--- /dev/null
+/*
+ * 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>
+#include <asm/asm.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
+
+#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
+
+ /*
+ * 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
+
+/* Version for PentiumII/PPro */
+
+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: 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:
+ popl %ebx
+ popl %esi
+ ret
+
+#endif
Code Review / kvmfornfv.git / blobdiff