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- use in-place bignum operations where available

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- runs approx. 30% faster

R=r
DELTA=24  (10 added, 2 deleted, 12 changed)
OCL=32984
CL=33005
This commit is contained in:
Robert Griesemer 2009-08-10 17:44:46 -07:00
parent 8db8682453
commit 0dbd8971a2
2 changed files with 22 additions and 14 deletions
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29
test/bench/pidigits.go
View File

@ -44,8 +44,6 @@ import (
) )
var n = flag.Int("n", 27, "number of digits"); var n = flag.Int("n", 27, "number of digits");
// TODO for easier profiling, remove eventually
var silent = flag.Bool("s", false, "don't print result"); var silent = flag.Bool("s", false, "don't print result");
var ( var (
@ -61,13 +59,16 @@ func extract_digit() int64 {
return -1; return -1;
} }
/* Compute (numer * 3 + accum) / denom */ // Compute (numer * 3 + accum) / denom
tmp1, tmp2 = numer.MulNat(bignum.Nat(3)).Add(accum).QuoRem(denom); tmp1 = numer.Shl(1);
bignum.Iadd(tmp1, tmp1, numer);
bignum.Iadd(tmp1, tmp1, accum);
tmp1, tmp2 := tmp1.QuoRem(denom);
/* Now, if (numer * 4 + accum) % denom... */ // Now, if (numer * 4 + accum) % denom...
tmp2 = tmp2.Add(numer); bignum.Iadd(tmp2, tmp2, numer);
/* ... is normalized, then the two divisions have the same result. */ // ... is normalized, then the two divisions have the same result.
if tmp2.Cmp(denom) >= 0 { if tmp2.Cmp(denom) >= 0 {
return -1; return -1;
} }
@ -79,16 +80,16 @@ func next_term(k int64) {
y2 := k*2 + 1; y2 := k*2 + 1;
tmp1 = numer.Shl(1); tmp1 = numer.Shl(1);
accum = accum.Add(tmp1); bignum.Iadd(accum, accum, tmp1);
accum = accum.Mul1(y2); bignum.Iscale(accum, y2);
numer = numer.Mul1(k); bignum.Iscale(numer, k);
denom = denom.Mul1(y2); bignum.Iscale(denom, y2);
} }
func eliminate_digit(d int64) { func eliminate_digit(d int64) {
accum = accum.Sub(denom.Mul1(d)); bignum.Isub(accum, accum, denom.Mul1(d));
accum = accum.Mul1(10); bignum.Iscale(accum, 10);
numer = numer.Mul1(10); bignum.Iscale(numer, 10);
} }
func printf(s string, arg ...) { func printf(s string, arg ...) {

7
test/bench/timing.log
View File

@ -231,3 +231,10 @@ chameneos 6000000
gcc -O2 chameneosredux.c -lpthread 17.93u 323.65s 88.47r gcc -O2 chameneosredux.c -lpthread 17.93u 323.65s 88.47r
gc chameneosredux 21.72u 0.00s 21.73r gc chameneosredux 21.72u 0.00s 21.73r
August 10 2009
# In-place versions for some bignum operations.
pidigits 10000
gcc -O2 pidigits.c -lgmp 2.56u 0.00s 2.57r
gc pidigits 55.22u 0.04s 55.29r # *** -23%
gc_B pidigits 55.49u 0.02s 55.60r # *** -23%