cmd/compile/internal/big: re-vendor
Pick up a bunch of changes and fixes.
Change-Id: If4101f7185d433a4c89096bc786ee5de8eeabac0
Reviewed-on: https://go-review.googlesource.com/27123
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/cmd/compile/internal/big/floatmarsh.go b/src/cmd/compile/internal/big/floatmarsh.go
index 44987ee..3725d4b 100644
--- a/src/cmd/compile/internal/big/floatmarsh.go
+++ b/src/cmd/compile/internal/big/floatmarsh.go
@@ -6,7 +6,94 @@
package big
-import "fmt"
+import (
+ "encoding/binary"
+ "fmt"
+)
+
+// Gob codec version. Permits backward-compatible changes to the encoding.
+const floatGobVersion byte = 1
+
+// GobEncode implements the gob.GobEncoder interface.
+// The Float value and all its attributes (precision,
+// rounding mode, accuracy) are marshalled.
+func (x *Float) GobEncode() ([]byte, error) {
+ if x == nil {
+ return nil, nil
+ }
+
+ // determine max. space (bytes) required for encoding
+ sz := 1 + 1 + 4 // version + mode|acc|form|neg (3+2+2+1bit) + prec
+ n := 0 // number of mantissa words
+ if x.form == finite {
+ // add space for mantissa and exponent
+ n = int((x.prec + (_W - 1)) / _W) // required mantissa length in words for given precision
+ // actual mantissa slice could be shorter (trailing 0's) or longer (unused bits):
+ // - if shorter, only encode the words present
+ // - if longer, cut off unused words when encoding in bytes
+ // (in practice, this should never happen since rounding
+ // takes care of it, but be safe and do it always)
+ if len(x.mant) < n {
+ n = len(x.mant)
+ }
+ // len(x.mant) >= n
+ sz += 4 + n*_S // exp + mant
+ }
+ buf := make([]byte, sz)
+
+ buf[0] = floatGobVersion
+ b := byte(x.mode&7)<<5 | byte((x.acc+1)&3)<<3 | byte(x.form&3)<<1
+ if x.neg {
+ b |= 1
+ }
+ buf[1] = b
+ binary.BigEndian.PutUint32(buf[2:], x.prec)
+
+ if x.form == finite {
+ binary.BigEndian.PutUint32(buf[6:], uint32(x.exp))
+ x.mant[len(x.mant)-n:].bytes(buf[10:]) // cut off unused trailing words
+ }
+
+ return buf, nil
+}
+
+// GobDecode implements the gob.GobDecoder interface.
+// The result is rounded per the precision and rounding mode of
+// z unless z's precision is 0, in which case z is set exactly
+// to the decoded value.
+func (z *Float) GobDecode(buf []byte) error {
+ if len(buf) == 0 {
+ // Other side sent a nil or default value.
+ *z = Float{}
+ return nil
+ }
+
+ if buf[0] != floatGobVersion {
+ return fmt.Errorf("Float.GobDecode: encoding version %d not supported", buf[0])
+ }
+
+ oldPrec := z.prec
+ oldMode := z.mode
+
+ b := buf[1]
+ z.mode = RoundingMode((b >> 5) & 7)
+ z.acc = Accuracy((b>>3)&3) - 1
+ z.form = form((b >> 1) & 3)
+ z.neg = b&1 != 0
+ z.prec = binary.BigEndian.Uint32(buf[2:])
+
+ if z.form == finite {
+ z.exp = int32(binary.BigEndian.Uint32(buf[6:]))
+ z.mant = z.mant.setBytes(buf[10:])
+ }
+
+ if oldPrec != 0 {
+ z.mode = oldMode
+ z.SetPrec(uint(oldPrec))
+ }
+
+ return nil
+}
// MarshalText implements the encoding.TextMarshaler interface.
// Only the Float value is marshaled (in full precision), other
