- Use C (and CPP) style comments for assembler-with-cpp sources,
for lines that start with a comment. - Preserve as(1) style comments for the rest.
This commit is contained in:
Ruslan Ermilov
parent
3ee3cd3165
commit
37e931894e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=128707
@ -1,365 +1,366 @@
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//
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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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/*
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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
|
||||
* paragraph and the following disclaimer are duplicated in all
|
||||
* 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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// $FreeBSD$
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// Memory Locations
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.set MEM_REL,0x700 // Relocation address
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.set MEM_ARG,0x900 // Arguments
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.set MEM_ORG,0x7c00 // Origin
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.set MEM_BUF,0x8cec // Load area
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.set MEM_BTX,0x9000 // BTX start
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.set MEM_JMP,0x9010 // BTX entry point
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.set MEM_USR,0xa000 // Client start
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.set BDA_BOOT,0x472 // Boot howto flag
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/* Memory Locations */
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.set MEM_REL,0x700 # Relocation address
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.set MEM_ARG,0x900 # Arguments
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.set MEM_ORG,0x7c00 # Origin
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.set MEM_BUF,0x8cec # Load area
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.set MEM_BTX,0x9000 # BTX start
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.set MEM_JMP,0x9010 # BTX entry point
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.set MEM_USR,0xa000 # Client start
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.set BDA_BOOT,0x472 # Boot howto flag
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// Partition Constants
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.set PRT_OFF,0x1be // Partition offset
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.set PRT_NUM,0x4 // Partitions
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.set PRT_BSD,0xa5 // Partition type
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/* Partition Constants */
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.set PRT_OFF,0x1be # Partition offset
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.set PRT_NUM,0x4 # Partitions
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.set PRT_BSD,0xa5 # Partition type
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// Flag Bits
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.set FL_PACKET,0x80 // Packet mode
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/* Flag Bits */
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.set FL_PACKET,0x80 # Packet mode
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// Misc. Constants
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.set SIZ_PAG,0x1000 // Page size
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.set SIZ_SEC,0x200 // Sector size
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/* Misc. Constants */
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.set SIZ_PAG,0x1000 # Page size
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.set SIZ_SEC,0x200 # Sector size
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.set NSECT,0x10
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.globl start
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.globl xread
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.code16
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start: jmp main // Start recognizably
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// This is the start of a standard BIOS Parameter Block (BPB). Most bootable
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// FAT disks have this at the start of their MBR. While normal BIOS's will
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// work fine without this section, IBM's El Torito emulation "fixes" up the
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// BPB by writing into the memory copy of the MBR. Rather than have data
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// written into our xread routine, we'll define a BPB to work around it.
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// The data marked with (T) indicates a field required for a ThinkPad to
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// recognize the disk and (W) indicates fields written from IBM BIOS code.
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// The use of the BPB is based on what OpenBSD and NetBSD implemented in
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// their boot code but the required fields were determined by trial and error.
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//
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// Note: If additional space is needed in boot1, one solution would be to
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// move the "prompt" message data (below) to replace the OEM ID.
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start: jmp main # Start recognizably
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/*
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* This is the start of a standard BIOS Parameter Block (BPB). Most bootable
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* FAT disks have this at the start of their MBR. While normal BIOS's will
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* work fine without this section, IBM's El Torito emulation "fixes" up the
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* BPB by writing into the memory copy of the MBR. Rather than have data
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* written into our xread routine, we'll define a BPB to work around it.
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* The data marked with (T) indicates a field required for a ThinkPad to
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* recognize the disk and (W) indicates fields written from IBM BIOS code.
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* The use of the BPB is based on what OpenBSD and NetBSD implemented in
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* their boot code but the required fields were determined by trial and error.
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*
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* Note: If additional space is needed in boot1, one solution would be to
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* move the "prompt" message data (below) to replace the OEM ID.
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*/
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.org 0x03, 0x00
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oemid: .space 0x08, 0x00 // OEM ID
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oemid: .space 0x08, 0x00 # OEM ID
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.org 0x0b, 0x00
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bpb: .word 512 // sector size (T)
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.byte 0 // sectors/clustor
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.word 0 // reserved sectors
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.byte 0 // number of FATs
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.word 0 // root entries
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.word 0 // small sectors
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.byte 0 // media type (W)
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.word 0 // sectors/fat
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.word 18 // sectors per track (T)
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.word 2 // number of heads (T)
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.long 0 // hidden sectors (W)
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.long 0 // large sectors
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bpb: .word 512 # sector size (T)
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.byte 0 # sectors/clustor
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.word 0 # reserved sectors
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.byte 0 # number of FATs
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.word 0 # root entries
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.word 0 # small sectors
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.byte 0 # media type (W)
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.word 0 # sectors/fat
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.word 18 # sectors per track (T)
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.word 2 # number of heads (T)
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.long 0 # hidden sectors (W)
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.long 0 # large sectors
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.org 0x24, 0x00
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ebpb: .byte 0 // BIOS physical drive number (W)
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ebpb: .byte 0 # BIOS physical drive number (W)
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.org 0x25,0x90
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//
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// Trampoline used by boot2 to call read to read data from the disk via
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// the BIOS. Call with:
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//
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// %cx:%ax - long - LBA to read in
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// %es:(%bx) - caddr_t - buffer to read data into
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// %dl - byte - drive to read from
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// %dh - byte - num sectors to read
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//
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/*
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* Trampoline used by boot2 to call read to read data from the disk via
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* the BIOS. Call with:
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*
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* %cx:%ax - long - LBA to read in
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* %es:(%bx) - caddr_t - buffer to read data into
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* %dl - byte - drive to read from
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* %dh - byte - num sectors to read
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*/
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xread: push %ss // Address
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pop %ds // data
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//
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// Setup an EDD disk packet and pass it to read
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//
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xread.1: // Starting
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pushl $0x0 // absolute
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push %cx // block
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push %ax // number
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push %es // Address of
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push %bx // transfer buffer
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xor %ax,%ax // Number of
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movb %dh,%al // blocks to
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push %ax // transfer
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push $0x10 // Size of packet
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mov %sp,%bp // Packet pointer
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callw read // Read from disk
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lea 0x10(%bp),%sp // Clear stack
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lret // To far caller
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//
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// Load the rest of boot2 and BTX up, copy the parts to the right locations,
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// and start it all up.
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//
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xread: push %ss # Address
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pop %ds # data
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/*
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* Setup an EDD disk packet and pass it to read
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*/
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xread.1: # Starting
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pushl $0x0 # absolute
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push %cx # block
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push %ax # number
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push %es # Address of
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push %bx # transfer buffer
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xor %ax,%ax # Number of
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movb %dh,%al # blocks to
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push %ax # transfer
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push $0x10 # Size of packet
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mov %sp,%bp # Packet pointer
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callw read # Read from disk
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lea 0x10(%bp),%sp # Clear stack
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lret # To far caller
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/*
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* Load the rest of boot2 and BTX up, copy the parts to the right locations,
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* and start it all up.
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*/
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//
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// Setup the segment registers to flat addressing (segment 0) and setup the
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// stack to end just below the start of our code.
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//
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main: cld // String ops inc
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xor %cx,%cx // Zero
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mov %cx,%es // Address
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mov %cx,%ds // data
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mov %cx,%ss // Set up
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mov $start,%sp // stack
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//
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// Relocate ourself to MEM_REL. Since %cx == 0, the inc %ch sets
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// %cx == 0x100.
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//
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mov %sp,%si // Source
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mov $MEM_REL,%di // Destination
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incb %ch // Word count
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rep // Copy
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movsw // code
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//
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// If we are on a hard drive, then load the MBR and look for the first
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// FreeBSD slice. We use the fake partition entry below that points to
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// the MBR when we call nread. The first pass looks for the first active
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// FreeBSD slice. The second pass looks for the first non-active FreeBSD
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// slice if the first one fails.
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//
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mov $part4,%si // Partition
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cmpb $0x80,%dl // Hard drive?
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jb main.4 // No
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movb $0x1,%dh // Block count
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callw nread // Read MBR
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mov $0x1,%cx // Two passes
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main.1: mov $MEM_BUF+PRT_OFF,%si // Partition table
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movb $0x1,%dh // Partition
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main.2: cmpb $PRT_BSD,0x4(%si) // Our partition type?
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jne main.3 // No
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jcxz main.5 // If second pass
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testb $0x80,(%si) // Active?
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jnz main.5 // Yes
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main.3: add $0x10,%si // Next entry
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incb %dh // Partition
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cmpb $0x1+PRT_NUM,%dh // In table?
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jb main.2 // Yes
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dec %cx // Do two
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jcxz main.1 // passes
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//
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// If we get here, we didn't find any FreeBSD slices at all, so print an
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// error message and die.
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//
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mov $msg_part,%si // Message
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jmp error // Error
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//
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// Floppies use partition 0 of drive 0.
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//
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main.4: xor %dx,%dx // Partition:drive
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//
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// Ok, we have a slice and drive in %dx now, so use that to locate and load
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// boot2. %si references the start of the slice we are looking for, so go
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// ahead and load up the first 16 sectors (boot1 + boot2) from that. When
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// we read it in, we conveniently use 0x8cec as our transfer buffer. Thus,
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// boot1 ends up at 0x8cec, and boot2 starts at 0x8cec + 0x200 = 0x8eec.
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// The first part of boot2 is the disklabel, which is 0x114 bytes long.
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// The second part is BTX, which is thus loaded into 0x9000, which is where
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// it also runs from. The boot2.bin binary starts right after the end of
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// BTX, so we have to figure out where the start of it is and then move the
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// binary to 0xc000. Normally, BTX clients start at MEM_USR, or 0xa000, but
|
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// when we use btxld to create boot2, we use an entry point of 0x2000. That
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// entry point is relative to MEM_USR; thus boot2.bin starts at 0xc000.
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//
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main.5: mov %dx,MEM_ARG // Save args
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movb $NSECT,%dh // Sector count
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callw nread // Read disk
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mov $MEM_BTX,%bx // BTX
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mov 0xa(%bx),%si // Get BTX length and set
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||||
add %bx,%si // %si to start of boot2.bin
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mov $MEM_USR+SIZ_PAG*2,%di // Client page 2
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||||
mov $MEM_BTX+(NSECT-1)*SIZ_SEC,%cx // Byte
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sub %si,%cx // count
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rep // Relocate
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movsb // client
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||||
sub %di,%cx // Byte count
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||||
xorb %al,%al // Zero assumed bss from
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rep // the end of boot2.bin
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||||
stosb // up to 0x10000
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||||
callw seta20 // Enable A20
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jmp start+MEM_JMP-MEM_ORG // Start BTX
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||||
//
|
||||
// Enable A20 so we can access memory above 1 meg.
|
||||
//
|
||||
seta20: cli // Disable interrupts
|
||||
seta20.1: inb $0x64,%al // Get status
|
||||
testb $0x2,%al // Busy?
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||||
jnz seta20.1 // Yes
|
||||
movb $0xd1,%al // Command: Write
|
||||
outb %al,$0x64 // output port
|
||||
seta20.2: inb $0x64,%al // Get status
|
||||
testb $0x2,%al // Busy?
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||||
jnz seta20.2 // Yes
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||||
movb $0xdf,%al // Enable
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||||
outb %al,$0x60 // A20
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||||
sti // Enable interrupts
|
||||
retw // To caller
|
||||
//
|
||||
// Trampoline used to call read from within boot1.
|
||||
//
|
||||
nread: mov $MEM_BUF,%bx // Transfer buffer
|
||||
mov 0x8(%si),%ax // Get
|
||||
mov 0xa(%si),%cx // LBA
|
||||
push %cs // Read from
|
||||
callw xread.1 // disk
|
||||
jnc return // If success, return
|
||||
mov $msg_read,%si // Otherwise, set the error
|
||||
// message and fall through to
|
||||
// the error routine
|
||||
//
|
||||
// Print out the error message pointed to by %ds:(%si) followed
|
||||
// by a prompt, wait for a keypress, and then reboot the machine.
|
||||
//
|
||||
error: callw putstr // Display message
|
||||
mov $prompt,%si // Display
|
||||
callw putstr // prompt
|
||||
xorb %ah,%ah // BIOS: Get
|
||||
int $0x16 // keypress
|
||||
movw $0x1234, BDA_BOOT // Do a warm boot
|
||||
ljmp $0xffff,$0x0 // reboot the machine
|
||||
//
|
||||
// Display a null-terminated string using the BIOS output.
|
||||
//
|
||||
putstr.0: mov $0x7,%bx // Page:attribute
|
||||
movb $0xe,%ah // BIOS: Display
|
||||
int $0x10 // character
|
||||
putstr: lodsb // Get char
|
||||
testb %al,%al // End of string?
|
||||
jne putstr.0 // No
|
||||
/*
|
||||
* Setup the segment registers to flat addressing (segment 0) and setup the
|
||||
* stack to end just below the start of our code.
|
||||
*/
|
||||
main: cld # String ops inc
|
||||
xor %cx,%cx # Zero
|
||||
mov %cx,%es # Address
|
||||
mov %cx,%ds # data
|
||||
mov %cx,%ss # Set up
|
||||
mov $start,%sp # stack
|
||||
/*
|
||||
* Relocate ourself to MEM_REL. Since %cx == 0, the inc %ch sets
|
||||
* %cx == 0x100.
|
||||
*/
|
||||
mov %sp,%si # Source
|
||||
mov $MEM_REL,%di # Destination
|
||||
incb %ch # Word count
|
||||
rep # Copy
|
||||
movsw # code
|
||||
/*
|
||||
* If we are on a hard drive, then load the MBR and look for the first
|
||||
* FreeBSD slice. We use the fake partition entry below that points to
|
||||
* the MBR when we call nread. The first pass looks for the first active
|
||||
* FreeBSD slice. The second pass looks for the first non-active FreeBSD
|
||||
* slice if the first one fails.
|
||||
*/
|
||||
mov $part4,%si # Partition
|
||||
cmpb $0x80,%dl # Hard drive?
|
||||
jb main.4 # No
|
||||
movb $0x1,%dh # Block count
|
||||
callw nread # Read MBR
|
||||
mov $0x1,%cx # Two passes
|
||||
main.1: mov $MEM_BUF+PRT_OFF,%si # Partition table
|
||||
movb $0x1,%dh # Partition
|
||||
main.2: cmpb $PRT_BSD,0x4(%si) # Our partition type?
|
||||
jne main.3 # No
|
||||
jcxz main.5 # If second pass
|
||||
testb $0x80,(%si) # Active?
|
||||
jnz main.5 # Yes
|
||||
main.3: add $0x10,%si # Next entry
|
||||
incb %dh # Partition
|
||||
cmpb $0x1+PRT_NUM,%dh # In table?
|
||||
jb main.2 # Yes
|
||||
dec %cx # Do two
|
||||
jcxz main.1 # passes
|
||||
/*
|
||||
* If we get here, we didn't find any FreeBSD slices at all, so print an
|
||||
* error message and die.
|
||||
*/
|
||||
mov $msg_part,%si # Message
|
||||
jmp error # Error
|
||||
/*
|
||||
* Floppies use partition 0 of drive 0.
|
||||
*/
|
||||
main.4: xor %dx,%dx # Partition:drive
|
||||
/*
|
||||
* Ok, we have a slice and drive in %dx now, so use that to locate and load
|
||||
* boot2. %si references the start of the slice we are looking for, so go
|
||||
* ahead and load up the first 16 sectors (boot1 + boot2) from that. When
|
||||
* we read it in, we conveniently use 0x8cec as our transfer buffer. Thus,
|
||||
* boot1 ends up at 0x8cec, and boot2 starts at 0x8cec + 0x200 = 0x8eec.
|
||||
* The first part of boot2 is the disklabel, which is 0x114 bytes long.
|
||||
* The second part is BTX, which is thus loaded into 0x9000, which is where
|
||||
* it also runs from. The boot2.bin binary starts right after the end of
|
||||
* BTX, so we have to figure out where the start of it is and then move the
|
||||
* binary to 0xc000. Normally, BTX clients start at MEM_USR, or 0xa000, but
|
||||
* when we use btxld to create boot2, we use an entry point of 0x2000. That
|
||||
* entry point is relative to MEM_USR; thus boot2.bin starts at 0xc000.
|
||||
*/
|
||||
main.5: mov %dx,MEM_ARG # Save args
|
||||
movb $NSECT,%dh # Sector count
|
||||
callw nread # Read disk
|
||||
mov $MEM_BTX,%bx # BTX
|
||||
mov 0xa(%bx),%si # Get BTX length and set
|
||||
add %bx,%si # %si to start of boot2.bin
|
||||
mov $MEM_USR+SIZ_PAG*2,%di # Client page 2
|
||||
mov $MEM_BTX+(NSECT-1)*SIZ_SEC,%cx # Byte
|
||||
sub %si,%cx # count
|
||||
rep # Relocate
|
||||
movsb # client
|
||||
sub %di,%cx # Byte count
|
||||
xorb %al,%al # Zero assumed bss from
|
||||
rep # the end of boot2.bin
|
||||
stosb # up to 0x10000
|
||||
callw seta20 # Enable A20
|
||||
jmp start+MEM_JMP-MEM_ORG # Start BTX
|
||||
/*
|
||||
* Enable A20 so we can access memory above 1 meg.
|
||||
*/
|
||||
seta20: cli # Disable interrupts
|
||||
seta20.1: inb $0x64,%al # Get status
|
||||
testb $0x2,%al # Busy?
|
||||
jnz seta20.1 # Yes
|
||||
movb $0xd1,%al # Command: Write
|
||||
outb %al,$0x64 # output port
|
||||
seta20.2: inb $0x64,%al # Get status
|
||||
testb $0x2,%al # Busy?
|
||||
jnz seta20.2 # Yes
|
||||
movb $0xdf,%al # Enable
|
||||
outb %al,$0x60 # A20
|
||||
sti # Enable interrupts
|
||||
retw # To caller
|
||||
/*
|
||||
* Trampoline used to call read from within boot1.
|
||||
*/
|
||||
nread: mov $MEM_BUF,%bx # Transfer buffer
|
||||
mov 0x8(%si),%ax # Get
|
||||
mov 0xa(%si),%cx # LBA
|
||||
push %cs # Read from
|
||||
callw xread.1 # disk
|
||||
jnc return # If success, return
|
||||
mov $msg_read,%si # Otherwise, set the error
|
||||
# message and fall through to
|
||||
# the error routine
|
||||
/*
|
||||
* Print out the error message pointed to by %ds:(%si) followed
|
||||
* by a prompt, wait for a keypress, and then reboot the machine.
|
||||
*/
|
||||
error: callw putstr # Display message
|
||||
mov $prompt,%si # Display
|
||||
callw putstr # prompt
|
||||
xorb %ah,%ah # BIOS: Get
|
||||
int $0x16 # keypress
|
||||
movw $0x1234, BDA_BOOT # Do a warm boot
|
||||
ljmp $0xffff,$0x0 # reboot the machine
|
||||
/*
|
||||
* Display a null-terminated string using the BIOS output.
|
||||
*/
|
||||
putstr.0: mov $0x7,%bx # Page:attribute
|
||||
movb $0xe,%ah # BIOS: Display
|
||||
int $0x10 # character
|
||||
putstr: lodsb # Get char
|
||||
testb %al,%al # End of string?
|
||||
jne putstr.0 # No
|
||||
|
||||
//
|
||||
// Overused return code. ereturn is used to return an error from the
|
||||
// read function. Since we assume putstr succeeds, we (ab)use the
|
||||
// same code when we return from putstr.
|
||||
//
|
||||
ereturn: movb $0x1,%ah // Invalid
|
||||
stc // argument
|
||||
return: retw // To caller
|
||||
//
|
||||
// Reads sectors from the disk. If EDD is enabled, then check if it is
|
||||
// installed and use it if it is. If it is not installed or not enabled, then
|
||||
// fall back to using CHS. Since we use a LBA, if we are using CHS, we have to
|
||||
// fetch the drive parameters from the BIOS and divide it out ourselves.
|
||||
// Call with:
|
||||
//
|
||||
// %dl - byte - drive number
|
||||
// stack - 10 bytes - EDD Packet
|
||||
//
|
||||
read: push %dx // Save
|
||||
movb $0x8,%ah // BIOS: Get drive
|
||||
int $0x13 // parameters
|
||||
movb %dh,%ch // Max head number
|
||||
pop %dx // Restore
|
||||
jc return // If error
|
||||
andb $0x3f,%cl // Sectors per track
|
||||
jz ereturn // If zero
|
||||
cli // Disable interrupts
|
||||
mov 0x8(%bp),%eax // Get LBA
|
||||
push %dx // Save
|
||||
movzbl %cl,%ebx // Divide by
|
||||
xor %edx,%edx // sectors
|
||||
div %ebx // per track
|
||||
movb %ch,%bl // Max head number
|
||||
movb %dl,%ch // Sector number
|
||||
inc %bx // Divide by
|
||||
xorb %dl,%dl // number
|
||||
div %ebx // of heads
|
||||
movb %dl,%bh // Head number
|
||||
pop %dx // Restore
|
||||
cmpl $0x3ff,%eax // Cylinder number supportable?
|
||||
sti // Enable interrupts
|
||||
ja read.7 // No, try EDD
|
||||
xchgb %al,%ah // Set up cylinder
|
||||
rorb $0x2,%al // number
|
||||
orb %ch,%al // Merge
|
||||
inc %ax // sector
|
||||
xchg %ax,%cx // number
|
||||
movb %bh,%dh // Head number
|
||||
subb %ah,%al // Sectors this track
|
||||
mov 0x2(%bp),%ah // Blocks to read
|
||||
cmpb %ah,%al // To read
|
||||
jb read.2 // this
|
||||
/*
|
||||
* Overused return code. ereturn is used to return an error from the
|
||||
* read function. Since we assume putstr succeeds, we (ab)use the
|
||||
* same code when we return from putstr.
|
||||
*/
|
||||
ereturn: movb $0x1,%ah # Invalid
|
||||
stc # argument
|
||||
return: retw # To caller
|
||||
/*
|
||||
* Reads sectors from the disk. If EDD is enabled, then check if it is
|
||||
* installed and use it if it is. If it is not installed or not enabled, then
|
||||
* fall back to using CHS. Since we use a LBA, if we are using CHS, we have to
|
||||
* fetch the drive parameters from the BIOS and divide it out ourselves.
|
||||
* Call with:
|
||||
*
|
||||
* %dl - byte - drive number
|
||||
* stack - 10 bytes - EDD Packet
|
||||
*/
|
||||
read: push %dx # Save
|
||||
movb $0x8,%ah # BIOS: Get drive
|
||||
int $0x13 # parameters
|
||||
movb %dh,%ch # Max head number
|
||||
pop %dx # Restore
|
||||
jc return # If error
|
||||
andb $0x3f,%cl # Sectors per track
|
||||
jz ereturn # If zero
|
||||
cli # Disable interrupts
|
||||
mov 0x8(%bp),%eax # Get LBA
|
||||
push %dx # Save
|
||||
movzbl %cl,%ebx # Divide by
|
||||
xor %edx,%edx # sectors
|
||||
div %ebx # per track
|
||||
movb %ch,%bl # Max head number
|
||||
movb %dl,%ch # Sector number
|
||||
inc %bx # Divide by
|
||||
xorb %dl,%dl # number
|
||||
div %ebx # of heads
|
||||
movb %dl,%bh # Head number
|
||||
pop %dx # Restore
|
||||
cmpl $0x3ff,%eax # Cylinder number supportable?
|
||||
sti # Enable interrupts
|
||||
ja read.7 # No, try EDD
|
||||
xchgb %al,%ah # Set up cylinder
|
||||
rorb $0x2,%al # number
|
||||
orb %ch,%al # Merge
|
||||
inc %ax # sector
|
||||
xchg %ax,%cx # number
|
||||
movb %bh,%dh # Head number
|
||||
subb %ah,%al # Sectors this track
|
||||
mov 0x2(%bp),%ah # Blocks to read
|
||||
cmpb %ah,%al # To read
|
||||
jb read.2 # this
|
||||
#ifdef TRACK_AT_A_TIME
|
||||
movb %ah,%al // track
|
||||
movb %ah,%al # track
|
||||
#else
|
||||
movb $1,%al // one sector
|
||||
movb $1,%al # one sector
|
||||
#endif
|
||||
read.2: mov $0x5,%di // Try count
|
||||
read.3: les 0x4(%bp),%bx // Transfer buffer
|
||||
push %ax // Save
|
||||
movb $0x2,%ah // BIOS: Read
|
||||
int $0x13 // from disk
|
||||
pop %bx // Restore
|
||||
jnc read.4 // If success
|
||||
dec %di // Retry?
|
||||
jz read.6 // No
|
||||
xorb %ah,%ah // BIOS: Reset
|
||||
int $0x13 // disk system
|
||||
xchg %bx,%ax // Block count
|
||||
jmp read.3 // Continue
|
||||
read.4: movzbw %bl,%ax // Sectors read
|
||||
add %ax,0x8(%bp) // Adjust
|
||||
jnc read.5 // LBA,
|
||||
incw 0xa(%bp) // transfer
|
||||
read.5: shlb %bl // buffer
|
||||
add %bl,0x5(%bp) // pointer,
|
||||
sub %al,0x2(%bp) // block count
|
||||
ja read // If not done
|
||||
read.6: retw // To caller
|
||||
read.7: testb $FL_PACKET,%cs:MEM_REL+flags-start // LBA support enabled?
|
||||
jz ereturn // No, so return an error
|
||||
mov $0x55aa,%bx // Magic
|
||||
push %dx // Save
|
||||
movb $0x41,%ah // BIOS: Check
|
||||
int $0x13 // extensions present
|
||||
pop %dx // Restore
|
||||
jc return // If error, return an error
|
||||
cmp $0xaa55,%bx // Magic?
|
||||
jne ereturn // No, so return an error
|
||||
testb $0x1,%cl // Packet interface?
|
||||
jz ereturn // No, so return an error
|
||||
mov %bp,%si // Disk packet
|
||||
movb $0x42,%ah // BIOS: Extended
|
||||
int $0x13 // read
|
||||
retw // To caller
|
||||
read.2: mov $0x5,%di # Try count
|
||||
read.3: les 0x4(%bp),%bx # Transfer buffer
|
||||
push %ax # Save
|
||||
movb $0x2,%ah # BIOS: Read
|
||||
int $0x13 # from disk
|
||||
pop %bx # Restore
|
||||
jnc read.4 # If success
|
||||
dec %di # Retry?
|
||||
jz read.6 # No
|
||||
xorb %ah,%ah # BIOS: Reset
|
||||
int $0x13 # disk system
|
||||
xchg %bx,%ax # Block count
|
||||
jmp read.3 # Continue
|
||||
read.4: movzbw %bl,%ax # Sectors read
|
||||
add %ax,0x8(%bp) # Adjust
|
||||
jnc read.5 # LBA,
|
||||
incw 0xa(%bp) # transfer
|
||||
read.5: shlb %bl # buffer
|
||||
add %bl,0x5(%bp) # pointer,
|
||||
sub %al,0x2(%bp) # block count
|
||||
ja read # If not done
|
||||
read.6: retw # To caller
|
||||
read.7: testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled?
|
||||
jz ereturn # No, so return an error
|
||||
mov $0x55aa,%bx # Magic
|
||||
push %dx # Save
|
||||
movb $0x41,%ah # BIOS: Check
|
||||
int $0x13 # extensions present
|
||||
pop %dx # Restore
|
||||
jc return # If error, return an error
|
||||
cmp $0xaa55,%bx # Magic?
|
||||
jne ereturn # No, so return an error
|
||||
testb $0x1,%cl # Packet interface?
|
||||
jz ereturn # No, so return an error
|
||||
mov %bp,%si # Disk packet
|
||||
movb $0x42,%ah # BIOS: Extended
|
||||
int $0x13 # read
|
||||
retw # To caller
|
||||
|
||||
// Messages
|
||||
/* Messages */
|
||||
|
||||
msg_read: .asciz "Read"
|
||||
msg_part: .asciz "Boot"
|
||||
|
||||
prompt: .asciz " error\r\n"
|
||||
|
||||
flags: .byte FLAGS // Flags
|
||||
flags: .byte FLAGS # Flags
|
||||
|
||||
.org PRT_OFF,0x90
|
||||
|
||||
// Partition table
|
||||
/* Partition table */
|
||||
|
||||
.fill 0x30,0x1,0x0
|
||||
part4: .byte 0x80, 0x00, 0x01, 0x00
|
||||
.byte 0xa5, 0xfe, 0xff, 0xff
|
||||
.byte 0x00, 0x00, 0x00, 0x00
|
||||
.byte 0x50, 0xc3, 0x00, 0x00 // 50000 sectors long, bleh
|
||||
.byte 0x50, 0xc3, 0x00, 0x00 # 50000 sectors long, bleh
|
||||
|
||||
.word 0xaa55 // Magic number
|
||||
.word 0xaa55 # Magic number
|
||||
|
||||
@ -1,19 +1,19 @@
|
||||
#
|
||||
# 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.
|
||||
#
|
||||
|
||||
# $FreeBSD$
|
||||
/*
|
||||
* 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.
|
||||
*
|
||||
* $FreeBSD$
|
||||
*/
|
||||
|
||||
.set SIO_PRT,SIOPRT # Base port
|
||||
.set SIO_FMT,SIOFMT # 8N1
|
||||
@ -25,7 +25,7 @@
|
||||
.globl sio_getc
|
||||
.globl sio_ischar
|
||||
|
||||
# void sio_init(void)
|
||||
/* void sio_init(void) */
|
||||
|
||||
sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
|
||||
movb $SIO_FMT|0x80,%al # Set format
|
||||
@ -42,14 +42,14 @@ sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
|
||||
outb %al,(%dx) # DTR
|
||||
incl %edx # Line status reg
|
||||
|
||||
# void sio_flush(void)
|
||||
/* void sio_flush(void) */
|
||||
|
||||
sio_flush.0: call sio_getc.1 # Get character
|
||||
sio_flush: call sio_ischar # Check for character
|
||||
jnz sio_flush.0 # Till none
|
||||
ret # To caller
|
||||
|
||||
# void sio_putc(int c)
|
||||
/* void sio_putc(int c) */
|
||||
|
||||
sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg
|
||||
xor %ecx,%ecx # Timeout
|
||||
@ -63,7 +63,7 @@ sio_putc.1: inb (%dx),%al # Transmitter
|
||||
outb %al,(%dx) # Write character
|
||||
sio_putc.2: ret $0x4 # To caller
|
||||
|
||||
# int sio_getc(void)
|
||||
/* int sio_getc(void) */
|
||||
|
||||
sio_getc: call sio_ischar # Character available?
|
||||
jz sio_getc # No
|
||||
@ -71,7 +71,7 @@ sio_getc.1: subb $0x5,%dl # Receiver buffer reg
|
||||
inb (%dx),%al # Read character
|
||||
ret # To caller
|
||||
|
||||
# int sio_ischar(void)
|
||||
/* int sio_ischar(void) */
|
||||
|
||||
sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register
|
||||
xorl %eax,%eax # Zero
|
||||
|
||||
Loading…
Reference in New Issue
Block a user