arch/ppc/lib/checksum.S

   1 /*
   2  * This file contains assembly-language implementations
   3  * of IP-style 1's complement checksum routines.
   4  *
   5  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   6  *
   7  *  This program is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU General Public License
   9  *  as published by the Free Software Foundation; either version
  10  *  2 of the License, or (at your option) any later version.
  11  *
  12  * Severely hacked about by Paul Mackerras (paulus@cs.anu.edu.au).
  13  */
  14
  15 #include <linux/sys.h>
  16 #include <asm/processor.h>
  17 #include <asm/errno.h>
  18 #include <asm/ppc_asm.h>
  19
  20         .text
  21
  22 /*
  23  * ip_fast_csum(buf, len) -- Optimized for IP header
  24  * len is in words and is always >= 5.
  25  */
  26 _GLOBAL(ip_fast_csum)
  27         lwz     r0,0(r3)
  28         lwzu    r5,4(r3)
  29         addic.  r4,r4,-2
  30         addc    r0,r0,r5
  31         mtctr   r4
  32         blelr-
  33 1:      lwzu    r4,4(r3)
  34         adde    r0,r0,r4
  35         bdnz    1b
  36         addze   r0,r0           /* add in final carry */
  37         rlwinm  r3,r0,16,0,31   /* fold two halves together */
  38         add     r3,r0,r3
  39         not     r3,r3
  40         srwi    r3,r3,16
  41         blr
  42
  43 /*
  44  * Compute checksum of TCP or UDP pseudo-header:
  45  *   csum_tcpudp_magic(saddr, daddr, len, proto, sum)
  46  */
  47 _GLOBAL(csum_tcpudp_magic)
  48         rlwimi  r5,r6,16,0,15   /* put proto in upper half of len */
  49         addc    r0,r3,r4        /* add 4 32-bit words together */
  50         adde    r0,r0,r5
  51         adde    r0,r0,r7
  52         addze   r0,r0           /* add in final carry */
  53         rlwinm  r3,r0,16,0,31   /* fold two halves together */
  54         add     r3,r0,r3
  55         not     r3,r3
  56         srwi    r3,r3,16
  57         blr
  58
  59 /*
  60  * computes the checksum of a memory block at buff, length len,
  61  * and adds in "sum" (32-bit)
  62  *
  63  * csum_partial(buff, len, sum)
  64  */
  65 _GLOBAL(csum_partial)
  66         addic   r0,r5,0
  67         subi    r3,r3,4
  68         srwi.   r6,r4,2
  69         beq     3f              /* if we're doing < 4 bytes */
  70         andi.   r5,r3,2         /* Align buffer to longword boundary */
  71         beq+    1f
  72         lhz     r5,4(r3)        /* do 2 bytes to get aligned */
  73         addi    r3,r3,2
  74         subi    r4,r4,2
  75         addc    r0,r0,r5
  76         srwi.   r6,r4,2         /* # words to do */
  77         beq     3f
  78 1:      mtctr   r6
  79 2:      lwzu    r5,4(r3)        /* the bdnz has zero overhead, so it should */
  80         adde    r0,r0,r5        /* be unnecessary to unroll this loop */
  81         bdnz    2b
  82         andi.   r4,r4,3
  83 3:      cmpwi   0,r4,2
  84         blt+    4f
  85         lhz     r5,4(r3)
  86         addi    r3,r3,2
  87         subi    r4,r4,2
  88         adde    r0,r0,r5
  89 4:      cmpwi   0,r4,1
  90         bne+    5f
  91         lbz     r5,4(r3)
  92         slwi    r5,r5,8         /* Upper byte of word */
  93         adde    r0,r0,r5
  94 5:      addze   r3,r0           /* add in final carry */
  95         blr
  96
  97 /*
  98  * Computes the checksum of a memory block at src, length len,
  99  * and adds in "sum" (32-bit), while copying the block to dst.
 100  * If an access exception occurs on src or dst, it stores -EFAULT
 101  * to *src_err or *dst_err respectively, and (for an error on
 102  * src) zeroes the rest of dst.
 103  *
 104  * csum_partial_copy_generic(src, dst, len, sum, src_err, dst_err)
 105  */
 106 _GLOBAL(csum_partial_copy_generic)
 107         addic   r0,r6,0
 108         subi    r3,r3,4
 109         subi    r4,r4,4
 110         srwi.   r6,r5,2
 111         beq     3f              /* if we're doing < 4 bytes */
 112         andi.   r9,r4,2         /* Align dst to longword boundary */
 113         beq+    1f
 114 81:     lhz     r6,4(r3)        /* do 2 bytes to get aligned */
 115         addi    r3,r3,2
 116         subi    r5,r5,2
 117 91:     sth     r6,4(r4)
 118         addi    r4,r4,2
 119         addc    r0,r0,r6
 120         srwi.   r6,r5,2         /* # words to do */
 121         beq     3f
 122 1:      srwi.   r6,r5,4         /* # groups of 4 words to do */
 123         beq     10f
 124         mtctr   r6
 125 71:     lwz     r6,4(r3)
 126 72:     lwz     r9,8(r3)
 127 73:     lwz     r10,12(r3)
 128 74:     lwzu    r11,16(r3)
 129         adde    r0,r0,r6
 130 75:     stw     r6,4(r4)
 131         adde    r0,r0,r9
 132 76:     stw     r9,8(r4)
 133         adde    r0,r0,r10
 134 77:     stw     r10,12(r4)
 135         adde    r0,r0,r11
 136 78:     stwu    r11,16(r4)
 137         bdnz    71b
 138 10:     rlwinm. r6,r5,30,30,31  /* # words left to do */
 139         beq     13f
 140         mtctr   r6
 141 82:     lwzu    r9,4(r3)
 142 92:     stwu    r9,4(r4)
 143         adde    r0,r0,r9
 144         bdnz    82b
 145 13:     andi.   r5,r5,3
 146 3:      cmpwi   0,r5,2
 147         blt+    4f
 148 83:     lhz     r6,4(r3)
 149         addi    r3,r3,2
 150         subi    r5,r5,2
 151 93:     sth     r6,4(r4)
 152         addi    r4,r4,2
 153         adde    r0,r0,r6
 154 4:      cmpwi   0,r5,1
 155         bne+    5f
 156 84:     lbz     r6,4(r3)
 157 94:     stb     r6,4(r4)
 158         slwi    r6,r6,8         /* Upper byte of word */
 159         adde    r0,r0,r6
 160 5:      addze   r3,r0           /* add in final carry */
 161         blr
 162
 163 /* These shouldn't go in the fixup section, since that would
 164    cause the ex_table addresses to get out of order. */
 165
 166 src_error_4:
 167         mfctr   r6              /* update # bytes remaining from ctr */
 168         rlwimi  r5,r6,4,0,27
 169         b       79f
 170 src_error_1:
 171         li      r6,0
 172         subi    r5,r5,2
 173 95:     sth     r6,4(r4)
 174         addi    r4,r4,2
 175 79:     srwi.   r6,r5,2
 176         beq     3f
 177         mtctr   r6
 178 src_error_2:
 179         li      r6,0
 180 96:     stwu    r6,4(r4)
 181         bdnz    96b
 182 3:      andi.   r5,r5,3
 183         beq     src_error
 184 src_error_3:
 185         li      r6,0
 186         mtctr   r5
 187         addi    r4,r4,3
 188 97:     stbu    r6,1(r4)
 189         bdnz    97b
 190 src_error:
 191         cmpwi   0,r7,0
 192         beq     1f
 193         li      r6,-EFAULT
 194         stw     r6,0(r7)
 195 1:      addze   r3,r0
 196         blr
 197
 198 dst_error:
 199         cmpwi   0,r8,0
 200         beq     1f
 201         li      r6,-EFAULT
 202         stw     r6,0(r8)
 203 1:      addze   r3,r0
 204         blr
 205
 206 .section __ex_table,"a"
 207         .long   81b,src_error_1
 208         .long   91b,dst_error
 209         .long   71b,src_error_4
 210         .long   72b,src_error_4
 211         .long   73b,src_error_4
 212         .long   74b,src_error_4
 213         .long   75b,dst_error
 214         .long   76b,dst_error
 215         .long   77b,dst_error
 216         .long   78b,dst_error
 217         .long   82b,src_error_2
 218         .long   92b,dst_error
 219         .long   83b,src_error_3
 220         .long   93b,dst_error
 221         .long   84b,src_error_3
 222         .long   94b,dst_error
 223         .long   95b,dst_error
 224         .long   96b,dst_error
 225         .long   97b,dst_error