/* Name: usbdrvasm.S
- * Project: AVR USB driver
+ * 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)
- * Revision: $Id: usbdrvasm.S 692 2008-11-07 15:07:40Z cs $
+ * Revision: $Id: usbdrvasm.S 785 2010-05-30 17:57:07Z cs $
*/
/*
#define cnt r19
#define x3 r20
#define x4 r21
-#define bitcnt r22
+#define x5 r22
+#define bitcnt x5
#define phase x4
#define leap x4
#else /* __IAR_SYSTEMS_ASM__ */
# ifndef USB_INTR_VECTOR /* default to hardware interrupt INT0 */
-# define USB_INTR_VECTOR SIG_INTERRUPT0
+# 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
#endif
-; extern unsigned usbCrc16(unsigned char *data, unsigned char len);
-; data: r24/25
-; len: r22
+#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:
-; r18: data byte
-; r19: bit counter
-; r20/21: polynomial
-; r23: scratch
-; r24/25: crc-sum
-; r26/27=X: ptr
+; 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 resCrcH, 0
ldi polyL, lo8(0xa001)
ldi polyH, hi8(0xa001)
- com argLen ; argLen = -argLen - 1
-crcByteLoop:
- subi argLen, -1
- brcc crcReady ; modified loop to ensure that carry is set below
+ 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+
- ldi bitCnt, -8 ; strange loop counter to ensure that carry is set where we need it
eor resCrcL, byte
-crcBitLoop:
- ror resCrcH ; carry is always set here
+usbCrcBitLoop:
+ ror resCrcH ; carry is always set here (see brcs jumps to here)
ror resCrcL
- brcs crcNoXor
+ brcs usbCrcNoXor
eor resCrcL, polyL
eor resCrcH, polyH
-crcNoXor:
- subi bitCnt, -1
- brcs crcBitLoop
- rjmp crcByteLoop
-crcReady:
+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
;----------------------------------------------------------------------------
#ifndef USB_CFG_CLOCK_KHZ
-# define USB_CFG_CLOCK_KHZ 12000
+# 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_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 rates!"
-#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 */
projects / pub / USBasp.git / blobdiff