emul16s.s

ICCAVR中所有的库函数源码

; 16 bit multiply
; using enhanced core MUL instructions
;
;
; input:  R16/R17, R18/R19
; output: R16/R17

	.define iLo	R16
	.define iHi R17
	.define dLo R18
	.define dHi R19
	.define rLo R24
	.define rHi R25

	.text
empy16s::
	st -Y,R0
	st -Y,R1
	st -Y,rLo
	st -Y,rHi

	mul iLo,dLo
	movw rLo,R0		; also rHi <-- R1
	mul iHi,dLo
	add rHi,R0
	mul iLo,dHi
	add rHi,R0

	movw R16,rLo

	ld rHi,Y+
	ld rLo,Y+
	ld R1,Y+
	ld R0,Y+

	ret