math/big: various cleanups

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/6295072

diff --git a/src/pkg/math/big/nat.go b/src/pkg/math/big/nat.go
index 10026c8b1615cd03da9425a672a5ef95474773be..f132507dfd22bb621eda434ba5e17b399a6beb3b 100644 (file)
--- a/src/pkg/math/big/nat.go
+++ b/src/pkg/math/big/nat.go
@@ -493,14 +493,9 @@ func (z nat) div(z2, u, v nat) (q, r nat) {
        }
 
        if len(v) == 1 {
-               var rprime Word
-               q, rprime = z.divW(u, v[0])
-               if rprime > 0 {
-                       r = z2.make(1)
-                       r[0] = rprime
-               } else {
-                       r = z2.make(0)
-               }
+               var r2 Word
+               q, r2 = z.divW(u, v[0])
+               r = z2.setWord(r2)
                return
        }
 
@@ -1011,7 +1006,7 @@ func trailingZeroBits(x Word) uint {
        case 64:
                return uint(deBruijn64Lookup[((x&-x)*(deBruijn64&_M))>>58])
        default:
-               panic("Unknown word size")
+               panic("unknown word size")
        }
 
        return 0
@@ -1198,17 +1193,19 @@ func (z nat) random(rand *rand.Rand, limit nat, n int) nat {
        mask := Word((1 << bitLengthOfMSW) - 1)
 
        for {
-               for i := range z {
-                       switch _W {
-                       case 32:
+               switch _W {
+               case 32:
+                       for i := range z {
                                z[i] = Word(rand.Uint32())
-                       case 64:
+                       }
+               case 64:
+                       for i := range z {
                                z[i] = Word(rand.Uint32()) | Word(rand.Uint32())<<32
                        }
+               default:
+                       panic("unknown word size")
                }
-
                z[len(limit)-1] &= mask
-
                if z.cmp(limit) < 0 {
                        break
                }