symbols.mac

;**********************************************************************;
;                                                                      ;
;   This file is part of ZSM4, a Z80/Z180/Z280 relocatable macro-      ;
;   assembler written in Z80 assembly.                                 ;
;   Copyright (C) 2017-2020, Hector Peraza.                            ;
;                                                                      ;
;   This work is derived from Z80ASM, originally written by Michael    ;
;   G. Lehman (1977) and with modifications by Ray Halls (1992) and    ;
;   Neil Harrison (1983).                                              ;
;                                                                      ;
;   This program is free software; you can redistribute it and/or      ;
;   modify it under the terms of the GNU General Public License as     ;
;   published by the Free Software Foundation; either version 2 of     ;
;   the License, or (at your option) any later version.                ;
;                                                                      ;
;   This program is distributed in the hope that it will be useful,    ;
;   but WITHOUT ANY WARRANTY; without even the implied warranty of     ;
;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the      ;
;   GNU General Public License for more details.                       ;
;                                                                      ;
;   You should have received a copy of the GNU General Public License  ;
;   along with this program; if not, write to the Free Software        ;
;   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.          ;
;                                                                      ;
;**********************************************************************;

	TITLE	Z80/Z180/Z280 Macro-Assembler
	SUBTTL	Symbol table routines

	.Z80

	include	ZSM.INC

	public	ID,ADDSYM,SYMLUK,FNDOPC,VALID,VALID1,WERROR

	extrn	GNC,PTR1,UCASE,IDBUF,IDLEN,MCHECK,ERRFLG
	extrn	NEWSYM,SYMTBL,SYMADR,IDADR,VAL,CMNPTR
	extrn	SYMPTR,SYMMOD,OPCODES,OPLEN,EVFLGS
;
;	ID - Collect ID and place in IDBUF
;	Returns delimiter character in A, symbol length in IDLEN
;
ID:	push	hl
	push	de
	push	bc		; save regs
	ld	de,IDBUF
	ld	b,IDMAX
	call	GNC		; skip blanks, get char, convert to uppercase
	call	VALID1
	jr	c,LERROR	; error if not a valid starting char
	ld	hl,(PTR1)
	jr	ID3
;
ID2:	ld	a,(hl)
	call	UCASE		; convert to uppercase
	call	VALID
	jr	c,ID4
	inc	hl
ID3:	ld	(de),a
	inc	de
	djnz	ID2
ID7:	ld	a,(hl)
	call	UCASE
	call	VALID
	jr	c,ID4
	inc	hl
	jr	ID7
;
ID4:	ld	(PTR1),hl
ID6:	cp	';'
	jr	nz,ID9
ID8:	xor	a
ID9:	ld	c,a
	ld	a,IDMAX
	sub	b
	ld	(IDLEN),a	; store symbol length
	ld	a,c
	pop	bc
	pop	de
	pop	hl
	ret
;
LERROR:	ld	a,'L'
	ld	(ERRFLG),a
	jr	ID8
;
VALID:	call	ISDIG
	ret	nc
VALID1:	call	ISLETR
	ret	nc
	cp	'_'
	ret	z
	cp	'$'
	ret	z
	cp	'?'
	ret	z
	cp	'.'
	ret	z
	cp	'@'
	ret	z
	scf
	ret
;
ISDIG:	cp	'0'
	ret	c
	cp	'9'+1
	ccf
	ret
;
ISLETR:	cp	'A'
	ret	c
	cp	'Z'+1
	ccf
	ret
;
;	ADDSYM - Add symbol to symbol table, if not already there
;
;	Upon entry, IDBUF contains the symbol name and IDLEN its length.
;
;	On return, HL and SYMADR point to value low byte in new entry for
;	possible further update, and IDADR is set to the address of the
;	length+flags field.
;
;	Z=1 if symbol already there, Z=0 otherwise.
;
;	Initial flags field is cleared.
;	Initial value is set to (VAL) and mode to (SYMMOD).
;
ADDSYM:	xor	a
	ld	(NEWSYM),a
	ld	de,(SYMTBL)	; no conflict with reg names
	ld	c,5
	call	SYMLUK		; lookup symbol
	push	hl		; save table ptr
	ld	(SYMADR),hl	; save address for EQU
	ld	(IDADR),de
	pop	hl		; restore symbol table ptr
	ret	nc		; return if already there, else continue below
;
;	SYMENT - Enter a symbol into the symbol table
;	Upon entry IDBUF is assumed to contain the name of the symbol
;	to enter, name length in IDLEN.
;
;	Entry format:	flags/length          (each 4 bits)
;			n a m e ...           (up to 16 bytes)
;			value                 (2 bytes)
;			address mode          (1 byte)
;			pointer to COMMON def (2 bytes)
;
;	On return HL points to value low byte in new entry for possible
;	further update (used by EQU pseudo operator)
;
SYMENT:	ld	bc,IDMAX+6+1	; max entry length + end marker
	call	MCHECK		; check for available memory
	jr	nc,SYMEN1	; jump if enough
WERROR:	ld	a,'W'
	ld	(ERRFLG),a
	ret
;
SYMEN1:	ld	a,(IDLEN)
	or	a
	jr	nz,SYMEN2
	ld	a,'L'
	ld	(ERRFLG),a
	scf
	ret			; else label error
;
SYMEN2:	ld	hl,(SYMPTR)
	ld	(IDADR),hl	; HL = dest ptr
	ld	c,a
	ld	b,0
	ld	(hl),a		; set up length, clear flags
	inc	hl
	ex	de,hl		; DE = dst
	ld	hl,IDBUF	; HL = src
	ldir			; copy name
	ld	hl,(VAL)
	ex	de,hl		; switch registers
	push	hl
	ld	(hl),e		; set value
	inc	hl
	ld	(hl),d
	inc	hl
	ld	a,(SYMMOD)
	ld	(hl),a		; set mode
	inc	hl
	ld	de,(CMNPTR)
	ld	(hl),e
	inc	hl
	ld	(hl),d
	inc	hl
	ld	(SYMPTR),hl
	ld	(hl),0		; set up new pointer and new end marker
	pop	hl
	ld	(SYMADR),hl	; save address for EQU
	or	0FFh		; set Z=0
	ld	(NEWSYM),a
	ret
;
;	SYMLUK - Look up symbols in table
;
;	On entry, DE points to table to search and C contains data field
;	length. Symbol name in IDBUF and length in IDLEN.
;
;	On return, CY set means symbol not found.
;	Else DE points to start of table entry and HL to value low byte
;	in table entry.
;
SYMLUK:	ld	a,(IDLEN)
	ld	b,a
	inc	c		; include flags+length field
SYML1:	ld	a,(de)
	or	a
	scf
	ret	z		; return if end of table
	and	0Fh		; get length of symbol
	cp	b
	jr	nz,SYML4
	push	de
	push	bc
	inc	de		; skip length
	ld	hl,IDBUF
SYML2:	ld	a,(de)
	cp	(hl)
	jr	nz,SYML3
	inc	hl
	inc	de
	djnz	SYML2
SYML3:	pop	bc
	pop	de
	jr	z,SYML5		; branch if match
	ld	a,b
SYML4:	add	a,c		; get full entry length
	ld	l,a
	ld	h,0
	add	hl,de
	ex	de,hl
	jr	SYML1		; advance pointer and continue to loop
;
SYML5:	ld	a,(de)
	ld	b,a
	and	0F0h
	ld	(EVFLGS),a	; save for main processor
	ld	a,b
	and	0Fh
	ld	l,a
	ld	h,0
	add	hl,de
	inc	hl
	xor	a
	ret			; point to value low and exit
;
;	Search opcode table using a binary search
;
FNDOPC:	ld	a,(IDLEN)
	sub	2
	ret	c
	cp	8+1-2
	ccf
	ret	c
	ld	c,a
	ld	b,0
	ld	hl,OPLEN
	add	hl,bc
	ex	de,hl
	ld	hl,OPCODES
	add	hl,bc
	add	hl,bc
	add	a,4+2
	ld	c,a		; save item size
	ld	a,(hl)
	inc	hl
	ld	h,(hl)
	ld	l,a		; get table base address into HL
	ld	a,(de)
	ld	b,a		; get number of table items into B
	ld	d,c		; get item size into D

	; binary search

	ld	e,0FFh		; mark M <> old M
	ld	c,0		; lower bound = 0
BNEXT:	ld	a,b
	add	a,c
	rra			; middle point = (upper+lower)/2
	cp	e		; same as last time?
	scf
	ret	z		; return error - not found

	ld	e,a		; new middle value
	push	hl		; table base addr
	push	de
	push	bc
	ld	b,d		; get item size into B and C
	ld	c,b		;  for loop counting below

	ld	d,0		; DE = middle point
BADD:	add	hl,de		; index into table (HL += DE times B)
	djnz	BADD		; count and loop

	push	hl
	inc	hl		; address of byte to compare
	ld	de,IDBUF
	ld	a,c
	sub	4
	ld	b,a		; B = string length
BCMP:	ld	a,(de)
	cp	(hl)
	inc	de
	inc	hl
	jr	nz,DIFF		; branch if no match
	djnz	BCMP
	pop	hl		; match found
	pop	bc
	pop	de
	pop	bc
	ld	a,e		; return index in A
	ex	de,hl
	jp	SYML5

DIFF:	pop	hl
	pop	bc		; restore bounds
	pop	de		; restore item size and middle point
	pop	hl		; restore table base address
	jr	c,LOWER		; IDBUF is lower
	ld	c,e		; lower = middle
	jr	BNEXT		; IDBUF is higher

LOWER:	ld	b,e		; upper = middle
	jr	BNEXT		; IDBUF is lower

	end