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   1 /*
   2  *  linux/arch/arm/lib/csumpartialcopygeneric.S
   3  *
   4  *  Copyright (C) 1995-2001 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 /*
  12  * unsigned int
  13  * csum_partial_copy_xxx(const char *src, char *dst, int len, int sum, )
  14  *  r0 = src, r1 = dst, r2 = len, r3 = sum
  15  *  Returns : r0 = checksum
  16  *
  17  * Note that 'tst' and 'teq' preserve the carry flag.
  18  */
  19
  20 src     .req    r0
  21 dst     .req    r1
  22 len     .req    r2
  23 sum     .req    r3
  24
  25 .zero:          mov     r0, sum
  26                 load_regs       ea
  27
  28                 /*
  29                  * Align an unaligned destination pointer.  We know that
  30                  * we have >= 8 bytes here, so we don't need to check
  31                  * the length.  Note that the source pointer hasn't been
  32                  * aligned yet.
  33                  */
  34 .dst_unaligned: tst     dst, #1
  35                 beq     .dst_16bit
  36
  37                 load1b  ip
  38                 sub     len, len, #1
  39                 adcs    sum, sum, ip, put_byte_1        @ update checksum
  40                 strb    ip, [dst], #1
  41                 tst     dst, #2
  42                 moveq   pc, lr                  @ dst is now 32bit aligned
  43
  44 .dst_16bit:     load2b  r8, ip
  45                 sub     len, len, #2
  46                 adcs    sum, sum, r8, put_byte_0
  47                 strb    r8, [dst], #1
  48                 adcs    sum, sum, ip, put_byte_1
  49                 strb    ip, [dst], #1
  50                 mov     pc, lr                  @ dst is now 32bit aligned
  51
  52                 /*
  53                  * Handle 0 to 7 bytes, with any alignment of source and
  54                  * destination pointers.  Note that when we get here, C = 0
  55                  */
  56 .less8:         teq     len, #0                 @ check for zero count
  57                 beq     .zero
  58
  59                 /* we must have at least one byte. */
  60                 tst     dst, #1                 @ dst 16-bit aligned
  61                 beq     .less8_aligned
  62
  63                 /* Align dst */
  64                 load1b  ip
  65                 sub     len, len, #1
  66                 adcs    sum, sum, ip, put_byte_1        @ update checksum
  67                 strb    ip, [dst], #1
  68                 tst     len, #6
  69                 beq     .less8_byteonly
  70
  71 1:              load2b  r8, ip
  72                 sub     len, len, #2
  73                 adcs    sum, sum, r8, put_byte_0
  74                 strb    r8, [dst], #1
  75                 adcs    sum, sum, ip, put_byte_1
  76                 strb    ip, [dst], #1
  77 .less8_aligned: tst     len, #6
  78                 bne     1b
  79 .less8_byteonly:
  80                 tst     len, #1
  81                 beq     .done
  82                 load1b  r8
  83                 adcs    sum, sum, r8, put_byte_0        @ update checksum
  84                 strb    r8, [dst], #1
  85                 b       .done
  86
  87 FN_ENTRY
  88                 mov     ip, sp
  89                 save_regs
  90                 sub     fp, ip, #4
  91
  92                 cmp     len, #8                 @ Ensure that we have at least
  93                 blo     .less8                  @ 8 bytes to copy.
  94
  95                 adds    sum, sum, #0            @ C = 0
  96                 tst     dst, #3                 @ Test destination alignment
  97                 blne    .dst_unaligned          @ align destination, return here
  98
  99                 /*
 100                  * Ok, the dst pointer is now 32bit aligned, and we know
 101                  * that we must have more than 4 bytes to copy.  Note
 102                  * that C contains the carry from the dst alignment above.
 103                  */
 104
 105                 tst     src, #3                 @ Test source alignment
 106                 bne     .src_not_aligned
 107
 108                 /* Routine for src & dst aligned */
 109
 110                 bics    ip, len, #15
 111                 beq     2f
 112
 113 1:              load4l  r4, r5, r6, r7
 114                 stmia   dst!, {r4, r5, r6, r7}
 115                 adcs    sum, sum, r4
 116                 adcs    sum, sum, r5
 117                 adcs    sum, sum, r6
 118                 adcs    sum, sum, r7
 119                 sub     ip, ip, #16
 120                 teq     ip, #0
 121                 bne     1b
 122
 123 2:              ands    ip, len, #12
 124                 beq     4f
 125                 tst     ip, #8
 126                 beq     3f
 127                 load2l  r4, r5
 128                 stmia   dst!, {r4, r5}
 129                 adcs    sum, sum, r4
 130                 adcs    sum, sum, r5
 131                 tst     ip, #4
 132                 beq     4f
 133
 134 3:              load1l  r4
 135                 str     r4, [dst], #4
 136                 adcs    sum, sum, r4
 137
 138 4:              ands    len, len, #3
 139                 beq     .done
 140                 load1l  r4
 141                 tst     len, #2
 142                 mov     r5, r4, get_byte_0
 143                 beq     .exit
 144                 adcs    sum, sum, r4, push #16
 145                 strb    r5, [dst], #1
 146                 mov     r5, r4, get_byte_1
 147                 strb    r5, [dst], #1
 148                 mov     r5, r4, get_byte_2
 149 .exit:          tst     len, #1
 150                 strneb  r5, [dst], #1
 151                 andne   r5, r5, #255
 152                 adcnes  sum, sum, r5, put_byte_0
 153
 154                 /*
 155                  * If the dst pointer was not 16-bit aligned, we
 156                  * need to rotate the checksum here to get around
 157                  * the inefficient byte manipulations in the
 158                  * architecture independent code.
 159                  */
 160 .done:          adc     r0, sum, #0
 161                 ldr     sum, [sp, #0]           @ dst
 162                 tst     sum, #1
 163                 movne   r0, r0, ror #8
 164                 load_regs       ea
 165
 166 .src_not_aligned:
 167                 adc     sum, sum, #0            @ include C from dst alignment
 168                 and     ip, src, #3
 169                 bic     src, src, #3
 170                 load1l  r5
 171                 cmp     ip, #2
 172                 beq     .src2_aligned
 173                 bhi     .src3_aligned
 174                 mov     r4, r5, pull #8         @ C = 0
 175                 bics    ip, len, #15
 176                 beq     2f
 177 1:              load4l  r5, r6, r7, r8
 178                 orr     r4, r4, r5, push #24
 179                 mov     r5, r5, pull #8
 180                 orr     r5, r5, r6, push #24
 181                 mov     r6, r6, pull #8
 182                 orr     r6, r6, r7, push #24
 183                 mov     r7, r7, pull #8
 184                 orr     r7, r7, r8, push #24
 185                 stmia   dst!, {r4, r5, r6, r7}
 186                 adcs    sum, sum, r4
 187                 adcs    sum, sum, r5
 188                 adcs    sum, sum, r6
 189                 adcs    sum, sum, r7
 190                 mov     r4, r8, pull #8
 191                 sub     ip, ip, #16
 192                 teq     ip, #0
 193                 bne     1b
 194 2:              ands    ip, len, #12
 195                 beq     4f
 196                 tst     ip, #8
 197                 beq     3f
 198                 load2l  r5, r6
 199                 orr     r4, r4, r5, push #24
 200                 mov     r5, r5, pull #8
 201                 orr     r5, r5, r6, push #24
 202                 stmia   dst!, {r4, r5}
 203                 adcs    sum, sum, r4
 204                 adcs    sum, sum, r5
 205                 mov     r4, r6, pull #8
 206                 tst     ip, #4
 207                 beq     4f
 208 3:              load1l  r5
 209                 orr     r4, r4, r5, push #24
 210                 str     r4, [dst], #4
 211                 adcs    sum, sum, r4
 212                 mov     r4, r5, pull #8
 213 4:              ands    len, len, #3
 214                 beq     .done
 215                 mov     r5, r4, get_byte_0
 216                 tst     len, #2
 217                 beq     .exit
 218                 adcs    sum, sum, r4, push #16
 219                 strb    r5, [dst], #1
 220                 mov     r5, r4, get_byte_1
 221                 strb    r5, [dst], #1
 222                 mov     r5, r4, get_byte_2
 223                 b       .exit
 224
 225 .src2_aligned:  mov     r4, r5, pull #16
 226                 adds    sum, sum, #0
 227                 bics    ip, len, #15
 228                 beq     2f
 229 1:              load4l  r5, r6, r7, r8
 230                 orr     r4, r4, r5, push #16
 231                 mov     r5, r5, pull #16
 232                 orr     r5, r5, r6, push #16
 233                 mov     r6, r6, pull #16
 234                 orr     r6, r6, r7, push #16
 235                 mov     r7, r7, pull #16
 236                 orr     r7, r7, r8, push #16
 237                 stmia   dst!, {r4, r5, r6, r7}
 238                 adcs    sum, sum, r4
 239                 adcs    sum, sum, r5
 240                 adcs    sum, sum, r6
 241                 adcs    sum, sum, r7
 242                 mov     r4, r8, pull #16
 243                 sub     ip, ip, #16
 244                 teq     ip, #0
 245                 bne     1b
 246 2:              ands    ip, len, #12
 247                 beq     4f
 248                 tst     ip, #8
 249                 beq     3f
 250                 load2l  r5, r6
 251                 orr     r4, r4, r5, push #16
 252                 mov     r5, r5, pull #16
 253                 orr     r5, r5, r6, push #16
 254                 stmia   dst!, {r4, r5}
 255                 adcs    sum, sum, r4
 256                 adcs    sum, sum, r5
 257                 mov     r4, r6, pull #16
 258                 tst     ip, #4
 259                 beq     4f
 260 3:              load1l  r5
 261                 orr     r4, r4, r5, push #16
 262                 str     r4, [dst], #4
 263                 adcs    sum, sum, r4
 264                 mov     r4, r5, pull #16
 265 4:              ands    len, len, #3
 266                 beq     .done
 267                 mov     r5, r4, get_byte_0
 268                 tst     len, #2
 269                 beq     .exit
 270                 adcs    sum, sum, r4
 271                 strb    r5, [dst], #1
 272                 mov     r5, r4, get_byte_1
 273                 strb    r5, [dst], #1
 274                 tst     len, #1
 275                 beq     .done
 276                 load1b  r5
 277                 b       .exit
 278
 279 .src3_aligned:  mov     r4, r5, pull #24
 280                 adds    sum, sum, #0
 281                 bics    ip, len, #15
 282                 beq     2f
 283 1:              load4l  r5, r6, r7, r8
 284                 orr     r4, r4, r5, push #8
 285                 mov     r5, r5, pull #24
 286                 orr     r5, r5, r6, push #8
 287                 mov     r6, r6, pull #24
 288                 orr     r6, r6, r7, push #8
 289                 mov     r7, r7, pull #24
 290                 orr     r7, r7, r8, push #8
 291                 stmia   dst!, {r4, r5, r6, r7}
 292                 adcs    sum, sum, r4
 293                 adcs    sum, sum, r5
 294                 adcs    sum, sum, r6
 295                 adcs    sum, sum, r7
 296                 mov     r4, r8, pull #24
 297                 sub     ip, ip, #16
 298                 teq     ip, #0
 299                 bne     1b
 300 2:              ands    ip, len, #12
 301                 beq     4f
 302                 tst     ip, #8
 303                 beq     3f
 304                 load2l  r5, r6
 305                 orr     r4, r4, r5, push #8
 306                 mov     r5, r5, pull #24
 307                 orr     r5, r5, r6, push #8
 308                 stmia   dst!, {r4, r5}
 309                 adcs    sum, sum, r4
 310                 adcs    sum, sum, r5
 311                 mov     r4, r6, pull #24
 312                 tst     ip, #4
 313                 beq     4f
 314 3:              load1l  r5
 315                 orr     r4, r4, r5, push #8
 316                 str     r4, [dst], #4
 317                 adcs    sum, sum, r4
 318                 mov     r4, r5, pull #24
 319 4:              ands    len, len, #3
 320                 beq     .done
 321                 mov     r5, r4, get_byte_0
 322                 tst     len, #2
 323                 beq     .exit
 324                 strb    r5, [dst], #1
 325                 adcs    sum, sum, r4
 326                 load1l  r4
 327                 mov     r5, r4, get_byte_0
 328                 strb    r5, [dst], #1
 329                 adcs    sum, sum, r4, push #24
 330                 mov     r5, r4, get_byte_1
 331                 b       .exit