collapseos/apps/zasm/glue.asm
Virgil Dupras 83b314c450 zasm: lower RAM requirements
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.
2019-10-06 15:42:09 -04:00

95 lines
2.4 KiB
NASM

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