libucontext/arch/arm/swapcontext.S

52 lines
1.4 KiB
ArmAsm

/*
* Copyright (c) 2018, 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#include "defs.h"
ALIAS(swapcontext, libucontext_swapcontext)
ALIAS(__swapcontext, libucontext_swapcontext)
FUNC(libucontext_swapcontext)
/* copy all of the current registers into the ucontext structure */
add r2, r0, #REG_OFFSET(0)
stmia r2, {r0-r12}
str r13, [r0,#REG_OFFSET(13)]
str r14, [r0,#REG_OFFSET(15)]
#ifndef FORCE_SOFT_FLOAT
#ifndef FORCE_HARD_FLOAT
/* test for vfp magic number, copy to other ucontext */
ldr r3, [r1, #VFP_MAGIC_OFFSET]
ldr r4, =#0x56465001
str r3, [r0, #VFP_MAGIC_OFFSET]
cmp r3, r4
bne 1f
#endif
/* if vfp in use, save and restore d8-d15 */
.fpu vfp
add r2, r0, #VFP_D8_OFFSET
vstmia r2, {d8-d15}
add r14, r1, #VFP_D8_OFFSET
vldmia r14, {d8-d15}
.fpu softvfp
1:
#endif
/* load new registers from the second ucontext structure */
add r14, r1, #REG_OFFSET(0)
ldmia r14, {r0-r12}
ldr r13, [r14, #52]
add r14, r14, #56
ldmia r14, {r14, pc}
END(libucontext_swapcontext)