#!/bin/bash
#
# This file is part of the coreboot project.
#
# Copyright (C) 2008 Carl-Daniel Hailfinger
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
#
#
# This program creates wrappers to be able to call non-PIC code from PIC code
# for the x86 instruction architecture. The wrappers are needed because of the
# ABI mismatch between PIC and non-PIC.
# Other architectures may need similar wrappers.

echo -e "\
# These wrappers must fulfill the following conditions:
# - They must not clobber the stuff already on the stack
# - They must not clobber any register
# - The jump/call must be absolute
# - Neither caller nor callee shall have to be modified
# - The parameters on the stack shall not be touched
# - Referencing fixed memory locations is a no-go for PIC
#
# That rules out the following instructions:
# - All relative jumps
# - All jumps with address given in register/fixed memory
# - All call instructions
#
# The only jump instructions left are far jumps, but hardcoding the code
# segment in advance is ugly/bad/unworkable.
#
# The trick is to push the destination address on the stack with an immediate
# instruction (no register/memory references), then return to that address.
# This emulates the nonexisting "Jump near, absolute, address in operand"
# instruction in the x86 instruction set.
#

	.text

"
while read a; do
echo -e "\
	.globl $a
	.type $a, @function
$a:
	pushl \$stage0_$a
	ret
"
done