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Annotation of Net2/arch/i386/boot/bios.s, revision 1.1

1.1     ! root        1: /*
        !             2:  * Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
        !             3:  *
        !             4:  * Mach Operating System
        !             5:  * Copyright (c) 1992, 1991 Carnegie Mellon University
        !             6:  * All Rights Reserved.
        !             7:  * 
        !             8:  * Permission to use, copy, modify and distribute this software and its
        !             9:  * documentation is hereby granted, provided that both the copyright
        !            10:  * notice and this permission notice appear in all copies of the
        !            11:  * software, derivative works or modified versions, and any portions
        !            12:  * thereof, and that both notices appear in supporting documentation.
        !            13:  * 
        !            14:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            15:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            16:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            17:  * 
        !            18:  * Carnegie Mellon requests users of this software to return to
        !            19:  * 
        !            20:  *  Software Distribution Coordinator  or  [email protected]
        !            21:  *  School of Computer Science
        !            22:  *  Carnegie Mellon University
        !            23:  *  Pittsburgh PA 15213-3890
        !            24:  * 
        !            25:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            26:  * the rights to redistribute these changes.
        !            27:  */
        !            28: 
        !            29: /*
        !            30:  * HISTORY
        !            31:  * $Log: bios.S,v $
        !            32:  * Revision 1.1  1993/03/21 18:08:23  cgd
        !            33:  * after 0.2.2 "stable" patches applied
        !            34:  *
        !            35:  * Revision 2.2  92/04/04  11:34:26  rpd
        !            36:  *     Fix Intel Copyright as per B. Davies authorization.
        !            37:  *     [92/04/03            rvb]
        !            38:  *     From 2.5 version
        !            39:  *     [92/03/30            mg32]
        !            40:  * 
        !            41:  * Revision 2.2  91/04/02  14:35:21  mbj
        !            42:  *     Add Intel copyright
        !            43:  *     [90/02/09            rvb]
        !            44:  * 
        !            45:  */
        !            46: 
        !            47: 
        !            48: /*
        !            49:   Copyright 1988, 1989, 1990, 1991, 1992 
        !            50:    by Intel Corporation, Santa Clara, California.
        !            51: 
        !            52:                 All Rights Reserved
        !            53: 
        !            54: Permission to use, copy, modify, and distribute this software and
        !            55: its documentation for any purpose and without fee is hereby
        !            56: granted, provided that the above copyright notice appears in all
        !            57: copies and that both the copyright notice and this permission notice
        !            58: appear in supporting documentation, and that the name of Intel
        !            59: not be used in advertising or publicity pertaining to distribution
        !            60: of the software without specific, written prior permission.
        !            61: 
        !            62: INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
        !            63: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
        !            64: IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
        !            65: CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
        !            66: LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
        !            67: NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
        !            68: WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
        !            69: */
        !            70: 
        !            71:        .file   "bios.s"
        !            72: 
        !            73: #include "asm.h"
        !            74:        .text
        !            75: 
        !            76: /*
        !            77: # biosread(dev, cyl, head, sec)
        !            78: #      Read one sector from disk into the internal buffer "intbuf" which
        !            79: #      is the first 512 bytes of the boot loader.
        !            80: # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
        !            81: #      Call with       %ah = 0x2
        !            82: #                      %al = number of sectors
        !            83: #                      %ch = cylinder
        !            84: #                      %cl = sector
        !            85: #                      %dh = head
        !            86: #                      %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
        !            87: #                      %es:%bx = segment:offset of buffer
        !            88: #      Return:         
        !            89: #                      %al = 0x0 on success; err code on failure
        !            90: */
        !            91: 
        !            92: ENTRY(biosread)
        !            93:        push    %ebp
        !            94:        mov     %esp, %ebp
        !            95: 
        !            96:        push    %ebx
        !            97:        push    %ecx
        !            98:        push    %edx
        !            99:        push    %es
        !           100: 
        !           101:        movb    0x10(%ebp), %dh
        !           102:        movw    0x0c(%ebp), %cx
        !           103:        xchgb   %ch, %cl        # cylinder; the highest 2 bits of cyl is in %cl
        !           104:        rorb    $2, %cl
        !           105:        movb    0x14(%ebp), %al
        !           106:        orb     %al, %cl
        !           107:        incb    %cl             # sector; sec starts from 1, not 0
        !           108:        movb    0x8(%ebp), %dl  # device
        !           109:        xor     %ebx, %ebx      # offset -- 0
        !           110:                                # prot_to_real will set %es to BOOTSEG
        !           111: 
        !           112:        call    EXT(prot_to_real)       # enter real mode
        !           113:        movb    $0x2, %ah       # subfunction
        !           114:        movb    $0x1, %al       # number of sectors -- one
        !           115: 
        !           116:        sti
        !           117:        int     $0x13
        !           118:        cli
        !           119: 
        !           120:        mov     %eax, %ebx      # save return value
        !           121: 
        !           122:        data16
        !           123:        call    EXT(real_to_prot) # back to protected mode
        !           124: 
        !           125:        xor     %eax, %eax
        !           126:        movb    %bh, %al        # return value in %ax
        !           127: 
        !           128:        pop     %es
        !           129:        pop     %edx
        !           130:        pop     %ecx
        !           131:        pop     %ebx
        !           132:        pop     %ebp
        !           133: 
        !           134:        ret
        !           135: 
        !           136: 
        !           137: /*
        !           138: # putc(ch)
        !           139: # BIOS call "INT 10H Function 0Eh" to write character to console
        !           140: #      Call with       %ah = 0x0e
        !           141: #                      %al = character
        !           142: #                      %bh = page
        !           143: #                      %bl = foreground color ( graphics modes)
        !           144: */
        !           145: 
        !           146: 
        !           147: ENTRY(putc)
        !           148:        push    %ebp
        !           149:        mov     %esp, %ebp
        !           150:        push    %ebx
        !           151:        push    %ecx
        !           152: 
        !           153:        movb    0x8(%ebp), %cl
        !           154: 
        !           155:        call    EXT(prot_to_real)
        !           156: 
        !           157:        data16
        !           158:        mov     $0x1, %ebx      # %bh=0, %bl=1 (blue)
        !           159:        movb    $0xe, %ah
        !           160:        movb    %cl, %al
        !           161:        sti
        !           162:        int     $0x10           # display a byte
        !           163:        cli
        !           164: 
        !           165:        data16
        !           166:        call    EXT(real_to_prot)
        !           167: 
        !           168:        pop     %ecx
        !           169:        pop     %ebx
        !           170:        pop     %ebp
        !           171:        ret
        !           172: 
        !           173: 
        !           174: /*
        !           175: # getc()
        !           176: # BIOS call "INT 16H Function 00H" to read character from keyboard
        !           177: #      Call with       %ah = 0x0
        !           178: #      Return:         %ah = keyboard scan code
        !           179: #                      %al = ASCII character
        !           180: */
        !           181: 
        !           182: ENTRY(getc)
        !           183:        push    %ebp
        !           184:        mov     %esp, %ebp
        !           185:        push    %ebx            # save %ebx
        !           186: 
        !           187:        call    EXT(prot_to_real)
        !           188: 
        !           189:        movb    $0x0, %ah
        !           190:        sti
        !           191:        int     $0x16
        !           192:        cli
        !           193: 
        !           194:        movb    %al, %bl        # real_to_prot uses %eax
        !           195: 
        !           196:        data16
        !           197:        call    EXT(real_to_prot)
        !           198: 
        !           199:        xor     %eax, %eax
        !           200:        movb    %bl, %al
        !           201: 
        !           202:        pop     %ebx
        !           203:        pop     %ebp
        !           204:        ret
        !           205: /*
        !           206: # ischar()
        !           207: #       if there is a character pending, return it; otherwise return 0
        !           208: # BIOS call "INT 16H Function 01H" to check whether a character is pending
        !           209: #      Call with       %ah = 0x1
        !           210: #      Return:
        !           211: #              If key waiting to be input:
        !           212: #                      %ah = keyboard scan code
        !           213: #                      %al = ASCII character
        !           214: #                      Zero flag = clear
        !           215: #              else
        !           216: #                      Zero flag = set
        !           217: */
        !           218: ENTRY(ischar)
        !           219:        push    %ebp
        !           220:        mov     %esp, %ebp
        !           221:        push    %ebx
        !           222: 
        !           223:        call    EXT(prot_to_real)               # enter real mode
        !           224: 
        !           225:        xor     %ebx, %ebx
        !           226:        movb    $0x1, %ah
        !           227:        sti
        !           228:        int     $0x16
        !           229:        cli
        !           230:        data16
        !           231:        jz      nochar
        !           232:        movb    %al, %bl
        !           233: 
        !           234: nochar:
        !           235:        data16
        !           236:        call    EXT(real_to_prot)
        !           237: 
        !           238:        xor     %eax, %eax
        !           239:        movb    %bl, %al
        !           240: 
        !           241:        pop     %ebx
        !           242:        pop     %ebp
        !           243:        ret
        !           244: 
        !           245: /*
        !           246: #
        !           247: # get_diskinfo():  return a word that represents the
        !           248: #      max number of sectors and  heads and drives for this device
        !           249: #
        !           250: */
        !           251: 
        !           252: ENTRY(get_diskinfo)
        !           253:        push    %ebp
        !           254:        mov     %esp, %ebp
        !           255:        push    %es
        !           256:        push    %ebx
        !           257:        push    %ecx
        !           258:        push    %edx
        !           259: 
        !           260:        movb    0x8(%ebp), %dl          # diskinfo(drive #)
        !           261:        call    EXT(prot_to_real)       # enter real mode
        !           262: 
        !           263:        movb    $0x8, %ah               # ask for disk info
        !           264: 
        !           265:        sti
        !           266:        int     $0x13
        !           267:        cli
        !           268: 
        !           269:        data16
        !           270:        call    EXT(real_to_prot)       # back to protected mode
        !           271: 
        !           272:        xor     %eax, %eax
        !           273: 
        !           274:        /*form a longword representing all this gunk*/
        !           275:        movb    %dh, %ah                # # heads
        !           276:        andb    $0x3f, %cl              # mask of cylinder gunk
        !           277:        movb    %cl, %al                # # sectors
        !           278: 
        !           279:        pop     %edx
        !           280:        pop     %ecx
        !           281:        pop     %ebx
        !           282:        pop     %es
        !           283:        pop     %ebp
        !           284:        ret
        !           285: 
        !           286: /*
        !           287: #
        !           288: # memsize(i) :  return the memory size in KB. i == 0 for conventional memory,
        !           289: #              i == 1 for extended memory
        !           290: #      BIOS call "INT 12H" to get conventional memory size
        !           291: #      BIOS call "INT 15H, AH=88H" to get extended memory size
        !           292: #              Both have the return value in AX.
        !           293: #
        !           294: */
        !           295: 
        !           296: ENTRY(memsize)
        !           297:        push    %ebp
        !           298:        mov     %esp, %ebp
        !           299:        push    %ebx
        !           300: 
        !           301:        mov     8(%ebp), %ebx
        !           302: 
        !           303:        call    EXT(prot_to_real)               # enter real mode
        !           304: 
        !           305:        cmpb    $0x1, %bl
        !           306:        data16
        !           307:        je      xext
        !           308:        
        !           309:        sti
        !           310:        int     $0x12
        !           311:        cli
        !           312:        data16
        !           313:        jmp     xdone
        !           314: 
        !           315: xext:  movb    $0x88, %ah
        !           316:        sti
        !           317:        int     $0x15
        !           318:        cli
        !           319: 
        !           320: xdone:
        !           321:        mov     %eax, %ebx
        !           322: 
        !           323:        data16
        !           324:        call    EXT(real_to_prot)
        !           325: 
        !           326:        mov     %ebx, %eax
        !           327:        pop     %ebx
        !           328:        pop     %ebp
        !           329:        ret

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