package task

import (
	"unsafe"
)

// Task is a state of goroutine for scheduling purposes.
type Task struct {
	// Next is a field which can be used to make a linked list of tasks.
	Next *Task

	// Ptr is a field which can be used for storing a pointer.
	Ptr unsafe.Pointer

	// Data is a field which can be used for storing state information.
	Data uint64

	// gcData holds data for the GC.
	gcData gcData

	// state is the underlying running state of the task.
	state state

	// DeferFrame stores a pointer to the (stack allocated) defer frame of the
	// goroutine that is used for the recover builtin.
	DeferFrame *DeferFrame
}

// DeferFrame is a stack allocated object that stores information for the
// current "defer frame", which is used in functions that use the `defer`
// keyword.
// The compiler knows the JumpPC struct offset.
type DeferFrame struct {
	JumpSP     unsafe.Pointer // stack pointer to return to
	JumpPC     unsafe.Pointer // pc to return to
	Previous   *DeferFrame    // previous recover buffer pointer
	Panicking  bool           // true iff this defer frame is panicking
	PanicValue interface{}    // panic value, might be nil for panic(nil) for example
}

// getGoroutineStackSize is a compiler intrinsic that returns the stack size for
// the given function and falls back to the default stack size. It is replaced
// with a load from a special section just before codegen.
func getGoroutineStackSize(fn uintptr) uintptr