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bug120

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R=r
OCL=20921
CL=20921
This commit is contained in:
Ken Thompson 2008-12-10 14:17:24 -08:00
parent fbfc9dddb2
commit 5f1a3be9dd
1 changed files with 17 additions and 8 deletions
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25
src/cmd/gc/mparith3.c
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@ -161,7 +161,7 @@ double
mpgetflt(Mpflt *a)
{
int s, i;
uvlong v;
uvlong v, vm;
double f;
if(a->val.ovf)
@ -186,22 +186,31 @@ mpgetflt(Mpflt *a)
// independently or in the 6g half of the compiler
// pick up the mantissa in a uvlong
s = 63;
s = 53;
v = 0;
for(i=Mpnorm-1; s>=Mpscale; i--) {
v = (v<<Mpscale) | a->val.a[i];
s -= Mpscale;
}
vm = v;
if(s > 0)
vm = (vm<<s) | (a->val.a[i]>>(Mpscale-s));
// continue with 64 more bits
s += 64;
for(; s>=Mpscale; i--) {
v = (v<<Mpscale) | a->val.a[i];
s -= Mpscale;
}
if(s > 0)
v = (v<<s) | (a->val.a[i]>>(Mpscale-s));
// 63 bits of mantissa being rounded to 53
// should do this in multi precision
if((v&0x3ffULL) != 0x200ULL || (v&0x400) != 0)
v += 0x200ULL; // round toward even
//print("vm=%.16llux v=%.16llux\n", vm, v);
// round toward even
if(v != (1ULL<<63) || (vm&1ULL) != 0)
vm += v>>63;
v >>= 10;
f = (double)(v);
f = (double)(vm);
f = ldexp(f, Mpnorm*Mpscale + a->exp - 53);
if(a->val.neg)