var c cbc
	c.b = b
	c.enc = cbcDecrypt
	copy(c.iv[:], iv)
	return &c
}

func (x *cbc) BlockSize() int { return BlockSize }

// cryptBlocksChain invokes the cipher message identifying encrypt or decrypt.
//
//go:noescape
func cryptBlocksChain(src, dst *byte, length int, key *uint32, iv *byte, enc int, nr int)

func (x *cbc) CryptBlocks(dst, src []byte) {
	if len(src)%BlockSize != 0 {

	copy(c.iv[:], iv)
	return &c
}

func (x *cbc) BlockSize() int { return BlockSize }

// cryptBlocksChain invokes the cipher message with chaining (KMC) instruction
// with the given function code. The length must be a multiple of BlockSize (16).
//
//go:noescape
func cryptBlocksChain(c code, iv, key, dst, src *byte, length int)

func (x *cbc) CryptBlocks(dst, src []byte) {
	if len(src)%BlockSize != 0 {

	MOVD	length+32(FP), R5
	MOVD	c+0(FP), R0
loop:
	KM	R2, R4      // cipher message (KM)
	BVS	loop        // branch back if interrupted
	XOR	R0, R0
	RET

// func cryptBlocksChain(c code, iv, key, dst, src *byte, length int)
TEXT ·cryptBlocksChain(SB),NOSPLIT,$48-48
	LA	params-48(SP), R1
	MOVD	iv+8(FP), R8
	MOVD	key+16(FP), R9
	MVC	$16, 0(R8), 0(R1)  // move iv into params
	MVC	$32, 0(R9), 16(R1) // move key into params