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/* Copyright (C) 2012-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <stdarg.h>
#include <ucontext.h>
/* Number of arguments that go in registers. */
#define NREG_ARGS 4
/* Take a context previously prepared via getcontext() and set to
call func() with the given int only args. */
void
__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
{
extern void __startcontext (void);
unsigned long *funcstack;
va_list vl;
unsigned long *regptr;
unsigned int reg;
int misaligned;
/* Start at the top of stack. */
funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
/* Ensure the stack stays eight byte aligned. */
misaligned = ((unsigned long) funcstack & 4) != 0;
if ((argc > NREG_ARGS) && (argc & 1) != 0)
misaligned = !misaligned;
if (misaligned)
funcstack -= 1;
va_start (vl, argc);
/* Reserve space for the on-stack arguments. */
if (argc > NREG_ARGS)
funcstack -= (argc - NREG_ARGS);
ucp->uc_mcontext.arm_sp = (unsigned long) funcstack;
ucp->uc_mcontext.arm_pc = (unsigned long) func;
/* Exit to startcontext() with the next context in R4 */
ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link;
ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext;
/* The first four arguments go into registers. */
regptr = &(ucp->uc_mcontext.arm_r0);
for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++)
*regptr++ = va_arg (vl, unsigned long);
/* And the remainder on the stack. */
for (; reg < argc; reg++)
*funcstack++ = va_arg (vl, unsigned long);
va_end (vl);
}
weak_alias (__makecontext, makecontext)
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