diff options
Diffstat (limited to 'sys/boot/i386/boot0/boot0sio.s')
| -rw-r--r-- | sys/boot/i386/boot0/boot0sio.s | 438 |
1 files changed, 0 insertions, 438 deletions
diff --git a/sys/boot/i386/boot0/boot0sio.s b/sys/boot/i386/boot0/boot0sio.s deleted file mode 100644 index 62e6556..0000000 --- a/sys/boot/i386/boot0/boot0sio.s +++ /dev/null @@ -1,438 +0,0 @@ -# -# Copyright (c) 2002 Bruce M. Simpson -# Copyright (c) 1998 Robert Nordier -# All rights reserved. -# -# Redistribution and use in source and binary forms are freely -# permitted provided that the above copyright notice and this -# paragraph and the following disclaimer are duplicated in all -# such forms. -# -# This software is provided "AS IS" and without any express or -# implied warranties, including, without limitation, the implied -# warranties of merchantability and fitness for a particular -# purpose. -# - -# $FreeBSD$ - -# A 512-byte boot manager which uses a serial console on COM1. - - .set NHRDRV,0x475 # Number of hard drives - .set ORIGIN,0x600 # Execution address - .set FAKE,0x800 # Partition entry - .set LOAD,0x7c00 # Load address - - .set PRT_OFF,0x1be # Partition table - - .set TBL0SZ,0x3 # Table 0 size - .set TBL1SZ,0xb # Table 1 size - - .set MAGIC,0xaa55 # Magic: bootable - .set B0MAGIC,0xbb66 # Identification - - .set KEY_ENTER,0x1c # Enter key scan code - .set KEY_F1,0x3b # F1 key scan code - .set KEY_1,0x02 # #1 key scan code - - .set ASCII_BEL,0x07 # ASCII code for <BEL> - .set ASCII_CR,0x0D # ASCII code for <CR> - .set ASCII_1,0x31 # ASCII code for '1' - -# -# Addresses in the sector of embedded data values. -# Accessed with negative offsets from the end of the relocated sector (%ebp). -# - .set _NXTDRV,-0x48 # Next drive - .set _OPT,-0x47 # Default option - .set _SETDRV,-0x46 # Drive to force - .set _FLAGS,-0x45 # Flags - .set _TICKS,-0x44 # Timeout ticks - .set _FAKE,0x0 # Fake partition entry - .set _MNUOPT,0xc # Menu options - - .globl start # Entry point - .code16 # This runs in real mode - -# -# Initialise segments and registers to known values. -# segments start at 0. -# The stack is immediately below the address we were loaded to. -# -start: cld # String ops inc - xorw %ax,%ax # Zero - movw %ax,%es # Address - movw %ax,%ds # data - movw %ax,%ss # Set up - movw $LOAD,%sp # stack - -# -# Copy this code to the address it was linked for -# - movw %sp,%si # Source - movw $start,%di # Destination - movw $0x100,%cx # Word count - rep # Relocate - movsw # code -# -# Set address for variable space beyond code, and clear it. -# Notice that this is also used to point to the values embedded in the block, -# by using negative offsets. -# - movw %di,%bp # Address variables - movb $0x8,%cl # Words to clear - rep # Zero - stosw # them -# -# Relocate to the new copy of the code. -# - incb -0xe(%di) # Sector number - jmp main-LOAD+ORIGIN # To relocated code - -# -# Initialize the serial port. -# Must save DX (contains drive number) -# -main: pushw %dx # Save - xorw %dx,%dx # Port: COM1 - movb COMSPEED,%al # defined by Makefile - movb $0x00,%ah # BIOS: Set COM Port - int $0x14 # Parameters - popw %dx # Restore -# -# Check what flags were loaded with us, specifically, Use a predefined Drive. -# If what the bios gives us is bad, use the '0' in the block instead, as well. -# - testb $0x20,_FLAGS(%bp) # Set number drive? - jnz main.1 # Yes - testb %dl,%dl # Drive number valid? - js main.2 # Possibly (0x80 set) -main.1: movb _SETDRV(%bp),%dl # Drive number to use -# -# Whatever we decided to use, now store it into the fake -# partition entry that lives in the data space above us. -# -main.2: movb %dl,_FAKE(%bp) # Save drive number - callw putn # To new line - pushw %dx # Save drive number -# -# Start out with a pointer to the 4th byte of the first table entry -# so that after 4 iterations it's beyond the end of the sector. -# and beyond a 256 byte boundary and has overflowed 8 bits (see next comment). -# (remember that the table starts 2 bytes earlier than you would expect -# as the bootable flag is after it in the block) -# - movw $(partbl+0x4),%bx # Partition table (+4) - xorw %dx,%dx # Item number -# -# Loop around on the partition table, printing values until we -# pass a 256 byte boundary. The end of loop test is at main.5. -# -main.3: movb %ch,-0x4(%bx) # Zero active flag (ch == 0) - btw %dx,_FLAGS(%bp) # Entry enabled? - jnc main.5 # No -# -# If any of the entries in the table are -# the same as the 'type' in the slice table entry, -# then this is an empty or non bootable partition. Skip it. -# - movb (%bx),%al # Load type - movw $tables,%di # Lookup tables - movb $TBL0SZ,%cl # Number of entries - repne # Exclude - scasb # partition? - je main.5 # Yes -# -# Now scan the table of known types -# - movb $TBL1SZ,%cl # Number of entries - repne # Known - scasb # type? - jne main.4 # No -# -# If it matches get the matching element in the -# next array. if it doesn't, we are already -# pointing at its first element which points to a "?". -# - addw $TBL1SZ,%di # Adjust -main.4: movb (%di),%cl # Partition - addw %cx,%di # description - callw putx # Display it -main.5: incw %dx # Next item - addb $0x10,%bl # Next entry - jnc main.3 # Till done -# -# Passed a 256 byte boundary.. -# table is finished. -# Add one to the drive number and check it is valid, -# - popw %ax # Drive number - subb $0x80-0x1,%al # Does next - cmpb NHRDRV,%al # drive exist? (from BIOS?) - jb main.6 # Yes -# If not then if there is only one drive, -# Don't display drive as an option. -# - decw %ax # Already drive 0? - jz main.7 # Yes -# If it was illegal or we cycled through them, -# then go back to drive 0. -# - xorb %al,%al # Drive 0 -# -# Whatever drive we selected, make it an ascii digit and save it back -# to the "next drive" location in the loaded block in case we -# want to save it for next time. -# This also is part of the printed drive string so add 0x80 to indicate -# end of string. -# -main.6: addb $'0'|0x80,%al # Save next - movb %al,_NXTDRV(%bp) # drive number - movw $drive,%di # Display - callw putx # item -# -# Now that we've printed the drive (if we needed to), display a prompt. -# Get ready for the input byte noting the time. -# -main.7: movw $prompt,%si # Display - callw putstr # prompt - movb _OPT(%bp),%dl # Display - decw %si # default - callw putkey # key -main.7_1: - xorb %ah,%ah # BIOS: Get - int $0x1a # system time - movw %dx,%si # Ticks when - addw _TICKS(%bp),%si # timeout - -# -# Busy loop, checking for a character on the serial port, but -# keeping one eye on the time. -# - -main.8: xorw %dx,%dx # Use COM1 - movb $0x03,%ah # BIOS: Read COM - int $0x14 # Status - testb $0x01,%ah # Check line status - jnz main.11 # (bit 1 indicates input) - - xorb %ah,%ah # BIOS: Get - int $0x1a # system time - cmpw %si,%dx # Timeout? - jb main.8 # No - -# -# If timed out or defaulting, come here. -# -main.9: movb _OPT(%bp),%al # Load default - jmp main.12 # Join common code -# -# User's last try was bad, beep in displeasure. -# Since nothing was printed, just continue on as if the user -# hadn't done anything. This gives the effect of the user getting a beep -# for all bad keystrokes but no action until either the timeout -# occurs or the user hits a good key. -# -main.10: movb $ASCII_BEL,%al # Signal - callw putchr # error - jmp main.7_1 # Go back -# -# Check the character we just got on the serial port. -# -main.11: movb $0x02,%ah # BIOS: Receive - int $0x14 # COM Byte -# -# If it's CR act as if timed out. -# - cmpb $ASCII_CR,%al # Enter pressed? - je main.9 # Yes -# -# Otherwise check if legal -# If not ask again. -# - subb $ASCII_1,%al # Less '1' ascii character - cmpb $0x4,%al # #1..#5? - ja main.10 # No -# -# We have a selection. -# but if it's a bad selection go back to complain. -# The bits in MNUOPT were set when the options were printed. -# Anything not printed is not an option. -# -main.12: cbtw # Option - btw %ax,_MNUOPT(%bp) # enabled? - jnc main.10 # No -# -# Save the info in the original tables -# for rewriting to the disk. -# - movb %al,_OPT(%bp) # Save option - movw $FAKE,%si # Partition for write - movb (%si),%dl # Drive number - movw %si,%bx # Partition for read - cmpb $0x4,%al # F5/#5 pressed? - pushf # Save - je main.13 # Yes - shlb $0x4,%al # Point to - addw $partbl,%ax # selected - xchgw %bx,%ax # partition - movb $0x80,(%bx) # Flag active -# -# If not asked to do a write-back (flags 0x40) don't do one. -# -main.13: pushw %bx # Save - testb $0x40,_FLAGS(%bp) # No updates? - jnz main.14 # Yes - movw $start,%bx # Data to write - movb $0x3,%ah # Write sector - callw intx13 # to disk -main.14: popw %si # Restore - popf # Restore -# -# If going to next drive, replace drive with selected one. -# Remember to un-ascii it. Hey 0x80 is already set, cool! -# - jne main.15 # If not F5/#5 - movb _NXTDRV(%bp),%dl # Next drive - subb $'0',%dl # number -# -# load selected bootsector to the LOAD location in RAM. -# If it fails to read or isn't marked bootable, treat it -# as a bad selection. -# XXX what does %si carry? -# -main.15: movw $LOAD,%bx # Address for read - movb $0x2,%ah # Read sector - callw intx13 # from disk - jc main.10 # If error - cmpw $MAGIC,0x1fe(%bx) # Bootable? - jne main.10 # No - pushw %si # Save - movw $crlf,%si # Leave some - callw puts # space - popw %si # Restore - jmp *%bx # Invoke bootstrap -# -# Display routines -# - -putkey: movb $ASCII_1,%al # Prepare - addb %dl,%al # digit - jmp putstr.1 # Display the rest - -# -# Display the option and note that it is a valid option. -# That last point is a bit tricky.. -# -putx: btsw %dx,_MNUOPT(%bp) # Enable menu option - movw $item,%si # Display - callw putkey # key - movw %di,%si # Display the rest - -puts: callw putstr # Display string - -putn: movw $crlf,%si # To next line - -putstr: lodsb # Get byte - testb $0x80,%al # End of string? - jnz putstr.2 # Yes -putstr.1: callw putchr # Display char - jmp putstr # Continue -putstr.2: andb $~0x80,%al # Clear MSB - -putchr: pushw %dx # Save - xorw %dx,%dx # Use COM1 - xorw %cx,%cx # No timeout - movb $0x01,%ah # BIOS: Send - int $0x14 # Character - popw %dx # Restore - retw # To caller - -# One-sector disk I/O routine - -intx13: movb 0x1(%si),%dh # Load head - movw 0x2(%si),%cx # Load cylinder:sector - movb $0x1,%al # Sector count - pushw %si # Save - movw %sp,%di # Save - testb $0x80,_FLAGS(%bp) # Use packet interface? - jz intx13.1 # No - pushl $0x0 # Set the - pushl 0x8(%si) # LBA address - pushw %es # Set the transfer - pushw %bx # buffer address - push $0x1 # Block count - push $0x10 # Packet size - movw %sp,%si # Packet pointer - decw %ax # Verify off - orb $0x40,%ah # Use disk packet -intx13.1: int $0x13 # BIOS: Disk I/O - movw %di,%sp # Restore - popw %si # Restore - retw # To caller - -# Menu strings - -item: .ascii " "; .byte ' '|0x80 -prompt: .ascii "\nDef:"; .byte ' '|0x80 -crlf: .ascii "\r"; .byte '\n'|0x80 - -# Partition type tables - -tables: -# -# These entries identify invalid or NON BOOT types and partitions. -# - .byte 0x0, 0x5, 0xf -# -# These values indicate bootable types we know the names of -# - .byte 0x1, 0x4, 0x6, 0xb, 0xc, 0xe, 0x83 - .byte 0x9f, 0xa5, 0xa6, 0xa9 -# -# These are offsets that match the known names above and point to the strings -# that will be printed. -# - .byte os_misc-. # Unknown - .byte os_dos-. # DOS - .byte os_dos-. # DOS - .byte os_dos-. # DOS - .byte os_dos-. # Windows - .byte os_dos-. # Windows - .byte os_dos-. # Windows - .byte os_linux-. # Linux - .byte os_bsd-. # BSD/OS - .byte os_freebsd-. # FreeBSD - .byte os_bsd-. # OpenBSD - .byte os_bsd-. # NetBSD -# -# And here are the strings themselves. 0x80 or'd into a byte indicates -# the end of the string. (not so great for Russians but...) -# -os_misc: .ascii "?"; .byte '?'|0x80 -os_dos: .ascii "DO"; .byte 'S'|0x80 -os_linux: .ascii "Linu"; .byte 'x'|0x80 -os_freebsd: .ascii "Free" -os_bsd: .ascii "BS"; .byte 'D'|0x80 - - .org PRT_OFF-0xe,0x90 - - .word B0MAGIC # Magic number - -# -# These values are sometimes changed before writing back to the drive -# Be especially careful that nxtdrv: must come after drive:, as it -# is part of the same string. -# -drive: .ascii "Drive " -nxtdrv: .byte 0x0 # Next drive number -opt: .byte 0x0 # Option -setdrv: .byte 0x80 # Drive to force -flags: .byte FLAGS # Flags -ticks: .word TICKS # Delay - -# -# here is the 64 byte partition table that fdisk would fiddle with. -# -partbl: .fill 0x40,0x1,0x0 # Partition table - .word MAGIC # Magic number |
