From 41eb3807f700014645eea6a34cd88827b8f92bf0 Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Mon, 14 Oct 2019 20:01:06 +0200
Subject: [PATCH] op: assume aux ops are always wrapped by a macro

Shaves off a length, and prepares for further simplification.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 internal/opconst/ops.go |  2 +-
 internal/ops/reader.go  | 21 ++++-----------------
 op/op.go                |  5 -----
 3 files changed, 5 insertions(+), 23 deletions(-)

diff --git a/internal/opconst/ops.go b/internal/opconst/ops.go
index 4f633fee..59177a28 100644
--- a/internal/opconst/ops.go
+++ b/internal/opconst/ops.go
@@ -44,7 +44,7 @@ const (
 	TypeHideInputLen    = 1
 	TypePushLen         = 1
 	TypePopLen          = 1
-	TypeAuxLen          = 1 + 4
+	TypeAuxLen          = 1
 	TypeClipLen         = 1 + 4*4
 	TypeProfileLen      = 1
 )
diff --git a/internal/ops/reader.go b/internal/ops/reader.go
index 25f30903..15d4ce98 100644
--- a/internal/ops/reader.go
+++ b/internal/ops/reader.go
@@ -53,10 +53,6 @@ type opMacroDef struct {
 	endpc pc
 }
 
-type opAux struct {
-	len int
-}
-
 // Reset start reading from the op list.
 func (r *Reader) Reset(ops *op.Ops) {
 	r.stack = r.stack[:0]
@@ -93,9 +89,10 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 		refs = refs[:nrefs]
 		switch t {
 		case opconst.TypeAux:
-			var op opAux
-			op.decode(data)
-			n += op.len
+			// An Aux operations is always wrapped in a macro, and
+			// its length is the remaining space.
+			block := r.stack[len(r.stack)-1]
+			n += block.endPC.data - r.pc.data - opconst.TypeAuxLen
 			data = data[:n]
 		case opconst.TypeMacro:
 			var op macroOp
@@ -151,16 +148,6 @@ func (op *opMacroDef) decode(data []byte) {
 	}
 }
 
-func (op *opAux) decode(data []byte) {
-	if opconst.OpType(data[0]) != opconst.TypeAux {
-		panic("invalid op")
-	}
-	bo := binary.LittleEndian
-	*op = opAux{
-		len: int(int32(bo.Uint32(data[1:]))),
-	}
-}
-
 func (m *macroOp) decode(data []byte, refs []interface{}) {
 	if opconst.OpType(data[0]) != opconst.TypeMacro {
 		panic("invalid op")
diff --git a/op/op.go b/op/op.go
index 526c229f..6ac3da1b 100644
--- a/op/op.go
+++ b/op/op.go
@@ -216,12 +216,7 @@ func (o *Ops) Write(op []byte, refs ...interface{}) {
 }
 
 func (o *Ops) endAux() {
-	if !o.inAux {
-		return
-	}
 	o.inAux = false
-	bo := binary.LittleEndian
-	bo.PutUint32(o.data[o.auxOff+1:], uint32(o.auxLen))
 }
 
 func (o *Ops) pc() pc {