patch-1.3.2 linux/arch/i386/lib/checksum.c

• Lines: 182
• Date: Fri Jun 16 21:11:21 1995
• Orig file: v1.3.1/linux/arch/i386/lib/checksum.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.1/linux/arch/i386/lib/checksum.c linux/arch/i386/lib/checksum.c
@@ -0,0 +1,181 @@
+/*
+ * 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>
+ *		Lots of code moved from tcp.c and ip.c; see those files
+ *		for more names.
+ *
+ *		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 <net/checksum.h>
+
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+
+unsigned int csum_partial(unsigned char * buff, int len, unsigned int sum) {
+#ifdef __i386__
+	__asm__("
+	    movl %%ecx, %%edx
+	    cld
+	    shrl $5, %%ecx
+	    jz 2f
+	    orl %%ecx, %%ecx
+1:	    movl (%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 4(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 8(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 12(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 16(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 20(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 24(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    movl 28(%%esi), %%eax
+	    adcl %%eax, %%ebx
+	    lea 32(%%esi), %%esi
+	    dec %%ecx
+	    jne 1b
+	    adcl $0, %%ebx
+2:	    movl %%edx, %%ecx
+	    andl $28, %%ecx
+	    je 4f
+	    shrl $2, %%ecx
+	    orl %%ecx, %%ecx
+3:	    adcl (%%esi), %%ebx
+	    lea 4(%%esi), %%esi
+	    dec %%ecx
+	    jne 3b
+	    adcl $0, %%ebx
+4:	    movl $0, %%eax
+	    testw $2, %%dx
+	    je 5f
+	    lodsw
+	    addl %%eax, %%ebx
+	    adcl $0, %%ebx
+	    movw $0, %%ax
+5:	    test $1, %%edx
+	    je 6f
+	    lodsb
+	    addl %%eax, %%ebx
+	    adcl $0, %%ebx
+6:	    "
+	: "=b"(sum)
+	: "0"(sum), "c"(len), "S"(buff)
+	: "ax", "bx", "cx", "dx", "si" );
+#else
+#error Not implemented for this CPU
+#endif
+	return(sum);
+}
+
+
+
+/*
+ * copy from fs while checksumming, otherwise like csum_partial
+ */
+
+unsigned int csum_partial_copyffs( char *src, char *dst, 
+				  int len, int sum) {
+#ifdef __i386__
+    __asm__("
+	push %%ds
+	push %%es
+	movw %%ds, %%dx
+	movw %%dx, %%es
+	movw %%fs, %%dx
+	movw %%dx, %%ds
+	cld
+	cmpl $32, %%ecx
+	jb 2f
+	pushl %%ecx
+	shrl $5, %%ecx
+	orl %%ecx, %%ecx
+1:	movl (%%esi), %%eax
+	movl 4(%%esi), %%edx
+	adcl %%eax, %%ebx
+	movl %%eax, %%es:(%%edi)
+	adcl %%edx, %%ebx
+	movl %%edx, %%es:4(%%edi)
+
+	movl 8(%%esi), %%eax
+	movl 12(%%esi), %%edx
+	adcl %%eax, %%ebx
+	movl %%eax, %%es:8(%%edi)
+	adcl %%edx, %%ebx
+	movl %%edx, %%es:12(%%edi)
+
+	movl 16(%%esi), %%eax
+	movl 20(%%esi), %%edx
+	adcl %%eax, %%ebx
+	movl %%eax, %%es:16(%%edi)
+	adcl %%edx, %%ebx
+	movl %%edx, %%es:20(%%edi)
+
+	movl 24(%%esi), %%eax
+	movl 28(%%esi), %%edx
+	adcl %%eax, %%ebx
+	movl %%eax, %%es:24(%%edi)
+	adcl %%edx, %%ebx
+	movl %%edx, %%es:28(%%edi)
+
+	lea 32(%%esi), %%esi
+	lea 32(%%edi), %%edi
+	dec %%ecx
+	jne 1b
+	adcl $0, %%ebx
+	popl %%ecx
+2:	movl %%ecx, %%edx
+	andl $28, %%ecx
+	je 4f
+	shrl $2, %%ecx
+	orl %%ecx, %%ecx
+3:	movl (%%esi), %%eax
+	adcl %%eax, %%ebx
+	movl %%eax, %%es:(%%edi)
+	lea 4(%%esi), %%esi
+	lea 4(%%edi), %%edi
+	dec %%ecx
+	jne 3b
+	adcl $0, %%ebx
+4:	movl $0, %%eax
+	testl $2, %%edx
+	je 5f
+	lodsw
+	stosw
+	addl %%eax, %%ebx
+	movw $0, %%ax
+	adcl %%eax, %%ebx
+5:	test $1, %%edx
+	je 6f
+	lodsb
+	stosb
+	addl %%eax, %%ebx
+	adcl $0, %%ebx
+6:	pop %%es
+	pop %%ds
+	"
+	: "=b"(sum)
+	: "0"(sum), "c"(len), "S"(src), "D"(dst)
+	: "ax", "bx", "cx", "dx", "si", "di" );
+#else
+#error Not implemented for this CPU
+#endif
+    return(sum);
+}
+
+
+