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math/big: use internal validation more consistently

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Change-Id: If77afa6474af6cad6512f6866725e3ae5acf2e3f
Reviewed-on: https://go-review.googlesource.com/4840
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Robert Griesemer 2015-02-13 10:12:25 -08:00
parent b5b11bdbc6
commit 7a77d8d1e9
2 changed files with 65 additions and 26 deletions
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79
src/math/big/float.go
View File

@ -232,7 +232,7 @@ func (z *Float) SetMantExp(mant *Float, exp int) *Float {
// ±Inf are not considered integers.
func (x *Float) IsInt() bool {
if debugFloat {
x.validate()
validate(x)
}
// pick off easy cases
if x.exp <= 0 {
@ -267,21 +267,23 @@ func (z *Float) setExp(e int64) {
}
// debugging support
func (x *Float) validate() {
const msb = 1 << (_W - 1)
m := len(x.mant)
if m == 0 {
// 0.0 or Inf
if x.exp != 0 && x.exp != infExp {
panic(fmt.Sprintf("empty matissa with invalid exponent %d", x.exp))
func validate(args ...*Float) {
for i, x := range args {
const msb = 1 << (_W - 1)
m := len(x.mant)
if m == 0 {
// 0.0 or Inf
if x.exp != 0 && x.exp != infExp {
panic(fmt.Sprintf("#%d: %empty matissa with invalid exponent %d", i, x.exp))
}
continue
}
if x.mant[m-1]&msb == 0 {
panic(fmt.Sprintf("#%d: msb not set in last word %#x of %s", i, x.mant[m-1], x.Format('p', 0)))
}
if x.prec <= 0 {
panic(fmt.Sprintf("#%d: invalid precision %d", i, x.prec))
}
return
}
if x.mant[m-1]&msb == 0 {
panic(fmt.Sprintf("msb not set in last word %#x of %s", x.mant[m-1], x.Format('p', 0)))
}
if x.prec <= 0 {
panic(fmt.Sprintf("invalid precision %d", x.prec))
}
}
@ -303,7 +305,7 @@ func (z *Float) round(sbit uint) {
// z.prec > 0
if debugFloat {
z.validate()
validate(z)
}
bits := m * _W // available mantissa bits
@ -440,7 +442,7 @@ func (z *Float) round(sbit uint) {
}
if debugFloat {
z.validate()
validate(z)
}
return
@ -668,7 +670,7 @@ func (x *Float) minPrec() uint {
// for x > math.MaxUint64.
func (x *Float) Uint64() (uint64, Accuracy) {
if debugFloat {
x.validate()
validate(x)
}
switch x.ord() {
case -2, -1:
@ -707,7 +709,7 @@ func (x *Float) Uint64() (uint64, Accuracy) {
// (math.MaxInt64, Below) for x > math.MaxInt64.
func (x *Float) Int64() (int64, Accuracy) {
if debugFloat {
x.validate()
validate(x)
}
switch x.ord() {
@ -786,7 +788,7 @@ func (x *Float) Float64() (float64, Accuracy) {
// otherwise it is Below for x > 0, and Above for x < 0.
func (x *Float) Int() (res *Int, acc Accuracy) {
if debugFloat {
x.validate()
validate(x)
}
// accuracy for inexact results
acc = Below // truncation
@ -1059,6 +1061,10 @@ func (x *Float) ucmp(y *Float) int {
// result error relative to the exact (not rounded)
// result.
func (z *Float) Add(x, y *Float) *Float {
if debugFloat {
validate(x, y)
}
if z.prec == 0 {
z.prec = umax(x.prec, y.prec)
}
@ -1096,6 +1102,10 @@ func (z *Float) Add(x, y *Float) *Float {
// Sub sets z to the rounded difference x-y and returns z.
// Precision, rounding, and accuracy reporting are as for Add.
func (z *Float) Sub(x, y *Float) *Float {
if debugFloat {
validate(x, y)
}
if z.prec == 0 {
z.prec = umax(x.prec, y.prec)
}
@ -1135,6 +1145,10 @@ func (z *Float) Sub(x, y *Float) *Float {
// Mul sets z to the rounded product x*y and returns z.
// Precision, rounding, and accuracy reporting are as for Add.
func (z *Float) Mul(x, y *Float) *Float {
if debugFloat {
validate(x, y)
}
if z.prec == 0 {
z.prec = umax(x.prec, y.prec)
}
@ -1159,6 +1173,10 @@ func (z *Float) Mul(x, y *Float) *Float {
// Quo sets z to the rounded quotient x/y and returns z.
// Precision, rounding, and accuracy reporting are as for Add.
func (z *Float) Quo(x, y *Float) *Float {
if debugFloat {
validate(x, y)
}
if z.prec == 0 {
z.prec = umax(x.prec, y.prec)
}
@ -1191,28 +1209,38 @@ func (z *Float) Quo(x, y *Float) *Float {
// and rounding mode; and z's accuracy reports the
// result error relative to the exact (not rounded)
// result.
func (z *Float) Lsh(x *Float, s uint, mode RoundingMode) *Float {
// BUG(gri) Lsh is not tested and may not work correctly.
func (z *Float) Lsh(x *Float, s uint) *Float {
if debugFloat {
validate(x)
}
if z.prec == 0 {
z.prec = x.prec
}
// TODO(gri) handle Inf
z.Round(x, z.prec, mode)
z.round(0)
z.setExp(int64(z.exp) + int64(s))
return z
}
// Rsh sets z to the rounded x / (1<<s) and returns z.
// Precision, rounding, and accuracy reporting are as for Lsh.
func (z *Float) Rsh(x *Float, s uint, mode RoundingMode) *Float {
// BUG(gri) Rsh is not tested and may not work correctly.
func (z *Float) Rsh(x *Float, s uint) *Float {
if debugFloat {
validate(x)
}
if z.prec == 0 {
z.prec = x.prec
}
// TODO(gri) handle Inf
z.Round(x, z.prec, mode)
z.round(0)
z.setExp(int64(z.exp) - int64(s))
return z
}
@ -1226,8 +1254,7 @@ func (z *Float) Rsh(x *Float, s uint, mode RoundingMode) *Float {
// Infinities with matching sign are equal.
func (x *Float) Cmp(y *Float) int {
if debugFloat {
x.validate()
y.validate()
validate(x, y)
}
mx := x.ord()

12
src/math/big/float_test.go
View File

@ -728,6 +728,18 @@ func TestFloatNeg(t *testing.T) {
}
}
func TestFloatInc(t *testing.T) {
var x, one Float
// x.prec = 256 TODO(gri) This doesn't work at the moment
one.SetInt64(1)
for i := 0; i < 10; i++ {
x.Add(&x, &one)
}
if s := x.Format('g', 10); s != "10" {
t.Errorf("got %s; want 10", s)
}
}
// Selected precisions with which to run various tests.
var precList = [...]uint{1, 2, 5, 8, 10, 16, 23, 24, 32, 50, 53, 64, 100, 128, 500, 511, 512, 513, 1000, 10000}