asmfile.68k

来自「tasking ede调试环境编译程序。」· 68K 代码 · 共 22 行

*@(#)m/r/tutor/tutor682/asmfile.68k	1.1	
	XDEF _foo            ; make _foo public
	XREF _bar            ; "extern" the _bar symbol so you can use it
	SECTION fooseg,,"code"
_foo
	MOVE.L  D2,-(A7)     ; save D2, we'll be using it 
	MOVE    8(A7),-(A7)  ; get value of a, push on stack for call to bar
	JSR     _bar         ; call bar(a)
	ADDQ.L  #2,A7        ; clean up stack (clear off a)
	MOVE    D0,D2        ; D0 has return value from bar(a), save it
* since it is a scratch register and our second call to bar will clobber it
	MOVE    10(A7),-(A7)  ; get value of b, push on stack for call to bar
        JSR     _bar         ; call bar(b)
	ADDQ.L  #2,A7        ; clean up stack (clear off b)
	ADD     D2,D0        ; D0 has return value from bar(b) this time,
*we add in the value of bar(a) (still safe and sound in D2, since the compiler
*will save and restore D2 if bar uses it)
        MOVE.L  (A7)+,D2     ; restore D2 before exiting
	RTS                  ; now we can return, since the return value
*from foo currently resides in D0, which is what the compiler expects