9068c00114
bioscom is called to set up serial port parameters because COMSPEED was treated as an address instead of an immediate value, causing serial port parameters to never be set. PR: i386/110828 Reviewed by: jhb MFC after: 2 weeks
465 lines
12 KiB
ArmAsm
465 lines
12 KiB
ArmAsm
/*
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* Copyright (c) 2002 Bruce M. Simpson
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* Copyright (c) 1998 Robert Nordier
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are freely
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* permitted provided that the above copyright notice and this
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* paragraph and the following disclaimer are duplicated in all
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* such forms.
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*
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* This software is provided "AS IS" and without any express or
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* implied warranties, including, without limitation, the implied
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* warranties of merchantability and fitness for a particular
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* purpose.
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*
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* $FreeBSD$
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*/
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/* A 512-byte boot manager. */
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#ifdef SIO
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/* ... using a serial console on COM1. */
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#endif
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.set NHRDRV,0x475 # Number of hard drives
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.set ORIGIN,0x600 # Execution address
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.set FAKE,0x800 # Partition entry
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.set LOAD,0x7c00 # Load address
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.set PRT_OFF,0x1be # Partition table
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.set TBL0SZ,0x3 # Table 0 size
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.set TBL1SZ,0xa # Table 1 size
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.set MAGIC,0xaa55 # Magic: bootable
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.set B0MAGIC,0xbb66 # Identification
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.set KEY_ENTER,0x1c # Enter key scan code
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.set KEY_F1,0x3b # F1 key scan code
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.set KEY_1,0x02 # #1 key scan code
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.set ASCII_BEL,0x07 # ASCII code for <BEL>
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.set ASCII_CR,0x0D # ASCII code for <CR>
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/*
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* Addresses in the sector of embedded data values.
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* Accessed with negative offsets from the end of the relocated sector (%ebp).
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*/
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.set _NXTDRV,-0x48 # Next drive
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.set _OPT,-0x47 # Default option
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.set _SETDRV,-0x46 # Drive to force
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.set _FLAGS,-0x45 # Flags
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.set _TICKS,-0x44 # Timeout ticks
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.set _FAKE,0x0 # Fake partition entry
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.set _MNUOPT,0xc # Menu options
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.globl start # Entry point
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.code16 # This runs in real mode
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/*
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* Initialise segments and registers to known values.
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* segments start at 0.
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* The stack is immediately below the address we were loaded to.
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*/
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start: cld # String ops inc
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xorw %ax,%ax # Zero
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movw %ax,%es # Address
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movw %ax,%ds # data
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movw %ax,%ss # Set up
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movw $LOAD,%sp # stack
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/*
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* Copy this code to the address it was linked for
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*/
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movw %sp,%si # Source
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movw $start,%di # Destination
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movw $0x100,%cx # Word count
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rep # Relocate
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movsw # code
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/*
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* Set address for variable space beyond code, and clear it.
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* Notice that this is also used to point to the values embedded in the block,
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* by using negative offsets.
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*/
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movw %di,%bp # Address variables
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movb $0x8,%cl # Words to clear
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rep # Zero
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stosw # them
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/*
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* Relocate to the new copy of the code.
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*/
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incb -0xe(%di) # Sector number
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jmp main-LOAD+ORIGIN # To relocated code
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main:
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#if defined(SIO) && COMSPEED != 0
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/*
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* Initialize the serial port. bioscom preserves the driver number in DX.
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*/
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movw $COMSPEED,%ax # defined by Makefile
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callw bioscom
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#endif
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/*
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* Check what flags were loaded with us, specifically if a predefined drive
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* number should be used. If what the bios gives us is bad, use the '0' in
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* the block instead.
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*/
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testb $0x20,_FLAGS(%bp) # Set drive number?
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jnz main.1 # Yes
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testb %dl,%dl # Drive number valid?
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js main.2 # Possibly (0x80 set)
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/*
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* Only update the boot-sector when there is a valid drive number or
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* the drive number is set manually.
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*/
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orb $0x40,_FLAGS(%bp) # Disable updates
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main.1: movb _SETDRV(%bp),%dl # Drive number to use
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/*
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* Whatever we decided to use, now store it into the fake
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* partition entry that lives in the data space above us.
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*/
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main.2: movb %dl,_FAKE(%bp) # Save drive number
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callw putn # To new line
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pushw %dx # Save drive number
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/*
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* Start out with a pointer to the 4th byte of the first table entry
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* so that after 4 iterations it's beyond the end of the sector
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* and beyond a 256 byte boundary and has overflowed 8 bits (see next comment).
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* Remember that the table starts 2 bytes earlier than you would expect
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* as the bootable flag is after it in the block.
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*/
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movw $(partbl+0x4),%bx # Partition table (+4)
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xorw %dx,%dx # Item number
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/*
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* Loop around on the partition table, printing values until we
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* pass a 256 byte boundary. The end of loop test is at main.5.
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*/
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main.3: movb %ch,-0x4(%bx) # Zero active flag (ch == 0)
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btw %dx,_FLAGS(%bp) # Entry enabled?
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jnc main.5 # No
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/*
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* If any of the entries in the table are the same as the 'type' in the slice
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* table entry, then this is an empty or non bootable partition. Skip it.
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*/
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movb (%bx),%al # Load type
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movw $tables,%di # Lookup tables
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movb $TBL0SZ,%cl # Number of entries
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repne # Exclude
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scasb # partition?
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je main.5 # Yes
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/*
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* Now scan the table of known types
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*/
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movb $TBL1SZ+1,%cl # Number of entries
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repne # Locate
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scasb # type
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/*
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* Get the matching element in the next array.
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*/
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addw $TBL1SZ-1, %di # Adjust
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movb (%di),%cl # Partition
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addw %cx,%di # description
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callw putx # Display it
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main.5: incw %dx # Next item
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addb $0x10,%bl # Next entry
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jnc main.3 # Till done
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/*
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* Passed a 256 byte boundary; the table is finished.
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* Add one to the drive number and check it is valid.
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*/
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popw %ax # Drive number
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subb $0x80-0x1,%al # Does next
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cmpb NHRDRV,%al # drive exist? (from BIOS?)
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jb main.6 # Yes
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/*
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* If this is the only drive, don't display it as an option.
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*/
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decw %ax # Already drive 0?
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jz main.7 # Yes
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/*
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* If it was illegal or we cycled through them, go back to drive 0.
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*/
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xorb %al,%al # Drive 0
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/*
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* Whatever drive we selected, make it an ascii digit and save it back to the
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* "next drive" location in the loaded block in case we want to save it later
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* for next time. This also is part of the printed drive string so add 0x80
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* to indicate end of string.
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*/
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main.6: addb $'0'|0x80,%al # Save next
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movb %al,_NXTDRV(%bp) # drive number
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movw $drive,%di # Display
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callw putx # item
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/*
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* Now that we've printed the drive (if we needed to), display a prompt.
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*/
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main.7: movw $prompt,%si # Display
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callw putstr # prompt
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movb _OPT(%bp),%dl # Display
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decw %si # default
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callw putkey # key
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jmp main.7_1 # Skip beep
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/*
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* Users's last try was bad, beep in displeasure.
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*/
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main.10: movb $ASCII_BEL,%al # Signal
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callw putchr # beep!
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/*
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* Start of input loop. Take note of time
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*/
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main.7_1: xorb %ah,%ah # BIOS: Get
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int $0x1a # system time
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movw %dx,%di # Ticks when
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addw _TICKS(%bp),%di # timeout
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/*
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* Busy loop, looking for keystrokes but keeping one eye on the time.
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*/
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main.8:
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#ifndef SIO
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movb $0x1,%ah # BIOS: Check
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int $0x16 # for keypress
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jnz main.11 # Have one
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#else /* SIO */
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movb $0x03,%ah # BIOS: Read COM
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call bioscom
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testb $0x01,%ah # Check line status
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jnz main.11 # (bit 1 indicates input)
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#endif /* SIO */
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xorb %ah,%ah # BIOS: Get
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int $0x1a # system time
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cmpw %di,%dx # Timeout?
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jb main.8 # No
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/*
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* If timed out or defaulting, come here.
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*/
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main.9: movb _OPT(%bp),%al # Load default
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jmp main.12 # Join common code
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/*
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* Get the keystroke.
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*/
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main.11:
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#ifndef SIO
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xorb %ah,%ah # BIOS: Get
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int $0x16 # keypress
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movb %ah,%al # Scan code
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#else
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movb $0x02,%ah # BIOS: Receive
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call bioscom
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#endif
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/*
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* If it's CR act as if timed out.
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*/
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#ifndef SIO
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cmpb $KEY_ENTER,%al # Enter pressed?
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#else
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cmpb $ASCII_CR,%al # Enter pressed?
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#endif
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je main.9 # Yes
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/*
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* Otherwise check if legal. If not ask again.
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*/
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#ifndef SIO
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subb $KEY_F1,%al # Less F1 scan code
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cmpb $0x4,%al # F1..F5?
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jna main.12 # Yes
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subb $(KEY_1 - KEY_F1),%al # Less #1 scan code
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#else
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subb $'1',%al # Less '1' ascii character
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#endif
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cmpb $0x4,%al # #1..#5?
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ja main.10 # No
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/*
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* We have a selection. If it's a bad selection go back to complain.
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* The bits in MNUOPT were set when the options were printed.
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* Anything not printed is not an option.
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*/
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main.12: cbtw # Option
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btw %ax,_MNUOPT(%bp) # enabled?
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jnc main.10 # No
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/*
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* Save the info in the original tables
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* for rewriting to the disk.
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*/
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movb %al,_OPT(%bp) # Save option
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movw $FAKE,%si # Partition for write
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movb (%si),%dl # Drive number
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movw %si,%bx # Partition for read
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cmpb $0x4,%al # F5/#5 pressed?
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pushf # Save
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je main.13 # Yes
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shlb $0x4,%al # Point to
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addw $partbl,%ax # selected
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xchgw %bx,%ax # partition
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movb $0x80,(%bx) # Flag active
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/*
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* If not asked to do a write-back (flags 0x40) don't do one.
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*/
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main.13: pushw %bx # Save
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testb $0x40,_FLAGS(%bp) # No updates?
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jnz main.14 # Yes
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movw $start,%bx # Data to write
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movb $0x3,%ah # Write sector
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callw intx13 # to disk
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main.14: popw %si # Restore
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popf # Restore
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/*
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* If going to next drive, replace drive with selected one.
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* Remember to un-ascii it. Hey 0x80 is already set, cool!
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*/
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jne main.15 # If not F5/#5
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movb _NXTDRV(%bp),%dl # Next drive
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subb $'0',%dl # number
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/*
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* Load selected bootsector to the LOAD location in RAM.
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* If it fails to read or isn't marked bootable, treat it as a bad selection.
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*/
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main.15: movw $LOAD,%bx # Address for read
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movb $0x2,%ah # Read sector
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callw intx13 # from disk
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jc main.10 # If error
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cmpw $MAGIC,0x1fe(%bx) # Bootable?
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jne main.10 # No
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movw $crlf,%si # Leave some
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callw puts # space
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jmp *%bx # Invoke bootstrap
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/*
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* Display routines
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*/
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putkey:
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#ifndef SIO
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movb $'F',%al # Display
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callw putchr # 'F'
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#endif
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movb $'1',%al # Prepare
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addb %dl,%al # digit
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jmp putstr.1 # Display the rest
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/*
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* Display the option and note that it is a valid option.
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* That last point is a bit tricky..
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*/
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putx: btsw %dx,_MNUOPT(%bp) # Enable menu option
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movw $item,%si # Display
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callw putkey # key
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movw %di,%si # Display the rest
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puts: callw putstr # Display string
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putn: movw $crlf,%si # To next line
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putstr: lodsb # Get byte
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testb $0x80,%al # End of string?
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jnz putstr.2 # Yes
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putstr.1: callw putchr # Display char
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jmp putstr # Continue
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putstr.2: andb $~0x80,%al # Clear MSB
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#ifndef SIO
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putchr:
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pushw %bx # Save
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movw $0x7,%bx # Page:attribute
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movb $0xe,%ah # BIOS: Display
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int $0x10 # character
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popw %bx # Restore
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retw # To caller
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#else /* SIO */
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putchr:
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movb $0x01,%ah # BIOS: Send
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bioscom:
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pushw %dx # Save
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xorw %dx,%dx # Use COM1
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int $0x14 # Character
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popw %dx # Restore
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retw # To caller
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#endif /* SIO */
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/* One-sector disk I/O routine */
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intx13: movb 0x1(%si),%dh # Load head
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movw 0x2(%si),%cx # Load cylinder:sector
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movb $0x1,%al # Sector count
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pushw %si # Save
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movw %sp,%di # Save
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testb $0x80,_FLAGS(%bp) # Use packet interface?
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jz intx13.1 # No
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pushl $0x0 # Set the
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pushl 0x8(%si) # LBA address
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pushw %es # Set the transfer
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pushw %bx # buffer address
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push $0x1 # Block count
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push $0x10 # Packet size
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movw %sp,%si # Packet pointer
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decw %ax # Verify off
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orb $0x40,%ah # Use disk packet
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intx13.1: int $0x13 # BIOS: Disk I/O
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movw %di,%sp # Restore
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popw %si # Restore
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retw # To caller
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/* Menu strings */
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item: .ascii " "; .byte ' '|0x80
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prompt: .ascii "\nDefault:"; .byte ' '|0x80
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crlf: .ascii "\r"; .byte '\n'|0x80
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/* Partition type tables */
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tables:
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/*
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* These entries identify invalid or NON BOOT types and partitions.
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*/
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.byte 0x0, 0x5, 0xf
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/*
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* These values indicate bootable types we know the names of.
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*/
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.byte 0x1, 0x6, 0x7, 0xb, 0xc, 0xe, 0x83
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.byte 0xa5, 0xa6, 0xa9
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/*
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* These are offsets that match the known names above and point to the strings
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* that will be printed. os_misc will be used if the search of the above table
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* runs over.
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*/
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.byte os_dos-. # DOS
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.byte os_dos-. # DOS
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.byte os_dos-. # Windows
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.byte os_dos-. # Windows
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.byte os_dos-. # Windows
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.byte os_dos-. # Windows
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.byte os_linux-. # Linux
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.byte os_freebsd-. # FreeBSD
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.byte os_bsd-. # OpenBSD
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.byte os_bsd-. # NetBSD
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.byte os_misc-. # Unknown
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/*
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* And here are the strings themselves. 0x80 or'd into a byte indicates
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* the end of the string. (not so great for Russians but...)
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*/
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os_misc: .ascii "?"; .byte '?'|0x80
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os_dos: .ascii "DO"; .byte 'S'|0x80
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os_linux: .ascii "Linu"; .byte 'x'|0x80
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os_freebsd: .ascii "Free"
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os_bsd: .ascii "BS"; .byte 'D'|0x80
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.org PRT_OFF-0xe,0x90
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.word B0MAGIC # Magic number
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/*
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* These values are sometimes changed before writing back to the drive
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* Be especially careful that nxtdrv: must come after drive:, as it
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* is part of the same string.
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*/
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drive: .ascii "Drive "
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nxtdrv: .byte 0x0 # Next drive number
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opt: .byte 0x0 # Option
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setdrv: .byte 0x80 # Drive to force
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flags: .byte FLAGS # Flags
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ticks: .word TICKS # Delay
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/*
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* Here is the 64 byte partition table that fdisk would fiddle with.
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*/
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partbl: .fill 0x40,0x1,0x0 # Partition table
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.word MAGIC # Magic number
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