/*
 * 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>

        .text

/*
 * ip_fast_csum(buf, len) -- Optimized for IP header
 * len is in words and is always >= 5.
 */
_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 */
        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(saddr, daddr, len, proto, sum)
 */     
_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
        addze   r0,r0           /* add in final carry */
        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)
 *
 * csum_partial(buff, len, sum)
 */
_GLOBAL(csum_partial)
        addic   r0,r5,0
        subi    r3,r3,4
        srwi.   r6,r4,2
        beq     3f              /* if we're doing < 4 bytes */
        andi.   r5,r3,2         /* Align buffer to longword boundary */
        beq+    1f
        lhz     r5,4(r3)        /* do 2 bytes to get aligned */
        addi    r3,r3,2
        subi    r4,r4,2
        addc    r0,r0,r5
        srwi.   r6,r4,2         /* # words to do */
        beq     3f
1:      mtctr   r6
2:      lwzu    r5,4(r3)        /* the bdnz has zero overhead, so it should */
        adde    r0,r0,r5        /* be unnecessary to unroll this loop */
        bdnz    2b
        andi.   r4,r4,3
3:      cmpwi   0,r4,2
        blt+    4f
        lhz     r5,4(r3)
        addi    r3,r3,2
        subi    r4,r4,2
        adde    r0,r0,r5
4:      cmpwi   0,r4,1
        bne+    5f
        lbz     r5,4(r3)
        slwi    r5,r5,8         /* Upper byte of word */
        adde    r0,r0,r5
5:      addze   r3,r0           /* add in final carry */
        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.
 *
 * csum_partial_copy_generic(src, dst, len, sum, src_err, 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:      srwi.   r6,r5,4         /* # groups of 4 words to do */
        beq     10f
        mtctr   r6
71:     lwz     r6,4(r3)
72:     lwz     r9,8(r3)
73:     lwz     r10,12(r3)
74:     lwzu    r11,16(r3)
        adde    r0,r0,r6
75:     stw     r6,4(r4)
        adde    r0,r0,r9
76:     stw     r9,8(r4)
        adde    r0,r0,r10
77:     stw     r10,12(r4)
        adde    r0,r0,r11
78:     stwu    r11,16(r4)
        bdnz    71b
10:     rlwinm. r6,r5,30,30,31  /* # words left to do */
        beq     13f
        mtctr   r6
82:     lwzu    r9,4(r3)
92:     stwu    r9,4(r4)
        adde    r0,r0,r9
        bdnz    82b
13:     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 */
        blr

/* These shouldn't go in the fixup section, since that would
   cause the ex_table addresses to get out of order. */

src_error_4:
        mfctr   r6              /* update # bytes remaining from ctr */
        rlwimi  r5,r6,4,0,27
        b       79f
src_error_1:
        li      r6,0
        subi    r5,r5,2
95:     sth     r6,4(r4)
        addi    r4,r4,2
79:     srwi.   r6,r5,2
        beq     3f
        mtctr   r6
src_error_2:
        li      r6,0
96:     stwu    r6,4(r4)
        bdnz    96b
3:      andi.   r5,r5,3
        beq     src_error
src_error_3:
        li      r6,0
        mtctr   r5
        addi    r4,r4,3
97:     stbu    r6,1(r4)
        bdnz    97b
src_error:
        cmpwi   0,r7,0
        beq     1f
        li      r6,-EFAULT
        stw     r6,0(r7)
1:      addze   r3,r0
        blr

dst_error:
        cmpwi   0,r8,0
        beq     1f
        li      r6,-EFAULT
        stw     r6,0(r8)
1:      addze   r3,r0
        blr

.section __ex_table,"a"
        .long   81b,src_error_1
        .long   91b,dst_error
        .long   71b,src_error_4
        .long   72b,src_error_4
        .long   73b,src_error_4
        .long   74b,src_error_4
        .long   75b,dst_error
        .long   76b,dst_error
        .long   77b,dst_error
        .long   78b,dst_error
        .long   82b,src_error_2
        .long   92b,dst_error
        .long   83b,src_error_3
        .long   93b,dst_error
        .long   84b,src_error_3
        .long   94b,dst_error
        .long   95b,dst_error
        .long   96b,dst_error
        .long   97b,dst_error