/* lksym.c */

/*
 *  Copyright (C) 1989-2026  Alan R. Baldwin
 *
 *  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 3 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, see <http://www.gnu.org/licenses/>.
 *
 *
 * Alan R. Baldwin
 * 721 Berkeley St.
 * Kent, Ohio  44240
 *
 *   With enhancements from
 *	John L. Hartman	(JLH)
 *	jhartman@compuserve.com
 *
 */

#include "aslink.h"

/*)Module	lksym.c
 *
 *	The module lksym.c contains the functions that operate
 *	on the symbol structures.
 *
 *	lksym.c contains the following functions:
 *		int	hash()
 *		sym *	lkpsym()
 *		char *	new()
 *		sym *	newsym()
 *		char *	strsto()
 *		void	symdef()
 *		int	symeq()
 *		void	syminit()
 *		void	symmod()
 *		a_uint	symval()
 *
 *	lksym.c contains the static variables:
 *		char *	pnext
 *		int	bytes
 *	used by the string store function.
 */

/*)Function	void	syminit(void)
 *
 *	The function syminit() is called to clear the hashtable.
 *
 *	local variables:
 *		sym **	spp		pointer to an array of
 *					sym structure pointers
 *
 *	global variables:
 *		sym * symhash[]		array of pointers to NHASH
 *					linked symbol lists
 *
 *	functions called:
 *		none
 *
 *	side effects:
 *		(1)	The symbol hash tables are cleared
 */

void
syminit(void)
{
	struct sym **spp;

	spp = &symhash[0];
	while (spp < &symhash[NHASH])
		*spp++ = NULL;
}

/*)Function	sym *	newsym(void)
 *
 *	The function newsym() is called to evaluate the symbol
 *	definition/reference directive from the .rel file(s).
 *	If the symbol is not found in the symbol table a new
 *	symbol structure is created.  Evaluation of the
 *	directive determines if this is a reference or a definition.
 *	Multiple definitions of the same variable will be flagged
 *	as an error if the values are not identical.  A symbol
 *	definition places the symbol value and area extension
 *	into the symbols data structure.  And finally, a pointer
 *	to the symbol structure is placed into the head structure
 *	symbol list.  Refer to the description of the header, symbol,
 *	area, and areax structures in lkdata.c for structure and
 *	linkage details.
 *
 *	local variables:
 *		int	c		character from input text
 *		int	i		evaluation value
 *		char	id[]		symbol name
 *		int	nglob		number of symbols in this header
 *		sym *	tsp		pointer to symbol structure
 *		sym **	s		list of pointers to symbol structures
 *
 *	global variables:
 *		areax	*axp		Pointer to the current
 *				 	areax structure
 *		head	*headp		The pointer to the first
 *				 	head structure of a linked list
 *		int	lkerr		error flag
 *
 *	functions called:
 *		a_uint	eval()		lkeval.c
 *		void	exit()		c_library
 *		int	fprintf()	c_library
 *		int	get()		lklex.c
 *		int	getnb()		lklex.c
 *		sym *	lkpsym()	lksym.c
 *
 *	side effects:
 *		A symbol structure is created and/or modified.
 *		If structure space allocation fails linker will abort.
 *		Several severe errors (these are internal errors
 *		indicating a corrupted .rel file or corrupted
 *		assembler or linker) will terminated the linker.
 */

/*
 * Find/Create a global symbol entry.
 *
 * S xxxxxx Defnnnn
 *   |      |  |
 *   |      |  `-- sp->s_addr
 *   |      `----- sp->s_type
 *   `------------ sp->s_id
 *
 */
struct sym *
newsym(void)
{
	a_uint ev;
	int c1, c2, c3, i, nsym;
	struct sym *tsp;
	struct sym **s;
	char id[NCPS];

	if (headp == NULL) {
		fprintf(stderr, "?ASlink-Error-No header defined\n");
		lkexit(ER_FATAL);
	}
	/*
	 * Create symbol entry
	 */
	getid(id, -1);
	tsp = lkpsym(id, 1);
	c1 = getnb(); c2 = get(); c3 = get();
	if (c1 == 'R') {
		tsp->s_type |= S_REF;
		if (eval()) {
			fprintf(stderr, "?ASlink-Error-Non zero S_REF\n");
			lkerr++;
		}
	} else
	if (c1 == 'D') {
		ev = eval();
		if (tsp->s_type & S_DEF) {
			if (tsp->s_addr != ev) {
				fprintf(stderr,
					"?ASlink-Error-Multiple definition of %s\n", id);
				lkerr++;
			}
		}
		/*
		 * Set value and area extension link.
		 */
		tsp->s_addr = ev;
		tsp->s_axp = axp;
		tsp->s_type |= S_DEF;
		tsp->m_id = hp->m_id;
	} else
	if ((c1 == '=') && (c2 == 'R')) {
		if (tsp->s_type & S_DEF) {
			fprintf(stderr,
				"?ASlink-Error-Multiple definition of %s\n", id);
			lkerr++;
		}
		/*
		 * Set Assembler MSB
		 */
		switch(c3) {
		case '0':	as_msb = 0;	break;
		default:
		case '1':	as_msb = 1;	break;
		case '2':	as_msb = 2;	break;
		case '3':	as_msb = 3;	break;
		}
		/*
		 * Set value and area extension link.
		 */
		tsp->s_addr = 0;
		tsp->s_axp = axp;
		tsp->s_flag = m1flag ? 0 : 1;
		tsp->s_type |= (S_DEF | S_HID | S_SWX);
		tsp->m_id = hp->m_id;
		tsp->s_expr = strsto(ip);
	} else
	if ((c1 == '=') && (c2 == 'D')) {
		ev = eval();
		if (tsp->s_type & S_DEF) {
			if (tsp->s_addr != ev) {
				fprintf(stderr,
					"?ASlink-Error-Multiple definition of %s\n", id);
				lkerr++;
			}
		}
		/*
		 * Set value and area extension link.
		 */
		tsp->s_addr = ev;
		tsp->s_axp = axp;
		tsp->s_type |= (S_DEF | S_HID);
		tsp->m_id = hp->m_id;
	} else {
		fprintf(stderr, "?ASlink-Error-Invalid symbol type %c%c%c for %s\n", c1, c2, c3, id);
		lkexit(ER_FATAL);
	}
	/*
	 * Place pointer in header symbol list
	 */
	nsym = hp->h_nsym;
	s = hp->s_list;
	for (i=0; i < nsym ;++i) {
		if (s[i] == NULL) {
			s[i] = tsp;
			return(tsp);
		}
	}
	fprintf(stderr, "?ASlink-Error-Header symbol list overflow\n");
	lkexit(ER_FATAL);
	return(NULL);
}

/*)Function	void	prcsym(void)
 *
 *	The function prcsym() searches the symbol hash tables for
 *	symbols with a type flag of S_SWX (Symbol With Expression).
 *	If S_SWX is found then the symbols value is calculated
 *	from the expression.
 *
 *	local variables:
 *		int	i		loop index
 *		struct sym *	sp	pointer to a sym structure
 *
 *	global varaibles:
 *		sym * symhash[]		array of pointers to NHASH
 *					linked symbol lists
 *		char *	ip		expression string pointer
 *
 *	functions called:
 *		a_uint	expr()		lkeval.c
 *
 *	side effects:
 *		All symbols with expressions are calculated.
 */

void
prcsym(void)
{
	struct sym *sp;
	int i;

	for (i=0; i<NHASH; ++i) {
		sp = symhash[i];
		while (sp) {
			if (sp->s_type & S_SWX) {
				ip = sp->s_expr;
				sp->s_addr = expr();
			}
			sp = sp->s_sp;
		}
	}
	return;
}

/*)Function	sym *	lkpsym(id, f)
 *
 *		char *	id		symbol name string
 *		int	f		f == 0, lookup only
 *					f != 0, create if not found
 *
 *	The function lookup() searches the symbol hash tables for
 *	a symbol name match returning a pointer to the sym structure.
 *	If the symbol is not found then a sym structure is created,
 *	initialized, and linked to the appropriate hash table if f != 0.
 *	A pointer to this new sym structure is returned or a NULL
 *	pointer is returned if f == 0.
 *
 *	local variables:
 *		int	h		computed hash value
 *		sym *	sp		pointer to a sym structure
 *
 *	global varaibles:
 *		sym * symhash[]		array of pointers to NHASH
 *					linked symbol lists
 *
 *	functions called:
 *		int	hash()		lksym.c
 *		char *	new()		lksym.c
 *		int	symeq()		lksym.c
 *
 *	side effects:
 *		If the function new() fails to allocate space
 *		for the new sym structure the linker terminates.
 */

struct sym *
lkpsym(char *id, int f)
{
	struct sym *sp;
	int h;

	h = hash(id, zflag);
	sp = symhash[h];
	while (sp != NULL) {
		if (symeq(id, sp->s_id, zflag))
			return (sp);
		sp = sp->s_sp;
	}
	if (f == 0)
		return (NULL);
	sp = (struct sym *) new (sizeof(struct sym));
	sp->s_sp = symhash[h];
	symhash[h] = sp;
	sp->s_id = strsto(id);		/* JLH */
	return (sp);
}

/*)Function	a_uint	symval(tsp)
 *
 *		sym *	tsp		pointer to a symbol structure
 *
 *	The function symval() returns the value of the
 *	relocated symbol by adding the variable definition
 *	value to the areax base address.
 *
 *	local variables:
 *		a_uint	val		relocated address value
 *
 *	global variables:
 *		none
 *
 *	functions called:
 *		none
 *
 *	side effects:
 *		none
 */

a_uint
symval(struct sym *tsp)
{
	a_uint val;

	val = tsp->s_addr;
	if (tsp->s_axp) {
		val += tsp->s_axp->a_addr;
	}
	return(val);
}

/*)Function	void	symdef(fp)
 *
 *		FILE *	fp		file handle for output
 *
 *	The function symdef() scans the hashed symbol table
 *	searching for variables referenced but not defined.
 *	Undefined variables are linked to the default
 *	area "_CODE" and reported as referenced by the
 *	appropriate module.
 *
 *	local variables:
 *		int	i		hash table index loop variable
 *		sym *	sp		pointer to linked symbol structure
 *
 *	global variables:
 *		area	*areap		The pointer to the first
 *				 	area structure of a linked list
 *		sym *symhash[NHASH] 	array of pointers to NHASH
 *				      	linked symbol lists
 *
 *	functions called:
 *		symmod()		lksym.c
 *
 *	side effects:
 *		Undefined variables have their areas set to "_CODE".
 */

void
symdef(FILE *fp)
{
	struct sym *sp;
	int i;

	for (i=0; i<NHASH; ++i) {
		sp = symhash[i];
		while (sp) {
			if (sp->s_axp == NULL)
				sp->s_axp = areap->a_axp;
			if ((sp->s_type & S_DEF) == 0)
				symmod(fp, sp);
			sp = sp->s_sp;
		}
	}
}

/*)Function	void	symmod(fp, tsp)
 *
 *		FILE *	fp		output file handle
 *		sym *	tsp		pointer to a symbol structure
 *
 *	The function symmod() scans the header structures
 *	searching for a reference to the symbol structure
 *	pointed to by tsp.  The function then generates an error
 *	message whichs names the module having referenced the
 *	undefined variable.
 *
 *	local variables:
 *		int	i		loop counter
 *		sym **	p		pointer to a list of pointers
 *					to symbol structures
 *
 *	global variables:
 *		head	*headp		The pointer to the first
 *				 	head structure of a linked list
 *		head	*hp		Pointer to the current
 *				 	head structure
 *		int	lkerr		error flag
 *
 *	functions called:
 *		int	fprintf()	c_library
 *
 *	side effects:
 *		Error output generated.
 */

void
symmod(FILE *fp, struct sym *tsp)
{
	int i;
	struct sym **p;

	if ((hp = headp) != NULL) {
	    while(hp) {
		p = hp->s_list;
		for (i=0; i<hp->h_nsym; ++i) {
		    if (p[i] == tsp) {
			fprintf(fp,
				"\n?ASlink-Warning-Undefined Global %s ",
				tsp->s_id);
			fprintf(fp,
				"referenced by module %s\n",
				hp->m_id);
			lkerr++;
		    }
		}
	    hp = hp->h_hp;
	    }
	}
}

/*)Function	int	symeq(p1, p2, cflag)
 *
 *		int	cflag		case sensitive flag
 *		char *	p1		name string
 *		char *	p2		name string
 *
 *	The function symeq() compares the two name strings for a match.
 *	The return value is 1 for a match and 0 for no match.
 *
 *		cflag == 0	case sensitve compare
 *		cflag != 0	case insensitive compare
 *
 *	local variables:
 *		int	n		loop counter
 *
 *	global variables:
 *		char	ccase[]		an array of characters which
 *					perform the case translation function
 *
 *	functions called:
 *		none
 *
 *	side effects:
 *		none
 *
 */

int
symeq(char *p1, char *p2, int cflag)
{
	int n;

	n = strlen(p1) + 1;
	if(cflag) {
		/*
		 * Case Insensitive Compare
		 */
		do {
			if (ccase[*p1++ & 0x007F] != ccase[*p2++ & 0x007F])
				return (0);
		} while (--n);
	} else {
		/*
		 * Case Sensitive Compare
		 */
		do {
			if (*p1++ != *p2++)
				return (0);
		} while (--n);
	}
	return (1);
}

/*)Function	int	hash(p, cflag)
 *
 *		char *	p		pointer to string to hash
 *		int	cflag		case sensitive flag
 *
 *	The function hash() computes a hash code using the sum
 *	of all characters mod table size algorithm.
 *
 *		cflag == 0	case sensitve hash
 *		cflag != 0	case insensitive hash
 *
 *	local variables:
 *		int	h		accumulated character sum
 *
 *	global variables:
 *		char	ccase[]		an array of characters which
 *					perform the case translation function
 *
 *	functions called:
 *		none
 *
 *	side effects:
 *		none
 */

int
hash(char *p, int cflag)
{
	int h;

	h = 0;
	while (*p) {
		if(cflag) {
			/*
			 * Case Insensitive Hash
			 */
			h += ccase[*p++ & 0x007F];
		} else {
			/*
			 * Case Sensitive Hash
			 */
			h += *p++;
		}
	}
	return (h&HMASK);
}

/*)Function	char *	strsto(str)
 *
 *		char *	str		pointer to string to save
 *
 *	Allocate space for "str", copy str into new space.
 *	Return a pointer to the allocated string.
 *
 *	This function based on code by
 *		John L. Hartman
 *		jhartman@compuserve.com
 *
 *	local variables:
 *		int	l		string length + 1
 *		int	bytes		bytes remaining in buffer area
 *		char *	p		pointer to head of copied string
 *		char *	pnext		next location in buffer area
 *
 *	global variables:
 *		none
 *
 *	functions called:
 *		char *	new()		assym.c
 *		char *	strncpy()	c_library
 *
 *	side effects:
 *		Space allocated for string, string copied
 *		to space.  Out of Space terminates assembler.
 */

/*
 * To avoid wasting memory headers on small allocations, we
 * allocate a big chunk and parcel it out as required.
 * These static variables remember our hunk
 */

#define	STR_SPC	1024
static	char *	pnext = NULL;
static	int	bytes = 0;

char *
strsto(char *str)
{
	int  l;
	char *p;

	/*
	 * What we need, including a null.
	 */
	l = strlen(str) + 1;

	if (l > bytes) {
		/*
		 * No space.  Allocate a new hunk.
		 * We lose the pointer to any old hunk.
		 * We don't care, as the strings are never deleted.
		*/
		pnext = (char *) new (STR_SPC);
		bytes = STR_SPC;
	}

	/*
	 * Copy the name and terminating null.
	 */
	p = pnext;
	strncpy(p, str, l);

	pnext += l;
	bytes -= l;

	return(p);
}

/*)Function	char *	new(n)
 *
 *		unsigned int	n	allocation size in bytes
 *
 *	The function new() allocates n bytes of space and returns
 *	a pointer to this memory.  If no space is available the
 *	linker is terminated.
 *
 *	local variables:
 *		char *	p		a general pointer
 *		char *	q		a general pointer
 *
 *	global variables:
 *		none
 *
 *	functions called:
 *		int	fprintf()	c_library
 *		void *	malloc()	c_library
 *
 *	side effects:
 *		Memory is allocated, if allocation fails
 *		the linker is terminated.
 */

char *
new(unsigned int n)
{
	char *p,*q;
	unsigned int i;

	if ((p = (char *) malloc(n)) == NULL) {
		fprintf(stderr, "?ASlink-Error-Out of space!\n");
		lkexit(ER_FATAL);
	}
	for (i=0,q=p; i<n; i++) {
		*q++ = 0;
	}
	return (p);
}

