src/fnvhash.s

   1 /*
   2  *  charybdis: a slightly useful ircd.
   3  *  fnvhash.s: x86-optimised FNV hashing implementation
   4  *
   5  *  Copyright (c) 2006 charybdis development team
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; if not, write to the Free Software
  19  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  20  *  USA
  21  *
  22  *  $Id: fnvhash.s 26 2006-09-20 18:02:06Z spb $
  23  */
  24
  25 /* Safely moves hashv from %edx to %eax and returns back to the calling parent. */
  26 fnv_out:
  27         movzbl  12(%ebp), %ecx
  28         movl    -4(%ebp), %eax
  29         movl    %eax, %edx
  30         shrl    %cl, %edx
  31         movl    12(%ebp), %eax
  32         xorl    $2, %eax
  33         decl    %eax
  34         andl    -4(%ebp), %eax
  35         xorl    %edx, %eax
  36         movl    %eax, -4(%ebp)
  37         movl    -4(%ebp), %eax
  38         leave
  39         ret
  40
  41 /*
  42  * Capitalizes the contents of %eax and adds it to the hashv in %edx.
  43  * Returns hashv in register %eax.
  44  *     - nenolod
  45  */
  46 .globl fnv_hash_upper
  47         .type   fnv_hash_upper, @function
  48 fnv_hash_upper:
  49         pushl   %ebp
  50         movl    %esp, %ebp
  51         subl    $4, %esp
  52         movl    $-2128831035, -4(%ebp)          /* u_int32_t h = FNV1_32_INIT */
  53 .eat_data_upper:                                /* while loop construct */
  54         movl    8(%ebp), %eax                   /* move value of *s to %eax */
  55         cmpb    $0, (%eax)                      /* is eax == 0? */
  56         jne     .hash_capitalized               /* if no, then capitalize and hash */
  57         jmp     fnv_out                         /* if yes, then exit out of the loop */
  58 .hash_capitalized:
  59         movl    8(%ebp), %eax
  60         movzbl  (%eax), %eax                    /* increment s (%eax) */
  61         movzbl  ToUpperTab(%eax), %edx          /* hashv ^= ToUpperTab(%eax) */
  62         leal    -4(%ebp), %eax
  63         xorl    %edx, (%eax)                    /* hashv = 0 */
  64         incl    8(%ebp)
  65         movl    -4(%ebp), %eax
  66         imull   $16777619, %eax, %eax           /* FNV1_32_PRIME */
  67         movl    %eax, -4(%ebp)                  /* add this byte to hashv, and */
  68         jmp     .eat_data_upper                 /*   go back for more...       */
  69
  70 /*
  71  * Hashes (no case change) the contents of %eax and adds it to the hashv in %edx.
  72  * Returns hashv in register %eax.
  73  *     - nenolod
  74  */
  75 .globl fnv_hash
  76         .type   fnv_hash, @function
  77 fnv_hash:
  78         pushl   %ebp
  79         movl    %esp, %ebp
  80         subl    $4, %esp
  81         movl    $-2128831035, -4(%ebp)          /* u_int32_t h = FNV1_32_INIT */
  82 .eat_data:                                      /* again, the while loop construct */
  83         movl    8(%ebp), %eax                   /* move value of *s to eax */
  84         cmpb    $0, (%eax)                      /* is eax == 0? */
  85         jne     .hash_lowercase                 /* if not, jump to .hash_lowercase */
  86         jmp     fnv_out                         /* otherwise, jump to fnv_out */
  87 .hash_lowercase:
  88         movl    8(%ebp), %eax
  89         movzbl  (%eax), %edx
  90         leal    -4(%ebp), %eax
  91         xorl    %edx, (%eax)
  92         incl    8(%ebp)                         /* h << 1 */
  93         movl    -4(%ebp), %eax
  94         imull   $16777619, %eax, %eax           /* FNV1_32_PRIME */
  95         movl    %eax, -4(%ebp)                  /* add this byte to hashv, then */
  96         jmp     .eat_data                       /*   check for more...          */
  97
  98 /*
  99  * Hashes (no case change) the contents of %eax and adds it to the hashv in %edx.
 100  * Returns hashv in register %eax.
 101  *
 102  * Bounds checking is performed.
 103  *     - nenolod
 104  */
 105 .globl fnv_hash_len
 106         .type   fnv_hash_len, @function
 107 fnv_hash_len:
 108         pushl   %ebp
 109         movl    %esp, %ebp
 110         subl    $8, %esp
 111         movl    $-2128831035, -4(%ebp)
 112         movl    16(%ebp), %eax
 113         addl    8(%ebp), %eax
 114         movl    %eax, -8(%ebp)
 115 .eat_data_len:
 116         movl    8(%ebp), %eax
 117         cmpb    $0, (%eax)
 118         je      fnv_out
 119         movl    8(%ebp), %eax
 120         cmpl    -8(%ebp), %eax
 121         jb      .hash_lowercase_len
 122         jmp     fnv_out
 123 .hash_lowercase_len:
 124         movl    8(%ebp), %eax
 125         movzbl  (%eax), %edx
 126         leal    -4(%ebp), %eax
 127         xorl    %edx, (%eax)
 128         incl    8(%ebp)
 129         movl    -4(%ebp), %eax
 130         imull   $16777619, %eax, %eax           /* FNV1_32_PRIME */
 131         movl    %eax, -4(%ebp)
 132         jmp     .eat_data_len
 133
 134 /*
 135  * Hashes (no case change) the contents of %eax and adds it to the hashv in %edx.
 136  * Returns hashv in register %eax.
 137  *
 138  * Bounds checking is performed.
 139  *     - nenolod
 140  */
 141 .globl fnv_hash_upper_len
 142         .type   fnv_hash_upper_len, @function
 143 fnv_hash_upper_len:
 144         pushl   %ebp
 145         movl    %esp, %ebp
 146         subl    $8, %esp
 147         movl    $-2128831035, -4(%ebp)
 148         movl    16(%ebp), %eax
 149         addl    8(%ebp), %eax
 150         movl    %eax, -8(%ebp)
 151 .eat_upper_len:
 152         movl    8(%ebp), %eax
 153         cmpb    $0, (%eax)
 154         je      fnv_out
 155         movl    8(%ebp), %eax
 156         cmpl    -8(%ebp), %eax
 157         jb      .hash_uppercase_len
 158         jmp     fnv_out
 159 .hash_uppercase_len:
 160         movl    8(%ebp), %eax
 161         movzbl  (%eax), %eax
 162         movzbl  ToUpperTab(%eax), %edx
 163         leal    -4(%ebp), %eax
 164         xorl    %edx, (%eax)
 165         incl    8(%ebp)
 166         movl    -4(%ebp), %eax
 167         imull   $16777619, %eax, %eax           /* FNV1_32_PRIME */
 168         movl    %eax, -4(%ebp)
 169         jmp     .eat_upper_len