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   1 /*
   2  * Copyright (c) 2005, Kohsuke Ohtani
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  30 #ifndef _ARM_SYSTRAP_H
  31 #define _ARM_SYSTRAP_H
  33 #if defined(__gba__)
  35 /*
  36  * Note:
  37  * GBA BIOS does not allow to an install SWI handler by user. So, the system
  38  * calls will jump to the system call entry point (0x200007c) in the kernel
  39  * code. Then, the kernel SWI handler will switch the CPU mode to SVC mode.
  40  * However, CPU mode can be changed only in privileged CPU mode. By this
  41  * reason, all applications run in SYS mode with GBA.
  42  *
  43  */
  45 #define SYSCALL0(name) \
  46         .global name; .align; \
name##: \
stmfd sp!, {r4, r5, lr}; \
mov r4, #SYS_##name; \
ldr r5, =0x200007c; \
add lr, pc, #2; \
mov pc, r5; \
ldmfd sp!, {r4, r5, pc};
  55 #else
  57 #define SYSCALL0(name) \
  58         .global name; .align; \
name##: swi #SYS_##name; \
mov pc, lr
  62 #endif
  65 #define SYSCALL1(name) SYSCALL0(name)
  66 #define SYSCALL2(name) SYSCALL0(name)
  67 #define SYSCALL3(name) SYSCALL0(name)
  68 #define SYSCALL4(name) SYSCALL0(name)
  70 #endif /* _ARM_SYSTRAP_H */