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74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
/* Copyright (C) 2012-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <stdarg.h>
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#include <ucontext.h>
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/* Number of arguments that go in registers. */
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#define NREG_ARGS 4
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/* Take a context previously prepared via getcontext() and set to
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call func() with the given int only args. */
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void
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__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
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{
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extern void __startcontext (void);
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unsigned long *funcstack;
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va_list vl;
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unsigned long *regptr;
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unsigned int reg;
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int misaligned;
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/* Start at the top of stack. */
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funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
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/* Ensure the stack stays eight byte aligned. */
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misaligned = ((unsigned long) funcstack & 4) != 0;
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if ((argc > NREG_ARGS) && (argc & 1) != 0)
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misaligned = !misaligned;
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if (misaligned)
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funcstack -= 1;
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va_start (vl, argc);
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/* Reserve space for the on-stack arguments. */
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if (argc > NREG_ARGS)
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funcstack -= (argc - NREG_ARGS);
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ucp->uc_mcontext.arm_sp = (unsigned long) funcstack;
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ucp->uc_mcontext.arm_pc = (unsigned long) func;
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/* Exit to startcontext() with the next context in R4 */
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ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link;
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ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext;
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/* The first four arguments go into registers. */
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regptr = &(ucp->uc_mcontext.arm_r0);
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for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++)
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*regptr++ = va_arg (vl, unsigned long);
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/* And the remainder on the stack. */
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for (; reg < argc; reg++)
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*funcstack++ = va_arg (vl, unsigned long);
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va_end (vl);
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}
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weak_alias (__makecontext, makecontext)
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