.0) /* Did we push it over 10? */
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{
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x = 1.0;
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ie++;
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}
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/*
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* Now convert result
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*/
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for(i=0; i<ndig; i++)
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{
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k = x; /* Truncate */
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*str++ = k + '0'; /* ASCIIfy */
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if(i == 0) /* Locate decimal point*/
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*str++ = '.';
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x -= (y=k);
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x *= 10.0;
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}
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/*
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* Now output exponent
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*/
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*str++ = 'E';
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if(ie < 0)
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{
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ie = -ie; /* Negate */
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*str++ = '-';
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}
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*str++ = ie/10 + '0'; /* Drop in 1st digit*/
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*str++ = ie%10 + '0'; /* and 2nd digit*/
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*str++ = '\0';
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return(savstr);
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}
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'0'; /* Drop in 1st digit*/
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*str++ = ie%10 + '0'; /* and 2nd digit*/
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*str++ = '\0';
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return(savstr);
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}
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'0'; /* Drop in 1st digit*/
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*str++ = ie%10 + '0'; /* and 2nd digit*/
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*str++ = '\0';
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return(savstr);
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}
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