m68k-coff SP changing

[Nick Papadonis]

Does anyone know why the following instructions change my SP?
My target is m68k-coff.

Thanks

0x858 in _stext ()
3: /x $fp = 0x7f8
2: x/i $pc  0x858 <_stext+88>:  movew #30960,0xfffa52
1: /x $sp = 0x7fc
(gdb) 
_main () at test.c:9
9       static void _main (void) {
3: /x $fp = 0x7f8
2: x/i $pc  0x860 <_main>:      linkw %fp,#-4
1: /x $sp = 0x7fc
(gdb) 
12        LCD_MR0 = 0x18; 
3: /x $fp = 0x7f8
2: x/i $pc  0x864 <_main+4>:    moveb #24,0x41ffe1
1: /x $sp = 0x7f4
(gdb) 
13        LCD_MR1 = 0xb0; 
3: /x $fp = 0x7f8
2: x/i $pc  0x86c <_main+12>:   moveb #-80,0x41ffe2
1: /x $sp = 0x7f0
(gdb) 
15        LCD_HPS = 0x27;       /* 320 / 8 - 1 in hex */
3: /x $fp = 0x7f8
2: x/i $pc  0x874 <_main+20>:   moveb #39,0x41ffe4
1: /x $sp = 0x7ec


-- 
- Nick