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I've tested RAM usage when self-assembling and there weren't as high as I thought. zasm's defaults now use less than 0x1800 bytes of RAM, making it possible, theoretically for now, for a Sega Master System to assemble Collapse OS from within itself.
95 lines
2.4 KiB
NASM
95 lines
2.4 KiB
NASM
; zasm
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;
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; Reads input from specified blkdev ID, assemble the binary in two passes and
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; spit the result in another specified blkdev ID.
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;
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; We don't buffer the whole source in memory, so we need our input blkdev to
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; support Seek so we can read the file a second time. So, for input, we need
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; GetC and Seek.
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;
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; For output, we only need PutC. Output doesn't start until the second pass.
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;
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; The goal of the second pass is to assign values to all symbols so that we
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; can have forward references (instructions referencing a label that happens
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; later).
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;
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; Labels and constants are both treated the same way, that is, they can be
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; forward-referenced in instructions. ".equ" directives, however, are evaluated
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; during the first pass so forward references are not allowed.
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;
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; *** Requirements ***
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; strncmp
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; addDE
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; addHL
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; upcase
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; unsetZ
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; intoDE
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; intoHL
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; writeHLinDE
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; findchar
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; parseHex
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; parseHexPair
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; blkSel
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; blkSet
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; fsFindFN
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; fsOpen
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; fsGetC
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; cpHLDE
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; parseArgs
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; _blkGetC
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; _blkPutC
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; _blkSeek
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; _blkTell
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; printstr
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; FS_HANDLE_SIZE
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; BLOCKDEV_SIZE
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.inc "user.h"
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; *** Overridable consts ***
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; NOTE: These limits below are designed to be *just* enough for zasm to assemble
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; itself. Considering that this app is Collapse OS' biggest app, it's safe to
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; assume that it will be enough for many many use cases. If you need to compile
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; apps with lots of big symbols, you'll need to adjust these.
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; With these default settings, zasm runs with less than 0x1800 bytes of RAM!
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; Maximum number of symbols we can have in the global and consts registry
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.equ ZASM_REG_MAXCNT 0xff
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; Maximum number of symbols we can have in the local registry
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.equ ZASM_LREG_MAXCNT 0x20
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; Size of the symbol name buffer size. This is a pool. There is no maximum name
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; length for a single symbol, just a maximum size for the whole pool.
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; Global labels and consts have the same buf size
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.equ ZASM_REG_BUFSZ 0x700
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; Size of the names buffer for the local context registry
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.equ ZASM_LREG_BUFSZ 0x100
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; ******
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.inc "err.h"
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.org USER_CODE
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jp zasmMain
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.inc "zasm/const.asm"
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.inc "lib/util.asm"
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.inc "zasm/util.asm"
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.equ IO_RAMSTART USER_RAMSTART
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.inc "zasm/io.asm"
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.equ TOK_RAMSTART IO_RAMEND
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.inc "zasm/tok.asm"
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.inc "lib/parse.asm"
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.equ INS_RAMSTART TOK_RAMEND
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.inc "zasm/instr.asm"
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.equ DIREC_RAMSTART INS_RAMEND
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.inc "zasm/directive.asm"
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.inc "zasm/parse.asm"
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.inc "zasm/expr.asm"
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.equ SYM_RAMSTART DIREC_RAMEND
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.inc "zasm/symbol.asm"
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.equ ZASM_RAMSTART SYM_RAMEND
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.inc "zasm/main.asm"
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