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+/*
+ * This file contains assembly-language implementations
+ * of IP-style 1's complement checksum routines.
+ *
+ * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ * 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.
+ *
+ * Severely hacked about by Paul Mackerras (paulus@cs.anu.edu.au).
+ */
+
+#include <linux/sys.h>
+#include <asm/processor.h>
+#include <asm/errno.h>
+#include <asm/ppc_asm.h>
+
+/*
+ * ip_fast_csum(r3=buf, r4=len) -- Optimized for IP header
+ * len is in words and is always >= 5.
+ *
+ * In practice len == 5, but this is not guaranteed. So this code does not
+ * attempt to use doubleword instructions.
+ */
+_GLOBAL(ip_fast_csum)
+ lwz r0,0(r3)
+ lwzu r5,4(r3)
+ addic. r4,r4,-2
+ addc r0,r0,r5
+ mtctr r4
+ blelr-
+1: lwzu r4,4(r3)
+ adde r0,r0,r4
+ bdnz 1b
+ addze r0,r0 /* add in final carry */
+ rldicl r4,r0,32,0 /* fold two 32-bit halves together */
+ add r0,r0,r4
+ srdi r0,r0,32
+ rlwinm r3,r0,16,0,31 /* fold two halves together */
+ add r3,r0,r3
+ not r3,r3
+ srwi r3,r3,16
+ blr
+
+/*
+ * Compute checksum of TCP or UDP pseudo-header:
+ * csum_tcpudp_magic(r3=saddr, r4=daddr, r5=len, r6=proto, r7=sum)
+ * No real gain trying to do this specially for 64 bit, but
+ * the 32 bit addition may spill into the upper bits of
+ * the doubleword so we still must fold it down from 64.
+ */
+_GLOBAL(csum_tcpudp_magic)
+ rlwimi r5,r6,16,0,15 /* put proto in upper half of len */
+ addc r0,r3,r4 /* add 4 32-bit words together */
+ adde r0,r0,r5
+ adde r0,r0,r7
+ rldicl r4,r0,32,0 /* fold 64 bit value */
+ add r0,r4,r0
+ srdi r0,r0,32
+ rlwinm r3,r0,16,0,31 /* fold two halves together */
+ add r3,r0,r3
+ not r3,r3
+ srwi r3,r3,16
+ blr
+
+/*
+ * Computes the checksum of a memory block at buff, length len,
+ * and adds in "sum" (32-bit).
+ *
+ * This code assumes at least halfword alignment, though the length
+ * can be any number of bytes. The sum is accumulated in r5.
+ *
+ * csum_partial(r3=buff, r4=len, r5=sum)
+ */
+_GLOBAL(csum_partial)
+ subi r3,r3,8 /* we'll offset by 8 for the loads */
+ srdi. r6,r4,3 /* divide by 8 for doubleword count */
+ addic r5,r5,0 /* clear carry */
+ beq 3f /* if we're doing < 8 bytes */
+ andi. r0,r3,2 /* aligned on a word boundary already? */
+ beq+ 1f
+ lhz r6,8(r3) /* do 2 bytes to get aligned */
+ addi r3,r3,2
+ subi r4,r4,2
+ addc r5,r5,r6
+ srdi. r6,r4,3 /* recompute number of doublewords */
+ beq 3f /* any left? */
+1: mtctr r6
+2: ldu r6,8(r3) /* main sum loop */
+ adde r5,r5,r6
+ bdnz 2b
+ andi. r4,r4,7 /* compute bytes left to sum after doublewords */
+3: cmpwi 0,r4,4 /* is at least a full word left? */
+ blt 4f
+ lwz r6,8(r3) /* sum this word */
+ addi r3,r3,4
+ subi r4,r4,4
+ adde r5,r5,r6
+4: cmpwi 0,r4,2 /* is at least a halfword left? */
+ blt+ 5f
+ lhz r6,8(r3) /* sum this halfword */
+ addi r3,r3,2
+ subi r4,r4,2
+ adde r5,r5,r6
+5: cmpwi 0,r4,1 /* is at least a byte left? */
+ bne+ 6f
+ lbz r6,8(r3) /* sum this byte */
+ slwi r6,r6,8 /* this byte is assumed to be the upper byte of a halfword */
+ adde r5,r5,r6
+6: addze r5,r5 /* add in final carry */
+ rldicl r4,r5,32,0 /* fold two 32-bit halves together */
+ add r3,r4,r5
+ srdi r3,r3,32
+ blr
+
+/*
+ * Computes the checksum of a memory block at src, length len,
+ * and adds in "sum" (32-bit), while copying the block to dst.
+ * If an access exception occurs on src or dst, it stores -EFAULT
+ * to *src_err or *dst_err respectively, and (for an error on
+ * src) zeroes the rest of dst.
+ *
+ * This code needs to be reworked to take advantage of 64 bit sum+copy.
+ * However, due to tokenring halfword alignment problems this will be very
+ * tricky. For now we'll leave it until we instrument it somehow.
+ *
+ * csum_partial_copy_generic(r3=src, r4=dst, r5=len, r6=sum, r7=src_err, r8=dst_err)
+ */
+_GLOBAL(csum_partial_copy_generic)
+ addic r0,r6,0
+ subi r3,r3,4
+ subi r4,r4,4
+ srwi. r6,r5,2
+ beq 3f /* if we're doing < 4 bytes */
+ andi. r9,r4,2 /* Align dst to longword boundary */
+ beq+ 1f
+81: lhz r6,4(r3) /* do 2 bytes to get aligned */
+ addi r3,r3,2
+ subi r5,r5,2
+91: sth r6,4(r4)
+ addi r4,r4,2
+ addc r0,r0,r6
+ srwi. r6,r5,2 /* # words to do */
+ beq 3f
+1: mtctr r6
+82: lwzu r6,4(r3) /* the bdnz has zero overhead, so it should */
+92: stwu r6,4(r4) /* be unnecessary to unroll this loop */
+ adde r0,r0,r6
+ bdnz 82b
+ andi. r5,r5,3
+3: cmpwi 0,r5,2
+ blt+ 4f
+83: lhz r6,4(r3)
+ addi r3,r3,2
+ subi r5,r5,2
+93: sth r6,4(r4)
+ addi r4,r4,2
+ adde r0,r0,r6
+4: cmpwi 0,r5,1
+ bne+ 5f
+84: lbz r6,4(r3)
+94: stb r6,4(r4)
+ slwi r6,r6,8 /* Upper byte of word */
+ adde r0,r0,r6
+5: addze r3,r0 /* add in final carry (unlikely with 64-bit regs) */
+ rldicl r4,r3,32,0 /* fold 64 bit value */
+ add r3,r4,r3
+ srdi r3,r3,32
+ blr
+
+/* These shouldn't go in the fixup section, since that would
+ cause the ex_table addresses to get out of order. */
+
+ .globl src_error_1
+src_error_1:
+ li r6,0
+ subi r5,r5,2
+95: sth r6,4(r4)
+ addi r4,r4,2
+ srwi. r6,r5,2
+ beq 3f
+ mtctr r6
+ .globl src_error_2
+src_error_2:
+ li r6,0
+96: stwu r6,4(r4)
+ bdnz 96b
+3: andi. r5,r5,3
+ beq src_error
+ .globl src_error_3
+src_error_3:
+ li r6,0
+ mtctr r5
+ addi r4,r4,3
+97: stbu r6,1(r4)
+ bdnz 97b
+ .globl src_error
+src_error:
+ cmpdi 0,r7,0
+ beq 1f
+ li r6,-EFAULT
+ stw r6,0(r7)
+1: addze r3,r0
+ blr
+
+ .globl dst_error
+dst_error:
+ cmpdi 0,r8,0
+ beq 1f
+ li r6,-EFAULT
+ stw r6,0(r8)
+1: addze r3,r0
+ blr
+
+.section __ex_table,"a"
+ .align 3
+ .llong 81b,src_error_1
+ .llong 91b,dst_error
+ .llong 82b,src_error_2
+ .llong 92b,dst_error
+ .llong 83b,src_error_3
+ .llong 93b,dst_error
+ .llong 84b,src_error_3
+ .llong 94b,dst_error
+ .llong 95b,dst_error
+ .llong 96b,dst_error
+ .llong 97b,dst_error
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