bug120

R=r
OCL=20921
CL=20921

diff --git a/src/cmd/gc/mparith3.c b/src/cmd/gc/mparith3.c
index 7098ba68b24fd24bb8fabdaa4a2e6734fc9cf9e4..8e3da7a4b3a2ac359d18f4d2e59014971244befd 100644 (file)
--- a/src/cmd/gc/mparith3.c
+++ b/src/cmd/gc/mparith3.c
@@ -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)