From 759ee2aa10323d1960405c93f7cd4cf6d383ae7a Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Thu, 23 Sep 2021 11:45:49 +0200
Subject: Each pointer needs its own stack, merging the two packages to avoid a
 circular dependency

---
 pkg/interpreter/interpreter.go      |  10 +-
 pkg/interpreter/interpreter_test.go |  50 +++++++
 pkg/pointer/pointer.go              |  52 +++++++-
 pkg/pointer/pointer_test.go         |  64 ++++++++-
 pkg/pointer/stack-stack.go          |  95 +++++++++++++
 pkg/pointer/stack-stack_test.go     | 260 ++++++++++++++++++++++++++++++++++++
 pkg/pointer/stack.go                |  51 +++++++
 pkg/pointer/stack_test.go           |  74 ++++++++++
 pkg/stack/stack-stack.go            |  91 -------------
 pkg/stack/stack-stack_test.go       | 251 ----------------------------------
 pkg/stack/stack.go                  |  51 -------
 pkg/stack/stack_test.go             |  74 ----------
 12 files changed, 649 insertions(+), 474 deletions(-)
 create mode 100644 pkg/interpreter/interpreter_test.go
 create mode 100644 pkg/pointer/stack-stack.go
 create mode 100644 pkg/pointer/stack-stack_test.go
 create mode 100644 pkg/pointer/stack.go
 create mode 100644 pkg/pointer/stack_test.go
 delete mode 100644 pkg/stack/stack-stack.go
 delete mode 100644 pkg/stack/stack-stack_test.go
 delete mode 100644 pkg/stack/stack.go
 delete mode 100644 pkg/stack/stack_test.go

diff --git a/pkg/interpreter/interpreter.go b/pkg/interpreter/interpreter.go
index ce2499d..b64e90a 100644
--- a/pkg/interpreter/interpreter.go
+++ b/pkg/interpreter/interpreter.go
@@ -25,7 +25,8 @@ func (i *Interpreter) Run() {
 func (i *Interpreter) Step() {
 	var prev *pointer.Pointer = nil
 	for p := i.p; p != nil; p = p.Next {
-		switch p.Get(*i.f) {
+		c := p.Get(*i.f)
+		switch c {
 		case '@':
 			if prev == nil {
 				i.p = p.Next
@@ -33,8 +34,13 @@ func (i *Interpreter) Step() {
 				prev.Next = p.Next
 			}
 			break
+		case '#':
+			p.Step(*i.f)
 		default:
-			log.Fatalf("Non implemented instruction code %d : %c", p.Get(*i.f), p.Get(*i.f))
+			if !p.Redirect(c) {
+				log.Fatalf("Non implemented instruction code %d : %c", c, c)
+			}
 		}
+		p.Step(*i.f)
 	}
 }
diff --git a/pkg/interpreter/interpreter_test.go b/pkg/interpreter/interpreter_test.go
new file mode 100644
index 0000000..ff633a2
--- /dev/null
+++ b/pkg/interpreter/interpreter_test.go
@@ -0,0 +1,50 @@
+package interpreter
+
+import (
+	"os"
+	"testing"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRun(t *testing.T) {
+	file, err := os.Open("../field/test_data/minimal.b98")
+	require.NoError(t, err)
+	defer file.Close()
+	f, err := field.Load(file)
+	require.NoError(t, err)
+	NewInterpreter(f, pointer.NewPointer()).Run()
+}
+
+func TestStep(t *testing.T) {
+	testCases := []struct {
+		name            string
+		filename        string
+		pointer         *pointer.Pointer
+		expectedField   *field.Field
+		expectedPointer *pointer.Pointer
+	}{
+		{"minimal", "../field/test_data/minimal.b98", nil, nil, nil},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			file, err := os.Open(tc.filename)
+			require.NoError(t, err)
+			defer file.Close()
+			f, err := field.Load(file)
+			require.NoError(t, err)
+			if tc.pointer == nil {
+				tc.pointer = pointer.NewPointer()
+			}
+			NewInterpreter(f, tc.pointer).Step()
+			if tc.expectedField != nil {
+				require.Equal(t, tc.expectedField, f)
+			}
+			if tc.expectedPointer != nil {
+				require.Equal(t, tc.expectedPointer, tc.pointer)
+			}
+		})
+	}
+}
diff --git a/pkg/pointer/pointer.go b/pkg/pointer/pointer.go
index a833f5b..4d847bf 100644
--- a/pkg/pointer/pointer.go
+++ b/pkg/pointer/pointer.go
@@ -1,6 +1,10 @@
 package pointer
 
-import "git.adyxax.org/adyxax/gofunge/pkg/field"
+import (
+	"math/rand"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+)
 
 type Pointer struct {
 	// the position
@@ -12,12 +16,14 @@ type Pointer struct {
 	// The Storage offset
 	sox int
 	soy int
+	// The stack
+	ss *StackStack
 	// The next element for the multi-"threaded" b98 interpreter
 	Next *Pointer
 }
 
 func NewPointer() *Pointer {
-	return &Pointer{dx: 1}
+	return &Pointer{dx: 1, ss: NewStackStack()}
 }
 
 func (p Pointer) Split() *Pointer {
@@ -31,3 +37,45 @@ func (p *Pointer) Step(f field.Field) {
 func (p Pointer) Get(f field.Field) int {
 	return f.Get(p.x, p.y)
 }
+
+func (p *Pointer) Set(x, y int) {
+	p.x, p.y = x, y
+}
+
+func (p *Pointer) RedirectTo(dx, dy int) {
+	p.dx, p.dy = dx, dy
+}
+
+func (p *Pointer) Reverse() {
+	p.dx, p.dy = -p.dx, -p.dy
+}
+
+func (p *Pointer) Redirect(c int) bool {
+	switch c {
+	case '^':
+		p.dx, p.dy = 0, -1
+	case '>':
+		p.dx, p.dy = 1, 0
+	case 'v':
+		p.dx, p.dy = 0, 1
+	case '<':
+		p.dx, p.dy = -1, 0
+	case '?':
+		directions := []int{0, -1, 1, 0, 0, 1, -1, 0}
+		r := 2 * rand.Intn(4)
+		p.dx, p.dy = directions[r], directions[r+1]
+	case '[':
+		p.dx, p.dy = p.dy, -p.dx
+	case ']':
+		p.dx, p.dy = -p.dy, p.dx
+	case 'r':
+		p.Reverse()
+	case 'x':
+		dy := p.ss.Pop()
+		dx := p.ss.Pop()
+		p.RedirectTo(dx, dy)
+	default:
+		return false
+	}
+	return true
+}
diff --git a/pkg/pointer/pointer_test.go b/pkg/pointer/pointer_test.go
index ccbf486..4885d6b 100644
--- a/pkg/pointer/pointer_test.go
+++ b/pkg/pointer/pointer_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 func TestNewPointer(t *testing.T) {
-	require.Equal(t, NewPointer(), &Pointer{dx: 1})
+	require.Equal(t, NewPointer(), &Pointer{dx: 1, ss: NewStackStack()})
 }
 
 func TestSplit(t *testing.T) {
@@ -23,8 +23,8 @@ func TestSplit(t *testing.T) {
 	// We check that p2 is a real copy
 	p.Step(*f)
 	p2.Step(*f)
-	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1}, p)
-	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1}, p2)
+	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1, ss: NewStackStack()}, p)
+	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1, ss: NewStackStack()}, p2)
 }
 
 func TestStep(t *testing.T) { // Step is thoroughly tested in the field package
@@ -50,3 +50,61 @@ func TestGet(t *testing.T) {
 	v := p.Get(*f)
 	require.Equal(t, int('@'), v)
 }
+
+func TestSet(t *testing.T) {
+	p := NewPointer()
+	p.Set(3, 14)
+	require.Equal(t, 3, p.x)
+	require.Equal(t, 14, p.y)
+}
+
+func TestRedirectTo(t *testing.T) {
+	p := NewPointer()
+	p.RedirectTo(3, 14)
+	require.Equal(t, 3, p.dx)
+	require.Equal(t, 14, p.dy)
+}
+
+func TestReverse(t *testing.T) {
+	p := NewPointer()
+	p.RedirectTo(3, 14)
+	p.Reverse()
+	require.Equal(t, -3, p.dx)
+	require.Equal(t, -14, p.dy)
+}
+
+func TestRedirect(t *testing.T) {
+	testCases := []struct {
+		name       string
+		input      byte
+		expectedDx int
+		expectedDy int
+	}{
+		{"up", '^', 0, -1},
+		{"right", '>', 1, 0},
+		{"down", 'v', 0, 1},
+		{"left", '<', -1, 0},
+		{"turn left", '[', 14, -3},
+		{"turn right", ']', -14, 3},
+		{"reverse", 'r', -3, -14},
+		{"redirectTo", 'x', 2, 7},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			p := NewPointer()
+			p.RedirectTo(3, 14)
+			p.ss.Push(2)
+			p.ss.Push(7)
+			v := p.Redirect(int(tc.input))
+			require.Equal(t, true, v)
+			require.Equal(t, tc.expectedDx, p.dx, "Invalid dx value")
+			require.Equal(t, tc.expectedDy, p.dy, "Invalid dy value")
+		})
+	}
+	// We cannot really test random, can we? This just gives coverage
+	p := NewPointer()
+	v := p.Redirect(int('?'))
+	require.Equal(t, true, v)
+	// A character that does not redirect should return false
+	require.Equal(t, false, p.Redirect(int('@')))
+}
diff --git a/pkg/pointer/stack-stack.go b/pkg/pointer/stack-stack.go
new file mode 100644
index 0000000..6d22f51
--- /dev/null
+++ b/pkg/pointer/stack-stack.go
@@ -0,0 +1,95 @@
+package pointer
+
+type StackStack struct {
+	head   *Stack
+	height int
+}
+
+func NewStackStack() *StackStack {
+	return &StackStack{
+		head:   NewStack(),
+		height: 1,
+	}
+}
+
+func (ss *StackStack) Begin(p *Pointer) {
+	ss.height++
+	soss := ss.head
+	n := soss.Pop()
+	np := n
+	if np < 0 {
+		np = -np
+	}
+	toss := &Stack{
+		size:   np,
+		height: np,
+		data:   make([]int, np),
+		next:   soss,
+	}
+	ss.head = toss
+	max := n - soss.height
+	if max < 0 {
+		max = 0
+	}
+	for i := n - 1; i >= max; i-- {
+		toss.data[i] = soss.data[soss.height-n+i]
+	}
+	x, y := p.GetStorageOffset()
+	soss.Push(x)
+	soss.Push(y)
+	p.CalculateNewStorageOffset()
+}
+
+func (ss *StackStack) End(p *Pointer) (reflect bool) {
+	if ss.height == 1 {
+		return true
+	}
+	soss := ss.head.next
+	n := ss.head.Pop()
+	y := soss.Pop()
+	x := soss.Pop()
+	p.SetStorageOffset(x, y)
+	if n > 0 {
+		soss.height += n
+		if soss.size < soss.height {
+			soss.data = append(soss.data, make([]int, soss.height-soss.size)...)
+			soss.size = soss.height
+		}
+		for i := n; i > 0; i-- {
+			soss.data[soss.height-i] = ss.head.data[ss.head.height-i]
+		}
+	} else {
+		soss.height += n
+		if soss.height < 0 {
+			soss.height = 0
+		}
+	}
+	ss.height--
+	ss.head = ss.head.next
+	return false
+}
+
+func (ss *StackStack) Under() (reflect bool) {
+	if ss.height == 1 {
+		return true
+	}
+	n := ss.head.Pop()
+	if n > 0 {
+		for i := 0; i < n; i++ {
+			ss.head.Push(ss.head.next.Pop())
+		}
+	} else {
+		for i := 0; i < -n; i++ {
+			ss.head.next.Push(ss.head.Pop())
+		}
+	}
+	return false
+}
+
+func (ss StackStack) Pop() int {
+	return ss.head.Pop()
+}
+
+func (ss StackStack) Push(v int) {
+	ss.head.Push(v)
+}
diff --git a/pkg/pointer/stack-stack_test.go b/pkg/pointer/stack-stack_test.go
new file mode 100644
index 0000000..fd4c9ea
--- /dev/null
+++ b/pkg/pointer/stack-stack_test.go
@@ -0,0 +1,260 @@
+package pointer
+
+import (
+	"os"
+	"testing"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBegin(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{data: make([]int, 0), next: expected.head}
+		expected.head.next.Push(0)
+		expected.head.next.Push(0)
+		expected.height++
+		ss := NewStackStack()
+		p := NewPointer()
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 1, x)
+		require.Equal(t, 0, y)
+		// Let's push another one
+		expected.head = &Stack{data: make([]int, 0), next: expected.head}
+		expected.head.next.Push(1)
+		expected.head.next.Push(0)
+		expected.height++
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y = p.GetStorageOffset()
+		require.Equal(t, 1, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("negative", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 5, height: 5, data: make([]int, 5), next: expected.head}
+		expected.head.next.Push(0)
+		expected.head.next.Push(0)
+		expected.height++
+		p := NewPointer()
+		file, err := os.Open("../field/test_data/hello.b98")
+		require.NoError(t, err, "Failed to open file")
+		f, err := field.Load(file)
+		p.Step(*f)
+		ss := NewStackStack()
+		ss.head.Push(-5)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 2, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("ask to copy more than we have", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 34, height: 34, data: make([]int, 34), next: expected.head}
+		expected.head.data[33] = 18
+		expected.head.next.Push(18)
+		expected.head.next.Push(2)
+		expected.head.next.Push(3)
+		expected.height++
+		p := NewPointer()
+		p.SetStorageOffset(2, 3)
+		file, err := os.Open("../field/test_data/hello.b98")
+		require.NoError(t, err, "Failed to open file")
+		f, err := field.Load(file)
+		p.Step(*f)
+		ss := NewStackStack()
+		ss.head.Push(18)
+		ss.head.Push(34)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 2, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("normal", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 4, height: 4, data: []int{12, 14, -2, 5}, next: expected.head}
+		expected.head.next.Push(7)
+		expected.head.next.Push(12)
+		expected.head.next.Push(14)
+		expected.head.next.Push(-2)
+		expected.head.next.Push(5)
+		expected.head.next.Push(36)
+		expected.head.next.Push(42)
+		expected.height++
+		p := NewPointer()
+		p.SetStorageOffset(36, 42)
+		ss := NewStackStack()
+		ss.head.Push(7)
+		ss.head.Push(12)
+		ss.head.Push(14)
+		ss.head.Push(-2)
+		ss.head.Push(5)
+		ss.head.Push(4)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+	})
+}
+
+func TestEnd(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		expected := NewStackStack()
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.Begin(p)
+		reflect := ss.End(p)
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("drop", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head.Push(7)
+		expected.head.Push(12)
+		expected.head.Push(14)
+		expected.head.Push(-2)
+		expected.head.Push(5)
+		expected.head.Pop()
+		expected.head.Pop()
+		expected.head.Pop()
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.head.Push(7)
+		ss.head.Push(12)
+		ss.head.Push(14)
+		ss.head.Push(-2)
+		ss.head.Push(5)
+		ss.head.Push(0)
+		ss.Begin(p)
+		ss.head.Push(18)
+		ss.head.Push(42)
+		ss.head.Push(-3)
+		reflect := ss.End(p)
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("drop too much", func(t *testing.T) {
+		expected := NewStackStack()
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.Begin(p)
+		ss.head.Push(-3)
+		reflect := ss.End(p)
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("reflect", func(t *testing.T) {
+		expected := NewStackStack()
+		p := NewPointer()
+		ss := NewStackStack()
+		reflect := ss.End(p)
+		require.Equal(t, true, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("transfert", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head.size = 5
+		expected.head.data = make([]int, 5)
+		expected.head.Push(7)
+		expected.head.Push(12)
+		expected.head.Push(14)
+		expected.head.Push(-2)
+		expected.head.Push(5)
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.head.size = 4
+		ss.head.data = make([]int, 4)
+		ss.head.Push(7)
+		ss.head.Push(0)
+		ss.Begin(p)
+		ss.head.Push(0)
+		ss.head.Push(18)
+		ss.head.Push(42)
+		ss.head.Push(7)
+		ss.head.Push(12)
+		ss.head.Push(14)
+		ss.head.Push(-2)
+		ss.head.Push(5)
+		ss.head.Push(4)
+		reflect := ss.End(p)
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+}
+
+func TestUnder(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		expected := NewStackStack()
+		ss := NewStackStack()
+		reflect := ss.Under()
+		require.Equal(t, true, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("positive", func(t *testing.T) {
+		pe := NewPointer()
+		expected := NewStackStack()
+		expected.head.Push(1)
+		expected.head.Push(2)
+		expected.head.Push(3)
+		expected.head.Push(6)
+		expected.head.Push(0)
+		expected.Begin(pe)
+		expected.head.Push(0)
+		expected.head.Push(0)
+		expected.head.Push(6)
+		expected.head.next.Pop()
+		expected.head.next.Pop()
+		expected.head.next.Pop()
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.head.Push(1)
+		ss.head.Push(2)
+		ss.head.Push(3)
+		ss.head.Push(6)
+		ss.head.Push(0)
+		ss.Begin(p)
+		ss.head.Push(3)
+		reflect := ss.Under()
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+	t.Run("negative", func(t *testing.T) {
+		pe := NewPointer()
+		expected := NewStackStack()
+		expected.Begin(pe)
+		expected.head.next.Push(12)
+		expected.head.next.Push(5)
+		expected.head.next.Push(8)
+		expected.head.Push(8)
+		expected.head.Push(5)
+		expected.head.Push(12)
+		expected.head.Push(-3)
+		expected.head.Pop()
+		expected.head.Pop()
+		expected.head.Pop()
+		expected.head.Pop()
+		p := NewPointer()
+		ss := NewStackStack()
+		ss.Begin(p)
+		ss.head.Push(8)
+		ss.head.Push(5)
+		ss.head.Push(12)
+		ss.head.Push(-3)
+		reflect := ss.Under()
+		require.Equal(t, false, reflect)
+		require.Equal(t, expected, ss)
+	})
+}
+
+func TestPushPop(t *testing.T) {
+	ss := NewStackStack()
+	ss.Push(12)
+	ss.Push(5)
+	v := ss.Pop()
+	require.Equal(t, 5, v)
+	v = ss.Pop()
+	require.Equal(t, 12, v)
+}
diff --git a/pkg/pointer/stack.go b/pkg/pointer/stack.go
new file mode 100644
index 0000000..1832dbb
--- /dev/null
+++ b/pkg/pointer/stack.go
@@ -0,0 +1,51 @@
+package pointer
+
+type Stack struct {
+	size   int
+	height int
+	data   []int
+	next   *Stack // Pointer to the next element in the stack stack
+}
+
+func NewStack() *Stack {
+	return &Stack{
+		size:   32,
+		height: 0,
+		data:   make([]int, 32),
+		next:   nil,
+	}
+}
+
+func (s *Stack) Clear() {
+	s.height = 0
+}
+
+func (s *Stack) Duplicate() {
+	if s.height > 0 {
+		s.Push(s.data[s.height-1])
+	}
+}
+
+func (s *Stack) Pop() int {
+	if s.height > 0 {
+		s.height--
+		return s.data[s.height]
+	}
+	return 0
+}
+
+func (s *Stack) Push(value int) {
+	if s.height >= s.size {
+		s.size += 32
+		s.data = append(s.data, make([]int, 32)...)
+	}
+	s.data[s.height] = value
+	s.height++
+}
+
+func (s *Stack) Swap() {
+	a := s.Pop()
+	b := s.Pop()
+	s.Push(a)
+	s.Push(b)
+}
diff --git a/pkg/pointer/stack_test.go b/pkg/pointer/stack_test.go
new file mode 100644
index 0000000..1b16085
--- /dev/null
+++ b/pkg/pointer/stack_test.go
@@ -0,0 +1,74 @@
+package pointer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestClear(t *testing.T) {
+	s := NewStack()
+	s.Clear()
+	require.Equal(t, 0, s.height)
+}
+
+func TestDupicate(t *testing.T) {
+	s := NewStack()
+	s2 := NewStack()
+	s.Duplicate()
+	require.Equal(t, s2.height, s.height)
+	s.Push(12)
+	s.Duplicate()
+	s2.Push(12)
+	s2.Push(12)
+	require.Equal(t, s2.height, s.height)
+	require.Equal(t, s2.data, s.data)
+}
+
+func TestPop(t *testing.T) {
+	s := NewStack()
+	v := s.Pop()
+	require.Equal(t, 0, v)
+	s.Push(12)
+	s.Push(14)
+	v = s.Pop()
+	require.Equal(t, 14, v)
+	v = s.Pop()
+	require.Equal(t, 12, v)
+	v = s.Pop()
+	require.Equal(t, 0, v)
+}
+
+func TestPush(t *testing.T) {
+	s := NewStack()
+	for i := 0; i < 32; i++ {
+		s.Push(i)
+	}
+	require.Equal(t, 32, s.size)
+	s.Push(-1)
+	require.Equal(t, 64, s.size)
+}
+
+func TestSwap(t *testing.T) {
+	s := NewStack()
+	s2 := NewStack()
+	s.Swap()
+	s2.Push(0)
+	s2.Push(0)
+	require.Equal(t, s2, s)
+	s.Clear()
+	s.Push(1)
+	s.Swap()
+	s2.Clear()
+	s2.Push(1)
+	s2.Push(0)
+	require.Equal(t, s2, s)
+	s.Clear()
+	s.Push(1)
+	s.Push(2)
+	s2.Clear()
+	s2.Push(2)
+	s2.Push(1)
+	s.Swap()
+	require.Equal(t, s2, s)
+}
diff --git a/pkg/stack/stack-stack.go b/pkg/stack/stack-stack.go
deleted file mode 100644
index 9b80079..0000000
--- a/pkg/stack/stack-stack.go
+++ /dev/null
@@ -1,91 +0,0 @@
-package stack
-
-import (
-	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
-)
-
-type StackStack struct {
-	head   *Stack
-	height int
-}
-
-func NewStackStack() *StackStack {
-	return &StackStack{
-		head:   NewStack(),
-		height: 1,
-	}
-}
-
-func (ss *StackStack) Begin(p *pointer.Pointer) {
-	ss.height++
-	soss := ss.head
-	n := soss.Pop()
-	np := n
-	if np < 0 {
-		np = -np
-	}
-	toss := &Stack{
-		size:   np,
-		height: np,
-		data:   make([]int, np),
-		next:   soss,
-	}
-	ss.head = toss
-	max := n - soss.height
-	if max < 0 {
-		max = 0
-	}
-	for i := n - 1; i >= max; i-- {
-		toss.data[i] = soss.data[soss.height-n+i]
-	}
-	x, y := p.GetStorageOffset()
-	soss.Push(x)
-	soss.Push(y)
-	p.CalculateNewStorageOffset()
-}
-
-func (ss *StackStack) End(p *pointer.Pointer) (reflect bool) {
-	if ss.height == 1 {
-		return true
-	}
-	soss := ss.head.next
-	n := ss.head.Pop()
-	y := soss.Pop()
-	x := soss.Pop()
-	p.SetStorageOffset(x, y)
-	if n > 0 {
-		soss.height += n
-		if soss.size < soss.height {
-			soss.data = append(soss.data, make([]int, soss.height-soss.size)...)
-			soss.size = soss.height
-		}
-		for i := n; i > 0; i-- {
-			soss.data[soss.height-i] = ss.head.data[ss.head.height-i]
-		}
-	} else {
-		soss.height += n
-		if soss.height < 0 {
-			soss.height = 0
-		}
-	}
-	ss.height--
-	ss.head = ss.head.next
-	return false
-}
-
-func (ss *StackStack) Under() (reflect bool) {
-	if ss.height == 1 {
-		return true
-	}
-	n := ss.head.Pop()
-	if n > 0 {
-		for i := 0; i < n; i++ {
-			ss.head.Push(ss.head.next.Pop())
-		}
-	} else {
-		for i := 0; i < -n; i++ {
-			ss.head.next.Push(ss.head.Pop())
-		}
-	}
-	return false
-}
diff --git a/pkg/stack/stack-stack_test.go b/pkg/stack/stack-stack_test.go
deleted file mode 100644
index d2a7949..0000000
--- a/pkg/stack/stack-stack_test.go
+++ /dev/null
@@ -1,251 +0,0 @@
-package stack
-
-import (
-	"os"
-	"testing"
-
-	"git.adyxax.org/adyxax/gofunge/pkg/field"
-	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
-	"github.com/stretchr/testify/require"
-)
-
-func TestBegin(t *testing.T) {
-	t.Run("empty", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head = &Stack{data: make([]int, 0), next: expected.head}
-		expected.head.next.Push(0)
-		expected.head.next.Push(0)
-		expected.height++
-		ss := NewStackStack()
-		p := pointer.NewPointer()
-		ss.Begin(p)
-		require.Equal(t, expected, ss)
-		x, y := p.GetStorageOffset()
-		require.Equal(t, 1, x)
-		require.Equal(t, 0, y)
-		// Let's push another one
-		expected.head = &Stack{data: make([]int, 0), next: expected.head}
-		expected.head.next.Push(1)
-		expected.head.next.Push(0)
-		expected.height++
-		ss.Begin(p)
-		require.Equal(t, expected, ss)
-		x, y = p.GetStorageOffset()
-		require.Equal(t, 1, x)
-		require.Equal(t, 0, y)
-	})
-	t.Run("negative", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head = &Stack{size: 5, height: 5, data: make([]int, 5), next: expected.head}
-		expected.head.next.Push(0)
-		expected.head.next.Push(0)
-		expected.height++
-		p := pointer.NewPointer()
-		file, err := os.Open("../field/test_data/hello.b98")
-		require.NoError(t, err, "Failed to open file")
-		f, err := field.Load(file)
-		p.Step(*f)
-		ss := NewStackStack()
-		ss.head.Push(-5)
-		ss.Begin(p)
-		require.Equal(t, expected, ss)
-		x, y := p.GetStorageOffset()
-		require.Equal(t, 2, x)
-		require.Equal(t, 0, y)
-	})
-	t.Run("ask to copy more than we have", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head = &Stack{size: 34, height: 34, data: make([]int, 34), next: expected.head}
-		expected.head.data[33] = 18
-		expected.head.next.Push(18)
-		expected.head.next.Push(2)
-		expected.head.next.Push(3)
-		expected.height++
-		p := pointer.NewPointer()
-		p.SetStorageOffset(2, 3)
-		file, err := os.Open("../field/test_data/hello.b98")
-		require.NoError(t, err, "Failed to open file")
-		f, err := field.Load(file)
-		p.Step(*f)
-		ss := NewStackStack()
-		ss.head.Push(18)
-		ss.head.Push(34)
-		ss.Begin(p)
-		require.Equal(t, expected, ss)
-		x, y := p.GetStorageOffset()
-		require.Equal(t, 2, x)
-		require.Equal(t, 0, y)
-	})
-	t.Run("normal", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head = &Stack{size: 4, height: 4, data: []int{12, 14, -2, 5}, next: expected.head}
-		expected.head.next.Push(7)
-		expected.head.next.Push(12)
-		expected.head.next.Push(14)
-		expected.head.next.Push(-2)
-		expected.head.next.Push(5)
-		expected.head.next.Push(36)
-		expected.head.next.Push(42)
-		expected.height++
-		p := pointer.NewPointer()
-		p.SetStorageOffset(36, 42)
-		ss := NewStackStack()
-		ss.head.Push(7)
-		ss.head.Push(12)
-		ss.head.Push(14)
-		ss.head.Push(-2)
-		ss.head.Push(5)
-		ss.head.Push(4)
-		ss.Begin(p)
-		require.Equal(t, expected, ss)
-	})
-}
-
-func TestEnd(t *testing.T) {
-	t.Run("empty", func(t *testing.T) {
-		expected := NewStackStack()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.Begin(p)
-		reflect := ss.End(p)
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("drop", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head.Push(7)
-		expected.head.Push(12)
-		expected.head.Push(14)
-		expected.head.Push(-2)
-		expected.head.Push(5)
-		expected.head.Pop()
-		expected.head.Pop()
-		expected.head.Pop()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.head.Push(7)
-		ss.head.Push(12)
-		ss.head.Push(14)
-		ss.head.Push(-2)
-		ss.head.Push(5)
-		ss.head.Push(0)
-		ss.Begin(p)
-		ss.head.Push(18)
-		ss.head.Push(42)
-		ss.head.Push(-3)
-		reflect := ss.End(p)
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("drop too much", func(t *testing.T) {
-		expected := NewStackStack()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.Begin(p)
-		ss.head.Push(-3)
-		reflect := ss.End(p)
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("reflect", func(t *testing.T) {
-		expected := NewStackStack()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		reflect := ss.End(p)
-		require.Equal(t, true, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("transfert", func(t *testing.T) {
-		expected := NewStackStack()
-		expected.head.size = 5
-		expected.head.data = make([]int, 5)
-		expected.head.Push(7)
-		expected.head.Push(12)
-		expected.head.Push(14)
-		expected.head.Push(-2)
-		expected.head.Push(5)
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.head.size = 4
-		ss.head.data = make([]int, 4)
-		ss.head.Push(7)
-		ss.head.Push(0)
-		ss.Begin(p)
-		ss.head.Push(0)
-		ss.head.Push(18)
-		ss.head.Push(42)
-		ss.head.Push(7)
-		ss.head.Push(12)
-		ss.head.Push(14)
-		ss.head.Push(-2)
-		ss.head.Push(5)
-		ss.head.Push(4)
-		reflect := ss.End(p)
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-}
-
-func TestUnder(t *testing.T) {
-	t.Run("empty", func(t *testing.T) {
-		expected := NewStackStack()
-		ss := NewStackStack()
-		reflect := ss.Under()
-		require.Equal(t, true, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("positive", func(t *testing.T) {
-		pe := pointer.NewPointer()
-		expected := NewStackStack()
-		expected.head.Push(1)
-		expected.head.Push(2)
-		expected.head.Push(3)
-		expected.head.Push(6)
-		expected.head.Push(0)
-		expected.Begin(pe)
-		expected.head.Push(0)
-		expected.head.Push(0)
-		expected.head.Push(6)
-		expected.head.next.Pop()
-		expected.head.next.Pop()
-		expected.head.next.Pop()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.head.Push(1)
-		ss.head.Push(2)
-		ss.head.Push(3)
-		ss.head.Push(6)
-		ss.head.Push(0)
-		ss.Begin(p)
-		ss.head.Push(3)
-		reflect := ss.Under()
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-	t.Run("negative", func(t *testing.T) {
-		pe := pointer.NewPointer()
-		expected := NewStackStack()
-		expected.Begin(pe)
-		expected.head.next.Push(12)
-		expected.head.next.Push(5)
-		expected.head.next.Push(8)
-		expected.head.Push(8)
-		expected.head.Push(5)
-		expected.head.Push(12)
-		expected.head.Push(-3)
-		expected.head.Pop()
-		expected.head.Pop()
-		expected.head.Pop()
-		expected.head.Pop()
-		p := pointer.NewPointer()
-		ss := NewStackStack()
-		ss.Begin(p)
-		ss.head.Push(8)
-		ss.head.Push(5)
-		ss.head.Push(12)
-		ss.head.Push(-3)
-		reflect := ss.Under()
-		require.Equal(t, false, reflect)
-		require.Equal(t, expected, ss)
-	})
-}
diff --git a/pkg/stack/stack.go b/pkg/stack/stack.go
deleted file mode 100644
index 4dbb72c..0000000
--- a/pkg/stack/stack.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package stack
-
-type Stack struct {
-	size   int
-	height int
-	data   []int
-	next   *Stack // Pointer to the next element in the stack stack
-}
-
-func NewStack() *Stack {
-	return &Stack{
-		size:   32,
-		height: 0,
-		data:   make([]int, 32),
-		next:   nil,
-	}
-}
-
-func (s *Stack) Clear() {
-	s.height = 0
-}
-
-func (s *Stack) Duplicate() {
-	if s.height > 0 {
-		s.Push(s.data[s.height-1])
-	}
-}
-
-func (s *Stack) Pop() int {
-	if s.height > 0 {
-		s.height--
-		return s.data[s.height]
-	}
-	return 0
-}
-
-func (s *Stack) Push(value int) {
-	if s.height >= s.size {
-		s.size += 32
-		s.data = append(s.data, make([]int, 32)...)
-	}
-	s.data[s.height] = value
-	s.height++
-}
-
-func (s *Stack) Swap() {
-	a := s.Pop()
-	b := s.Pop()
-	s.Push(a)
-	s.Push(b)
-}
diff --git a/pkg/stack/stack_test.go b/pkg/stack/stack_test.go
deleted file mode 100644
index e48c615..0000000
--- a/pkg/stack/stack_test.go
+++ /dev/null
@@ -1,74 +0,0 @@
-package stack
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestClear(t *testing.T) {
-	s := NewStack()
-	s.Clear()
-	require.Equal(t, 0, s.height)
-}
-
-func TestDupicate(t *testing.T) {
-	s := NewStack()
-	s2 := NewStack()
-	s.Duplicate()
-	require.Equal(t, s2.height, s.height)
-	s.Push(12)
-	s.Duplicate()
-	s2.Push(12)
-	s2.Push(12)
-	require.Equal(t, s2.height, s.height)
-	require.Equal(t, s2.data, s.data)
-}
-
-func TestPop(t *testing.T) {
-	s := NewStack()
-	v := s.Pop()
-	require.Equal(t, 0, v)
-	s.Push(12)
-	s.Push(14)
-	v = s.Pop()
-	require.Equal(t, 14, v)
-	v = s.Pop()
-	require.Equal(t, 12, v)
-	v = s.Pop()
-	require.Equal(t, 0, v)
-}
-
-func TestPush(t *testing.T) {
-	s := NewStack()
-	for i := 0; i < 32; i++ {
-		s.Push(i)
-	}
-	require.Equal(t, 32, s.size)
-	s.Push(-1)
-	require.Equal(t, 64, s.size)
-}
-
-func TestSwap(t *testing.T) {
-	s := NewStack()
-	s2 := NewStack()
-	s.Swap()
-	s2.Push(0)
-	s2.Push(0)
-	require.Equal(t, s2, s)
-	s.Clear()
-	s.Push(1)
-	s.Swap()
-	s2.Clear()
-	s2.Push(1)
-	s2.Push(0)
-	require.Equal(t, s2, s)
-	s.Clear()
-	s.Push(1)
-	s.Push(2)
-	s2.Clear()
-	s2.Push(2)
-	s2.Push(1)
-	s.Swap()
-	require.Equal(t, s2, s)
-}
-- 
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