/* * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992 * * Mach Operating System * Copyright (c) 1992, 1991 Carnegie Mellon University * All Rights Reserved. * * Permission to use, copy, modify and distribute this software and its * documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie Mellon * the rights to redistribute these changes. */ /* * HISTORY * $Log: bios.s,v $ * Revision 2.2 92/04/04 11:34:26 rpd * Fix Intel Copyright as per B. Davies authorization. * [92/04/03 rvb] * From 2.5 version * [92/03/30 mg32] * * Revision 2.2 91/04/02 14:35:21 mbj * Add Intel copyright * [90/02/09 rvb] * */ /* Copyright 1988, 1989, 1990, 1991, 1992 by Intel Corporation, Santa Clara, California. All Rights Reserved Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both the copyright notice and this permission notice appear in supporting documentation, and that the name of Intel not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ .file "bios.s" #include "asm.h" .text /* # biosread(dev, cyl, head, sec) # Read one sector from disk into the internal buffer "intbuf" which # is the first 512 bytes of the boot loader. # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory # Call with %ah = 0x2 # %al = number of sectors # %ch = cylinder # %cl = sector # %dh = head # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) # %es:%bx = segment:offset of buffer # Return: # %al = 0x0 on success; err code on failure */ ENTRY(biosread) push %ebp mov %esp, %ebp push %ebx push %ecx push %edx push %es movb 0x10(%ebp), %dh movw 0x0c(%ebp), %cx xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl rorb $2, %cl movb 0x14(%ebp), %al orb %al, %cl incb %cl # sector; sec starts from 1, not 0 movb 0x8(%ebp), %dl # device xor %ebx, %ebx # offset -- 0 # prot_to_real will set %es to BOOTSEG call EXT(prot_to_real) # enter real mode movb $0x2, %ah # subfunction movb $0x1, %al # number of sectors -- one sti int $0x13 cli mov %eax, %ebx # save return value data16 call EXT(real_to_prot) # back to protected mode xor %eax, %eax movb %bh, %al # return value in %ax pop %es pop %edx pop %ecx pop %ebx pop %ebp ret /* # putc(ch) # BIOS call "INT 10H Function 0Eh" to write character to console # Call with %ah = 0x0e # %al = character # %bh = page # %bl = foreground color ( graphics modes) */ ENTRY(putc) push %ebp mov %esp, %ebp push %ebx push %ecx movb 0x8(%ebp), %cl call EXT(prot_to_real) data16 mov $0x1, %ebx # %bh=0, %bl=1 (blue) movb $0xe, %ah movb %cl, %al sti int $0x10 # display a byte cli data16 call EXT(real_to_prot) pop %ecx pop %ebx pop %ebp ret /* # getc() # BIOS call "INT 16H Function 00H" to read character from keyboard # Call with %ah = 0x0 # Return: %ah = keyboard scan code # %al = ASCII character */ ENTRY(getc) push %ebp mov %esp, %ebp push %ebx # save %ebx call EXT(prot_to_real) movb $0x0, %ah sti int $0x16 cli movb %al, %bl # real_to_prot uses %eax data16 call EXT(real_to_prot) xor %eax, %eax movb %bl, %al pop %ebx pop %ebp ret /* # ischar() # if there is a character pending, return it; otherwise return 0 # BIOS call "INT 16H Function 01H" to check whether a character is pending # Call with %ah = 0x1 # Return: # If key waiting to be input: # %ah = keyboard scan code # %al = ASCII character # Zero flag = clear # else # Zero flag = set */ ENTRY(ischar) push %ebp mov %esp, %ebp push %ebx call EXT(prot_to_real) # enter real mode xor %ebx, %ebx movb $0x1, %ah sti int $0x16 cli data16 jz nochar movb %al, %bl nochar: data16 call EXT(real_to_prot) xor %eax, %eax movb %bl, %al pop %ebx pop %ebp ret /* # # get_diskinfo(): return a word that represents the # max number of sectors and heads and drives for this device # */ ENTRY(get_diskinfo) push %ebp mov %esp, %ebp push %es push %ebx push %ecx push %edx movb 0x8(%ebp), %dl # diskinfo(drive #) call EXT(prot_to_real) # enter real mode movb $0x8, %ah # ask for disk info sti int $0x13 cli data16 call EXT(real_to_prot) # back to protected mode xor %eax, %eax /*form a longword representing all this gunk*/ movb %dh, %ah # # heads andb $0x3f, %cl # mask of cylinder gunk movb %cl, %al # # sectors pop %edx pop %ecx pop %ebx pop %es pop %ebp ret /* # # memsize(i) : return the memory size in KB. i == 0 for conventional memory, # i == 1 for extended memory # BIOS call "INT 12H" to get conventional memory size # BIOS call "INT 15H, AH=88H" to get extended memory size # Both have the return value in AX. # */ ENTRY(memsize) push %ebp mov %esp, %ebp push %ebx mov 8(%ebp), %ebx call EXT(prot_to_real) # enter real mode cmpb $0x1, %bl data16 je xext sti int $0x12 cli data16 jmp xdone xext: movb $0x88, %ah sti int $0x15 cli xdone: mov %eax, %ebx data16 call EXT(real_to_prot) mov %ebx, %eax pop %ebx pop %ebp ret