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[/] [System09/] [trunk/] [Tools/] [as09/] [eval.c] - Blame information for rev 83

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/*
 *      eval --- evaluate expression
 *
 *      an expression is constructed like this:
 *
 *      expr ::=  expr + term |
 *                expr - term ;
 *                expr * term ;
 *                expr / term ;
 *                expr | term ;
 *                expr & term ;
 *                expr % term ;
 *                expr ^ term ;
 *
 *      term ::=  symbol |
 *                * |
 *                constant ;
 *
 *      symbol ::=  string of alphanumerics with non-initial digit
 *
 *      constant ::= hex constant |
 *                   binary constant |
 *                   octal constant |
 *                   decimal constant |
 *                   ascii constant;
 *
 *      hex constant ::= '$' {hex digits};
 *
 *      octal constant ::= '@' {octal digits};
 *
 *      binary constant ::= '%' { 1 | 0 };
 *
 *      decimal constant ::= {decimal digits};
 *
 *      ascii constant ::= ''' any printing char;
 *
 */
eval()
{
        int     left,right;     /* left and right terms for expression */
        char    o;              /* operator character */
 
#ifdef DEBUG
        printf("Evaluating %s\n",Optr);
#endif
        Force_byte = NO;
        Force_word = NO;
        if(*Optr=='<'){
                Force_byte++;
                Optr++;
                }
        else if(*Optr=='>'){
                Force_word++;
                Optr++;
                }
        left = get_term();         /* pickup first part of expression */
 
        while( is_op(*Optr)){
                o = *Optr++; /* pickup connector and skip */
                right = get_term();     /* pickup current rightmost side */
                switch(o){
                        case '+': left += right; break;
                        case '-': left -= right; break;
                        case '*': left *= right; break;
                        case '/': left /= right; break;
                        case '|': left |= right; break;
                        case '&': left &= right; break;
                        case '%': left %= right; break;
                        case '^': left = left^right; break;
                        }
                }
 
        Result= left;
#ifdef DEBUG
        printf("Result=%x\n",Result);
        printf("Force_byte=%d  Force_word=%d\n",Force_byte,Force_word);
#endif
        return(YES);
}
 
/*
 *      is_op --- is character an expression operator?
 */
is_op(c)
char c;
{
        if( any(c,"+-*/&%|^"))
                return(YES);
        return(NO);
}
 
 
/*
 *      get_term --- evaluate a single item in an expression
 */
get_term()
{
        char    hold[MAXBUF];
        char    *tmp;
        int     val = 0;        /* local value being built */
        int     minus;          /* unary minus flag */
        struct nlist *pointer;
        struct link *pnt,*bpnt;
 
        if( *Optr == '-' ){
                Optr++;
                minus =YES;
                }
        else
                minus = NO;
 
        while( *Optr == '#' ) Optr++;
 
        /* look at rest of expression */
 
        if(*Optr=='%'){ /* binary constant */
                Optr++;
                while( any(*Optr,"01"))
                        val = (val * 2) + ( (*Optr++)-'0');
                }
        else if(*Optr=='@'){ /* octal constant */
                Optr++;
                while( any(*Optr,"01234567"))
                        val = (val * 8) + ((*Optr++)-'0');
                }
        else if(*Optr=='$'){ /* hex constant */
                Optr++;
                while( any(*Optr,"0123456789abcdefABCDEF"))
                        if( *Optr > '9' )
                                val = (val * 16) + 10 + (mapdn(*Optr++)-'a');
                        else
                                val = (val * 16) + ((*Optr++)-'0');
                }
        else if( any(*Optr,"0123456789")){ /* decimal constant */
                while(*Optr >= '0' && *Optr <= '9')
                        val = (val * 10) + ( (*Optr++)-'0');
                }
        else if(*Optr=='*'){    /* current location counter */
                Optr++;
                val = Old_pc;
                }
        else if(*Optr=='\''){   /* character literal */
                Optr++;
                if(*Optr == EOS)
                        val = 0;
                else
                        val = *Optr++;
                }
        else if( alpha(*Optr) ){ /* a symbol */
                tmp = hold;     /* collect symbol name */
                while(alphan(*Optr))
                        *tmp++ = *Optr++;
                *tmp = EOS;
                pointer = lookup(hold);
                  if (pointer != NULL)
                   {
                   if (Pass == 2)
                    {
                       pnt = pointer->L_list;
                        bpnt = NULL;
                        while (pnt != NULL)
                         {
                           bpnt = pnt;
                           pnt = pnt->next;
                         }
                        pnt = (struct link *) alloc(sizeof(struct link));
                      if (bpnt == NULL)
                       pointer->L_list = pnt;
                      else bpnt->next = pnt;
                     pnt->L_num = Line_num;
                    pnt->next = NULL;
                    }
                       val = Last_sym;
                   }
                else{
                        if(Pass==1){    /* forward ref here */
                                fwdmark();
                                if( !Force_byte )
                                        Force_word++;
                                val = 0;
                                }
                        else    /* added ver TER_2.0  2 Jul 89 */
                                error("Symbol undefined Pass 2");
                        }
                if(Pass==2 && Line_num==F_ref && Cfn==Ffn){
                        if( !Force_byte  )
                                Force_word++;
                        fwdnext();
                        }
                }
        else
                /* none of the above */
                val = 0;
 
        if(minus)
                return(-val);
        else
                return(val);
}

Line No.	Rev	Author	Line
1	83	davidgb	`/*`
2			`* eval --- evaluate expression`
3			`*`
4			`* an expression is constructed like this:`
5			`*`
6			`* expr ::= expr + term \|`
7			`* expr - term ;`
8			`* expr * term ;`
9			`* expr / term ;`
10			`* expr \| term ;`
11			`* expr & term ;`
12			`* expr % term ;`
13			`* expr ^ term ;`
14			`*`
15			`* term ::= symbol \|`
16			`* * \|`
17			`* constant ;`
18			`*`
19			`* symbol ::= string of alphanumerics with non-initial digit`
20			`*`
21			`* constant ::= hex constant \|`
22			`* binary constant \|`
23			`* octal constant \|`
24			`* decimal constant \|`
25			`* ascii constant;`
26			`*`
27			`* hex constant ::= '$' {hex digits};`
28			`*`
29			`* octal constant ::= '@' {octal digits};`
30			`*`
31			`* binary constant ::= '%' { 1 \| 0 };`
32			`*`
33			`* decimal constant ::= {decimal digits};`
34			`*`
35			`* ascii constant ::= ''' any printing char;`
36			`*`
37			`*/`
38			`eval()`
39			`{`
40			`int left,right; /* left and right terms for expression */`
41			`char o; /* operator character */`
42
43			`#ifdef DEBUG`
44			`printf("Evaluating %s\n",Optr);`
45			`#endif`
46			`Force_byte = NO;`
47			`Force_word = NO;`
48			`if(*Optr=='<'){`
49			`Force_byte++;`
50			`Optr++;`
51			`}`
52			`else if(*Optr=='>'){`
53			`Force_word++;`
54			`Optr++;`
55			`}`
56			`left = get_term(); /* pickup first part of expression */`
57
58			`while( is_op(*Optr)){`
59			`o = Optr++; / pickup connector and skip */`
60			`right = get_term(); /* pickup current rightmost side */`
61			`switch(o){`
62			`case '+': left += right; break;`
63			`case '-': left -= right; break;`
64			`case '': left = right; break;`
65			`case '/': left /= right; break;`
66			`case '\|': left \|= right; break;`
67			`case '&': left &= right; break;`
68			`case '%': left %= right; break;`
69			`case '^': left = left^right; break;`
70			`}`
71			`}`
72
73			`Result= left;`
74			`#ifdef DEBUG`
75			`printf("Result=%x\n",Result);`
76			`printf("Force_byte=%d Force_word=%d\n",Force_byte,Force_word);`
77			`#endif`
78			`return(YES);`
79			`}`
80
81			`/*`
82			`* is_op --- is character an expression operator?`
83			`*/`
84			`is_op(c)`
85			`char c;`
86			`{`
87			`if( any(c,"+-*/&%\|^"))`
88			`return(YES);`
89			`return(NO);`
90			`}`
91
92
93			`/*`
94			`* get_term --- evaluate a single item in an expression`
95			`*/`
96			`get_term()`
97			`{`
98			`char hold[MAXBUF];`
99			`char *tmp;`
100			`int val = 0; /* local value being built */`
101			`int minus; /* unary minus flag */`
102			`struct nlist *pointer;`
103			`struct link pnt,bpnt;`
104
105			`if( *Optr == '-' ){`
106			`Optr++;`
107			`minus =YES;`
108			`}`
109			`else`
110			`minus = NO;`
111
112			`while( *Optr == '#' ) Optr++;`
113
114			`/* look at rest of expression */`
115
116			`if(Optr=='%'){ / binary constant */`
117			`Optr++;`
118			`while( any(*Optr,"01"))`
119			`val = (val * 2) + ( (*Optr++)-'0');`
120			`}`
121			`else if(Optr=='@'){ / octal constant */`
122			`Optr++;`
123			`while( any(*Optr,"01234567"))`
124			`val = (val * 8) + ((*Optr++)-'0');`
125			`}`
126			`else if(Optr=='$'){ / hex constant */`
127			`Optr++;`
128			`while( any(*Optr,"0123456789abcdefABCDEF"))`
129			`if( *Optr > '9' )`
130			`val = (val * 16) + 10 + (mapdn(*Optr++)-'a');`
131			`else`
132			`val = (val * 16) + ((*Optr++)-'0');`
133			`}`
134			`else if( any(Optr,"0123456789")){ / decimal constant */`
135			`while(Optr >= '0' && Optr <= '9')`
136			`val = (val * 10) + ( (*Optr++)-'0');`
137			`}`
138			`else if(Optr==''){ /* current location counter */`
139			`Optr++;`
140			`val = Old_pc;`
141			`}`
142			`else if(Optr=='\''){ / character literal */`
143			`Optr++;`
144			`if(*Optr == EOS)`
145			`val = 0;`
146			`else`
147			`val = *Optr++;`
148			`}`
149			`else if( alpha(Optr) ){ / a symbol */`
150			`tmp = hold; /* collect symbol name */`
151			`while(alphan(*Optr))`
152			`tmp++ = Optr++;`
153			`*tmp = EOS;`
154			`pointer = lookup(hold);`
155			`if (pointer != NULL)`
156			`{`
157			`if (Pass == 2)`
158			`{`
159			`pnt = pointer->L_list;`
160			`bpnt = NULL;`
161			`while (pnt != NULL)`
162			`{`
163			`bpnt = pnt;`
164			`pnt = pnt->next;`
165			`}`
166			`pnt = (struct link *) alloc(sizeof(struct link));`
167			`if (bpnt == NULL)`
168			`pointer->L_list = pnt;`
169			`else bpnt->next = pnt;`
170			`pnt->L_num = Line_num;`
171			`pnt->next = NULL;`
172			`}`
173			`val = Last_sym;`
174			`}`
175			`else{`
176			`if(Pass==1){ /* forward ref here */`
177			`fwdmark();`
178			`if( !Force_byte )`
179			`Force_word++;`
180			`val = 0;`
181			`}`
182			`else /* added ver TER_2.0 2 Jul 89 */`
183			`error("Symbol undefined Pass 2");`
184			`}`
185			`if(Pass==2 && Line_num==F_ref && Cfn==Ffn){`
186			`if( !Force_byte )`
187			`Force_word++;`
188			`fwdnext();`
189			`}`
190			`}`
191			`else`
192			`/* none of the above */`
193			`val = 0;`
194
195			`if(minus)`
196			`return(-val);`
197			`else`
198			`return(val);`
199			`}`

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[/] [System09/] [trunk/] [Tools/] [as09/] [eval.c] - Blame information for rev 83