libc/unistd/lseek.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2009  Tomas 'ZeXx86' Jedrzejek (zexx86@gmail.com)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19
  20 #include <sys/types.h>
  21
  22 off_t lseek (int fd, off_t offset, int whence)
  23 {
  24         asm volatile (
  25                 "movl $54, %%eax;"
  26                 "movl %0, %%ebx;"
  27                 "movl %1, %%ecx;"
  28                 "movl %2, %%edx;"
  29                 "int $0x80;" :: "g" (fd), "g" (offset), "g" (whence) : "%eax", "%ebx", "%ecx", "%edx");
  30
  31         /* get return value */
  32         off_t *memptr = (off_t *) 0x9006;
  33
  34         return (off_t) *memptr;
  35 }