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// Rom layout and bios assembler to C interface.
//
// Copyright (C) 2009-2013 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "asm-offsets.h" // BREGS_*
#include "config.h" // CONFIG_*
#include "entryfuncs.S" // ENTRY_*
/****************************************************************
* Rom Header
****************************************************************/
.section .rom.header
.code16
.global _rom_header, _rom_header_size, _rom_header_checksum
_rom_header:
.word 0xaa55
_rom_header_size:
.byte 0
_rom_header_entry:
jmp _optionrom_entry
_rom_header_checksum:
.byte 0
_rom_header_other:
.space 17
_rom_header_pcidata:
#if CONFIG_VGA_PCI == 1
.word rom_pci_data
#else
.word 0
#endif
_rom_header_pnpdata:
.word 0
_rom_header_other2:
.word 0
_rom_header_signature:
.asciz "IBM"
/****************************************************************
* Entry points
****************************************************************/
// Force a fault if found to be running on broken x86emu versions.
DECLFUNC x86emu_fault
msg: .ascii "SeaVGABIOS: x86emu leal trap!\n"
x86emu_fault:
#if CONFIG_DEBUG_IO
movw %cs:DebugOutputPort, %dx
movw $msg, %si
1: movb %cs:(%si), %al
outb %al, (%dx)
incw %si
cmpw $x86emu_fault, %si
jl 1b
#endif
1: hlt
jmp 1b
// This macro implements a call while avoiding instructions
// that old versions of x86emu have problems with.
.macro VGA_CALLL cfunc
// Make sure leal instruction works.
movl $0x8000, %ecx
leal (%ecx, %ecx, 1), %ecx
cmpl $0x10000, %ecx
jne x86emu_fault
// Use callw instead of calll
push %ax
callw \cfunc
.endm
// This macro is the same as ENTRY_ARG except VGA_CALLL is used.
.macro ENTRY_ARG_VGA cfunc
cli
cld
PUSHBREGS
movw %ss, %ax // Move %ss to %ds
movw %ax, %ds
movl %esp, %ebx // Backup %esp, then zero high bits
movzwl %sp, %esp
movl %esp, %eax // First arg is pointer to struct bregs
VGA_CALLL \cfunc
movl %ebx, %esp // Restore %esp (including high bits)
POPBREGS
.endm
DECLFUNC entry_104f05
entry_104f05:
ENTRY_ARG_VGA vbe_104f05
lretw
DECLFUNC _optionrom_entry
_optionrom_entry:
ENTRY_ARG_VGA vga_post
lretw
DECLFUNC entry_10
entry_10:
ENTRY_ARG_VGA handle_10
iretw
// Entry point using extra stack
DECLFUNC entry_10_extrastack
entry_10_extrastack:
cli
cld
pushw %ds // Set %ds:%eax to space on ExtraStack
pushl %eax
movw %cs:ExtraStackSeg, %ds
movl $(CONFIG_VGA_EXTRA_STACK_SIZE-BREGS_size-8), %eax
SAVEBREGS_POP_DSEAX // Save registers on extra stack
movl %esp, BREGS_size+0(%eax)
movw %ss, BREGS_size+4(%eax)
popl BREGS_code(%eax)
popw BREGS_flags(%eax)
movw %ds, %dx // Setup %ss/%esp and call function
movw %dx, %ss
movl %eax, %esp
VGA_CALLL handle_10
movl %esp, %eax // Restore registers and return
movw BREGS_size+4(%eax), %ss
movl BREGS_size+0(%eax), %esp
popl %edx
popw %dx
pushw BREGS_flags(%eax)
pushl BREGS_code(%eax)
RESTOREBREGS_DSEAX
iretw
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