44 lines
732 B
C
44 lines
732 B
C
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#include "os.h"
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#include <mp.h>
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#include "dat.h"
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//
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// divide two digits by one and return quotient
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//
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void
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mpdigdiv(mpdigit *dividend, mpdigit divisor, mpdigit *quotient)
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{
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mpdigit hi, lo, q, x, y;
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int i;
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hi = dividend[1];
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lo = dividend[0];
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// return highest digit value if the result >= 2**32
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if(hi >= divisor || divisor == 0){
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divisor = 0;
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*quotient = ~divisor;
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return;
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}
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// at this point we know that hi < divisor
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// just shift and subtract till we're done
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q = 0;
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x = divisor;
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for(i = Dbits-1; hi > 0 && i >= 0; i--){
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x >>= 1;
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if(x > hi)
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continue;
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y = divisor<<i;
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if(x == hi && y > lo)
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continue;
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if(y > lo)
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hi--;
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lo -= y;
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hi -= x;
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q |= 1<<i;
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}
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q += lo/divisor;
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*quotient = q;
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}
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