Category : Assembly Language Source Code
Archive : CUG292.ZIP
Filename : ASEXPR.C
Output of file : ASEXPR.C contained in archive : CUG292.ZIP
/*
* (C) Copyright 1989,1990
* All Rights Reserved
*
* Alan R. Baldwin
* 721 Berkeley St.
* Kent, Ohio 44240
*/
#include
#include
#include
#include
#include "asm.h"
/*
* Read an expression. The value of the
* expression and its associated relocation
* information is stored into the `expr'
* structure supplied by the user. `N' is
* a firewall priority; all top level calls
* (from the user) should be made with `n'
* set to 0.
*/
VOID
expr(esp, n)
register struct expr *esp;
{
register c, d, p;
struct area *ap;
struct expr re;
term(esp);
while (ctype[c = getnb()] & BINOP) {
if ((p = oprio(c)) <= n)
break;
if ((c == '>' || c == '<') && c != get())
qerr();
expr(&re, p);
if (c == '+') {
if (esp->e_base.e_ap == NULL) {
esp->e_flag = re.e_flag;
esp->e_base.e_ap = re.e_base.e_ap;
} else
if (re.e_base.e_ap) {
rerr();
}
esp->e_addr += re.e_addr;
} else
if (c == '-') {
if ((ap = re.e_base.e_ap) != NULL) {
if (esp->e_base.e_ap == ap) {
esp->e_base.e_ap = NULL;
} else {
rerr();
}
if (esp->e_flag || re.e_flag) {
rerr();
}
}
esp->e_addr -= re.e_addr;
} else {
abscheck(esp);
abscheck(&re);
switch (c) {
case '*':
esp->e_addr *= re.e_addr;
break;
case '/':
esp->e_addr /= re.e_addr;
break;
case '&':
esp->e_addr &= re.e_addr;
break;
case '|':
esp->e_addr |= re.e_addr;
break;
case '%':
esp->e_addr %= re.e_addr;
break;
case '^':
esp->e_addr ^= re.e_addr;
break;
case '<':
esp->e_addr <<= re.e_addr;
break;
case '>':
esp->e_addr >>= re.e_addr;
break;
}
}
}
unget(c);
}
/*
* Read an absolute expression.
*/
addr_t
absexpr()
{
struct expr e;
expr(&e, 0);
abscheck(&e);
return (e.e_addr);
}
/*
* Read a term.
* Handles unary operators, brackets,
* constants in decimal, octal or hexadecimal
* and identifiers. This routine is also
* responsible for setting the relocation type
* to symbol based (e.flag != 0) on global
* references.
*/
VOID
term(esp)
register struct expr *esp;
{
register c, n;
register char *jp;
char id[NCPS];
struct sym *sp;
struct tsym *tp;
int r, v;
c = getnb();
if (c == '#') { c = getnb(); }
if (c == LFTERM) {
expr(esp, 0);
if (getnb() != RTTERM)
qerr();
return;
}
if (c == '-') {
expr(esp, 100);
abscheck(esp);
esp->e_addr = -esp->e_addr;
return;
}
if (c == '~') {
expr(esp, 100);
abscheck(esp);
esp->e_addr = ~esp->e_addr;
return;
}
if (c == '\'') {
esp->e_mode = S_USER;
esp->e_flag = 0;
esp->e_base.e_ap = NULL;
esp->e_addr = getmap(-1);
return;
}
if (c == '\"') {
esp->e_mode = S_USER;
esp->e_flag = 0;
esp->e_base.e_ap = NULL;
if (hilo) {
esp->e_addr = (getmap(-1)&0377)<<8;
esp->e_addr |= (getmap(-1)&0377);
} else {
esp->e_addr = (getmap(-1)&0377);
esp->e_addr |= (getmap(-1)&0377)<<8;
}
return;
}
if (c == '>' || c == '<') {
expr(esp, 100);
abscheck(esp);
if (c == '>')
esp->e_addr >>= 8;
esp->e_addr &= 0377;
return;
}
if (ctype[c] & DIGIT) {
esp->e_mode = S_USER;
esp->e_flag = 0;
esp->e_base.e_ap = NULL;
jp = ip;
while (ctype[*jp] & RAD10) {
jp++;
}
if (*jp == '$') {
n = 0;
while ((v = digit(c, 10)) >= 0) {
n = 10*n + v;
c = get();
}
tp = symp->s_tsym;
while (tp) {
if (n == tp->t_num) {
esp->e_base.e_ap = tp->t_area;
esp->e_addr = tp->t_addr;
return;
}
tp = tp->t_lnk;
}
err('u');
esp->e_addr = 0;
return;
}
r = radix;
if (c == '0') {
c = get();
switch (c) {
case 'b':
case 'B':
r = 2;
c = get();
break;
case '@':
case 'o':
case 'O':
case 'q':
case 'Q':
r = 8;
c = get();
break;
case 'd':
case 'D':
r = 10;
c = get();
break;
case 'h':
case 'H':
case 'x':
case 'X':
r = 16;
c = get();
break;
default:
break;
}
}
n = 0;
while ((v = digit(c, r)) >= 0) {
n = r*n + v;
c = get();
}
unget(c);
esp->e_addr = n;
return;
}
if (ctype[c] & LETTER) {
esp->e_mode = S_USER;
esp->e_flag = 0;
esp->e_base.e_ap = NULL;
esp->e_addr = 0;
getid(id, c);
sp = lookup(id);
if (sp->s_type == S_NEW) {
if (sp->s_flag&S_GBL) {
esp->e_flag = 1;
esp->e_base.e_sp = sp;
return;
}
err('u');
} else {
esp->e_mode = sp->s_type;
esp->e_addr = sp->s_addr;
esp->e_base.e_ap = sp->s_area;
}
return;
}
qerr();
}
/*
* If `c' is a legal radix `r' digit
* return its value; otherwise return
* -1.
*/
int
digit(c, r)
register c, r;
{
if (r == 16) {
if (ctype[c] & RAD16) {
if (c >= 'A' && c <= 'F')
return (c - 'A' + 10);
if (c >= 'a' && c <= 'f')
return (c - 'a' + 10);
return (c - '0');
}
} else
if (r == 10) {
if (ctype[c] & RAD10)
return (c - '0');
} else
if (r == 8) {
if (ctype[c] & RAD8)
return (c - '0');
} else
if (r == 2) {
if (ctype[c] & RAD2)
return (c - '0');
}
return (-1);
}
/*
* Check if the value of the supplied
* expression is absolute; if not give
* a relocation error and force the
* type to absolute.
*/
VOID
abscheck(esp)
register struct expr *esp;
{
if (esp->e_flag || esp->e_base.e_ap) {
esp->e_flag = 0;
esp->e_base.e_ap = NULL;
rerr();
}
}
/*
* Return the priority of the binary
* operator `c'.
*/
int
oprio(c)
register c;
{
if (c == '*' || c == '/' || c == '%')
return (10);
if (c == '+' || c == '-')
return (7);
if (c == '<' || c == '>')
return (5);
if (c == '^')
return (4);
if (c == '&')
return (3);
if (c == '|')
return (1);
return (0);
}
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/