commit dddef0d55840bc0112cddca6e31288c0d4272909
Author: Carl Kittelberger <icedream@icedream.pw>
Date:   Thu Sep 7 11:55:48 2017 +0200

    Initial commit.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ef00b3f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,24 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+gobfy
+*.exe
+*.test
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..f293872
--- /dev/null
+++ b/main.go
@@ -0,0 +1,214 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+)
+
+const (
+	InstMoveRight byte = '>'
+	InstMoveLeft       = '<'
+	InstIncrement      = '+'
+	InstDecrement      = '-'
+	InstOutput         = '.'
+	InstInput          = ','
+	InstLoopStart      = '['
+	InstLoopEnd        = ']'
+)
+
+const (
+	DefaultPageSize = 1024
+)
+
+type Closure struct {
+	Skip  bool
+	Root  bool
+	Start int
+}
+
+type Processor struct {
+	Data        []byte
+	DataPointer int
+
+	stdin *bufio.Reader
+
+	instructionPointer int
+	instructionBuffer  []byte
+
+	closures []*Closure
+}
+
+func NewProcessor() *Processor {
+	return &Processor{
+		Data:  make([]byte, DefaultPageSize),
+		stdin: bufio.NewReader(os.Stdin),
+		closures: []*Closure{
+			&Closure{Root: true},
+		},
+		instructionBuffer: []byte{},
+	}
+}
+
+func (p *Processor) Stdin(r io.Reader) {
+	p.stdin = bufio.NewReader(r)
+}
+
+func (p *Processor) ensureDataSize() {
+	if p.DataPointer >= len(p.Data) {
+		// Increase data array, lock to next page size
+		nextPagedSize := (1 + (p.DataPointer / DefaultPageSize)) * DefaultPageSize
+		p.Data = append(p.Data, make([]byte, 1+nextPagedSize-len(p.Data))...)
+	}
+}
+
+func (p *Processor) Load(instructions []byte) {
+	p.instructionBuffer = instructions
+	p.instructionPointer = 0
+}
+
+func (p *Processor) Execute() {
+	for p.instructionPointer < len(p.instructionBuffer) {
+		instruction := p.instructionBuffer[p.instructionPointer]
+
+		/*log.Printf("exec 0x%[2]x = %[1]q, data: 0x%[3]x = %[3]q (0x%[4]x), reserved data size: %[5]d B",
+		instruction,
+		p.instructionPointer,
+		p.Data[p.DataPointer],
+		p.DataPointer,
+		len(p.Data))*/
+
+		switch instruction {
+		case InstMoveRight:
+			p.MoveRight()
+		case InstMoveLeft:
+			p.MoveLeft()
+		case InstDecrement:
+			p.Decrement()
+		case InstIncrement:
+			p.Increment()
+		case InstInput:
+			p.Input()
+		case InstOutput:
+			p.Output()
+		case InstLoopStart:
+			p.StartLoop()
+		case InstLoopEnd:
+			p.EndLoop()
+		default:
+			// Skip
+		}
+
+		p.instructionPointer++
+	}
+}
+
+func (p *Processor) Current() byte {
+	return p.Data[p.DataPointer]
+}
+
+func (p *Processor) Increment() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	p.Data[p.DataPointer]++
+}
+
+func (p *Processor) Decrement() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	p.Data[p.DataPointer]--
+}
+
+func (p *Processor) MoveRight() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	p.DataPointer++
+	p.ensureDataSize()
+}
+
+func (p *Processor) MoveLeft() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	if p.DataPointer == 0 {
+		log.Fatal("can not move data pointer left, already at beginning of data")
+	}
+
+	p.DataPointer--
+}
+
+func (p *Processor) Output() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	fmt.Printf("%c", rune(p.Data[p.DataPointer]))
+}
+
+func (p *Processor) Input() {
+	if p.closures[0].Skip {
+		return
+	}
+
+	input, err := p.stdin.ReadByte()
+	if err != nil {
+		log.Fatal(err)
+	}
+	p.Data[p.DataPointer] = input
+}
+
+func (p *Processor) StartLoop() {
+	p.closures = append([]*Closure{
+		&Closure{
+			Start: p.instructionPointer,
+			Skip:  p.Data[p.DataPointer] == 0,
+		},
+	}, p.closures...)
+}
+
+func (p *Processor) EndLoop() {
+	if len(p.closures) <= 1 {
+		log.Fatal("unexpected end of closure, not in any closure")
+	}
+
+	currentClosure := p.closures[0]
+
+	if !currentClosure.Skip {
+		if p.Data[p.DataPointer] > 0 {
+			p.instructionPointer = currentClosure.Start
+			return
+		}
+	}
+
+	p.closures = p.closures[1:]
+}
+
+func (p *Processor) ExpectEnd() {
+	if len(p.closures) > 1 {
+		log.Fatal("unexpected end of instructions, still in a closure")
+	}
+}
+
+func main() {
+	inputFilePath := os.Args[1]
+
+	// Open BF source code
+	input, err := ioutil.ReadFile(inputFilePath)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	p := NewProcessor()
+	p.Load(input)
+	p.Execute()
+}