Make memory sizes parameters

asm/parse.go

@@ -1,9 +1,13 @@
 package asm
 
+import "fmt"
+
 import "gopkg.in/yaml.v2"
 
 type program struct {
-	Functions []function `yaml:"functions"`
+	GlobalMemorySize   uint64     `yaml:"global_memory_size"`
+	FunctionMemorySize uint64     `yaml:"function_memory_size"`
+	Functions          []function `yaml:"functions"`
 }
 
 type function []instruction
@@ -18,5 +22,13 @@ func parse(src []byte) (*program, error) {
 		return nil, err
 	}
 
+	if prog.GlobalMemorySize == 0 {
+		return nil, fmt.Errorf("global_memory_size must be set and non-zero")
+	}
+
+	if prog.FunctionMemorySize == 0 {
+		return nil, fmt.Errorf("function_memory_size must be set and non-zero")
+	}
+
 	return prog, nil
 }