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function call on MIPS (newbie question)

To: "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>
Subject: function call on MIPS (newbie question)
From: Harald Krapfenbauer <krapfenbauer@ict.tuwien.ac.at>
Date: Tue, 24 Jun 2008 12:18:37 +0200
Organization: Institute of Computer Technology, Vienna University of Technology
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Thunderbird 2.0.0.14 (X11/20080502)
Hi!

I'm a newbie to the MIPS architecture and I want to port some program to
MIPS.
I must call a function within the .text segment with 2 simple
parameters. So I figured out the following code which
*) loads arg1 into register $4
*) loads arg2 into register $5
*) loads the address into $15
*) executes a jalr
*) breaks afterwards


        *((guint32 *)(code)) = ((method_argument1 >> 16) & 0xffff) |
0x3c040000;    /* arg 1 upper half word */
        *((guint32 *)(code+4)) = (method_argument1 & 0xffff) | 0x24040000;
     /* arg 1 lower half word */
        *((guint32 *)(code+8)) = ((method_argument2 >> 16) & 0xffff) |
0x3c050000;  /* arg 2 upper half word */
        *((guint32 *)(code+12)) = (method_argument2 & 0xffff) | 0x24050000;
     /* arg 2 lower half word */
        *((guint32 *)(code+16)) = ((method_address >> 16) & 0xffff) |
0x3c0f0000;   /* address upper half word */
        *((guint32 *)(code+20)) = (method_address & 0xffff) | 0x240f0000;
     /* address lower half word */
        *((guint32 *)(code+24)) = 0x01e0f809;
     /* jalr */
        *((guint32 *)(code+28)) = 0x0;
     /* branch delay slot */
        *((guint32 *)(code+32)) = 0x0d;
     /* breakpoint */



The code is written to the stack, the SP and the PC are then set to the
beginning of the code on the stack.

Something must be going wrong because after the program stops again, the
PC is 0xffffcb38 (The method address is 0x53cb38) and my program
receives signal 10.

Did I miss something or is my code wrong?
Any help appreciated!

Best regards,
Harald Krapfenbauer

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