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// Copyright 2017 The go-interpreter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package exec
import (
"fmt"
"math"
"reflect"
"github.com/go-interpreter/wagon/exec/internal/compile"
)
type function interface {
call(vm *VM, index int64)
}
type compiledFunction struct {
code []byte
branchTables []*compile.BranchTable
maxDepth int // maximum stack depth reached while executing the function body
totalLocalVars int // number of local variables used by the function
args int // number of arguments the function accepts
returns bool // whether the function returns a value
}
type goFunction struct {
val reflect.Value
typ reflect.Type
}
func (fn goFunction) call(vm *VM, index int64) {
// numIn = # of call inputs + vm, as the function expects
// an additional *VM argument
numIn := fn.typ.NumIn()
args := make([]reflect.Value, numIn)
proc := NewProcess(vm)
// Pass proc as an argument. Check that the function indeed
// expects a *Process argument.
if reflect.ValueOf(proc).Kind() != fn.typ.In(0).Kind() {
panic(fmt.Sprintf("exec: the first argument of a host function was %s, expected %s", fn.typ.In(0).Kind(), reflect.ValueOf(vm).Kind()))
}
args[0] = reflect.ValueOf(proc)
for i := numIn - 1; i >= 1; i-- {
val := reflect.New(fn.typ.In(i)).Elem()
raw := vm.popUint64()
kind := fn.typ.In(i).Kind()
switch kind {
case reflect.Float64, reflect.Float32:
val.SetFloat(math.Float64frombits(raw))
case reflect.Uint32, reflect.Uint64:
val.SetUint(raw)
case reflect.Int32, reflect.Int64:
val.SetInt(int64(raw))
default:
panic(fmt.Sprintf("exec: args %d invalid kind=%v", i, kind))
}
args[i] = val
}
rtrns := fn.val.Call(args)
for i, out := range rtrns {
kind := out.Kind()
switch kind {
case reflect.Float64, reflect.Float32:
vm.pushFloat64(out.Float())
case reflect.Uint32, reflect.Uint64:
vm.pushUint64(out.Uint())
case reflect.Int32, reflect.Int64:
vm.pushInt64(out.Int())
default:
panic(fmt.Sprintf("exec: return value %d invalid kind=%v", i, kind))
}
}
}
func (compiled compiledFunction) call(vm *VM, index int64) {
newStack := make([]uint64, compiled.maxDepth)
locals := make([]uint64, compiled.totalLocalVars)
for i := compiled.args - 1; i >= 0; i-- {
locals[i] = vm.popUint64()
}
//save execution context
prevCtxt := vm.ctx
vm.ctx = context{
stack: newStack,
locals: locals,
code: compiled.code,
pc: 0,
curFunc: index,
}
rtrn := vm.execCode(compiled)
//restore execution context
vm.ctx = prevCtxt
if compiled.returns {
vm.pushUint64(rtrn)
}
}
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