80x86 Common PC BIOS Module

80x86 Common PC BIOS Module
File: 80x86/sys_src/p1/pc_bios/commonpc/0index.asm

Copyright © Brendan Trotter 2008

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Overview

This index file determines the layout of all other source files in memory. The final binary is used to complete the firmware specific part of boot on behalf of boot loaders designed for the PC BIOS (so that all the code here doesn't need to be duplicated in each of these boot loaders).

The boot loader is responsible for complying with the Common PC BIOS Module Transition State Specification before starting this code. This code is responsible for complying with the BCOS Transition State 1 Specification before starting the (firmware independant) Boot Manager.

Start Of Code

Included System Files

The following line/s include standard "include" files into the binary.

26: ;Standard include files
27:
28: %include "asm.inc"
29: %include "ff/header.inc"
30: %include "kernel/log.inc"
31:
32: %include "options.inc"
33: %include "vbe.inc"
34: %include "kernel/a20.inc"
35: %ifdef ENABLE_INTERACTIVE
36: %include "kernel/pasm.inc"
37: %include "object.inc"
38: %endif

Assembler Setup

Here we tell the assembler what address the code starts at, what mode the CPU is expected to be operating in and which instructions to accept.

47:       ORG 0x00001000
48:
49:       BITS 16
50:       CPU 486
51:
52: TEXT_START:
53:       section .bss
54: BSS_START:
55:       section .text

Executable Header

61: ;Native File Format Header
62:
63: NFF_HEADER TEXT_END - TEXT_START, FILETYPE_BCOS_commonPCBIOS
64:
65: ;Extended Header (see the BCOS 80x86 Common PC BIOS Module File Format Specification)
66:
67: dw START ;Entry Point

Source Code

The End

Here we define a few labels that are used later.

221:       align 4
222: TEXT_END:
223:       section .bss
224:       alignb 4
225:       resb 2048                                 ;Stack space
226: STACK_TOP:
227: BSS_END:

Generated on Sat Oct 17 14:06:01 2009