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+/* Name: usbdrvasm.S
+ * Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers
+ * Author: Christian Starkjohann
+ * Creation Date: 2007-06-13
+ * Tabsize: 4
+ * Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH
+ * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt)
+ */
+
+/*
+General Description:
+This module is the assembler part of the USB driver. This file contains
+general code (preprocessor acrobatics and CRC computation) and then includes
+the file appropriate for the given clock rate.
+*/
+
+#define __SFR_OFFSET 0 /* used by avr-libc's register definitions */
+#include "usbportability.h"
+#include "usbdrv.h" /* for common defs */
+
+/* register names */
+#define x1 r16
+#define x2 r17
+#define shift r18
+#define cnt r19
+#define x3 r20
+#define x4 r21
+#define x5 r22
+#define bitcnt x5
+#define phase x4
+#define leap x4
+
+/* Some assembler dependent definitions and declarations: */
+
+#ifdef __IAR_SYSTEMS_ASM__
+ extern usbRxBuf, usbDeviceAddr, usbNewDeviceAddr, usbInputBufOffset
+ extern usbCurrentTok, usbRxLen, usbRxToken, usbTxLen
+ extern usbTxBuf, usbTxStatus1, usbTxStatus3
+# if USB_COUNT_SOF
+ extern usbSofCount
+# endif
+ public usbCrc16
+ public usbCrc16Append
+
+ COMMON INTVEC
+# ifndef USB_INTR_VECTOR
+ ORG INT0_vect
+# else /* USB_INTR_VECTOR */
+ ORG USB_INTR_VECTOR
+# undef USB_INTR_VECTOR
+# endif /* USB_INTR_VECTOR */
+# define USB_INTR_VECTOR usbInterruptHandler
+ rjmp USB_INTR_VECTOR
+ RSEG CODE
+
+#else /* __IAR_SYSTEMS_ASM__ */
+
+# ifndef USB_INTR_VECTOR /* default to hardware interrupt INT0 */
+# ifdef INT0_vect
+# define USB_INTR_VECTOR INT0_vect // this is the "new" define for the vector
+# else
+# define USB_INTR_VECTOR SIG_INTERRUPT0 // this is the "old" vector
+# endif
+# endif
+ .text
+ .global USB_INTR_VECTOR
+ .type USB_INTR_VECTOR, @function
+ .global usbCrc16
+ .global usbCrc16Append
+#endif /* __IAR_SYSTEMS_ASM__ */
+
+
+#if USB_INTR_PENDING < 0x40 /* This is an I/O address, use in and out */
+# define USB_LOAD_PENDING(reg) in reg, USB_INTR_PENDING
+# define USB_STORE_PENDING(reg) out USB_INTR_PENDING, reg
+#else /* It's a memory address, use lds and sts */
+# define USB_LOAD_PENDING(reg) lds reg, USB_INTR_PENDING
+# define USB_STORE_PENDING(reg) sts USB_INTR_PENDING, reg
+#endif
+
+#define usbTxLen1 usbTxStatus1
+#define usbTxBuf1 (usbTxStatus1 + 1)
+#define usbTxLen3 usbTxStatus3
+#define usbTxBuf3 (usbTxStatus3 + 1)
+
+
+;----------------------------------------------------------------------------
+; Utility functions
+;----------------------------------------------------------------------------
+
+#ifdef __IAR_SYSTEMS_ASM__
+/* Register assignments for usbCrc16 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".
+ */
+RTMODEL "__rt_version", "3"
+/* The line above will generate an error if cc calling conventions change.
+ * The value "3" above is valid for IAR 4.10B/W32
+ */
+# define argLen r18 /* argument 2 */
+# define argPtrL r16 /* argument 1 */
+# define argPtrH r17 /* argument 1 */
+
+# define resCrcL r16 /* result */
+# define resCrcH r17 /* result */
+
+# define ptrL ZL
+# define ptrH ZH
+# define ptr Z
+# define byte r22
+# define bitCnt r19
+# define polyL r20
+# define polyH r21
+# define scratch r23
+
+#else /* __IAR_SYSTEMS_ASM__ */
+/* Register assignments for usbCrc16 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 argLen r22 /* argument 2 */
+# define argPtrL r24 /* argument 1 */
+# define argPtrH r25 /* argument 1 */
+
+# define resCrcL r24 /* result */
+# define resCrcH r25 /* result */
+
+# define ptrL XL
+# define ptrH XH
+# define ptr x
+# define byte r18
+# define bitCnt r19
+# define polyL r20
+# define polyH r21
+# define scratch r23
+
+#endif
+
+#if USB_USE_FAST_CRC
+
+; This implementation is faster, but has bigger code size
+; Thanks to Slawomir Fras (BoskiDialer) for this code!
+; It implements the following C pseudo-code:
+; unsigned table(unsigned char x)
+; {
+; unsigned value;
+;
+; value = (unsigned)x << 6;
+; value ^= (unsigned)x << 7;
+; if(parity(x))
+; value ^= 0xc001;
+; return value;
+; }
+; unsigned usbCrc16(unsigned char *argPtr, unsigned char argLen)
+; {
+; unsigned crc = 0xffff;
+;
+; while(argLen--)
+; crc = table(lo8(crc) ^ *argPtr++) ^ hi8(crc);
+; return ~crc;
+; }
+
+; extern unsigned usbCrc16(unsigned char *argPtr, unsigned char argLen);
+; argPtr r24+25 / r16+r17
+; argLen r22 / r18
+; temp variables:
+; byte r18 / r22
+; scratch r23
+; resCrc r24+r25 / r16+r17
+; ptr X / Z
+usbCrc16:
+ mov ptrL, argPtrL
+ mov ptrH, argPtrH
+ ldi resCrcL, 0xFF
+ ldi resCrcH, 0xFF
+ rjmp usbCrc16LoopTest
+usbCrc16ByteLoop:
+ ld byte, ptr+
+ eor resCrcL, byte ; resCrcL is now 'x' in table()
+ mov byte, resCrcL ; compute parity of 'x'
+ swap byte
+ eor byte, resCrcL
+ mov scratch, byte
+ lsr byte
+ lsr byte
+ eor byte, scratch
+ inc byte
+ lsr byte
+ andi byte, 1 ; byte is now parity(x)
+ mov scratch, resCrcL
+ mov resCrcL, resCrcH
+ eor resCrcL, byte ; low byte of if(parity(x)) value ^= 0xc001;
+ neg byte
+ andi byte, 0xc0
+ mov resCrcH, byte ; high byte of if(parity(x)) value ^= 0xc001;
+ clr byte
+ lsr scratch
+ ror byte
+ eor resCrcH, scratch
+ eor resCrcL, byte
+ lsr scratch
+ ror byte
+ eor resCrcH, scratch
+ eor resCrcL, byte
+usbCrc16LoopTest:
+ subi argLen, 1
+ brsh usbCrc16ByteLoop
+ com resCrcL
+ com resCrcH
+ ret
+
+#else /* USB_USE_FAST_CRC */
+
+; This implementation is slower, but has less code size
+;
+; extern unsigned usbCrc16(unsigned char *argPtr, unsigned char argLen);
+; argPtr r24+25 / r16+r17
+; argLen r22 / r18
+; temp variables:
+; byte r18 / r22
+; bitCnt r19
+; poly r20+r21
+; scratch r23
+; resCrc r24+r25 / r16+r17
+; ptr X / Z
+usbCrc16:
+ mov ptrL, argPtrL
+ mov ptrH, argPtrH
+ ldi resCrcL, 0
+ ldi resCrcH, 0
+ ldi polyL, lo8(0xa001)
+ ldi polyH, hi8(0xa001)
+ com argLen ; argLen = -argLen - 1: modified loop to ensure that carry is set
+ ldi bitCnt, 0 ; loop counter with starnd condition = end condition
+ rjmp usbCrcLoopEntry
+usbCrcByteLoop:
+ ld byte, ptr+
+ eor resCrcL, byte
+usbCrcBitLoop:
+ ror resCrcH ; carry is always set here (see brcs jumps to here)
+ ror resCrcL
+ brcs usbCrcNoXor
+ eor resCrcL, polyL
+ eor resCrcH, polyH
+usbCrcNoXor:
+ subi bitCnt, 224 ; (8 * 224) % 256 = 0; this loop iterates 8 times
+ brcs usbCrcBitLoop
+usbCrcLoopEntry:
+ subi argLen, -1
+ brcs usbCrcByteLoop
+usbCrcReady:
+ ret
+; Thanks to Reimar Doeffinger for optimizing this CRC routine!
+
+#endif /* USB_USE_FAST_CRC */
+
+; extern unsigned usbCrc16Append(unsigned char *data, unsigned char len);
+usbCrc16Append:
+ rcall usbCrc16
+ st ptr+, resCrcL
+ st ptr+, resCrcH
+ ret
+
+#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 */
+
+;----------------------------------------------------------------------------
+; Now include the clock rate specific code
+;----------------------------------------------------------------------------
+
+#ifndef USB_CFG_CLOCK_KHZ
+# ifdef F_CPU
+# define USB_CFG_CLOCK_KHZ (F_CPU/1000)
+# else
+# error "USB_CFG_CLOCK_KHZ not defined in usbconfig.h and no F_CPU set!"
+# endif
+#endif
+
+#if USB_CFG_CHECK_CRC /* separate dispatcher for CRC type modules */
+# if USB_CFG_CLOCK_KHZ == 18000
+# include "usbdrvasm18-crc.inc"
+# else
+# error "USB_CFG_CLOCK_KHZ is not one of the supported crc-rates!"
+# endif
+#else /* USB_CFG_CHECK_CRC */
+# if USB_CFG_CLOCK_KHZ == 12000
+# include "usbdrvasm12.inc"
+# elif USB_CFG_CLOCK_KHZ == 12800
+# include "usbdrvasm128.inc"
+# elif USB_CFG_CLOCK_KHZ == 15000
+# include "usbdrvasm15.inc"
+# elif USB_CFG_CLOCK_KHZ == 16000
+# include "usbdrvasm16.inc"
+# elif USB_CFG_CLOCK_KHZ == 16500
+# include "usbdrvasm165.inc"
+# elif USB_CFG_CLOCK_KHZ == 20000
+# include "usbdrvasm20.inc"
+# else
+# error "USB_CFG_CLOCK_KHZ is not one of the supported non-crc-rates!"
+# endif
+#endif /* USB_CFG_CHECK_CRC */
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