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author | rsc <devnull@localhost> | 2004-03-21 14:06:38 +0000 |
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committer | rsc <devnull@localhost> | 2004-03-21 14:06:38 +0000 |
commit | b3f61791f1e9095ce8ae9c6d6415b4ee94e2f7eb (patch) | |
tree | deaa85427ae73a045ddef39395bd286f9d3dc2ff /src/libmp/port/mpdigdiv.c | |
parent | 498bb22174aa2c76493e8c67b92949271131ebfb (diff) | |
download | plan9port-b3f61791f1e9095ce8ae9c6d6415b4ee94e2f7eb.tar.gz plan9port-b3f61791f1e9095ce8ae9c6d6415b4ee94e2f7eb.tar.bz2 plan9port-b3f61791f1e9095ce8ae9c6d6415b4ee94e2f7eb.zip |
Add libmp.
Diffstat (limited to 'src/libmp/port/mpdigdiv.c')
-rw-r--r-- | src/libmp/port/mpdigdiv.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/src/libmp/port/mpdigdiv.c b/src/libmp/port/mpdigdiv.c new file mode 100644 index 00000000..4a73bb3a --- /dev/null +++ b/src/libmp/port/mpdigdiv.c @@ -0,0 +1,43 @@ +#include "os.h" +#include <mp.h> +#include "dat.h" + +// +// divide two digits by one and return quotient +// +void +mpdigdiv(mpdigit *dividend, mpdigit divisor, mpdigit *quotient) +{ + mpdigit hi, lo, q, x, y; + int i; + + hi = dividend[1]; + lo = dividend[0]; + + // return highest digit value if the result >= 2**32 + if(hi >= divisor || divisor == 0){ + divisor = 0; + *quotient = ~divisor; + return; + } + + // at this point we know that hi < divisor + // just shift and subtract till we're done + q = 0; + x = divisor; + for(i = Dbits-1; hi > 0 && i >= 0; i--){ + x >>= 1; + if(x > hi) + continue; + y = divisor<<i; + if(x == hi && y > lo) + continue; + if(y > lo) + hi--; + lo -= y; + hi -= x; + q |= 1<<i; + } + q += lo/divisor; + *quotient = q; +} |