genrel.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 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	REL file generation

	.Z80

	include	ZSM.INC

	cseg

	public	WMNAME,WIDENT,WCSIZE,WDSIZE,WLOC,WOBJ,WOBJ16
	public	WENTRY,WDFENT,WDFEXT,WCMSIZ,WSELCM,WEOFFS,WRQST
	public	INIOBJ,CLSOBJ

	extrn	OFLAG,CLOSE2,WNB2,NAMLEN
;
;	WMNAME - Write module name, HL = name, E = length
;	This is normally the first item in a REL file
;
WMNAME:	ld	c,84h		; 1 00 0010 - special item: program name
	ld	b,7
	call	WRBITS
	jp	WRNAME
;
;	WRQST - Write request library search, HL = name, E = length
;
WRQST:	ld	c,86h		; 1 00 0011 - special item: request library
	ld	b,7
	call	WRBITS
	jp	WRNAME
;
;	WIDENT - Write ident, HL = name, E = length
;	Used by RSX180
;
WIDENT:	ld	c,88h		; 1 00 0100 - special item: extension link
	ld	b,7
	call	WRBITS
	ld	a,e
	inc	a
	rrca
	rrca
	rrca
	ld	c,a
	ld	b,3
	call	WRBITS		; write length
	ld	c,'I'
	call	WR8B		; write type
	jp	WRN1		; output name

	IF	0
;
;	WALIGN - Write segment alignment information, C = seg type,
;	B = align bits [Not yet implemented]
;
WALIGN:	push	bc
	ld	c,88h		; 1 00 0100 - special item: extension link
	ld	b,7
	call	WRBITS
	ld	c,40h		; 010 - len = 2
	ld	b,3
	call	WRBITS		; write length
	ld	c,'L'
	call	WR8B		; write type
	pop	bc
	ld	a,b
	and	0Fh
	or	c
	ld	c,a
	jp	WR8B		; write segment and alignment

	ENDIF
;
;	WOBJ - Write absolute byte in A
;
WOBJ:	push	af
	ld	c,0
	call	WRBIT		; 0 - load next 8 bits
	pop	af
	ld	c,a
	jp	WR8B
;
;	WBOJ16 - Write relative word in HL, C = seg type.
;
WOBJ16:	ld	a,c
	or	a
	jr	z,W2X8
	scf
	rr	c		; push '1' bit - reloc item
	ld	b,3
	call	WRBITS		; output bit and seg type
	ld	c,l
	ld	b,h
	call	WR16B		; output word value
	ret
W2X8:	ld	a,l
	call	WOBJ
	ld	a,h
	jp	WOBJ
;
;	WCSIZE - Write CSEG size: HL = size
;
WCSIZE:	ld	c,9Ah		; 1 00 1101 - special item: define cseg size
	ld	b,7
	call	WRBITS
	ld	c,40h		; program relative value follows
	ld	b,2
	call	WRBITS
	ld	c,l
	ld	b,h
	jp	WR16B		; output size
;
;	WDSIZE - Write DSEG size: HL = size
;	Note: L80 wants an 'absolute' argument and not a 'data-relative' one
;	as one would expect. DR LINK does not care.
;
WDSIZE:	ld	c,94h		; 1 00 1010 - special item: define dseg size
	ld	b,7
	call	WRBITS
;--	ld	c,80h		; data relative value follows
	ld	c,00h		; absolute value follows (L80 wants it that way)
	ld	b,2
	call	WRBITS
	ld	c,l
	ld	b,h
	jp	WR16B		; output size
;
;	WLOC - Write loc counter: HL = address, E = seg type (40h = CSEG,
;	80h = DSEG, 0C0h = COMMON)
;
WLOC:	ld	c,96h
WLC1:	ld	b,7
	call	WRBITS		; 1 00 1011 - special item: set loc counter
	ld	c,e
	ld	b,2
	call	WRBITS		; segment-relative value follows
	ld	c,l
	ld	b,h
	jp	WR16B		; output address
;
;	WENTRY - Write entry symbol record: HL = name, E = length
;
WENTRY:	ld	c,80h		; 1 00 0000 - special item: entry symbol
	ld	b,7
	call	WRBITS
	jp	WRNAME
;
;	WDFENT - Write entry point record: DE = address, C = seg type,
;	HL = name, B = length
;
WDFENT:	push	bc
	ld	c,8Eh		; 1 00 0111 - special item: define entry point
WRENT1:	ld	b,7
	call	WRBITS
	pop	bc
	push	bc
	ld	b,2
	call	WRBITS		; segment-relative value follows
	ld	c,e
	ld	b,d
	call	WR16B		; output address
	pop	bc
	ld	e,b
	jp	WRNAME
;
;	WDFEXT - Write External chain head: DE = address, C = seg type,
;	HL = name, B = length
;
WDFEXT:	push	bc
	ld	c,8Ch		; 1 00 0110 - special item: chain external
	jr	WRENT1
;
;	WSELCM - Write Select COMMON block: HL = name, B = length
;
WSELCM:	ld	c,82h		; 1 00 0001 - special item: program name
	ld	b,7
	call	WRBITS
	jp	WRNAME
;
;	WCMSIZ - Write COMMON size record: DE = size, C = seg type,
;	HL = name, B = length
;
WCMSIZ:	push	bc
	ld	c,8Ah		; 1 00 0101 - special item: define COMMON size
	jr	WRENT1
;
;	WEOFFS - Write External + Offset entry: HL = offset, E = seg type
;
WEOFFS:	ld	c,92h		; 1 00 1001
	jr	WLC1
;
;	BPAD - Pad to byte boundary (end of module)
;
BPAD:	ld	a,(BITCNT)
	cp	8
	ret	z
	ld	c,0
	call	WRBIT		; pad to byte boundary
	jr	BPAD
;
;	WRNAME - Write name field (len + chars), HL points to string,
;	E = length
;
WRNAME:	ld	a,(NAMLEN)
	cp	e
	jr	nc,WRN0
	ld	e,a		; truncate to max REL symbol length
WRN0:	ld	a,e		; length
	rrca			; shift left 5 (same as shift right 3)
	rrca
	rrca
	ld	c,a
	ld	b,3
	call	WRBITS
WRN1:	ld	c,(hl)
	inc	hl
	call	WR8B
	dec	e
	jr	nz,WRN1
	ret
;
;	WR16B - Write 16 bits, word in BC
;
WR16B:	push	bc
	call	WR8B
	pop	bc
	ld	c,b
	; fall thru
;
;	WR8B - Write 8 bits, byte in C
;
WR8B:	ld	b,8
	; fall thru
;
;	WRBITS - Write up to 8 bits, bits in reg C, num of bits in B
;
WRBITS:	call	WRBIT
	djnz	WRBITS
	ret
;
;	WRBIT - Write a single bit, bit is in MSB of C
;
WRBIT:	ld	a,(BITCNT)
	cp	8
	jr	nz,WB1
	ld	a,(OFLAG)
	cp	'O'		; check if REL file specified
	ld	a,(BYTE)
	push	bc
	call	c,WNB2		; write byte to REL file
	pop	bc
	xor	a
WB1:	inc	a
	ld	(BITCNT),a
	rl	c
	ld	a,(BYTE)
	rla
	ld	(BYTE),a
	ret

INIOBJ:	xor	a
	ld	(BYTE),a
	ld	(BITCNT),a
	ret
;
;	CLSOBJ - Write end of module record, end of file record, and
;	close object file.
;
CLSOBJ:	ld	a,(OFLAG)
	cp	'O'
	ret	nc		; return if no REL file output
	push	hl
	push	bc
	ld	c,9Ch
	ld	b,7
	call	WRBITS		; 1 00 1110 - special item: end of module
	pop	bc
	ld	b,2
	call	WRBITS		; segment relative value follows
	pop	bc
	call	WR16B		; 0000'
	call	BPAD		; pad to byte boundary
	ld	c,9Eh
	ld	b,7
	call	WRBITS		; 1 00 1111 - special item: end of file
	call	BPAD		; pad to byte boundary
	ld	a,(BYTE)
	call	WNB2
	jp	CLOSE2		; close REL file

	DSEG

BITCNT:	ds	1		; bit counter
BYTE:	ds	1		; bit accumulator

	END