+#undef argLen
+#undef argPtrL
+#undef argPtrH
+#undef resCrcL
+#undef resCrcH
+#undef ptrL
+#undef ptrH
+#undef ptr
+#undef byte
+#undef bitCnt
+#undef polyL
+#undef polyH
+#undef scratch
+
+
+#if USB_CFG_HAVE_MEASURE_FRAME_LENGTH
+#ifdef __IAR_SYSTEMS_ASM__
+/* Register assignments for usbMeasureFrameLength on IAR cc */
+/* Calling conventions on IAR:
+ * First parameter passed in r16/r17, second in r18/r19 and so on.
+ * Callee must preserve r4-r15, r24-r29 (r28/r29 is frame pointer)
+ * Result is passed in r16/r17
+ * In case of the "tiny" memory model, pointers are only 8 bit with no
+ * padding. We therefore pass argument 1 as "16 bit unsigned".
+ */
+# define resL r16
+# define resH r17
+# define cnt16L r30
+# define cnt16H r31
+# define cntH r18
+
+#else /* __IAR_SYSTEMS_ASM__ */
+/* Register assignments for usbMeasureFrameLength on gcc */
+/* Calling conventions on gcc:
+ * First parameter passed in r24/r25, second in r22/23 and so on.
+ * Callee must preserve r1-r17, r28/r29
+ * Result is passed in r24/r25
+ */
+# define resL r24
+# define resH r25
+# define cnt16L r24
+# define cnt16H r25
+# define cntH r26
+#endif
+# define cnt16 cnt16L
+
+; extern unsigned usbMeasurePacketLength(void);
+; returns time between two idle strobes in multiples of 7 CPU clocks
+.global usbMeasureFrameLength
+usbMeasureFrameLength:
+ ldi cntH, 6 ; wait ~ 10 ms for D- == 0
+ clr cnt16L
+ clr cnt16H
+usbMFTime16:
+ dec cntH
+ breq usbMFTimeout
+usbMFWaitStrobe: ; first wait for D- == 0 (idle strobe)
+ sbiw cnt16, 1 ;[0] [6]
+ breq usbMFTime16 ;[2]
+ sbic USBIN, USBMINUS ;[3]
+ rjmp usbMFWaitStrobe ;[4]
+usbMFWaitIdle: ; then wait until idle again
+ sbis USBIN, USBMINUS ;1 wait for D- == 1
+ rjmp usbMFWaitIdle ;2
+ ldi cnt16L, 1 ;1 represents cycles so far
+ clr cnt16H ;1
+usbMFWaitLoop:
+ in cntH, USBIN ;[0] [7]
+ adiw cnt16, 1 ;[1]
+ breq usbMFTimeout ;[3]
+ andi cntH, USBMASK ;[4]
+ brne usbMFWaitLoop ;[5]
+usbMFTimeout:
+#if resL != cnt16L
+ mov resL, cnt16L
+ mov resH, cnt16H
+#endif
+ ret
+
+#undef resL
+#undef resH
+#undef cnt16
+#undef cnt16L
+#undef cnt16H
+#undef cntH
+
+#endif /* USB_CFG_HAVE_MEASURE_FRAME_LENGTH */