patch-2.2.0-pre1 linux/arch/i386/lib/checksum.S

• Lines: 451
• Date: Sun Dec 27 10:32:09 1998
• Orig file: v2.1.132/linux/arch/i386/lib/checksum.S
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.132/linux/arch/i386/lib/checksum.S linux/arch/i386/lib/checksum.S
@@ -0,0 +1,450 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		IP/TCP/UDP checksumming routines
+ *
+ * Authors:	Jorge Cwik, <jorge@laser.satlink.net>
+ *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ *		Tom May, <ftom@netcom.com>
+ *              Pentium Pro/II routines:
+ *              Alexander Kjeldaas <astor@guardian.no>
+ *              Finn Arne Gangstad <finnag@guardian.no>
+ *		Lots of code moved from tcp.c and ip.c; see those files
+ *		for more names.
+ *
+ * Changes:     Ingo Molnar, converted csum_partial_copy() to 2.1 exception
+ *			     handling.
+ *		Andi Kleen,  add zeroing on error
+ *                   converted to pure assembler
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#include <asm/errno.h>
+				
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+
+/*	
+unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
+ */
+		
+.text
+.align 4
+.globl csum_partial								
+		
+#if CPU!=686
+
+	  /*		
+	   * Experiments with Ethernet and SLIP connections show that buff
+	   * is aligned on either a 2-byte or 4-byte boundary.  We get at
+	   * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
+	   * Fortunately, it is easy to convert 2-byte alignment to 4-byte
+	   * alignment for the unrolled loop.
+	   */		
+csum_partial:	
+	pushl %esi
+	pushl %ebx
+	movl 20(%esp),%eax	# Function arg: unsigned int sum
+	movl 16(%esp),%ecx	# Function arg: int len
+	movl 12(%esp),%esi	# Function arg: unsigned char *buff
+	testl $2, %esi		# Check alignment.
+	jz 2f			# Jump if alignment is ok.
+	subl $2, %ecx		# Alignment uses up two bytes.
+	jae 1f			# Jump if we had at least two bytes.
+	addl $2, %ecx		# ecx was < 2.  Deal with it.
+	jmp 4f
+1:	movw (%esi), %bx
+	addl $2, %esi
+	addw %bx, %ax
+	adcl $0, %eax
+2:
+	movl %ecx, %edx
+	shrl $5, %ecx
+	jz 2f
+	testl %esi, %esi
+1:	movl (%esi), %ebx
+	adcl %ebx, %eax
+	movl 4(%esi), %ebx
+	adcl %ebx, %eax
+	movl 8(%esi), %ebx
+	adcl %ebx, %eax
+	movl 12(%esi), %ebx
+	adcl %ebx, %eax
+	movl 16(%esi), %ebx
+	adcl %ebx, %eax
+	movl 20(%esi), %ebx
+	adcl %ebx, %eax
+	movl 24(%esi), %ebx
+	adcl %ebx, %eax
+	movl 28(%esi), %ebx
+	adcl %ebx, %eax
+	lea 32(%esi), %esi
+	dec %ecx
+	jne 1b
+	adcl $0, %eax
+2:	movl %edx, %ecx
+	andl $0x1c, %edx
+	je 4f
+	shrl $2, %edx		# This clears CF
+3:	adcl (%esi), %eax
+	lea 4(%esi), %esi
+	dec %edx
+	jne 3b
+	adcl $0, %eax
+4:	andl $3, %ecx
+	jz 7f
+	cmpl $2, %ecx
+	jb 5f
+	movw (%esi),%cx
+	leal 2(%esi),%esi
+	je 6f
+	shll $16,%ecx
+5:	movb (%esi),%cl
+6:	addl %ecx,%eax
+	adcl $0, %eax 
+7:	
+	popl %ebx
+	popl %esi
+	ret
+
+#else /* CPU==686 */
+
+csum_partial:
+	movl 12(%esp),%eax	# Function arg: unsigned int sum
+	movl 8(%esp),%ecx	# Function arg: int len
+	movl 4(%esp),%esi	# Function arg:	const unsigned char *buf
+
+	testl $2, %esi         
+	jnz 30f                 
+10:
+	movl %ecx, %edx
+	movl %ecx, %ebx
+	andl $0x7c, %ebx
+	shrl $7, %ecx
+	addl %ebx,%esi
+	shrl $2, %ebx  
+	negl %ebx
+	lea 45f(%ebx,%ebx,2), %ebx
+	testl %esi, %esi
+	jmp *%ebx
+
+	# Handle 2-byte-aligned regions
+20:	addw (%esi), %ax
+	lea 2(%esi), %esi
+	adcl $0, %eax
+	jmp 10b
+
+30:	subl $2, %ecx          
+	ja 20b                 
+	je 32f
+	movzbl (%esi),%ebx	# csumming 1 byte, 2-aligned
+	addl %ebx, %eax
+	adcl $0, %eax
+	jmp 80f
+32:
+	addw (%esi), %ax	# csumming 2 bytes, 2-aligned
+	adcl $0, %eax
+	jmp 80f
+
+40: 
+	addl -128(%esi), %eax
+	adcl -124(%esi), %eax
+	adcl -120(%esi), %eax
+	adcl -116(%esi), %eax   
+	adcl -112(%esi), %eax   
+	adcl -108(%esi), %eax
+	adcl -104(%esi), %eax
+	adcl -100(%esi), %eax
+	adcl -96(%esi), %eax
+	adcl -92(%esi), %eax
+	adcl -88(%esi), %eax
+	adcl -84(%esi), %eax
+	adcl -80(%esi), %eax
+	adcl -76(%esi), %eax
+	adcl -72(%esi), %eax
+	adcl -68(%esi), %eax
+	adcl -64(%esi), %eax     
+	adcl -60(%esi), %eax     
+	adcl -56(%esi), %eax     
+	adcl -52(%esi), %eax   
+	adcl -48(%esi), %eax   
+	adcl -44(%esi), %eax
+	adcl -40(%esi), %eax
+	adcl -36(%esi), %eax
+	adcl -32(%esi), %eax
+	adcl -28(%esi), %eax
+	adcl -24(%esi), %eax
+	adcl -20(%esi), %eax
+	adcl -16(%esi), %eax
+	adcl -12(%esi), %eax
+	adcl -8(%esi), %eax
+	adcl -4(%esi), %eax
+45:
+	lea 128(%esi), %esi
+	adcl $0, %eax
+	dec %ecx
+	jge 40b
+	movl %edx, %ecx
+50:	andl $3, %ecx
+	jz 80f
+
+	# Handle the last 1-3 bytes without jumping
+	notl %ecx		# 1->2, 2->1, 3->0, higher bits are masked
+	movl $0xffffff,%ebx	# by the shll and shrl instructions
+	shll $3,%ecx
+	shrl %cl,%ebx
+	andl -128(%esi),%ebx	# esi is 4-aligned so should be ok
+	addl %ebx,%eax
+	adcl $0,%eax
+80: 
+	ret
+				
+#endif /* CPU==686 */ 
+
+/*
+unsigned int csum_partial_copy_generic (const char *src, char *dst,
+				  int len, int sum, int *src_err_ptr, int *dst_err_ptr)
+ */ 
+
+/*
+ * Copy from ds while checksumming, otherwise like csum_partial
+ *
+ * The macros SRC and DST specify the type of access for the instruction.
+ * thus we can call a custom exception handler for all access types.
+ *
+ * FIXME: could someone double-check whether I haven't mixed up some SRC and
+ *	  DST definitions? It's damn hard to trigger all cases.  I hope I got
+ *	  them all but there's no guarantee.
+ */
+
+#define SRC(y...)			\
+	9999: y;			\
+	.section __ex_table, "a";	\
+	.long 9999b, 6001f	;	\
+	.previous
+
+#define DST(y...)			\
+	9999: y;			\
+	.section __ex_table, "a";	\
+	.long 9999b, 6002f	;	\
+	.previous
+
+.align 4
+.globl csum_partial_copy_generic
+				
+#if CPU!=686
+
+#define ARGBASE 16		
+#define FP		12
+		
+csum_partial_copy_generic:
+	subl  $4,%esp	
+	pushl %edi
+	pushl %esi
+	pushl %ebx
+	movl ARGBASE+16(%esp),%eax	# sum
+	movl ARGBASE+12(%esp),%ecx	# len
+	movl ARGBASE+4(%esp),%esi	# src
+	movl ARGBASE+8(%esp),%edi	# dst
+
+	testl $2, %edi			# Check alignment. 
+	jz 2f				# Jump if alignment is ok.
+	subl $2, %ecx			# Alignment uses up two bytes.
+	jae 1f				# Jump if we had at least two bytes.
+	addl $2, %ecx			# ecx was < 2.  Deal with it.
+	jmp 4f
+SRC(1:	movw (%esi), %bx	)
+	addl $2, %esi
+DST(	movw %bx, (%edi)	)
+	addl $2, %edi
+	addw %bx, %ax	
+	adcl $0, %eax
+2:
+	movl %ecx, FP(%esp)
+	shrl $5, %ecx
+	jz 2f
+	testl %esi, %esi
+SRC(1:	movl (%esi), %ebx	)
+SRC(	movl 4(%esi), %edx	)
+	adcl %ebx, %eax
+DST(	movl %ebx, (%edi)	)
+	adcl %edx, %eax
+DST(	movl %edx, 4(%edi)	)
+
+SRC(	movl 8(%esi), %ebx	)
+SRC(	movl 12(%esi), %edx	)
+	adcl %ebx, %eax
+DST(	movl %ebx, 8(%edi)	)
+	adcl %edx, %eax
+DST(	movl %edx, 12(%edi)	)
+
+SRC(	movl 16(%esi), %ebx 	)
+SRC(	movl 20(%esi), %edx	)
+	adcl %ebx, %eax
+DST(	movl %ebx, 16(%edi)	)
+	adcl %edx, %eax
+DST(	movl %edx, 20(%edi)	)
+
+SRC(	movl 24(%esi), %ebx	)
+SRC(	movl 28(%esi), %edx	)
+	adcl %ebx, %eax
+DST(	movl %ebx, 24(%edi)	)
+	adcl %edx, %eax
+DST(	movl %edx, 28(%edi)	)
+
+SRC(	lea 32(%esi), %esi	)
+DST(	lea 32(%edi), %edi	)
+	dec %ecx
+	jne 1b
+	adcl $0, %eax
+2:	movl FP(%esp), %edx
+	movl %edx, %ecx
+	andl $0x1c, %edx
+	je 4f
+	shrl $2, %edx			# This clears CF
+SRC(3:	movl (%esi), %ebx	)
+	adcl %ebx, %eax
+DST(	movl %ebx, (%edi)	)
+SRC(	lea 4(%esi), %esi	)
+DST(	lea 4(%edi), %edi	)
+	dec %edx
+	jne 3b
+	adcl $0, %eax
+4:	andl $3, %ecx
+	jz 7f
+	cmpl $2, %ecx
+	jb 5f
+SRC(	movw (%esi), %cx	)
+SRC(	leal 2(%esi), %esi	)
+DST(	movw %cx, (%edi)	)
+DST(	leal 2(%edi), %edi	)
+	je 6f
+	shll $16,%ecx
+SRC(5:	movb (%esi), %cl	)
+DST(	movb %cl, (%edi)	)
+6:	addl %ecx, %eax
+	adcl $0, %eax
+7:
+5000:
+
+# Exception handler:
+.section .fixup, "ax"							
+
+6000:
+
+	movl $-EFAULT, (%ebx)
+
+	# zero the complete destination - computing the rest
+	# is too much work 
+	movl ARGBASE+8(%esp), %edi	# dst
+	movl ARGBASE+12(%esp), %ecx	# len
+	xorl %eax,%eax
+	rep ; stosb
+
+	jmp 5000b
+
+6001:
+	movl ARGBASE+20(%esp), %ebx	# src_err_ptr
+	jmp 6000b
+
+6002:
+	movl ARGBASE+24(%esp), %ebx	# dst_err_ptr
+	jmp 6000b
+
+.previous
+
+	popl %ebx
+	popl %esi
+	popl %edi
+	popl %ecx			# equivalent to addl $4,%esp
+	ret	
+
+#else
+
+/* Version for PentiumII/PPro */
+
+#define ROUND1(x) \
+	SRC(movl x(%esi), %ebx	)	;	\
+	addl %ebx, %eax\n		;	\
+	DST(movl %ebx, x(%edi)	)	; 
+
+#define ROUND(x) \
+	SRC(movl x(%esi), %ebx	)	;	\
+	adcl %ebx, %eax			;	\
+	DST(movl %ebx, x(%edi)	)	;
+
+#define ARGBASE 12
+		
+csum_partial_copy_generic:
+	pushl %ebx
+	pushl %edi
+	pushl %esi
+	movl ARGBASE+4(%esp),%esi	#src
+	movl ARGBASE+8(%esp),%edi	#dst	
+	movl ARGBASE+12(%esp),%ecx	#len
+	movl ARGBASE+16(%esp),%eax	#sum
+	movl %ecx, %edx  
+	movl %ecx, %ebx  
+	shrl $6, %ecx     
+	andl $0x3c, %ebx  
+	negl %ebx
+	subl %ebx, %esi  
+	subl %ebx, %edi  
+	lea 3f(%ebx,%ebx), %ebx
+	testl %esi, %esi 
+	jmp *%ebx         
+1:	addl $64,%esi
+	addl $64,%edi 
+	ROUND1(-64) ROUND(-60) ROUND(-56) ROUND(-52)	
+	ROUND (-48) ROUND(-44) ROUND(-40) ROUND(-36)	
+	ROUND (-32) ROUND(-28) ROUND(-24) ROUND(-20)	
+	ROUND (-16) ROUND(-12) ROUND(-8)  ROUND(-4)	
+3:	adcl $0,%eax
+	dec %ecx
+	jge 1b
+4:      andl $3, %edx
+	jz 7f
+	cmpl $2, %edx
+	jb 5f
+SRC(	movw (%esi), %dx         )
+	leal 2(%esi), %esi
+DST(	movw %dx, (%edi)         )
+	leal 2(%edi), %edi
+	je 6f
+	shll $16,%edx
+5:
+SRC(	movb (%esi), %dl         )
+DST(	movb %dl, (%edi)         )
+6:	addl %edx, %eax
+	adcl $0, %eax
+7:
+.section .fixup, "ax"
+6000:	movl $-EFAULT, (%ebx)
+	# zero the complete destination (computing the rest is too much work)
+	movl ARGBASE+8(%esp),%edi	# dst
+	movl ARGBASE+12(%esp),%ecx	# len
+	xorl %eax,%eax
+	rep; stosb
+	jmp 7b
+6001:	movl ARGBASE+20(%esp), %ebx	# src_err_ptr
+	jmp 6000b	
+6002:	movl ARGBASE+24(%esp), %ebx	# dst_err_ptr
+	jmp 6000b
+.previous				
+
+	popl %esi
+	popl %edi
+	popl %ebx
+	ret
+				
+#undef ROUND
+#undef ROUND1		
+		
+#endif	/* CPU==i686 */