package reflect2

import "unsafe"

//go:linkname unsafe_New reflect.unsafe_New
func unsafe_New(rtype unsafe.Pointer) unsafe.Pointer

//go:linkname typedmemmove reflect.typedmemmove
func typedmemmove(rtype unsafe.Pointer, dst, src unsafe.Pointer)

//go:linkname unsafe_NewArray reflect.unsafe_NewArray
func unsafe_NewArray(rtype unsafe.Pointer, length int) unsafe.Pointer

// typedslicecopy copies a slice of elemType values from src to dst,
// returning the number of elements copied.
//go:linkname typedslicecopy reflect.typedslicecopy
//go:noescape
func typedslicecopy(elemType unsafe.Pointer, dst, src sliceHeader) int

//go:linkname mapassign reflect.mapassign
//go:noescape
func mapassign(rtype unsafe.Pointer, m unsafe.Pointer, key, val unsafe.Pointer)

//go:linkname mapaccess reflect.mapaccess
//go:noescape
func mapaccess(rtype unsafe.Pointer, m unsafe.Pointer, key unsafe.Pointer) (val unsafe.Pointer)

// m escapes into the return value, but the caller of mapiterinit
// doesn't let the return value escape.
//go:noescape
//go:linkname mapiterinit reflect.mapiterinit
func mapiterinit(rtype unsafe.Pointer, m unsafe.Pointer) *hiter

//go:noescape
//go:linkname mapiternext reflect.mapiternext
func mapiternext(it *hiter)

//go:linkname ifaceE2I reflect.ifaceE2I
func ifaceE2I(rtype unsafe.Pointer, src interface{}, dst unsafe.Pointer)

// A hash iteration structure.
// If you modify hiter, also change cmd/internal/gc/reflect.go to indicate
// the layout of this structure.
type hiter struct {
	key   unsafe.Pointer // Must be in first position.  Write nil to indicate iteration end (see cmd/internal/gc/range.go).
	value unsafe.Pointer // Must be in second position (see cmd/internal/gc/range.go).
	// rest fields are ignored
}

// add returns p+x.
//
// The whySafe string is ignored, so that the function still inlines
// as efficiently as p+x, but all call sites should use the string to
// record why the addition is safe, which is to say why the addition
// does not cause x to advance to the very end of p's allocation
// and therefore point incorrectly at the next block in memory.
func add(p unsafe.Pointer, x uintptr, whySafe string) unsafe.Pointer {
	return unsafe.Pointer(uintptr(p) + x)
}

// arrayAt returns the i-th element of p,
// an array whose elements are eltSize bytes wide.
// The array pointed at by p must have at least i+1 elements:
// it is invalid (but impossible to check here) to pass i >= len,
// because then the result will point outside the array.
// whySafe must explain why i < len. (Passing "i < len" is fine;
// the benefit is to surface this assumption at the call site.)
func arrayAt(p unsafe.Pointer, i int, eltSize uintptr, whySafe string) unsafe.Pointer {
	return add(p, uintptr(i)*eltSize, "i < len")
}