source: soft/tp8/correction/reset.s @ 24

Last change on this file since 24 was 7, checked in by alain, 14 years ago

fichiers tp12
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1/*********************************************************************************
2*   File : reset.s
3*   Author : Alain Greiner
4*   Date : 28/08/2006
5*********************************************************************************
6*   This is a minimal boot code :
7*   - It initializes the Status Register (SR)
8*   - It defines the stack size  and initializes the stack pointer ($29)
9*   - It initializes the global pointer ($28) that is used by GCC to
10*       optimize acces to the global variables.
11*   - It initializes the EPC register, and jump to the main address
12*********************************************************************************/
13
14    .section .reset,"ax",@progbits
15
16    .extern seg_stack_base
17    .extern seg_data_base
18    .extern main
19
20    .globl  reset   /* makes reset an external symbol */
21    .ent    reset
22    .func   reset
23    .align  2
24
25reset:
26    .set noreorder
27
28/* initializes SR register */
29    li      $26,    0x00000013
30    mtc0    $26,    $12
31
32/* initializes stack pointer */
33    la      $29,    seg_stack_base
34    addiu   $29,    $29,    0x4000
35
36/* initializes global pointer */
37    la      $28,    seg_data_base
38
39/* jump to main in kernel mode */
40    la      $26,    main
41    mtc0    $26,    $14
42    eret
43
44.end    reset
45.size   reset, .-reset
46
47.set reorder
48
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