-
Notifications
You must be signed in to change notification settings - Fork 0
/
ram.c
183 lines (169 loc) · 5.64 KB
/
ram.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
/**
* ram.c
*
* (c) Copyright 2010, P. Jakubco
*
* This module handles the RAM state
*/
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include "ram.h"
RAM_env ram_env;
/**
* The function initializes static state of RAM machine.
*/
void ram_init(int input_size) {
ram_env.pc = 0;
memset(ram_env.r, 0, 100);
ram_env.input = (char *)calloc(1, input_size);
memset(ram_env.output, 0, RAM_OUTPUT_SIZE);
ram_env.p_input = 0;
ram_env.p_output = 0;
ram_env.state = RAM_OK;
}
/**
* Frees memory
*/
void ram_destroy() {
free(ram_env.input);
}
/**
* The function prints the error code description.
* @param error_code the error code
*/
const char *ram_error(int error_code) {
switch (error_code) {
case RAM_HALT: return "RAM_HALT";
case RAM_UNKNOWN_INSTRUCTION: return "RAM_UNKNOWN_INSTRUCTION";
case RAM_ADDRESS_FALLOUT: return "RAM_ADDRESS_FALLOUT";
case RAM_OUTPUT_FULL: return "RAM_OUTPUT_FULL";
case RAM_DIVISION_BY_ZERO: return "RAM_DIVISION_BY_ZERO";
default: return "unknown";
}
}
/**
* The function prints out the output tape.
*/
void ram_output() {
int stop = ram_env.p_output;
int i;
for (i = 0; i < stop; i++)
printf("%d ", ram_env.output[i]);
printf("\n");
}
/**
* This function interprets single instruction. This is an interpreter.
* It is assumed that the syntax and semantics are correct.
*
* @param program - the memory with program
* @return error code (0 - ok)
*/
int ram_interpret(const char *program, int ram_size) {
int c,t;
if (ram_size < 0) {
printf("Error: RAM program was not loaded properly.");
return 1;
}
if (ram_env.pc >= ram_size) {
printf("Error: Address fallout.\n");
return 2;
}
c = program[ram_env.pc++];
if ((c > 0) && (ram_env.pc >= ram_size)) {
printf("Error: Address fallout.\n");
return 2;
}
/* printf("PC: %d, Instr: %d\n", ram_env.pc, c); */
switch (c) {
case 0: return RAM_HALT;
case 1: /* READ i */
ram_env.r[program[ram_env.pc++]] = ram_env.input[ram_env.p_input++];
break;
case 2: /* READ *i */
ram_env.r[ram_env.r[program[ram_env.pc++]]] = ram_env.input[ram_env.p_input++];
break;
case 3: /* WRITE =i */
if (ram_env.p_output >= RAM_OUTPUT_SIZE) {
printf("Error: Output tape is full.\n");
return RAM_OUTPUT_FULL;
}
ram_env.output[ram_env.p_output++] = program[ram_env.pc++];
break;
case 4: /* WRITE i */
if (ram_env.p_output >= RAM_OUTPUT_SIZE) {
printf("Error: Output tape is full.\n");
return RAM_OUTPUT_FULL;
}
ram_env.output[ram_env.p_output++] = ram_env.r[program[ram_env.pc++]];
break;
case 5: /* WRITE *i */
if (ram_env.p_output >= RAM_OUTPUT_SIZE) {
printf("Error: Output tape is full.\n");
return RAM_OUTPUT_FULL;
}
ram_env.output[ram_env.p_output++] = ram_env.r[ram_env.r[program[ram_env.pc++]]];
break;
case 6: /* LOAD =i */
ram_env.r[0] = (unsigned char)program[ram_env.pc++]; break;
case 7: /* LOAD i */
ram_env.r[0] = ram_env.r[(unsigned char)program[ram_env.pc++]]; break;
case 8: /* LOAD *i */
ram_env.r[0] = ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]]; break;
case 9: /* STORE i */
ram_env.r[(unsigned char)program[ram_env.pc++]] = ram_env.r[0]; break;
case 10: /* STORE *i */
ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]] = ram_env.r[0]; break;
case 11: /* ADD =i */
ram_env.r[0] += (unsigned char)program[ram_env.pc++]; break;
case 12: /* ADD i */
ram_env.r[0] += ram_env.r[(unsigned char)program[ram_env.pc++]]; break;
case 13: /* ADD *i */
ram_env.r[0] += ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]]; break;
case 14: /* SUB =i */
ram_env.r[0] -= (unsigned char)program[ram_env.pc++]; break;
case 15: /* SUB i */
ram_env.r[0] -= ram_env.r[(unsigned char)program[ram_env.pc++]]; break;
case 16: /* SUB *i */
ram_env.r[0] -= ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]]; break;
case 17: /* MUL =i */
ram_env.r[0] *= (unsigned char)program[ram_env.pc++]; break;
case 18: /* MUL i */
ram_env.r[0] *= ram_env.r[(unsigned char)program[ram_env.pc++]]; break;
case 19: /* MUL *i */
ram_env.r[0] *= ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]]; break;
case 20: /* DIV =i */
t = (unsigned char)program[ram_env.pc++];
if (!t) {
printf("Error: division by zero.\n");
return RAM_DIVISION_BY_ZERO;
}
ram_env.r[0] /= t; break;
case 21: /* DIV i */
t = ram_env.r[(unsigned char)program[ram_env.pc++]];
if (!t) {
printf("Error: division by zero.\n");
return RAM_DIVISION_BY_ZERO;
}
ram_env.r[0] /= t; break;
case 22: /* DIV *i */
t = ram_env.r[ram_env.r[(unsigned char)program[ram_env.pc++]]];
if (!t) {
printf("Error: division by zero.\n");
return RAM_DIVISION_BY_ZERO;
}
ram_env.r[0] /= t; break;
case 23: /* JMP i */
ram_env.pc = (unsigned char)program[ram_env.pc]; break;
case 24: /* JGTZ i */
ram_env.pc = ((unsigned int)ram_env.r[0] > 0) ? (unsigned char)program[ram_env.pc] : ram_env.pc+1;
break;
case 25: /* JZ i */
ram_env.pc = (ram_env.r[0] == 0) ? (unsigned char)program[ram_env.pc] : ram_env.pc+1;
break;
default:
printf("Error: unknown insruction (%d).\n",c);
return RAM_UNKNOWN_INSTRUCTION;
}
return RAM_OK;
}