Change active flag handling; sanity check passed drive number; pass
partition pointer to bootstrap; optimise away 10 bytes; cosmetics.
This commit is contained in:
Robert Nordier
parent
66e98eef2b
commit
97a62e386d
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=48010
@ -13,7 +13,7 @@
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# purpose.
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#
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# $Id: boot0.m4,v 1.2 1998/10/19 19:13:53 rnordier Exp $
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# $Id: boot0.m4,v 1.3 1998/11/29 14:09:00 rnordier Exp $
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define(_al,0x0)dnl
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define(_cl,0x1)dnl
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@ -51,6 +51,7 @@ define(_bx_,0x7)dnl
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define(o16,`.byte 0x66')dnl
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define(addw1r,`.byte 0x3; .byte 0x40 | ($3 << 0x3) | $2; .byte $1')dnl
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define(addwia,`.byte 0x5; .word $1')dnl
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define(btwr1,`.word 0xa30f; .byte 0x40 | ($1 << 0x3) | $3; .byte $2')dnl
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define(btswr1,`.word 0xab0f; .byte 0x40 | ($1 << 0x3) | $3; .byte $2')dnl
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@ -62,6 +63,7 @@ define(movbr0,`.byte 0x88; .byte ($1 << 0x3) | $2')dnl
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define(movbr1,`.byte 0x88; .byte 0x40 | ($1 << 0x3) | $3; .byte $2')dnl
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define(movwr1,`.byte 0x89; .byte 0x40 | ($1 << 0x3) | $3; .byte $2')dnl
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define(movb0r,`.byte 0x8a; .byte ($2 << 0x3) | $1')dnl
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define(addb0r,`.byte 0x2; .byte ($2 << 0x3) | $1')dnl
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define(movb1r,`.byte 0x8a; .byte 0x40 | ($3 << 0x3) | $2; .byte $1')dnl
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define(movw1r,`.byte 0x8b; .byte 0x40 | ($3 << 0x3) | $2; .byte $1')dnl
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define(movws1,`.byte 0x8c; .byte 0x40 | ($1 << 0x3) | $3; .byte $2')dnl
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@ -71,3 +73,4 @@ define(callwi,`.byte 0xe8; .word $1 - . - 0x2')dnl
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define(jmpnwi,`.byte 0xe9; .word $1 - . - 0x2')dnl
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define(tstbi1,`.byte 0xf6; .byte 0x40 | $3; .byte $2; .byte $1')dnl
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define(incb1,`.byte 0xfe; .byte 0x40 | $2; .byte $1')dnl
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define(pushw1,`.byte 0xff; .byte 0x70 | $2; .byte $1')dnl
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@ -13,14 +13,13 @@
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# purpose.
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#
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# $Id: boot0.s,v 1.7 1999/02/26 14:51:14 rnordier Exp $
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# $Id: boot0.s,v 1.8 1999/03/01 02:42:47 rnordier Exp $
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# A 512-byte boot manager.
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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 DSKPKT,0x800 # Disk packet
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.set FAKE,0x810 # Partition entry
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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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@ -38,8 +37,8 @@
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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,0x10 # Fake partition entry
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.set _MNUOPT,0x1c # Menu options
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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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@ -55,115 +54,114 @@ start: cld # String ops inc
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rep # Relocate
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movsl # code
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movl %edi,%ebp # Address variables
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movb $0x10,%cl # Words to clear
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movb $0x8,%cl # Words to clear
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rep # Zero
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stosl # them
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incb1(-0xe,_di_) # Sector number
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jmpnwi(main-LOAD+ORIGIN) # To relocated code
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main: tstbi1(0x20,_FLAGS,_bp_) # Set drive?
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jz main.0 # No
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movb1r(_SETDRV,_bp_,_dl) # Drive to force
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main.0: movbr1(_dl,_FAKE,_bp_) # Save drive number
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main: tstbi1(0x20,_FLAGS,_bp_) # Set number drive?
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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
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main.1: movb1r(_SETDRV,_bp_,_dl) # Drive number to use
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main.2: movbr1(_dl,_FAKE,_bp_) # Save drive number
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callwi(putn) # To new line
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movwir(partbl,_bx) # Partition table
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xorl %edx,%edx # Item
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main.1: movb1r(0x4,_bx_,_al) # Load type
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pushl %edx # Save drive number
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movwir(partbl+0x4,_bx) # Partition table
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xorl %edx,%edx # Item number
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main.3: movbr1(_ch,-0x4,_bx_) # Zero active flag
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movb0r(_bx_,_al) # Load type
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movwir(tables,_di) # Lookup tables
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movb $TBL0SZ,%cl # Entries
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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.3 # Yes
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movb $TBL1SZ,%cl # Entries
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je main.5 # Yes
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movb $TBL1SZ,%cl # Number of entries
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repne # Known
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scasb # type?
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jne main.2 # No
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jne main.4 # No
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addwir(TBL1SZ,_di) # Adjust
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main.2: movb0r(_di_,_cl) # Partition
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main.4: movb0r(_di_,_cl) # Partition
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addl %ecx,%edi # description
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callwi(putx) # Display it
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main.3: addwir(0x10,_bx) # Next entry
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incl %edx # Next item
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cmpb $0x4,%dl # Done?
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jb main.1 # No
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movb1r(_FAKE,_bp_,_al) # Drive number
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main.5: incl %edx # Next item
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addb $0x10,%bl # Next entry
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jnc main.3 # Till done
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popl %eax # Drive number
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subb $0x80-0x1,%al # Does next
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cmpbmr(NHRDRV,_al) # drive exist?
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jb main.4 # Yes
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decb %al # Already drive 0?
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jz main.5 # Yes
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jb main.6 # Yes
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decl %eax # Already drive 0?
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jz main.7 # Yes
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xorb %al,%al # Drive 0
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main.4: addb $'0'|0x80,%al # Save
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movbr1(_al,_NXTDRV,_bp_) # it
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main.6: addb $'0'|0x80,%al # Save next
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movbr1(_al,_NXTDRV,_bp_) # drive number
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movwir(drive,_di) # Display
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callwi(putx) # item
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main.5: movwir(prompt,_si) # Display
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main.7: movwir(prompt,_si) # Display
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callwi(putstr) # prompt
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movb1r(_OPT,_bp_,_dl) # Display
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decl %esi # default
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callwi(putkey) # key
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xorb %ah,%ah # BIOS: Get
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int $0x1a # system time
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movl %edx,%edi # Save ticks
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main.6: movb $0x1,%ah # BIOS: Check
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movl %edx,%edi # Ticks when
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addw1r(_TICKS,_bp_,_di) # timeout
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main.8: movb $0x1,%ah # BIOS: Check
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int $0x16 # for keypress
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jnz main.9 # Have one
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jnz main.11 # Have one
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xorb %ah,%ah # BIOS: Get
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int $0x1a # system time
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subl %edi,%edx # Elapsed time
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cmpw1r(_TICKS,_bp_,_dx) # Timeout?
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jb main.6 # No
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main.7: movb1r(_OPT,_bp_,_al) # Load default
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jmp main.10 # Join common code
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main.8: movb $0x7,%al # Signal
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cmpl %edi,%edx # Timeout?
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jb main.8 # No
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main.9: movb1r(_OPT,_bp_,_al) # Load default
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jmp main.12 # Join common code
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main.10: movb $0x7,%al # Signal
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callwi(putchr) # error
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main.9: xorb %ah,%ah # BIOS: Get
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main.11: 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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cmpb $KEY_ENTER,%al # Enter pressed?
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je main.7 # No
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je main.9 # Yes
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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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ja main.8 # No
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main.10: cwtl # Option
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ja main.10 # No
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main.12: cwtl # Option
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btwr1(_ax,_MNUOPT,_bp_) # enabled?
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jnc main.8 # No
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jnc main.10 # No
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movbr1(_al,_OPT,_bp_) # Save option
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movwir(FAKE,_si) # Partition for write
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movb0r(_si_,_dl) # Drive number
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movl %esi,%ebx # Partition for read
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cmpb $0x4,%al # F5 pressed?
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pushfl # Save
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je main.12 # Yes
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movwir(partbl,_bx) # Partition table
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pushl %ebx # Save
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main.11: movbr0(_ah,_bx_) # Mark inactive
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addb $0x10,%bl # To next entry
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cmpb $0xfe,%bl # Till
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jb main.11 # done
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popl %ebx # Restore
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shlb $0x4,%al # Selected
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addb %al,%bl # partition
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je main.13 # Yes
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shlb $0x4,%al # Point to
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addwia(partbl) # selected
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xchgl %ebx,%eax # partition
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movbi0(0x80,_bx_) # Flag active
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main.12: pushl %ebx # Save
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main.13: pushl %ebx # Save
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tstbi1(0x40,_FLAGS,_bp_) # No updates?
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jnz main.13 # Yes
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jnz main.14 # Yes
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movwir(start,_bx) # Data to write
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movwir(0x301,_ax) # Write sector
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movb $0x3,%ah # Write sector
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callwi(intx13) # to disk
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main.13: popl %esi # Restore
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main.14: popl %esi # Restore
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popfl # Restore
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jne main.14 # If not F5
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jne main.15 # If not F5
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movb1r(_NXTDRV,_bp_,_dl) # Next drive
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subb $'0',%dl # number
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main.14: movwir(LOAD,_bx) # Address for read
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movwir(0x201,_ax) # Read sector
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main.15: movwir(LOAD,_bx) # Address for read
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movb $0x2,%ah # Read sector
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callwi(intx13) # from disk
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jc main.8 # If error
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jc main.10 # If error
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cmpwi2(MAGIC,0x1fe,_bx_) # Bootable?
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jne main.8 # No
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jne main.10 # No
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pushl %esi # Save
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movwir(crlf,_si) # Leave some
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callwi(puts) # space
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popl %esi # Restore
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jmp *%ebx # Invoke bootstrap
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# Display routines
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@ -197,26 +195,29 @@ putchr: pushl %ebx # Save
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popl %ebx # Restore
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ret # To caller
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# Disk I/O routine
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# One-sector disk I/O routine
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intx13: cli # Disable interrupts
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movb1r(0x1,_si_,_dh) # Load head
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intx13: movb1r(0x1,_si_,_dh) # Load head
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movw1r(0x2,_si_,_cx) # Load cylinder:sector
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o16 # Load
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movw1r(0x8,_si_,_di) # offset
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movwir(DSKPKT,_si) # Packet pointer
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movbi0(0x10,_si_) # Packet size
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movbr1(_al,0x2,_si_) # Block count
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movwr1(_bx,0x4,_si_) # Transfer
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movws1(_es,0x6,_si_) # buffer
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o16 # LBA
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movwr1(_di,0x8,_si_) # address
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sti # Enable interrupts
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movb $0x1,%al # Sector count
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pushl %esi # Save
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movl %esp,%edi # Save
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tstbi1(0x80,_FLAGS,_bp_) # Use packet interface?
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jz intx13.1 # No
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orb $0x40,%ah # Use disk packet
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o16 # Set
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pushb $0x0 # the
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o16 # LBA
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pushw1(0x8,_si_) # address
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pushl %es # Set the transfer
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pushl %ebx # buffer address
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pushb $0x1 # Block count
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pushb $0x10 # Packet size
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movl %esp,%esi # Packet pointer
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decl %eax # 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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movl %edi,%esp # Restore
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popl %esi # Restore
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ret # To caller
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# Menu strings
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