scalar decoders

R=rsc
DELTA=897  (728 added, 14 deleted, 155 changed)
OCL=30955
CL=30955

src/pkg/gob/decode.go

@@ -6,6 +6,7 @@ package gob
 
 import (
 	"io";
+	"math";
 	"os";
 	"unsafe";
 )
@@ -52,3 +53,283 @@ func DecodeInt(state *DecState) int64 {
 	}
 	return int64(x >> 1)
 }
+
+// The 'instructions' of the decoding machine
+type decInstr struct {
+	op	func(i *decInstr, state *DecState);
+	field		int;	// field number
+	indir	int;	// how many pointer indirections to reach the value in the struct
+	offset	uintptr;	// offset in the structure of the field to encode
+}
+
+// Since the encoder writes no zeros, if we arrive at a decoder we have
+// a value to extract and store.  The field number has already been read
+// (it's how we knew to call this decoder).
+// Each decoder is responsible for handling any indirections associated
+// with the data structure.  If any pointer so reached is nil, allocation must
+// be done.
+
+// Walk the pointer hierarchy, allocating if we find a nil.  Stop one before the end.
+func decIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
+	for ; indir > 1; indir-- {
+		if *(*unsafe.Pointer)(p) == nil {
+			// Allocation required
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(unsafe.Pointer));
+		}
+		p = *(*unsafe.Pointer)(p);
+	}
+	return p
+}
+
+func decBool(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int(DecodeInt(state));
+	if state.err == nil {
+		*(*bool)(p) = v != 0;
+	}
+}
+
+func decInt(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int(DecodeInt(state));
+	if state.err == nil {
+		*(*int)(p) = v;
+	}
+}
+
+func decUint(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := uint(DecodeUint(state));
+	if state.err == nil {
+		*(*uint)(p) = v;
+	}
+}
+
+func decInt8(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int8(DecodeInt(state));
+	if state.err == nil {
+		*(*int8)(p) = v;
+	}
+}
+
+func decUint8(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := uint8(DecodeUint(state));
+	if state.err == nil {
+		*(*uint8)(p) = v;
+	}
+}
+
+func decInt16(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int16(DecodeInt(state));
+	if state.err == nil {
+		*(*int16)(p) = v;
+	}
+}
+
+func decUint16(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := uint16(DecodeUint(state));
+	if state.err == nil {
+		*(*uint16)(p) = v;
+	}
+}
+
+func decInt32(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int32(DecodeInt(state));
+	if state.err == nil {
+		*(*int32)(p) = v;
+	}
+}
+
+func decUint32(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := uint32(DecodeUint(state));
+	if state.err == nil {
+		*(*uint32)(p) = v;
+	}
+}
+
+func decInt64(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := int64(DecodeInt(state));
+	if state.err == nil {
+		*(*int64)(p) = v;
+	}
+}
+
+func decUint64(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := uint64(DecodeUint(state));
+	if state.err == nil {
+		*(*uint64)(p) = v;
+	}
+}
+
+// Floating-point numbers are transmitted as uint64s holding the bits
+// of the underlying representation.  They are sent byte-reversed, with
+// the exponent end coming out first, so integer floating point numbers
+// (for example) transmit more compactly.  This routine does the
+// unswizzling.
+func floatFromBits(u uint64) float64 {
+	var v uint64;
+	for i := 0; i < 8; i++ {
+		v <<= 8;
+		v |= u & 0xFF;
+		u >>= 8;
+	}
+	return math.Float64frombits(v);
+}
+
+func decFloat(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := float(floatFromBits(uint64(DecodeUint(state))));
+	if state.err == nil {
+		*(*float)(p) = v;
+	}
+}
+
+func decFloat32(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := float32(floatFromBits(uint64(DecodeUint(state))));
+	if state.err == nil {
+		*(*float32)(p) = v;
+	}
+}
+
+func decFloat64(i *decInstr, state *DecState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if i.indir > 1 {
+			p = decIndirect(p, i.indir);
+		}
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(int));
+			p = *(*unsafe.Pointer)(p);
+		}
+	}
+	v := floatFromBits(uint64(DecodeUint(state)));
+	if state.err == nil {
+		*(*float64)(p) = v;
+	}
+}

src/pkg/gob/encode.go

@@ -67,11 +67,20 @@ type encInstr struct {
 // Otherwise, the output (for a scalar) is the field number, as an encoded integer,
 // followed by the field data in its appropriate format.
 
-func encBool(i *encInstr, state *EncState) {
-	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
+func encIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
+	for ; indir > 0; indir-- {
 		p = *(*unsafe.Pointer)(p);
 		if p == nil {
+			return unsafe.Pointer(nil)
+		}
+	}
+	return p
+}
+
+func encBool(i *encInstr, state *EncState) {
+	p := unsafe.Pointer(state.base+i.offset);
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -84,9 +93,8 @@ func encBool(i *encInstr, state *EncState) {
 
 func encInt(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -99,9 +107,8 @@ func encInt(i *encInstr, state *EncState) {
 
 func encUint(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -114,9 +121,8 @@ func encUint(i *encInstr, state *EncState) {
 
 func encInt8(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -129,9 +135,8 @@ func encInt8(i *encInstr, state *EncState) {
 
 func encUint8(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -144,9 +149,8 @@ func encUint8(i *encInstr, state *EncState) {
 
 func encInt16(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -159,9 +163,8 @@ func encInt16(i *encInstr, state *EncState) {
 
 func encUint16(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -174,9 +177,8 @@ func encUint16(i *encInstr, state *EncState) {
 
 func encInt32(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -189,9 +191,8 @@ func encInt32(i *encInstr, state *EncState) {
 
 func encUint32(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -204,9 +205,8 @@ func encUint32(i *encInstr, state *EncState) {
 
 func encInt64(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -219,9 +219,8 @@ func encInt64(i *encInstr, state *EncState) {
 
 func encUint64(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -250,9 +249,8 @@ func floatBits(f float64) uint64 {
 
 func encFloat(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -266,9 +264,8 @@ func encFloat(i *encInstr, state *EncState) {
 
 func encFloat32(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}
@@ -282,9 +279,8 @@ func encFloat32(i *encInstr, state *EncState) {
 
 func encFloat64(i *encInstr, state *EncState) {
 	p := unsafe.Pointer(state.base+i.offset);
-	for indir := i.indir; indir > 0; indir-- {
-		p = *(*unsafe.Pointer)(p);
-		if p == nil {
+	if i.indir > 0 {
+		if p = encIndirect(p, i.indir); p == nil {
 			return
 		}
 	}