summaryrefslogtreecommitdiff
path: root/miscutils/dc.c
blob: 193929c8e48fa3fcddb208bba3cb0ed050208eb6 (plain)
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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include <math.h>

/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */


struct globals {
	unsigned pointer;
	unsigned base;
	double stack[1];
};
enum { STACK_SIZE = (COMMON_BUFSIZE - offsetof(struct globals, stack)) / sizeof(double) };
#define G (*(struct globals*)&bb_common_bufsiz1)
#define pointer   (G.pointer   )
#define base      (G.base      )
#define stack     (G.stack     )
#define INIT_G() do { \
} while (0)


static void push(double a)
{
	if (pointer >= STACK_SIZE)
		bb_error_msg_and_die("stack overflow");
	stack[pointer++] = a;
}

static double pop(void)
{
	if (pointer == 0)
		bb_error_msg_and_die("stack underflow");
	return stack[--pointer];
}

static void add(void)
{
	push(pop() + pop());
}

static void sub(void)
{
	double subtrahend = pop();

	push(pop() - subtrahend);
}

static void mul(void)
{
	push(pop() * pop());
}

static void power(void)
{
	double topower = pop();

	push(pow(pop(), topower));
}

static void divide(void)
{
	double divisor = pop();

	push(pop() / divisor);
}

static void mod(void)
{
	unsigned d = pop();

	push((unsigned) pop() % d);
}

static void and(void)
{
	push((unsigned) pop() & (unsigned) pop());
}

static void or(void)
{
	push((unsigned) pop() | (unsigned) pop());
}

static void eor(void)
{
	push((unsigned) pop() ^ (unsigned) pop());
}

static void not(void)
{
	push(~(unsigned) pop());
}

static void set_output_base(void)
{
	base = (unsigned)pop();
	if ((base != 10) && (base != 16)) {
		bb_error_msg("error, base %d is not supported", base);
		base = 10;
	}
}

static void print_base(double print)
{
	if (base == 16)
		printf("%x\n", (unsigned)print);
	else
		printf("%g\n", print);
}

static void print_stack_no_pop(void)
{
	unsigned i = pointer;
	while (i)
		print_base(stack[--i]);
}

static void print_no_pop(void)
{
	print_base(stack[pointer-1]);
}

struct op {
	const char name[4];
	void (*function) (void);
};

static const struct op operators[] = {
	{"+",   add},
	{"add", add},
	{"-",   sub},
	{"sub", sub},
	{"*",   mul},
	{"mul", mul},
	{"/",   divide},
	{"div", divide},
	{"**",  power},
	{"exp", power},
	{"pow", power},
	{"%",   mod},
	{"mod", mod},
	{"and", and},
	{"or",  or},
	{"not", not},
	{"eor", eor},
	{"xor", eor},
	{"p", print_no_pop},
	{"f", print_stack_no_pop},
	{"o", set_output_base},
	{ /* zero filled */ }
};

static void stack_machine(const char *argument)
{
	char *endPointer;
	double d;
	const struct op *o = operators;

	if (argument == 0)
		return;

	d = strtod(argument, &endPointer);

	if (endPointer != argument) {
		push(d);
		return;
	}

	while (o->name[0]) {
		if (strcmp(o->name, argument) == 0) {
			o->function();
			return;
		}
		o++;
	}
	bb_error_msg_and_die("%s: syntax error", argument);
}

/* return pointer to next token in buffer and set *buffer to one char
 * past the end of the above mentioned token
 */
static char *get_token(char **buffer)
{
	char *current = skip_whitespace(*buffer);
	if (*current != '\0') {
		*buffer = skip_non_whitespace(current);
		return current;
	}
	return NULL;
}

int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int dc_main(int argc ATTRIBUTE_UNUSED, char **argv)
{
	INIT_G();

	argv++;
	if (!argv[0]) {
		/* take stuff from stdin if no args are given */
		char *line;
		char *cursor;
		char *token;
		while ((line = xmalloc_fgetline(stdin)) != NULL) {
			cursor = line;
			while (1) {
				token = get_token(&cursor);
				if (!token) break;
				*cursor++ = '\0';
				stack_machine(token);
			}
			free(line);
		}
	} else {
		if (argv[0][0] == '-')
			bb_show_usage();
		do {
			stack_machine(*argv);
		} while (*++argv);
	}
	return EXIT_SUCCESS;
}