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1.1 root 1: #
2: /*
3: * px - Berkeley Pascal interpreter
4: *
5: * Version 2.0, January 1979
6: *
7: * Original version by Ken Thompson
8: *
9: * Substantial revisions by Bill Joy and Chuck Haley
10: * November-December 1976
11: *
12: * Rewritten for VAX 11/780 by Kirk McKusick
13: * Fall 1978
14: *
15: * Px is described in detail in the "PX 1.0 Implementation Notes"
16: * The source code for px is in several major pieces:
17: *
18: * int.c C main program which reads in interpreter code
19: * 00case.s Driver including main interpreter loop
20: * dd*.s Where dd are digits, interpreter instructions
21: * grouped by their positions in the interpreter table.
22: * p*.c Various C language routines supporting the system.
23: *
24: * In addition there are several headers defining mappings for error
25: * messages names into codes, and a definition of the interpreter transfer
26: * table. These are made by the script Emake in this directory and the scripts
27: * in the directory '../opcodes'.
28: */
29:
30: long argc;
31: char **argv;
32:
33: /*
34: * Pascal runtime errors transfer to the routine
35: * 'error' in the file perror.c to decode them.
36: */
37: int perrno; /* number of error which occurred */
38:
39: /*
40: * Definitions for memory allocation
41: * Memory allocation is done by palloc in utilities.c
42: */
43:
44: /*
45: * The file i/o routines maintain a notion of a "current file".
46: * The printing name of this file is kept in the variable
47: * "file" for use in error messages.
48: */
49: char *file; /* ptr to active file name */
50: long fchain; /* head of active file chain */
51: int bufopt; /* controls flushing of std output as follows:
52: * 0 => flush on every write
53: * 1 => flush before std read or at end of line
54: * 2 => normal buffering
55: */
56: /*
57: * THE RUNTIME DISPLAY
58: *
59: * The entries in the display point to the active static block marks.
60: * The first entry in the display is for the global variables,
61: * then the procedure or function at level one, etc.
62: * Each display entry points to a stack frame as shown:
63: *
64: * base of stack frame
65: * ---------------
66: * | |
67: * | block mark |
68: * | |
69: * --------------- <-- display entry points here
70: * | |
71: * | local |
72: * | variables |
73: * | |
74: * ---------------
75: * | |
76: * | expression |
77: * | temporary |
78: * | storage |
79: * | |
80: * - - - - - - - -
81: *
82: * The information in the block mark is thus at positive offsets from
83: * the display pointer entries while the local variables are at negative
84: * offsets. The block mark actually consists of two parts. The first
85: * part is created at CALL and the second at entry, i.e. BEGIN. Thus:
86: *
87: * -------------------------
88: * | |
89: * | Saved lino |
90: * | Saved lc |
91: * | Saved dp |
92: * | |
93: * -------------------------
94: * | |
95: * | Saved (dp) |
96: * | |
97: * | Current section name |
98: * | and entry line ptr |
99: * | |
100: * | Saved file name and |
101: * | file buffer ptr |
102: * | |
103: * | Empty tos value |
104: * | |
105: * -------------------------
106: */
107:
108: /*
109: * Structure for accessing things in the block mark
110: */
111: struct stack {
112: long *tos; /* pointer to top of stack frame */
113: char *file; /* pointer to active file name */
114: long buf; /* pointer to active file record */
115: struct {
116: char name[8];/* name of active procedure */
117: short offset; /* offset of procedure in source file */
118: } *entry;
119: struct stack *disp; /* previous display value for this level */
120: struct stack **dp; /* pointer to active display entry */
121: long lc; /* previous location counter */
122: long lino; /* previous line number */
123: } *display[40];
124:
125: long addrsze; /* size of display addresses */
126:
127:
128: /*
129: * Program option variables
130: */
131: long stcnt; /* number of statements executed */
132: long stlim; /* max number of statements to execute */
133: long llimit; /* max number of lines per text file */
134: short nodump; /* 1 => no post mortum dump */
135: short mode; /* mode of input to interpreter */
136: #define PX 0 /* normal run of px */
137: #define PIX 1 /* load and go */
138: #define PIPE 2 /* bootstrap via a pipe */
139:
140: /*
141: * Pxp variables
142: */
143: char *pxpbuf; /* pointer to pxp buffer */
144: long pxpsize; /* size of pxp buffer */
145:
146: #ifdef profile
147: /*
148: * Px execution profile data
149: */
150: #define numops 256
151: struct cntrec {
152: double counts[numops]; /* instruction counts */
153: long runs; /* number of interpreter runs */
154: long startdate; /* date profile started */
155: long usrtime; /* total user time consumed */
156: long systime; /* total system time consumed */
157: double stmts; /* number of pascal statements executed */
158: } profdata;
159: long profcnts[numops];
160: #define proffile "/usr/ucb/pascal/px/pcnt.out"
161: FILE *datafile; /* input datafiles */
162: #else
163: int profcnts; /* dummy just to keep the linker happy */
164: #endif
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