mpdigdiv.c (750B)
1 #include "os.h" 2 #include <mp.h> 3 #include "dat.h" 4 5 /* */ 6 /* divide two digits by one and return quotient */ 7 /* */ 8 void 9 mpdigdiv(mpdigit *dividend, mpdigit divisor, mpdigit *quotient) 10 { 11 mpdigit hi, lo, q, x, y; 12 int i; 13 14 hi = dividend[1]; 15 lo = dividend[0]; 16 17 /* return highest digit value if the result >= 2**32 */ 18 if(hi >= divisor || divisor == 0){ 19 divisor = 0; 20 *quotient = ~divisor; 21 return; 22 } 23 24 /* at this point we know that hi < divisor */ 25 /* just shift and subtract till we're done */ 26 q = 0; 27 x = divisor; 28 for(i = Dbits-1; hi > 0 && i >= 0; i--){ 29 x >>= 1; 30 if(x > hi) 31 continue; 32 y = divisor<<i; 33 if(x == hi && y > lo) 34 continue; 35 if(y > lo) 36 hi--; 37 lo -= y; 38 hi -= x; 39 q |= 1<<i; 40 } 41 q += lo/divisor; 42 *quotient = q; 43 }