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libmp: optimize case x/0xffffffff in mpdigdiv() (helps arm)

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cinap_lenrek 2015-11-01 12:12:41 +01:00
parent d901fbe4f1
commit a4e32b43ea
1 changed files with 13 additions and 0 deletions
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13
sys/src/libmp/port/mpdigdiv.c
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@ -21,6 +21,19 @@ mpdigdiv(mpdigit *dividend, mpdigit divisor, mpdigit *quotient)
return; return;
} }
// very common case
if(~divisor == 0){
lo += hi;
if(lo < hi){
hi++;
lo++;
}
if(lo+1 == 0)
hi++;
*quotient = hi;
return;
}
// at this point we know that hi < divisor // at this point we know that hi < divisor
// just shift and subtract till we're done // just shift and subtract till we're done
q = 0; q = 0;