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113 lines
1.6 KiB
NASM
113 lines
1.6 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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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 findchar
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jp parseHexPair
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jp blkSel
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jp fsFindFN
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jp fsOpen
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jp fsGetC
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jp fsSeek
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jp fsTell
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#include "core.asm"
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.equ BLOCKDEV_RAMSTART RAMSTART
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.equ BLOCKDEV_COUNT 3
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#include "blockdev.asm"
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; List of devices
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.dw emulGetC, 0, emulSeek, emulTell
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.dw 0, emulPutC, 0, 0
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.dw fsdevGetC, fsdevPutC, fsdevSeek, fsdevTell
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.equ FS_RAMSTART BLOCKDEV_RAMEND
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.equ FS_HANDLE_COUNT 0
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#include "fs.asm"
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init:
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di
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; We put the stack at the end of the kernel memory
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ld hl, USER_CODE-1
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ld sp, hl
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ld a, 2 ; select fsdev
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ld de, BLOCKDEV_GETC
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call blkSel
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call fsOn
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ld h, 0 ; input blkdev
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ld l, 1 ; output blkdev
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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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emulGetC:
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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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emulPutC:
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out (STDIO_PORT), a
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ret
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emulSeek:
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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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ret
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emulTell:
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; same principle as STDIN_SEEK
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in a, (STDIN_SEEK)
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ld h, a
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in a, (STDIN_SEEK)
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ld l, a
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ret
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fsdevGetC:
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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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fsdevPutC:
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out (FS_DATA_PORT), a
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ret
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fsdevSeek:
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push af
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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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pop af
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ret
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fsdevTell:
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push af
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in a, (FS_SEEK_PORT)
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ld h, a
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in a, (FS_SEEK_PORT)
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ld l, a
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pop af
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ret
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