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8 changed files with 292 additions and 828 deletions
196
as386.sed
196
as386.sed
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@ -1,196 +0,0 @@
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#\
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# @(#)as386.sed 1.1 - 86/11/17\
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#\
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# This is a sed script which converts Intel 386 assembly code to Unix\
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# 386 assembly code\
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#\
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# This script does not attempt to convert 100% of the ASM386 source code,\
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# it cannot handle the following constructs:\
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#\
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# - strange segmentation schemes\
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# - data declarations beyond the simple db/dw/dd with simple init list\
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# - ascii strings\
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# - structure template addressing (i.e., [ebp].foo)\
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# - complex expressions (parenthesis and operators other than +-*/)\
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# - immediate operands that are not simple constants\
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# - immediate operands with automatically typed memory operands\
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# - source files in upper case\
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# - source files with continued lines\
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#\
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# A typical way to use this sed script is:\
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# tr "[A-Z]" "[a-z]" <infile | sed -f this-script >outfile\
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#\
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#\
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# Meaning of labels:\
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#\
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# cmpress preserve comments, insert tabs, change '?' to '_'\
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# control convert '$' control lines\
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# segment convert segmentation directives\
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# equate convert 'equ' directives\
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# data convert db/dw/dd data declarations\
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# modifer delete address/type modifiers\
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# registr convert register names\
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# bincons convert binary/octal/hex conatants\
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# address regularize addess expressions, delete unneeded tabs\
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# normliz normalize instruction formats (name-tab-opcode-tab-operands)\
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# operand swap operands, convert scale/index/base address format\
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# opcode append b/w to opcode for byte/word register operands\
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# comment restore preserved comments\
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:cmpress
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h
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s/;.*$//
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s/[ ]*$/ /
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s/[ ][ ]*/ /g
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s/\([][)(.,:*/+-]\)/ \1 /g
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s/ ? / 0 /g
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s/?/_/g
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s/[ ][ ]*/ /g
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:control
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s/^\$[ ]*include ( \([^ .)]*\)[^)]*)/#include "\1.h"/
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s/^\$[ ]*eject /; /
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/^\$/ s/^/;/
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:segment
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/ segment e[or] / s/^/ .text ;/
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/ segment ro / s/^/ .text ;/
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/ segment rw / s/^/ .data ;/
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/ ends / s/^/;/
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/ stackseg / s/^/;/
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s/^[ ]*name \([^ ]*\)/ .file "\1"/
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/^[ ]*end / s/^/;/
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/^[ ]*assume / s/^/;/
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/^[ ]*extrn / s/^/;/
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/^[ ]*public [^ ,]* , / {
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s/^[ ]*public / .globl /
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s/ , .*$//
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G
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s/\n\([ ]*\)public\([ ]\)[^,]*,/\
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\1public\2/
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P
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D
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}
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s/^[ ]*public / .globl /
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s/^[ ]*comm / .comm /
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s/^\([^ ][^ ]*\) proc /\1 : ;proc /
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/ endp / s/^/;/
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s/^\([^ ][^ ]*\) label /\1 : ;label /
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s/^[ ]*even / .even /
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:equate
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s/^\([^ ]*\) equ \(.*\) $/#define : \1 \2 /
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:data
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s/^[ ]*db / .byte /
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s/^\([^ ][^ ]*\) db /\1 : .byte /
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s/^[ ]*dw / .value /
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s/^\([^ ][^ ]*\) dw /\1 : .value /
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s/^[ ]*dd / .long /
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s/^\([^ ][^ ]*\) dd /\1 : .long /
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/^[ ]*dp / {
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s/^[ ]*dp / .value /
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s/$/\/selector of dp pointer/
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G
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s/\n\([ ]*\)dp\([ ]\)/\
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\1dd\2/
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P
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D
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}
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/^\([^ ][^ ]*\) dp / {
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s/^\([^ ][^ ]*\) dp /\1: .value /
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s/$/\/selector of dp pointer/
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G
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s/\n[^ ]*\([ ]*\)dp\([ ]\)/\
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\1dd\2/
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P
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D
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}
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s/^\([^ ][^ ]*\) struc /\1 : ;struc /
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s/^\([^ ][^ ]*\) record /\1 : ;record /
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:modifer
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s/ : near / /g
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s/ : far / /g
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s/ : byte / /g
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s/ : word / /g
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s/ : dword / /g
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s/ short / /g
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s/ offset / $/g
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/ byte ptr / s/$/?%al?/
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s/ byte ptr / /g
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/ word ptr / s/$/?%ax?/
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s/ word ptr / /g
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s/ dword ptr / /g
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s/ pword ptr / /g
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:registr
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s/ e\([abcd]\)x / %e\1x /g
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s/ \([abcd]\)\([hlx]\) / %\1\2 /g
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s/ e\([ds]\)i / %e\1i /g
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s/ \([ds]\)i / %\1i /g
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s/ e\([bs]\)p / %e\1p /g
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s/ \([bs]\)p / %\1p /g
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s/ \([cdefgs]\)s / %\1s /g
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:bincons
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s/ \([01][01]*\)b / 0b\1 /g
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s/ \([0-7][0-7]*\)[oq] / 0\1 /g
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s/ \([0-9][0-9a-f]*\)h / 0x\1 /g
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t address
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:address
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s/\[/+/g
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/;/ !s/ ] \. / + /g
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s/ ]//g
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s/ %\([^ ]*\) \* \([248]\) + \([^ %][^ ]*\)/ \3 + %\1 * \2/g
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s/ %\([^ ]*\) + \([^ %][^ ]*\)/ \2 + %\1/g
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s/ %\([^ ]*\) \* \([248]\) - \([^ %][^ ]*\)/ - \3 + %\1 * \2/g
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s/ %\([^ ]*\) - \([^ %][^ ]*\)/ - \2 + %\1/g
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s/ + - / - /g
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t address
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s/ \([)(,*/+-]\)/\1/g
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s/\([)(,*/+-]\) /\1/g
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s/ :/:/g
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s/%\([cdefgs]\)s: /%\1s:/g
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:normliz
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/: / !s/^\([^ ;#][^ ]*\)/ \1/
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/: / !s/^ \([^ +,-]*\)\([+-]\)/ \1 \2/g
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/: / !s/^ \([^ +,]*\)+%/ \1 +%/g
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/: / s/^\([^ ]*\) \([^ +,-]*\)\([+-]\)/\1 \2 \3/g
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/: / s/^\([^ ]*\) \([^ +,]*\)+%/\1 \2 +%/g
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s/+%\([^ ,]*\)/(%\1)/g
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s/ +/ /g
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s/\([:,]\)+/\1/g
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:operand
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/[.;#]/ !s/^ \([^ ]*\) \([^,]*\),\([^ ]*\)/ \1 \3,\2/
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/[.;#]/ !s/^\([^ ][^ ]*\) \([^ ]*\) \([^,]*\),\([^ ]*\)/\1 \2 \4,\3/
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/[.;#]/ !s/^ \([^ ]*\) \([0-9][0-9a-fx]*\)\([ ,]\)/ \1 $\2\3/
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/[.;#]/ !s/^\([^ ][^ ]*\) \([^ ]*\) \([0-9][0-9a-fx]*\)\([ ,]\)/\1 \2 $\3\4/
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s/(%\([^)+*]*\)+%\([^)*]*\)\*\([248]\))/(%\1,%\2,\3)/g
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s/(%\([^)+*]*\)\*\([248]\)+%\([^)]*\))/(%\3,%\1,\2)/g
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s/(%\([^)+*]*\)+%\([^)]*\))/(%\1,%\2)/g
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s/(%\([^)+*]*\)\*\([248]\))/(,%\1,\2)/g
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:opcode
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/[ ,]%[abcd][hl]/ s/$/?%al?/
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/[ ,]%[abcd]x/ s/$/?%ax?/
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/[ ,]%[ds]i/ s/$/?%ax?/
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/[ ,]%[bs]p/ s/$/?%ax?/
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/?%al?/ s/^\([^ ]*\) \([^ ]*\) /\1 \2b /
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/?%ax?/ s/^\([^ ]*\) \([^ ]*\) /\1 \2w /
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s/^#define:/#define/
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s/?%a[xl]?//g
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:comment
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s/ *$//
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x
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/;/ !s/^.*$//
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s/\([ ]*\);/;\1;/
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s/^[^;]*;//
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x
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G
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s/\n//
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s/;/\//
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107
build.zig
107
build.zig
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@ -1,13 +1,12 @@
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const std = @import("std");
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const std = @import("std");
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const LazyPath = std.Build.LazyPath;
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// Although this function looks imperative, note that its job is to
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// Although this function looks imperative, note that its job is to
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// declaratively construct a build graph that will be executed by an external
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// declaratively construct a build graph that will be executed by an external
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// runner.
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// runner.
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pub fn build(b: *std.Build) void {
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pub fn build(b: *std.Build) void {
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const bootloader = addNasmFiles(b, AddNasmFilesOptions{
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const initramfs = addNasmFiles(b, AddNasmFilesOptions{
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.filename = "src/bootloader.asm",
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.filename = "src/initramfs.asm",
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.outputname = "bootloader.bin",
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.outputname = "initramfs.bin",
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.flags = &.{"-f bin"},
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.flags = &.{"-f bin"},
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});
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});
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const kernel = addNasmFiles(b, AddNasmFilesOptions{
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const kernel = addNasmFiles(b, AddNasmFilesOptions{
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@ -16,47 +15,19 @@ pub fn build(b: *std.Build) void {
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.flags = &.{"-f bin"},
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.flags = &.{"-f bin"},
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});
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});
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const target = b.standardTargetOptions(.{
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var floppy = createFloppy(b, "main_floppy.img");
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.default_target = .{
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floppy.run = formatFloppyFat12(b, floppy);
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.os_tag = .uefi,
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.cpu_arch = .x86,
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},
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});
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const floppy = createFloppy(b, "main_floppy.img");
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const img_install = b.addInstallBinFile(floppy.obj, "main_floppy.img");
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img_install.step.dependOn(&installImgToFloppy(b, floppy, initramfs, kernel).step);
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var installToFloppy = installImgToFloppy(b, floppy, bootloader, &.{
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NamedFile{ .file = kernel, .name = "::kernel.bin" },
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NamedFile{ .file = b.path("src/reference_implementations/test.txt"), .name = "::test.txt" },
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});
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const img_install = b.addInstallBinFile(floppy, "main_floppy.img");
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img_install.step.dependOn(&installToFloppy.step);
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b.getInstallStep().dependOn(&img_install.step);
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b.getInstallStep().dependOn(&img_install.step);
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const fat_reference_mod = b.createModule(.{
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const run = b.addSystemCommand(&.{ "qemu-system-i386", "-fda" });
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.root_source_file = b.path("src/reference_implementations/fat.zig"),
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run.addFileArg(floppy.obj);
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.target = target,
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.link_libc = true,
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|
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});
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const run = b.addSystemCommand(&.{ "qemu-system-i386", "-fda", "zig-out/bin/main_floppy.img" });
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const run_step = b.step("run", "run the os in qemu");
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const run_step = b.step("run", "run the os in qemu");
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run_step.dependOn(&run.step);
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run_step.dependOn(&run.step);
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const fat_reference = b.addExecutable(.{
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.root_module = fat_reference_mod,
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|
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.name = "fat_reference_implementation",
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|
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.use_lld = false,
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|
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.use_llvm = false,
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|
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});
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|
||||||
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|
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const fat_install = b.addInstallArtifact(fat_reference, .{});
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|
||||||
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const build_references = b.step("references", "build the reference implementations");
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build_references.dependOn(&fat_install.step);
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|
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}
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}
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|
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const AddNasmFilesOptions = struct {
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const AddNasmFilesOptions = struct {
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||||||
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|
@ -65,45 +36,53 @@ const AddNasmFilesOptions = struct {
|
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flags: []const []const u8 = &.{},
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flags: []const []const u8 = &.{},
|
||||||
};
|
};
|
||||||
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|
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const NamedFile = struct {
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const NasmFile = struct {
|
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file: std.Build.LazyPath,
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run: *std.Build.Step.Run,
|
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name: []const u8,
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obj: std.Build.LazyPath,
|
||||||
};
|
};
|
||||||
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|
||||||
fn createFloppy(b: *std.Build, name: []const u8) LazyPath {
|
const Floppydisk = NasmFile;
|
||||||
|
|
||||||
|
fn createFloppy(b: *std.Build, name: []const u8) Floppydisk {
|
||||||
const dd = b.addSystemCommand(&.{ "dd", "if=/dev/zero" });
|
const dd = b.addSystemCommand(&.{ "dd", "if=/dev/zero" });
|
||||||
const Floppy = dd.addPrefixedOutputFileArg("of=", name);
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const Floppy = dd.addPrefixedOutputFileArg("of=", name);
|
||||||
dd.has_side_effects = true;
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|
||||||
dd.addArgs(&.{ "bs=512", "count=2880" });
|
dd.addArgs(&.{ "bs=512", "count=2880" });
|
||||||
|
|
||||||
return Floppy;
|
return Floppydisk{
|
||||||
|
.run = dd,
|
||||||
|
.obj = Floppy,
|
||||||
|
};
|
||||||
}
|
}
|
||||||
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|
||||||
fn installImgToFloppy(b: *std.Build, floppy: LazyPath, bootloader: LazyPath, additional_files: []const NamedFile) *std.Build.Step.Run {
|
fn formatFloppyFat12(b: *std.Build, floppy: Floppydisk) *std.Build.Step.Run {
|
||||||
const mkfs = b.addSystemCommand(&.{ "mkfs.fat", "-F12", "-nNBOS" });
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const mkfs = b.addSystemCommand(&.{ "mkfs.fat", "-F12", "-nNBOS" });
|
||||||
mkfs.addFileArg(floppy);
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mkfs.addFileArg(floppy.obj);
|
||||||
mkfs.has_side_effects = true;
|
|
||||||
|
|
||||||
|
mkfs.step.dependOn(&floppy.run.step);
|
||||||
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|
||||||
|
return mkfs;
|
||||||
|
}
|
||||||
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|
||||||
|
fn installImgToFloppy(b: *std.Build, floppy: Floppydisk, bootloader: NasmFile, kernel: NasmFile) *std.Build.Step.Run {
|
||||||
const dd = b.addSystemCommand(&.{"dd"});
|
const dd = b.addSystemCommand(&.{"dd"});
|
||||||
dd.addPrefixedFileArg("if=", bootloader);
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dd.addPrefixedFileArg("if=", bootloader.obj);
|
||||||
dd.addPrefixedFileArg("of=", floppy);
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dd.addPrefixedFileArg("of=", floppy.obj);
|
||||||
dd.addArg("conv=notrunc");
|
dd.addArg("conv=notrunc");
|
||||||
dd.step.dependOn(&mkfs.step);
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dd.step.dependOn(&floppy.run.step);
|
||||||
|
dd.step.dependOn(&bootloader.run.step);
|
||||||
|
|
||||||
var last_step = dd;
|
const mcopy = b.addSystemCommand(&.{"mcopy"});
|
||||||
for (additional_files) |f| {
|
mcopy.addPrefixedFileArg("-i", floppy.obj);
|
||||||
const mcopy = b.addSystemCommand(&.{"mcopy"});
|
mcopy.addFileArg(kernel.obj);
|
||||||
mcopy.addPrefixedFileArg("-i", floppy);
|
mcopy.addArg("::kernel.bin");
|
||||||
mcopy.addFileArg(f.file);
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mcopy.step.dependOn(&dd.step);
|
||||||
mcopy.addArg(f.name);
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mcopy.step.dependOn(&kernel.run.step);
|
||||||
mcopy.step.dependOn(&last_step.step);
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|
||||||
last_step = mcopy;
|
return mcopy;
|
||||||
}
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|
||||||
return last_step;
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|
||||||
}
|
}
|
||||||
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|
||||||
// adapted from https://codeberg.org/raddari/zig-nasm-lib.git
|
// adapted from https://codeberg.org/raddari/zig-nasm-lib.git
|
||||||
fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) LazyPath {
|
fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) NasmFile {
|
||||||
std.debug.assert(!std.fs.path.isAbsolute(options.filename));
|
std.debug.assert(!std.fs.path.isAbsolute(options.filename));
|
||||||
const src_file = b.path(options.filename);
|
const src_file = b.path(options.filename);
|
||||||
const output = options.outputname orelse b.fmt("{s}.o", .{std.mem.sliceTo(options.filename, '.')});
|
const output = options.outputname orelse b.fmt("{s}.o", .{std.mem.sliceTo(options.filename, '.')});
|
||||||
|
|
@ -113,7 +92,9 @@ fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) LazyPath {
|
||||||
nasm.addPrefixedDirectoryArg("-i", b.path("src"));
|
nasm.addPrefixedDirectoryArg("-i", b.path("src"));
|
||||||
const obj = nasm.addPrefixedOutputFileArg("-o", output);
|
const obj = nasm.addPrefixedOutputFileArg("-o", output);
|
||||||
nasm.addFileArg(src_file);
|
nasm.addFileArg(src_file);
|
||||||
nasm.has_side_effects = true;
|
|
||||||
|
|
||||||
return obj;
|
return .{
|
||||||
|
.run = nasm,
|
||||||
|
.obj = obj,
|
||||||
|
};
|
||||||
}
|
}
|
||||||
|
|
|
||||||
|
|
@ -28,7 +28,7 @@
|
||||||
|
|
||||||
// Tracks the earliest Zig version that the package considers to be a
|
// Tracks the earliest Zig version that the package considers to be a
|
||||||
// supported use case.
|
// supported use case.
|
||||||
.minimum_zig_version = "0.15.0",
|
.minimum_zig_version = "0.14.1",
|
||||||
|
|
||||||
// This field is optional.
|
// This field is optional.
|
||||||
// Each dependency must either provide a `url` and `hash`, or a `path`.
|
// Each dependency must either provide a `url` and `hash`, or a `path`.
|
||||||
|
|
|
||||||
|
|
@ -1,379 +0,0 @@
|
||||||
; vim: ft=nasm
|
|
||||||
org 0x7C00
|
|
||||||
bits 16
|
|
||||||
|
|
||||||
|
|
||||||
%define ENDL 0x0D, 0x0A
|
|
||||||
|
|
||||||
|
|
||||||
;
|
|
||||||
; FAT12 Header
|
|
||||||
;
|
|
||||||
jmp short start
|
|
||||||
nop
|
|
||||||
|
|
||||||
bdb_oem: db "mkfs.fat" ; 8 bytes
|
|
||||||
bdb_bytes_per_sector: dw 512
|
|
||||||
bdb_sectors_per_cluster: db 1
|
|
||||||
bdb_reserved_sectors: dw 1
|
|
||||||
bdb_fat_count: db 2
|
|
||||||
bdb_dir_entries_count: dw 0E0h
|
|
||||||
bdb_total_sectors: dw 2880 ; 2880 * 512 = 1.44MB
|
|
||||||
bdb_media_descriptor_type: db 0F0h ; F0 = 3.5" floppy disk
|
|
||||||
bdb_sectors_per_fat: dw 9 ; 9 sectors/fat
|
|
||||||
bdb_sectors_per_track: dw 18
|
|
||||||
bdb_heads: dw 2
|
|
||||||
bdb_hidden_sectors: dd 0
|
|
||||||
bdb_large_sector_count: dd 0
|
|
||||||
|
|
||||||
; Extended boot record
|
|
||||||
ebr_drive_number: db 0 ; 0x00 floppy, 0x80 hdd, useless
|
|
||||||
db 0 ; reserved
|
|
||||||
ebr_signature: db 29h
|
|
||||||
ebr_volume_id: db 68h, 6Fh, 6Dh, 6Fh ; serial number, value doesn't matter
|
|
||||||
ebr_volume_label: db 'zos disk' ; 11 bytes, padded with spaces
|
|
||||||
ebr_system_id: db 'FAT12 ' ; 8 bytes
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
start:
|
|
||||||
; setup data segments
|
|
||||||
mov ax, 0 ; use ax as and intermediary as we can't write to es/ds directly
|
|
||||||
mov ds, ax
|
|
||||||
mov es, ax
|
|
||||||
|
|
||||||
; setup stack
|
|
||||||
mov ss, ax
|
|
||||||
mov sp, 0x7C00 ; stack grows downward from where we are loaded in memory
|
|
||||||
|
|
||||||
; some BIOS start us at 07C00:0000 instead of 0000:07C0, make sure we are in the right place
|
|
||||||
|
|
||||||
push es
|
|
||||||
push word .after
|
|
||||||
retf
|
|
||||||
|
|
||||||
.after:
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
mov [ebr_drive_number], dl
|
|
||||||
|
|
||||||
|
|
||||||
mov si, msg_loading
|
|
||||||
call echo
|
|
||||||
|
|
||||||
|
|
||||||
; read drive parameters (you never know)
|
|
||||||
push es
|
|
||||||
mov ah, 08h
|
|
||||||
int 13h
|
|
||||||
jc floppy_error
|
|
||||||
pop es
|
|
||||||
|
|
||||||
and cl, 0x3F ; remove top 2 bites
|
|
||||||
xor ch, ch
|
|
||||||
mov [bdb_sectors_per_track], cx ; sectors count
|
|
||||||
|
|
||||||
inc dh
|
|
||||||
mov [bdb_heads], dh ; head count
|
|
||||||
|
|
||||||
; read FAT root directory
|
|
||||||
; compute LBA of root directory = reserved + fats * sectors_per_fat
|
|
||||||
mov ax, [bdb_sectors_per_fat]
|
|
||||||
mov bl, [bdb_fat_count]
|
|
||||||
xor bh, bh
|
|
||||||
mul bx ; ax = fats * sectors_per_fat
|
|
||||||
add ax, [bdb_reserved_sectors] ; ax = LBA of root dir
|
|
||||||
push ax
|
|
||||||
|
|
||||||
; compute size of root directory = (32 * number_of_entries) / bytes_per_sector
|
|
||||||
mov ax, [bdb_dir_entries_count]
|
|
||||||
shl ax, 5 ; ax *= 32
|
|
||||||
xor dx, dx
|
|
||||||
div word [bdb_bytes_per_sector] ; number of sectors we need to read
|
|
||||||
|
|
||||||
test dx, dx ; if != 0 add 1
|
|
||||||
jz .root_dir_after
|
|
||||||
inc ax ; divistion reminder != 0, add 1
|
|
||||||
|
|
||||||
.root_dir_after:
|
|
||||||
|
|
||||||
; read root dir
|
|
||||||
mov cl, al ; cl = number of sectors to read = size of root directory
|
|
||||||
pop ax ; ax = LBA of root directory
|
|
||||||
mov dl, [ebr_drive_number] ; dl = drive number (as saved previously)
|
|
||||||
mov bx, buffer ; es:bx = buffer
|
|
||||||
call disk_read
|
|
||||||
|
|
||||||
; search for kernel.bin
|
|
||||||
xor bx, bx
|
|
||||||
mov di, buffer
|
|
||||||
|
|
||||||
.search_kernel:
|
|
||||||
mov si, file_kernel_bin
|
|
||||||
mov cx, 11 ; compare up to 11 characters
|
|
||||||
push di
|
|
||||||
repe cmpsb ; repe: repeat until cx = 0
|
|
||||||
; cmpsb: compare ds:si to es:di, they are also incremented or decremented based on a flag
|
|
||||||
pop di
|
|
||||||
je .found_kernel
|
|
||||||
|
|
||||||
add di, 32
|
|
||||||
inc bx
|
|
||||||
cmp bx, [bdb_dir_entries_count]
|
|
||||||
jl .search_kernel
|
|
||||||
|
|
||||||
; kernel not found
|
|
||||||
jmp kernel_not_found_error
|
|
||||||
|
|
||||||
.found_kernel:
|
|
||||||
|
|
||||||
; di should point to the adress of the entry
|
|
||||||
mov ax, [di + 26] ; first logical cluster (offset 26)
|
|
||||||
mov [kernel_cluster], ax
|
|
||||||
|
|
||||||
; load FAT from disk into memory
|
|
||||||
mov ax, [bdb_reserved_sectors]
|
|
||||||
mov bx, buffer
|
|
||||||
mov cl, [bdb_sectors_per_fat]
|
|
||||||
mov dl, [ebr_drive_number]
|
|
||||||
call disk_read
|
|
||||||
|
|
||||||
; read kernel and process FAT chain
|
|
||||||
mov bx, KERNEL_LOAD_SEGMENT
|
|
||||||
mov es, bx
|
|
||||||
mov bx, KERNEL_LOAD_OFFSET
|
|
||||||
|
|
||||||
.load_kernel_loop:
|
|
||||||
|
|
||||||
; read next cluster
|
|
||||||
mov ax, [kernel_cluster]
|
|
||||||
|
|
||||||
|
|
||||||
add ax, 31 ; tmp hardcoding ; first cluster = (kernel_cluster - 2) * sectors_per_cluster + start_sector
|
|
||||||
; start_sector = reserved + fats + root_directory_size = 1 + 18 + 134 = 33
|
|
||||||
mov cl, 1
|
|
||||||
mov dl, [ebr_drive_number]
|
|
||||||
call disk_read
|
|
||||||
|
|
||||||
; can overflow, risky!!!!
|
|
||||||
add bx, [bdb_bytes_per_sector]
|
|
||||||
|
|
||||||
; cumpute location of next cluster
|
|
||||||
mov ax, [kernel_cluster]
|
|
||||||
mov cx, 3
|
|
||||||
mul cx
|
|
||||||
mov cx, 2
|
|
||||||
div cx ; ax = index of entry in FAT, dx = cluster mod 2
|
|
||||||
|
|
||||||
mov si, buffer
|
|
||||||
add si, ax
|
|
||||||
mov ax, [ds:si] ; read entry from FAT table at index ax
|
|
||||||
|
|
||||||
or dx, dx
|
|
||||||
jz .even
|
|
||||||
|
|
||||||
.odd:
|
|
||||||
shr ax, 4
|
|
||||||
jmp .next_cluster_after
|
|
||||||
|
|
||||||
.even:
|
|
||||||
and ax, 0x0FFF
|
|
||||||
|
|
||||||
.next_cluster_after:
|
|
||||||
cmp ax, 0x0FF8 ; end of chain
|
|
||||||
jae .read_finish
|
|
||||||
|
|
||||||
mov [kernel_cluster], ax
|
|
||||||
jmp .load_kernel_loop
|
|
||||||
|
|
||||||
.read_finish:
|
|
||||||
|
|
||||||
; jump to kernel
|
|
||||||
mov dl, [ebr_drive_number] ; boot device in dl
|
|
||||||
|
|
||||||
mov ax, KERNEL_LOAD_SEGMENT ; set segment registers
|
|
||||||
mov ds, ax
|
|
||||||
mov es, ax
|
|
||||||
|
|
||||||
jmp KERNEL_LOAD_SEGMENT:KERNEL_LOAD_OFFSET
|
|
||||||
|
|
||||||
jmp wait_key_and_reboot ; should never happen
|
|
||||||
|
|
||||||
cli
|
|
||||||
hlt
|
|
||||||
|
|
||||||
; errors
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
floppy_error:
|
|
||||||
mov si, msg_read_failed
|
|
||||||
call echo
|
|
||||||
jmp wait_key_and_reboot
|
|
||||||
|
|
||||||
kernel_not_found_error:
|
|
||||||
mov si, msg_kernel_not_found
|
|
||||||
call echo
|
|
||||||
jmp wait_key_and_reboot
|
|
||||||
|
|
||||||
wait_key_and_reboot:
|
|
||||||
mov ah, 0
|
|
||||||
int 16h ; wait for keypress
|
|
||||||
jmp 0FFFFh:0 ; jump to start of bios, should reboot
|
|
||||||
|
|
||||||
.halt:
|
|
||||||
cli ; disable interrupts, this way we shouldn't be able to get out of halt
|
|
||||||
hlt
|
|
||||||
|
|
||||||
|
|
||||||
;
|
|
||||||
; echo:
|
|
||||||
; print something to the screen
|
|
||||||
; - ds:si points to string
|
|
||||||
;
|
|
||||||
echo:
|
|
||||||
; save the registers we want to modify
|
|
||||||
push si
|
|
||||||
push ax
|
|
||||||
push bx
|
|
||||||
|
|
||||||
.loop:
|
|
||||||
lodsb ; load byte from ds:si to al
|
|
||||||
or al, al ; check if next char is null
|
|
||||||
jz .done
|
|
||||||
|
|
||||||
mov ah, 0x0E
|
|
||||||
mov bh, 0
|
|
||||||
int 0x10
|
|
||||||
|
|
||||||
jmp .loop
|
|
||||||
|
|
||||||
.done:
|
|
||||||
pop bx
|
|
||||||
pop ax
|
|
||||||
pop si
|
|
||||||
ret
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
;
|
|
||||||
; args:
|
|
||||||
; ax = lba adress
|
|
||||||
; return:
|
|
||||||
; cx[0..5] = sector number
|
|
||||||
; cx[6-15] = cilinder number
|
|
||||||
; dh: head
|
|
||||||
;
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
lba_to_chs:
|
|
||||||
|
|
||||||
push ax
|
|
||||||
push dx
|
|
||||||
|
|
||||||
xor dx, dx ; clear dw
|
|
||||||
div word [bdb_sectors_per_track] ; ax = LBA / SectorsPerTrack
|
|
||||||
; dx = LBA % SectorsPerTrack
|
|
||||||
|
|
||||||
inc dx
|
|
||||||
mov cx, dx ; cx = sector
|
|
||||||
|
|
||||||
xor dx, dx ; clear dx
|
|
||||||
div word [bdb_heads] ; ax = (LBA / SectorsPerTrack) / Heads = cylinder
|
|
||||||
; dx = (LBA / SectorsPerTrack) % Heads = head
|
|
||||||
mov dh, dl
|
|
||||||
mov ch, al
|
|
||||||
shl ah, 6
|
|
||||||
or cl, ah ; put upper 2 bits of cylinder in CL
|
|
||||||
|
|
||||||
pop ax
|
|
||||||
mov dl, al
|
|
||||||
pop ax
|
|
||||||
ret
|
|
||||||
|
|
||||||
|
|
||||||
;
|
|
||||||
; args:
|
|
||||||
; ax = LBA adress
|
|
||||||
; cl = number of sectors to read
|
|
||||||
; dl = drive number
|
|
||||||
; es:bx = pointer to where to store the data
|
|
||||||
;
|
|
||||||
|
|
||||||
disk_read:
|
|
||||||
|
|
||||||
push ax
|
|
||||||
push bx
|
|
||||||
push cx
|
|
||||||
push dx
|
|
||||||
push di
|
|
||||||
|
|
||||||
push cx ; cx will be overridden
|
|
||||||
call lba_to_chs
|
|
||||||
pop ax ; al = number of sectors to read
|
|
||||||
|
|
||||||
mov ah, 02h
|
|
||||||
mov di, 3 ; hoe many times to try
|
|
||||||
|
|
||||||
.retry:
|
|
||||||
pusha
|
|
||||||
stc ; set carry flag
|
|
||||||
int 13h ; if no carry flag => it work
|
|
||||||
jnc .done
|
|
||||||
|
|
||||||
; read fail
|
|
||||||
popa
|
|
||||||
call disk_reset
|
|
||||||
|
|
||||||
dec di
|
|
||||||
test di, di
|
|
||||||
jnz .retry
|
|
||||||
|
|
||||||
.fail:
|
|
||||||
; all attempts exausted
|
|
||||||
jmp floppy_error
|
|
||||||
|
|
||||||
.done:
|
|
||||||
popa
|
|
||||||
|
|
||||||
pop di
|
|
||||||
pop dx
|
|
||||||
pop cx
|
|
||||||
pop bx
|
|
||||||
pop ax
|
|
||||||
ret
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
; arg: dl = drive number
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
disk_reset:
|
|
||||||
pusha
|
|
||||||
mov ah, 0
|
|
||||||
stc ; set carry
|
|
||||||
int 13h
|
|
||||||
jc floppy_error
|
|
||||||
popa
|
|
||||||
ret
|
|
||||||
|
|
||||||
msg_loading: db 'starting zos', ENDL, 0
|
|
||||||
msg_read_failed: db 'error on floppy read', ENDL, 0
|
|
||||||
msg_kernel_not_found: db 'kernel.bin not found', ENDL, 0
|
|
||||||
file_kernel_bin: db 'KERNEL BIN'
|
|
||||||
kernel_cluster: dw 0
|
|
||||||
|
|
||||||
KERNEL_LOAD_SEGMENT equ 0x2000
|
|
||||||
KERNEL_LOAD_OFFSET equ 0
|
|
||||||
|
|
||||||
|
|
||||||
times 510-($-$$) db 0
|
|
||||||
dw 0AA55h
|
|
||||||
|
|
||||||
buffer:
|
|
||||||
217
src/initramfs.asm
Normal file
217
src/initramfs.asm
Normal file
|
|
@ -0,0 +1,217 @@
|
||||||
|
; vim: ft=nasm
|
||||||
|
org 0x7C00
|
||||||
|
bits 16
|
||||||
|
|
||||||
|
|
||||||
|
%define ENDL 0x0D, 0x0A
|
||||||
|
|
||||||
|
;
|
||||||
|
; FAT12 Header
|
||||||
|
;
|
||||||
|
jmp short start
|
||||||
|
nop
|
||||||
|
|
||||||
|
bdb_oem: db "mkfs.fat"
|
||||||
|
bdb_bytes_per_sector: dw 512
|
||||||
|
bdb_sectors_per_cluster: db 1
|
||||||
|
bdb_reserved_sectors: dw 1
|
||||||
|
bdb_fat_count: db 2
|
||||||
|
bdb_dir_entries_count: dw 0E0h
|
||||||
|
bdb_total_sectors: dw 2880
|
||||||
|
bdb_media_descriptor_type: db 0F0h
|
||||||
|
bdb_sectors_per_fat: dw 9
|
||||||
|
bdb_sectors_per_track: dw 18
|
||||||
|
bdb_heads: dw 2
|
||||||
|
bdb_hidden_sectors: dd 0
|
||||||
|
bdb_large_sector_count: dd 0
|
||||||
|
|
||||||
|
; Extended boot record
|
||||||
|
ebr_drive_number: db 0
|
||||||
|
db 0
|
||||||
|
ebr_signature: db 29h
|
||||||
|
ebr_volume_id: db 68h, 6Fh, 6Dh, 6Fh
|
||||||
|
ebr_volume_laber: db 'zos disk '
|
||||||
|
ebr_system_id: db 'FAT12 '
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
start:
|
||||||
|
jmp main
|
||||||
|
|
||||||
|
;
|
||||||
|
; echo:
|
||||||
|
; print something to the screen
|
||||||
|
; - ds:si points to string
|
||||||
|
;
|
||||||
|
echo:
|
||||||
|
; save the registers we want to modify
|
||||||
|
push si
|
||||||
|
push ax
|
||||||
|
push bx
|
||||||
|
|
||||||
|
mov ah, 0xe
|
||||||
|
mov bh, 0
|
||||||
|
|
||||||
|
.loop:
|
||||||
|
lodsb ; load byte from ds:si to al
|
||||||
|
or al, al ; check if next char is null
|
||||||
|
jz .done
|
||||||
|
|
||||||
|
int 0x10
|
||||||
|
jmp .loop
|
||||||
|
|
||||||
|
.done:
|
||||||
|
pop bx
|
||||||
|
pop ax
|
||||||
|
pop si
|
||||||
|
ret
|
||||||
|
|
||||||
|
main:
|
||||||
|
|
||||||
|
; setup data segments
|
||||||
|
; use ax as and intermediary as we can't write to es/ds directly
|
||||||
|
mov ax, 0
|
||||||
|
mov ds, ax
|
||||||
|
mov es, ax
|
||||||
|
|
||||||
|
; setup stack
|
||||||
|
mov ss, ax
|
||||||
|
mov sp, 0x7C00 ; stack grows downward from where we are loaded in memory
|
||||||
|
|
||||||
|
mov si, msg_startup
|
||||||
|
call echo
|
||||||
|
|
||||||
|
mov si, msg_reading_from_disk
|
||||||
|
call echo
|
||||||
|
mov [ebr_drive_number], dl
|
||||||
|
|
||||||
|
mov ax, 1 ; second sector from disk
|
||||||
|
mov cl, 1 ; 1 sector to read
|
||||||
|
mov bx, 0x7E00 ; data should be after the bootloader
|
||||||
|
call disk_read
|
||||||
|
|
||||||
|
cli
|
||||||
|
hlt
|
||||||
|
|
||||||
|
; errors
|
||||||
|
|
||||||
|
floppy_error:
|
||||||
|
mov si, msg_read_failed
|
||||||
|
call echo
|
||||||
|
jmp .wait_and_reboot
|
||||||
|
|
||||||
|
.wait_and_reboot:
|
||||||
|
mov ah, 0
|
||||||
|
int 16h
|
||||||
|
|
||||||
|
jmp 0FFFFh:0 ; jump to start of bios, should reboot
|
||||||
|
|
||||||
|
hlt
|
||||||
|
|
||||||
|
.halt:
|
||||||
|
cli ; disable interrupts, this way we shouldn't be able to get out of halt
|
||||||
|
hlt
|
||||||
|
jmp .halt
|
||||||
|
|
||||||
|
|
||||||
|
;
|
||||||
|
; args:
|
||||||
|
; ax = lba adress
|
||||||
|
; return:
|
||||||
|
; cx[0..5] = sector number
|
||||||
|
; cx[6-15] = cilinder number
|
||||||
|
; dh: head
|
||||||
|
;
|
||||||
|
lba_to_chs:
|
||||||
|
push ax
|
||||||
|
push dx
|
||||||
|
|
||||||
|
xor dx, dx ; clear dw
|
||||||
|
div word [bdb_sectors_per_track] ; ax = LBA / SectorsPerTrack
|
||||||
|
; dx = LBA % SectorsPerTrack
|
||||||
|
|
||||||
|
inc dx
|
||||||
|
mov cx, dx ; cx = sector
|
||||||
|
|
||||||
|
xor dx, dx ; clear dx
|
||||||
|
div word [bdb_heads] ; ax = (LBA / SectorsPerTrack) / Heads = cylinder
|
||||||
|
; dx = (LBA / SectorsPerTrack) % Heads = head
|
||||||
|
mov dh, dl
|
||||||
|
mov ch, al
|
||||||
|
shl ah, 6
|
||||||
|
or cl, ah ; put upper 2 bits of cylinder in CL
|
||||||
|
|
||||||
|
pop ax
|
||||||
|
mov dl, al
|
||||||
|
pop ax
|
||||||
|
|
||||||
|
ret
|
||||||
|
|
||||||
|
|
||||||
|
;
|
||||||
|
; args:
|
||||||
|
; ax = LBA adress
|
||||||
|
; cl = number of sectors to read
|
||||||
|
; dl = drive number
|
||||||
|
; es:bx = pointer to where to store the data
|
||||||
|
;
|
||||||
|
|
||||||
|
disk_read:
|
||||||
|
push ax
|
||||||
|
push bx
|
||||||
|
push cx
|
||||||
|
push dx
|
||||||
|
push di
|
||||||
|
|
||||||
|
push cx ; cx will be overridden
|
||||||
|
call lba_to_chs
|
||||||
|
pop ax ; al = number of sectors to read
|
||||||
|
mov ah, 02h
|
||||||
|
mov di, 3 ; hoe many times to try
|
||||||
|
|
||||||
|
.retry:
|
||||||
|
pusha
|
||||||
|
stc ; set carry flag
|
||||||
|
int 13h ; if no carry flag => it work
|
||||||
|
|
||||||
|
jnc .done
|
||||||
|
|
||||||
|
; read fail
|
||||||
|
popa
|
||||||
|
call disk_reset
|
||||||
|
dec di
|
||||||
|
|
||||||
|
test di, di
|
||||||
|
jnz .retry
|
||||||
|
|
||||||
|
.fail:
|
||||||
|
jmp floppy_error
|
||||||
|
|
||||||
|
.done:
|
||||||
|
popa
|
||||||
|
|
||||||
|
pop di
|
||||||
|
pop dx
|
||||||
|
pop cx
|
||||||
|
pop bx
|
||||||
|
pop ax
|
||||||
|
ret
|
||||||
|
|
||||||
|
; arg: dl = drive number
|
||||||
|
|
||||||
|
disk_reset:
|
||||||
|
pusha
|
||||||
|
mov ah, 0
|
||||||
|
stc ; set carry
|
||||||
|
int 13h
|
||||||
|
jc floppy_error
|
||||||
|
popa
|
||||||
|
ret
|
||||||
|
|
||||||
|
msg_startup: db 'starting zos, please hold while we check for any problems', ENDL, 0
|
||||||
|
msg_reading_from_disk: db 'testing reading from disk', ENDL, 0
|
||||||
|
msg_read_failed: db 'error when trying to read from floppy', ENDL, 0
|
||||||
|
|
||||||
|
times 510-($-$$) db 0
|
||||||
|
dw 0AA55h
|
||||||
|
|
@ -1,18 +1,11 @@
|
||||||
; vim: ft=nasm
|
; vim: ft=nasm
|
||||||
org 0x0
|
org 0x7C00
|
||||||
bits 16
|
bits 16
|
||||||
|
|
||||||
|
|
||||||
%define ENDL 0x0D, 0x0A
|
%define ENDL 0x0D, 0x0A
|
||||||
|
|
||||||
|
|
||||||
start:
|
start:
|
||||||
mov si, msg_init
|
jmp main
|
||||||
call echo
|
|
||||||
|
|
||||||
.halt:
|
|
||||||
cli
|
|
||||||
hlt
|
|
||||||
|
|
||||||
;
|
;
|
||||||
; echo:
|
; echo:
|
||||||
|
|
@ -25,15 +18,15 @@ echo:
|
||||||
push ax
|
push ax
|
||||||
push bx
|
push bx
|
||||||
|
|
||||||
|
mov ah, 0xe
|
||||||
|
mov bh, 0
|
||||||
|
|
||||||
.loop:
|
.loop:
|
||||||
lodsb ; load byte from ds:si to al
|
lodsb ; load byte from ds:si to al
|
||||||
or al, al ; check if next char is null
|
or al, al ; check if next char is null
|
||||||
jz .done
|
jz .done
|
||||||
|
|
||||||
mov ah, 0x0E
|
|
||||||
mov bh, 0
|
|
||||||
int 0x10
|
int 0x10
|
||||||
|
|
||||||
jmp .loop
|
jmp .loop
|
||||||
|
|
||||||
.done:
|
.done:
|
||||||
|
|
@ -42,4 +35,28 @@ echo:
|
||||||
pop si
|
pop si
|
||||||
ret
|
ret
|
||||||
|
|
||||||
msg_init: db 'started kernel', ENDL, 0
|
main:
|
||||||
|
|
||||||
|
; setup data segments
|
||||||
|
; use ax as and intermediary as we can't write to es/ds directly
|
||||||
|
mov ax, 0
|
||||||
|
mov ds, ax
|
||||||
|
mov es, ax
|
||||||
|
|
||||||
|
; setup stack
|
||||||
|
mov ss, ax
|
||||||
|
mov sp, 0x7C00 ; stack grows downward from where we are loaded in memory
|
||||||
|
|
||||||
|
; print the hello world
|
||||||
|
mov si, msg_hello
|
||||||
|
call echo
|
||||||
|
|
||||||
|
hlt
|
||||||
|
|
||||||
|
.halt:
|
||||||
|
jmp .halt
|
||||||
|
|
||||||
|
msg_hello: db 'Hello, world!', ENDL, 0
|
||||||
|
|
||||||
|
times 510-($-$$) db 0
|
||||||
|
dw 0AA55h
|
||||||
|
|
|
||||||
|
|
@ -1,173 +0,0 @@
|
||||||
const std = @import("std");
|
|
||||||
|
|
||||||
const Errors = error{ InvalidSyntax, ReadSectors, FileNotFound };
|
|
||||||
|
|
||||||
var buffer: [1024]u8 = undefined;
|
|
||||||
|
|
||||||
var g_Fat: []u8 = undefined;
|
|
||||||
|
|
||||||
pub const std_options: std.Options = .{
|
|
||||||
.log_level = .info,
|
|
||||||
};
|
|
||||||
|
|
||||||
const BootSector = extern struct {
|
|
||||||
BootJumpInstruction: [3]u8 align(1),
|
|
||||||
OemIdentifier: [8]u8 align(1),
|
|
||||||
BytesPerSector: u16 align(1),
|
|
||||||
SectorsPerCluster: u8 align(1),
|
|
||||||
ReservedSectors: u16 align(1),
|
|
||||||
FatCount: u8 align(1),
|
|
||||||
DirEntryCount: u16 align(1),
|
|
||||||
TotalSectors: u16 align(1),
|
|
||||||
MediaDescriptorType: u8 align(1),
|
|
||||||
SectorsPerFat: u16 align(1),
|
|
||||||
SectorsPerTrack: u16 align(1),
|
|
||||||
Heads: u16 align(1),
|
|
||||||
HiddenSectors: u32 align(1),
|
|
||||||
LargeSectorCount: u32 align(1),
|
|
||||||
|
|
||||||
// ebr
|
|
||||||
DriveNumber: u8 align(1),
|
|
||||||
_Reserved: u8 align(1),
|
|
||||||
Signature: u8 align(1),
|
|
||||||
VolumeId: u32 align(1),
|
|
||||||
VolumeLaber: [11]u8 align(1),
|
|
||||||
SystemId: [8]u8 align(1),
|
|
||||||
};
|
|
||||||
|
|
||||||
var g_BootSector: BootSector = undefined;
|
|
||||||
|
|
||||||
const DirectoryEntry = extern struct {
|
|
||||||
Name: [11]u8 align(1),
|
|
||||||
Attributes: u8 align(1),
|
|
||||||
_Reserved: u8 align(1),
|
|
||||||
CreatedTimeTenths: u8 align(1),
|
|
||||||
CreatedTime: u16 align(1),
|
|
||||||
CreatedDate: u16 align(1),
|
|
||||||
AccessedDate: u16 align(1),
|
|
||||||
FirstClusterHigh: u16 align(1),
|
|
||||||
ModifiedTime: u16 align(1),
|
|
||||||
ModifiedDate: u16 align(1),
|
|
||||||
FirstClusterLow: u16 align(1),
|
|
||||||
Size: u32 align(1),
|
|
||||||
};
|
|
||||||
|
|
||||||
var g_RootDirectory: []DirectoryEntry = undefined;
|
|
||||||
var g_RootDirectoryEnd: u32 = undefined;
|
|
||||||
|
|
||||||
fn readStruct(reader: *std.fs.File.Reader, T: type) !T {
|
|
||||||
var ret: [@sizeOf(T)]u8 = undefined;
|
|
||||||
_ = try reader.*.readStreaming(&ret);
|
|
||||||
return @bitCast(ret);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn readBootSector(disk: *std.fs.File) !void {
|
|
||||||
var reader = disk.*.reader(&buffer);
|
|
||||||
g_BootSector = try readStruct(&reader, BootSector);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn readSectors(disk: *std.fs.File, lba: u32, count: u32, bufferOut: *[]u8) !void {
|
|
||||||
const dest: []u8 = try std.heap.smp_allocator.alloc(u8, g_BootSector.BytesPerSector * count);
|
|
||||||
defer std.heap.smp_allocator.free(dest);
|
|
||||||
try disk.seekTo(lba * g_BootSector.BytesPerSector);
|
|
||||||
var reader = disk.readerStreaming(&buffer);
|
|
||||||
if (try reader.readStreaming(dest) != g_BootSector.BytesPerSector * count) return Errors.ReadSectors;
|
|
||||||
@memcpy(bufferOut.*, dest);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn readFat(disk: *std.fs.File) !void {
|
|
||||||
g_Fat = try std.heap.smp_allocator.alloc(u8, g_BootSector.SectorsPerFat * g_BootSector.BytesPerSector);
|
|
||||||
errdefer std.heap.smp_allocator.free(g_Fat);
|
|
||||||
try readSectors(disk, g_BootSector.ReservedSectors, g_BootSector.SectorsPerFat, &g_Fat);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn readRootDirectory(disk: *std.fs.File) !void {
|
|
||||||
const lba: u32 = g_BootSector.ReservedSectors + g_BootSector.SectorsPerFat * g_BootSector.FatCount;
|
|
||||||
const size: u32 = @sizeOf(DirectoryEntry) * g_BootSector.DirEntryCount;
|
|
||||||
var sectors: u32 = (size / g_BootSector.BytesPerSector);
|
|
||||||
if (@rem(size, g_BootSector.BytesPerSector) > 0)
|
|
||||||
sectors += 1;
|
|
||||||
|
|
||||||
g_RootDirectory = try std.heap.smp_allocator.alloc(DirectoryEntry, sectors * g_BootSector.BytesPerSector);
|
|
||||||
g_RootDirectoryEnd = lba + sectors;
|
|
||||||
try readSectors(disk, lba, sectors, @ptrCast(&g_RootDirectory));
|
|
||||||
for (g_RootDirectory) |Entry| {
|
|
||||||
std.log.debug("Entry: {any}, Entry.Name: {s}", .{
|
|
||||||
Entry, Entry.Name,
|
|
||||||
});
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
fn findFile(name: []const u8) !*DirectoryEntry {
|
|
||||||
for (g_RootDirectory, 0..) |Entry, i| {
|
|
||||||
std.log.debug("looking at {s}", .{Entry.Name});
|
|
||||||
if (std.mem.eql(u8, &Entry.Name, name))
|
|
||||||
return &g_RootDirectory[i];
|
|
||||||
}
|
|
||||||
return Errors.FileNotFound;
|
|
||||||
}
|
|
||||||
|
|
||||||
fn readFile(file: *DirectoryEntry, disk: *std.fs.File, outputBuffer: *[]u8) !void {
|
|
||||||
var currentCluster: u16 = file.FirstClusterLow;
|
|
||||||
const offset = g_BootSector.SectorsPerCluster * g_BootSector.BytesPerSector;
|
|
||||||
var i: usize = 0;
|
|
||||||
|
|
||||||
while (currentCluster < 0x0FF8) {
|
|
||||||
std.log.debug("currentCluster: {}", .{currentCluster});
|
|
||||||
const lba: u32 = g_RootDirectoryEnd + (currentCluster -% 2) * g_BootSector.SectorsPerCluster;
|
|
||||||
var sizedOutput = outputBuffer.*[i .. i + offset];
|
|
||||||
try readSectors(disk, lba, g_BootSector.SectorsPerCluster, &sizedOutput);
|
|
||||||
std.log.debug("sizedOutput: {s}", .{sizedOutput});
|
|
||||||
i += offset;
|
|
||||||
|
|
||||||
const fatindex = currentCluster * 3 / 2;
|
|
||||||
|
|
||||||
std.log.debug("@as(u16, g_Fat[fatindex]): {}, g_Fat[fatindex]: {}", .{ @as(*align(1) u16, @ptrCast(&g_Fat[fatindex])).*, g_Fat[fatindex] });
|
|
||||||
if (@rem(currentCluster, 2) == 0) {
|
|
||||||
currentCluster = @as(*align(1) u16, @ptrCast(&g_Fat[fatindex])).* & 0x0FFF;
|
|
||||||
} else {
|
|
||||||
currentCluster = @as(*align(1) u16, @ptrCast(&g_Fat[fatindex])).* >> 4;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
pub fn main() !void {
|
|
||||||
var args = try std.process.argsWithAllocator(std.heap.smp_allocator);
|
|
||||||
defer args.deinit();
|
|
||||||
if (args.inner.count < 3) {
|
|
||||||
std.log.err("syntax: {s} <disk image> <file name>", .{std.os.argv[0]});
|
|
||||||
return Errors.InvalidSyntax;
|
|
||||||
}
|
|
||||||
|
|
||||||
_ = args.skip();
|
|
||||||
|
|
||||||
var disk = try std.fs.cwd().openFileZ(args.next().?, .{ .mode = .read_only });
|
|
||||||
std.log.debug("opened disk {any}", .{disk});
|
|
||||||
|
|
||||||
try readBootSector(&disk);
|
|
||||||
std.log.debug("read BootSector from disk, {any}", .{g_BootSector});
|
|
||||||
|
|
||||||
try readFat(&disk);
|
|
||||||
defer std.heap.smp_allocator.free(g_Fat);
|
|
||||||
std.log.debug("read file allocation table from disk, {any}", .{g_Fat});
|
|
||||||
|
|
||||||
try readRootDirectory(&disk);
|
|
||||||
defer std.heap.smp_allocator.free(g_RootDirectory);
|
|
||||||
std.log.debug("read root directory from disk, {any}", .{g_RootDirectory});
|
|
||||||
|
|
||||||
const fileEntry = try findFile(try std.fmt.allocPrint(std.heap.smp_allocator, "{s}", .{args.next().?}));
|
|
||||||
|
|
||||||
var fileBuffer = try std.heap.smp_allocator.alloc(u8, fileEntry.Size + g_BootSector.BytesPerSector);
|
|
||||||
@memset(fileBuffer, 0);
|
|
||||||
defer std.heap.smp_allocator.free(fileBuffer);
|
|
||||||
|
|
||||||
try readFile(fileEntry, &disk, &fileBuffer);
|
|
||||||
const stdout = std.fs.File.stdout();
|
|
||||||
defer stdout.close();
|
|
||||||
var writer = stdout.writer(&buffer);
|
|
||||||
try writer.interface.print("{s}\n", .{@as(*[:0]u8, @ptrCast(&fileBuffer)).*});
|
|
||||||
|
|
||||||
const newline = "\n";
|
|
||||||
_ = try std.posix.write(0, fileBuffer);
|
|
||||||
_ = try std.posix.write(0, newline);
|
|
||||||
}
|
|
||||||
|
|
@ -1,3 +0,0 @@
|
||||||
testing file
|
|
||||||
aabaacaadaaeaafaagaahaaiaajaakaalaamaanaaoaapaaqaaraasaataauaavaawaaxaayaaz
|
|
||||||
tstngfl
|
|
||||||
Loading…
Add table
Add a link
Reference in a new issue