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https://github.com/hsoft/collapseos.git
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2a55bfd375
We use zasm's ability to use labels in .equ directive. We didn't do it before because for a while, we were in between scas and zasm (scas was used in automated tests) so we needed to use the lowest common denominator: zasm doesn't have macros and scas can't use labels in .equ directives. This forced us to add this layer of indirection. But now that we are completely cut from scas' dependency, we can use this nice zasm's ability.
132 lines
1.9 KiB
NASM
132 lines
1.9 KiB
NASM
; Glue code for the emulated environment
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.equ RAMSTART 0x4000
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.equ USER_CODE 0x4800
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.equ STDIO_PORT 0x00
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.equ STDIN_SEEK 0x01
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.equ FS_DATA_PORT 0x02
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.equ FS_SEEK_PORT 0x03
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.equ STDERR_PORT 0x04
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jp init ; 3 bytes
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; *** JUMP TABLE ***
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jp strncmp
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jp addDE
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jp addHL
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jp upcase
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jp unsetZ
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jp intoDE
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jp intoHL
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jp writeHLinDE
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jp findchar
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jp parseHex
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jp parseHexPair
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jp blkSel
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jp blkSet
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jp fsFindFN
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jp fsOpen
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jp fsGetB
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jp cpHLDE
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jp parseArgs
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jp _blkGetB
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jp _blkPutB
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jp _blkSeek
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jp _blkTell
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jp printstr
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.inc "core.asm"
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.inc "err.h"
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.inc "parse.asm"
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.equ BLOCKDEV_RAMSTART RAMSTART
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.equ BLOCKDEV_COUNT 3
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.inc "blockdev.asm"
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; List of devices
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.dw emulGetB, unsetZ
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.dw unsetZ, emulPutB
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.dw fsdevGetB, fsdevPutB
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.equ STDIO_RAMSTART BLOCKDEV_RAMEND
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.equ STDIO_GETC noop
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.equ STDIO_PUTC stderrPutC
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.inc "stdio.asm"
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.equ FS_RAMSTART STDIO_RAMEND
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.equ FS_HANDLE_COUNT 0
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.inc "fs.asm"
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init:
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di
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ld hl, 0xffff
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ld sp, hl
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ld a, 2 ; select fsdev
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ld de, BLOCKDEV_SEL
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call blkSel
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call fsOn
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ld hl, .zasmArgs
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call USER_CODE
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; signal the emulator we're done
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halt
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.zasmArgs:
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.db "0 1", 0
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; *** I/O ***
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emulGetB:
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; the STDIN_SEEK port works by poking it twice. First poke is for high
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; byte, second poke is for low one.
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ld a, h
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out (STDIN_SEEK), a
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ld a, l
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out (STDIN_SEEK), a
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in a, (STDIO_PORT)
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or a ; cp 0
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jr z, .eof
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cp a ; ensure z
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ret
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.eof:
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call unsetZ
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ret
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emulPutB:
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out (STDIO_PORT), a
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cp a ; ensure Z
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ret
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stderrPutC:
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out (STDERR_PORT), a
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cp a ; ensure Z
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ret
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fsdevGetB:
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ld a, e
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out (FS_SEEK_PORT), a
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ld a, h
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out (FS_SEEK_PORT), a
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ld a, l
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out (FS_SEEK_PORT), a
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in a, (FS_SEEK_PORT)
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or a
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ret nz
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in a, (FS_DATA_PORT)
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cp a ; ensure Z
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ret
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fsdevPutB:
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push af
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ld a, e
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out (FS_SEEK_PORT), a
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ld a, h
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out (FS_SEEK_PORT), a
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ld a, l
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out (FS_SEEK_PORT), a
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in a, (FS_SEEK_PORT)
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or a
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jr nz, .error
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pop af
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out (FS_DATA_PORT), a
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cp a ; ensure Z
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ret
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.error:
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pop af
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jp unsetZ ; returns
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