| /* |
| * 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 |
