71 lines
1.8 KiB
ArmAsm
71 lines
1.8 KiB
ArmAsm
/*
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* Copyright (C) 2009 Juergen Beisert, Pengutronix
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*
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* Mostly stolen from the GRUB2 project
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* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2006,2007,2008 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*
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*/
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/**
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* @file
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* @brief Do BIOS calls to load or save data from disks
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*
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* @note These functions are running in flat and real mode. Due to some
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* other restrictions these routines must running from an address
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* space below 0x10000
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*/
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/*
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* int bios_disk_rw_int13_extensions (int ah, int drive, void *dap)
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*
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* Call IBM/MS INT13 Extensions (int 13 %ah=AH) for DRIVE. DAP
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* is passed for disk address packet. If an error occurs, return
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* non-zero, otherwise zero.
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*/
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.section .boot.text.bios_disk_rw_int13_extensions, "ax"
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.code32
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.globl bios_disk_rw_int13_extensions
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.type bios_disk_rw_int13_extensions, @function
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.extern prot_to_real
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.extern real_to_prot
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bios_disk_rw_int13_extensions:
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pushl %ebp
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pushl %esi
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/* compute the address of disk_address_packet */
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movw %cx, %si
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xorw %cx, %cx
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shrl $4, %ecx /* save the segment to cx */
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movb %al, %dh
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call prot_to_real /* enter real mode right now */
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.code16
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movb %dh, %ah
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movw %cx, %ds
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int $0x13 /* do the operation */
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movb %ah, %dl /* save return value */
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/* back to protected mode */
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DATA32 call real_to_prot
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.code32
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movb %dl, %al /* return value in %eax */
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popl %esi
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popl %ebp
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ret
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