Added basic implementation that executes text files

.gitignore

@@ -0,0 +1 @@
+/cmd/creature/creature

cmd/creature/examples/echo

@@ -0,0 +1,10 @@
+---
+0 0
+F
+
+0 1
+F
+
+0 1
+0 0
+E

cmd/creature/main.go

@@ -0,0 +1,104 @@
+package main
+
+import "io"
+import "os"
+import "fmt"
+import "bufio"
+import "strconv"
+import cre "git.tebibyte.media/sashakoshka/creature"
+
+func main() {
+	if len(os.Args) != 2 {
+		logLine("ERR file unspecified")
+		os.Exit(1)
+	}
+
+	file, err := os.Open(os.Args[1])
+	if err != nil {
+		logLine("ERR could not open file: " + err.Error())
+		os.Exit(1)
+	}
+
+	program, block, err := readFile(file)
+	if err != nil {
+		logLine("ERR could not read file: " + err.Error())
+		os.Exit(1)
+	}
+
+	machine := cre.Machine[int]{}
+	
+	machine.LoadProgram(program)
+	machine.LoadMemory(block)
+	
+	machine.Register(0, read)
+	machine.Register(1, write)
+
+	err = machine.Execute(0)
+	if err != nil {
+		logLine("XXX machine failed: " + err.Error())
+		os.Exit(1)
+	}
+}
+
+func read(machine *cre.Machine[int]) (stop bool) {
+	ch := []byte{0}
+	os.Stdin.Read(ch)
+	machine.Push(int(ch[0]))
+	return
+}
+
+func write(machine *cre.Machine[int]) (stop bool) {
+	print(string(rune(machine.Pop())))
+	return
+}
+
+func logLine (message ...any) {
+	fmt.Fprintln(os.Stderr, message...)
+}
+
+func readFile (reader io.Reader) (program []int, block []int, err error) {
+	scanner := bufio.NewScanner(reader)
+	scanner.Split(bufio.ScanWords)
+
+	blockLen := 0
+	block = make([]int, 8)
+	for scanner.Scan() {
+		if scanner.Text() == "---" {
+			break
+		}
+		if blockLen >= len(block) {
+			newSlice := make([]int, len(block) * 2)
+			copy(newSlice, block)
+			block = newSlice
+		}
+		var number int64
+		number, err = strconv.ParseInt(scanner.Text(), 16, 64)
+		if err != nil {
+			return
+		}
+		block[blockLen] = int(number)
+		blockLen ++
+	}
+	block = block[:blockLen]
+
+	programLen := 0
+	program = make([]int, 8)
+	for scanner.Scan() {
+		if programLen >= len(program) {
+			newSlice := make([]int, len(program) * 2)
+			copy(newSlice, program)
+			program = newSlice
+		}
+		var number int64
+		number, err = strconv.ParseInt(scanner.Text(), 16, 64)
+		if err != nil {
+			return
+		}
+		program[programLen] = int(number)
+		programLen ++
+	}
+	program = program[:programLen]
+	return
+}
+
+

cmd/main.go

@@ -1 +0,0 @@
-package main