mirror of
https://github.com/hsoft/collapseos.git
synced 2024-07-23 09:10:22 +10:00
ae028e3a86
This huge refactoring remove the Seek and Tell routine from blockdev implementation requirements and change GetC and PutC's API so that they take an address to read and write (through HL/DE) at each call. The "PTR" approach in blockdev implementation was very redundant from device to device and it made more sense to generalize. It's possible that future device aren't "random access", but we'll be able to add more device types later. Another important change in this commit is that the "blockdev handle" is now opaque. Previously, consumers of the API would happily call routines directly from one of the 4 offsets. We can't do that any more. This makes the API more solid for future improvements. This change forced me to change a lot of things in fs, but overall, things are now simpler. No more `FS_PTR`: the "device handle" now holds the active pointer. Lots, lots of changes, but it also feels a lot cleaner and solid.
222 lines
5.2 KiB
NASM
222 lines
5.2 KiB
NASM
; *** Variables ***
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; A bool flag indicating that we're on first pass. When we are, we don't care
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; about actual output, but only about the length of each upcode. This means
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; that when we parse instructions and directive that error out because of a
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; missing symbol, we don't error out and just write down a dummy value.
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.equ ZASM_FIRST_PASS ZASM_RAMSTART
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; whether we're in "local pass", that is, in local label scanning mode. During
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; this special pass, ZASM_FIRST_PASS will also be set so that the rest of the
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; code behaves as is we were in the first pass.
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.equ ZASM_LOCAL_PASS ZASM_FIRST_PASS+1
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; What IO_PC was when we started our context
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.equ ZASM_CTX_PC ZASM_LOCAL_PASS+1
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; current ".org" offset, that is, what we must offset all our label by.
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.equ ZASM_ORG ZASM_CTX_PC+2
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.equ ZASM_RAMEND ZASM_ORG+2
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; Takes 2 byte arguments, blkdev in and blkdev out, expressed as IDs.
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; Read file through blkdev in and outputs its upcodes through blkdev out.
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; HL is set to the last lineno to be read.
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; Sets Z on success, unset on error. On error, A contains an error code (ERR_*)
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zasmMain:
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; Parse args. HL points to string already
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; We don't allocate memory just to hold this. Because this happens
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; before initialization, we don't really care where those args are
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; parsed.
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ld de, .argspecs
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ld ix, ZASM_RAMSTART
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call parseArgs
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jr z, .goodargs
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; bad args
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ld hl, 0
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ld de, 0
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ld a, SHELL_ERR_BAD_ARGS
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ret
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.goodargs:
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; HL now points to parsed args
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; Init I/O
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ld a, (ZASM_RAMSTART) ; blkdev in ID
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ld de, IO_IN_BLK
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call blkSel
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ld a, (ZASM_RAMSTART+1) ; blkdev out ID
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ld de, IO_OUT_BLK
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call blkSel
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; Init modules
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xor a
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ld (ZASM_LOCAL_PASS), a
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ld (ZASM_ORG), a
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ld (ZASM_ORG+1), a
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call ioInit
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call symInit
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; First pass
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ld a, 1
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ld (ZASM_FIRST_PASS), a
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call zasmParseFile
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jr nz, .end
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; Second pass
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xor a
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ld (ZASM_FIRST_PASS), a
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call zasmParseFile
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.end:
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jp ioLineNo ; --> HL, --> DE, returns
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.argspecs:
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.db 0b001, 0b001, 0
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; Sets Z according to whether we're in first pass.
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zasmIsFirstPass:
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ld a, (ZASM_FIRST_PASS)
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cp 1
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ret
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; Sets Z according to whether we're in local pass.
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zasmIsLocalPass:
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ld a, (ZASM_LOCAL_PASS)
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cp 1
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ret
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; Set ZASM_ORG to specified number in HL
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zasmSetOrg:
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ld (ZASM_ORG), hl
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ret
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; Return current PC (properly .org offsetted) in HL
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zasmGetPC:
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push de
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ld hl, (ZASM_ORG)
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ld de, (IO_PC)
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add hl, de
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pop de
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ret
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; Repeatedly reads lines from IO, assemble them and spit the binary code in
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; IO. Z is set on success, unset on error. DE contains the last line number to
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; be read (first line is 1).
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zasmParseFile:
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call ioRewind
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.loop:
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call parseLine
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ret nz ; error
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ld a, b ; TOK_*
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cp TOK_EOF
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jr z, .eof
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jr .loop
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.eof:
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call zasmIsLocalPass
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jr nz, .end ; EOF and not local pass
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; we're in local pass and EOF. Unwind this
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call _endLocalPass
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jr .loop
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.end:
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cp a ; ensure Z
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ret
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; Parse next token and accompanying args (when relevant) in I/O, write the
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; resulting opcode(s) through ioPutC and increases (IO_PC) by the number of
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; bytes written. BC is set to the result of the call to tokenize.
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; Sets Z if parse was successful, unset if there was an error. EOF is not an
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; error. If there is an error, A is set to the corresponding error code (ERR_*).
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parseLine:
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call tokenize
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ld a, b ; TOK_*
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cp TOK_INSTR
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jp z, _parseInstr
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cp TOK_DIRECTIVE
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jp z, _parseDirec
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cp TOK_LABEL
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jr z, _parseLabel
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cp TOK_EOF
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ret z ; We're finished, no error.
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; Bad token
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ld a, ERR_UNKNOWN
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jp unsetZ ; return with Z unset
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_parseInstr:
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ld a, c ; I_*
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jp parseInstruction
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_parseDirec:
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ld a, c ; D_*
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jp parseDirective
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_parseLabel:
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; The string in (scratchpad) is a label with its trailing ':' removed.
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ld hl, scratchpad
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call zasmIsLocalPass
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jr z, .processLocalPass
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; Is this a local label? If yes, we don't process it in the context of
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; parseLine, whether it's first or second pass. Local labels are only
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; parsed during the Local Pass
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call symIsLabelLocal
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jr z, .success ; local? don't do anything.
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call zasmIsFirstPass
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jr z, .registerLabel ; When we encounter a label in the first
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; pass, we register it in the symbol
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; list
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; At this point, we're in second pass, we've encountered a global label
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; and we'll soon continue processing our file. However, before we do
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; that, we should process our local labels.
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call _beginLocalPass
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jr .success
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.processLocalPass:
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call symIsLabelLocal
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jr z, .registerLabel ; local label? all good, register it
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; normally
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; not a local label? Then we need to end local pass
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call _endLocalPass
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jr .success
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.registerLabel:
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push hl
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call zasmGetPC
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ex de, hl
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pop hl
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call symRegister
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jr nz, .error
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; continue to .success
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.success:
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xor a ; ensure Z
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ret
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.error:
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call unsetZ
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ret
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_beginLocalPass:
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; remember were I/O was
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call ioSavePos
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; Remember where PC was
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ld hl, (IO_PC)
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ld (ZASM_CTX_PC), hl
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; Fake first pass
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ld a, 1
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ld (ZASM_FIRST_PASS), a
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; Set local pass
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ld (ZASM_LOCAL_PASS), a
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; Empty local label registry
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xor a
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ld (SYM_LOC_NAMES), a
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call symSelectLocalRegistry
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ret
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_endLocalPass:
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call symSelectGlobalRegistry
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; recall I/O pos
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call ioRecallPos
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; recall PC
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ld hl, (ZASM_CTX_PC)
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ld (IO_PC), hl
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; unfake first pass
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xor a
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ld (ZASM_FIRST_PASS), a
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; Unset local pass
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ld (ZASM_LOCAL_PASS), a
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cp a ; ensure Z
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ret
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