1 /*
2 * 4obj.c - identify and parse a mips object file
3 */
4 #include <u.h>
5 #include <libc.h>
6 #include <bio.h>
7 #include <mach.h>
8 #include "4c/4.out.h"
9 #include "obj.h"
10
11 typedef struct Addr Addr;
12 struct Addr
13 {
14 char type;
15 char sym;
16 char name;
17 };
18 static Addr addr(Biobuf*);
19 static char type2char(int);
20 static void skip(Biobuf*, int);
21
22 int
_is4(char * s)23 _is4(char *s)
24 {
25 return s[0] == ANAME /* ANAME */
26 && s[1] == D_FILE /* type */
27 && s[2] == 1 /* sym */
28 && s[3] == '<'; /* name of file */
29 }
30
31 int
_read4(Biobuf * bp,Prog * p)32 _read4(Biobuf *bp, Prog *p)
33 {
34 int as, n;
35 Addr a;
36
37 as = Bgetc(bp); /* as */
38 if(as < 0)
39 return 0;
40 p->kind = aNone;
41 p->sig = 0;
42 if(as == ANAME || as == ASIGNAME){
43 if(as == ASIGNAME){
44 Bread(bp, &p->sig, 4);
45 p->sig = leswal(p->sig);
46 }
47 p->kind = aName;
48 p->type = type2char(Bgetc(bp)); /* type */
49 p->sym = Bgetc(bp); /* sym */
50 n = 0;
51 for(;;) {
52 as = Bgetc(bp);
53 if(as < 0)
54 return 0;
55 n++;
56 if(as == 0)
57 break;
58 }
59 p->id = malloc(n);
60 if(p->id == 0)
61 return 0;
62 Bseek(bp, -n, 1);
63 if(Bread(bp, p->id, n) != n)
64 return 0;
65 return 1;
66 }
67 if(as == ATEXT)
68 p->kind = aText;
69 else if(as == AGLOBL)
70 p->kind = aData;
71 skip(bp, 5); /* reg(1), lineno(4) */
72 a = addr(bp);
73 addr(bp);
74 if(a.type != D_OREG || a.name != D_STATIC && a.name != D_EXTERN)
75 p->kind = aNone;
76 p->sym = a.sym;
77 return 1;
78 }
79
80 static Addr
addr(Biobuf * bp)81 addr(Biobuf *bp)
82 {
83 Addr a;
84 vlong off;
85 long l;
86
87 a.type = Bgetc(bp); /* a.type */
88 skip(bp,1); /* reg */
89 a.sym = Bgetc(bp); /* sym index */
90 a.name = Bgetc(bp); /* sym type */
91 switch(a.type){
92 default:
93 case D_NONE: case D_REG: case D_FREG: case D_MREG:
94 case D_FCREG: case D_LO: case D_HI:
95 break;
96 case D_OREG:
97 case D_CONST:
98 case D_BRANCH:
99 case D_VCONST:
100 l = Bgetc(bp);
101 l |= Bgetc(bp) << 8;
102 l |= Bgetc(bp) << 16;
103 l |= Bgetc(bp) << 24;
104 off = l;
105 if(a.type == D_VCONST){
106 l = Bgetc(bp);
107 l |= Bgetc(bp) << 8;
108 l |= Bgetc(bp) << 16;
109 l |= Bgetc(bp) << 24;
110 off = ((vlong)l << 32) | (off & 0xFFFFFFFF);
111 a.type = D_CONST; /* perhaps */
112 }
113 if(off < 0)
114 off = -off;
115 if(a.sym && (a.name==D_PARAM || a.name==D_AUTO))
116 _offset(a.sym, off);
117 break;
118 case D_SCONST:
119 skip(bp, NSNAME);
120 break;
121 case D_FCONST:
122 skip(bp, 8);
123 break;
124 }
125 return a;
126 }
127
128 static char
type2char(int t)129 type2char(int t)
130 {
131 switch(t){
132 case D_EXTERN: return 'U';
133 case D_STATIC: return 'b';
134 case D_AUTO: return 'a';
135 case D_PARAM: return 'p';
136 default: return UNKNOWN;
137 }
138 }
139
140 static void
skip(Biobuf * bp,int n)141 skip(Biobuf *bp, int n)
142 {
143 while (n-- > 0)
144 Bgetc(bp);
145 }
146