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/* Swap to new context.
Copyright (C) 2008-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Helge Deller <deller@gmx.de>, 2008.
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
<https://www.gnu.org/licenses/>. */
#include <ucontext.h>
#include "ucontext_i.h"
extern int __getcontext (ucontext_t *ucp);
extern int __setcontext (const ucontext_t *ucp);
int
__swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
{
/* Save rp for debugger. */
asm ("stw %rp,-20(%sp)");
asm (".cfi_offset 2, -20");
/* Copy rp to ret0 (r28). */
asm ("copy %rp,%ret0");
/* Create a frame. */
asm ("ldo 64(%sp),%sp");
asm (".cfi_def_cfa_offset -64");
/* Save the current machine context to oucp. */
asm ("bl __getcontext,%rp");
/* Copy oucp to register ret1 (r29). __getcontext saves and restores it
on a normal return. It is restored from oR29 on reactivation. */
asm ("copy %r26,%ret1");
/* Pop frame. */
asm ("ldo -64(%sp),%sp");
asm (".cfi_def_cfa_offset 0");
/* Load return pointer from oR28. */
asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
/* Return if error. */
asm ("or,= %r0,%ret0,%r0");
asm ("bv,n %r0(%rp)");
/* Load sc_sar flag. */
asm ("ldb %0(%%ret1),%%r20" : : "i" (oSAR));
/* Return if oucp context has been reactivated. */
asm ("or,= %r0,%r20,%r0");
asm ("bv,n %r0(%rp)");
/* Mark sc_sar flag. */
asm ("1: ldi 1,%r20");
asm ("stb %%r20,%0(%%ret1)" : : "i" (oSAR));
/* Activate the machine context in ucp. */
asm ("bl __setcontext,%rp");
asm ("ldw %0(%%ret1),%%r26" : : "i" (oR25));
/* Load return pointer. */
asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
/* A successful call to setcontext does not return. */
asm ("bv,n %r0(%rp)");
/* Make gcc happy. */
return 0;
}
weak_alias (__swapcontext, swapcontext)
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