40 lines
1.4 KiB
ArmAsm
40 lines
1.4 KiB
ArmAsm
/*
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* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* This software is provided 'as is' and without any warranty, express or
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* implied. In no event shall the authors be liable for any damages arising
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* from the use of this software.
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*/
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#include "defs.h"
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ALIAS(swapcontext, __swapcontext)
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FUNC(__swapcontext)
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move.l 4(%sp), %a0 /* load save ucontext_t pointer from stack */
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movem.l %d2-%d7, REG_OFFSET(REG_D2)(%a0) /* preserve $d2 through $d7 */
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movem.l %a2-%a6, REG_OFFSET(REG_A2)(%a0) /* preserve $a2 through $a6 */
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lea 4(%sp), %a1 /* load stack pointer into $a1 */
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move.l %a1, REG_OFFSET(REG_SP)(%a0) /* store $a1 in ucontext */
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move.l (%sp), REG_OFFSET(REG_PC)(%a0) /* store return address in ucontext's PC register */
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move.l 8(%sp), %a0 /* load new ucontext_t pointer from stack */
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move.l REG_OFFSET(REG_SP)(%a0), %sp /* load new stack pointer */
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movem.l REG_OFFSET(REG_D2)(%a0), %d2-%d7 /* load $d2 through $d7 */
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movem.l REG_OFFSET(REG_A2)(%a0), %a2-%a6 /* load $a2 through $a6 */
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clr.l %d0 /* clear $d0 */
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move.l REG_OFFSET(REG_PC)(%a0), %a1 /* load jump target */
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jmp (%a1) /* jump to *$a1 */
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END(__swapcontext)
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