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-rw-r--r--libc/sysdeps/linux/arm/swapcontext.S63
1 files changed, 63 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/arm/swapcontext.S b/libc/sysdeps/linux/arm/swapcontext.S
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index 000000000..ba6e31c4d
--- /dev/null
+++ b/libc/sysdeps/linux/arm/swapcontext.S
@@ -0,0 +1,63 @@
+/* Copyright (C) 2012 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 <sysdep.h>
+
+#include "ucontext_i.h"
+
+ .syntax unified
+ .text
+
+/* int swapcontext (ucontext_t *oucp, const ucontext_t *ucp) */
+
+ENTRY(swapcontext)
+
+ /* Have getcontext() do most of the work then fix up
+ LR afterwards. Save R3 to keep the stack aligned. */
+ push {r0,r1,r3,r14}
+ cfi_adjust_cfa_offset (16)
+ cfi_rel_offset (r0,0)
+ cfi_rel_offset (r1,4)
+ cfi_rel_offset (r3,8)
+ cfi_rel_offset (r14,12)
+
+ bl __getcontext
+ mov r4, r0
+
+ pop {r0,r1,r3,r14}
+ cfi_adjust_cfa_offset (-16)
+ cfi_restore (r0)
+ cfi_restore (r1)
+ cfi_restore (r3)
+ cfi_restore (r14)
+
+ /* Exit if getcontext() failed. */
+ cmp r4, #0
+ itt ne
+ movne r0, r4
+ RETINSTR(ne, r14)
+
+ /* Fix up LR and the PC. */
+ str r13,[r0, #MCONTEXT_ARM_SP]
+ str r14,[r0, #MCONTEXT_ARM_LR]
+ str r14,[r0, #MCONTEXT_ARM_PC]
+
+ /* And swap using swapcontext(). */
+ mov r0, r1
+ b __setcontext
+
+END(swapcontext)