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#
# __mmap.S, part of the i960 support for the uClibc library.
#
# Copyright (C) 2002 by Okiok Data Ltd. http://www.okiok.com/
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU Library General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option) any
# later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more
# details.
#
# You should have received a copy of the GNU Library General Public License
# along with this program; if not, see <http://www.gnu.org/licenses/>.
#
# Derived from an old port of uC-libc to the i960 by Keith Adams (kma@cse.ogi.edu).
#
#include <sys/syscall.h>
/* This is a plain system call. The 6 arguments are already set up correctly */
/* void * mmap(void *start, size_t length, int prot , int flags, int fd, off_t offset) */
.globl _mmap
_mmap:
mov g13, r3
ldconst __NR_mmap, g13
calls 0
mov r3, g13
/* We now need to check if the return value is a small negative integer. */
/* This is somewhat tricky as the return code (normally an address) is an */
/* unsigned type, or an ordinal in i960 assembler. */
/* We'll use the fact that, integers from -256 to -1 are ordinals 0xFFFFFF00 to 0xFFFFFFFF. */
/* So by checking that the return address is in the top range of the ordinals, we'll */
/* in fact be checking if it's not an encoded negated erro code. */
/* The range -256 to -1 should be enough since that in uClinux 2.0.39, there are */
/* 124 system calls for the i960. */
ldconst 0xFFFFFF00, r3 /* This is the integer's -256 representation */
cmpobl g0, r3, 1f /* Something smaller than this means it's out of the range, and a valid address */
subi g0, 0, r3 /* If it's an errno, save its negated (now positive) value in _errno. */
st r3, _errno
subi 1, 0, g0 /* And return -1. */
1:
ret
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