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path: root/miscutils/dc.c (plain)
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1/* vi: set sw=4 ts=4: */
2/*
3 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
4 */
5//config:config DC
6//config: bool "dc"
7//config: default y
8//config: help
9//config: Dc is a reverse-polish desk calculator which supports unlimited
10//config: precision arithmetic.
11//config:
12//config:config FEATURE_DC_LIBM
13//config: bool "Enable power and exp functions (requires libm)"
14//config: default y
15//config: depends on DC
16//config: help
17//config: Enable power and exp functions.
18//config: NOTE: This will require libm to be present for linking.
19
20//applet:IF_DC(APPLET(dc, BB_DIR_USR_BIN, BB_SUID_DROP))
21
22//kbuild:lib-$(CONFIG_DC) += dc.o
23
24//usage:#define dc_trivial_usage
25//usage: "EXPRESSION..."
26//usage:
27//usage:#define dc_full_usage "\n\n"
28//usage: "Tiny RPN calculator. Operations:\n"
29//usage: "+, add, -, sub, *, mul, /, div, %, mod, "IF_FEATURE_DC_LIBM("**, exp, ")"and, or, not, xor,\n"
30//usage: "p - print top of the stack (without popping),\n"
31//usage: "f - print entire stack,\n"
32//usage: "o - pop the value and set output radix (must be 10, 16, 8 or 2).\n"
33//usage: "Examples: 'dc 2 2 add p' -> 4, 'dc 8 8 mul 2 2 + / p' -> 16"
34//usage:
35//usage:#define dc_example_usage
36//usage: "$ dc 2 2 + p\n"
37//usage: "4\n"
38//usage: "$ dc 8 8 \\* 2 2 + / p\n"
39//usage: "16\n"
40//usage: "$ dc 0 1 and p\n"
41//usage: "0\n"
42//usage: "$ dc 0 1 or p\n"
43//usage: "1\n"
44//usage: "$ echo 72 9 div 8 mul p | dc\n"
45//usage: "64\n"
46
47#include "libbb.h"
48#include "common_bufsiz.h"
49#include <math.h>
50
51#if 0
52typedef unsigned data_t;
53#define DATA_FMT ""
54#elif 0
55typedef unsigned long data_t;
56#define DATA_FMT "l"
57#else
58typedef unsigned long long data_t;
59#define DATA_FMT "ll"
60#endif
61
62
63struct globals {
64 unsigned pointer;
65 unsigned base;
66 double stack[1];
67} FIX_ALIASING;
68enum { STACK_SIZE = (COMMON_BUFSIZE - offsetof(struct globals, stack)) / sizeof(double) };
69#define G (*(struct globals*)bb_common_bufsiz1)
70#define pointer (G.pointer )
71#define base (G.base )
72#define stack (G.stack )
73#define INIT_G() do { \
74 setup_common_bufsiz(); \
75 base = 10; \
76} while (0)
77
78
79static void check_under(void)
80{
81 if (pointer == 0)
82 bb_error_msg_and_die("stack underflow");
83}
84
85static void push(double a)
86{
87 if (pointer >= STACK_SIZE)
88 bb_error_msg_and_die("stack overflow");
89 stack[pointer++] = a;
90}
91
92static double pop(void)
93{
94 check_under();
95 return stack[--pointer];
96}
97
98static void add(void)
99{
100 push(pop() + pop());
101}
102
103static void sub(void)
104{
105 double subtrahend = pop();
106
107 push(pop() - subtrahend);
108}
109
110static void mul(void)
111{
112 push(pop() * pop());
113}
114
115#if ENABLE_FEATURE_DC_LIBM
116static void power(void)
117{
118 double topower = pop();
119
120 push(pow(pop(), topower));
121}
122#endif
123
124static void divide(void)
125{
126 double divisor = pop();
127
128 push(pop() / divisor);
129}
130
131static void mod(void)
132{
133 data_t d = pop();
134
135 push((data_t) pop() % d);
136}
137
138static void and(void)
139{
140 push((data_t) pop() & (data_t) pop());
141}
142
143static void or(void)
144{
145 push((data_t) pop() | (data_t) pop());
146}
147
148static void eor(void)
149{
150 push((data_t) pop() ^ (data_t) pop());
151}
152
153static void not(void)
154{
155 push(~(data_t) pop());
156}
157
158static void set_output_base(void)
159{
160 static const char bases[] ALIGN1 = { 2, 8, 10, 16, 0 };
161 unsigned b = (unsigned)pop();
162
163 base = *strchrnul(bases, b);
164 if (base == 0) {
165 bb_error_msg("error, base %u is not supported", b);
166 base = 10;
167 }
168}
169
170static void print_base(double print)
171{
172 data_t x, i;
173
174 x = (data_t) print;
175 if (base == 10) {
176 if (x == print) /* exactly representable as unsigned integer */
177 printf("%"DATA_FMT"u\n", x);
178 else
179 printf("%g\n", print);
180 return;
181 }
182
183 switch (base) {
184 case 16:
185 printf("%"DATA_FMT"x\n", x);
186 break;
187 case 8:
188 printf("%"DATA_FMT"o\n", x);
189 break;
190 default: /* base 2 */
191 i = MAXINT(data_t) - (MAXINT(data_t) >> 1);
192 /* i is 100000...00000 */
193 do {
194 if (x & i)
195 break;
196 i >>= 1;
197 } while (i > 1);
198 do {
199 bb_putchar('1' - !(x & i));
200 i >>= 1;
201 } while (i);
202 bb_putchar('\n');
203 }
204}
205
206static void print_stack_no_pop(void)
207{
208 unsigned i = pointer;
209 while (i)
210 print_base(stack[--i]);
211}
212
213static void print_no_pop(void)
214{
215 check_under();
216 print_base(stack[pointer-1]);
217}
218
219struct op {
220 const char name[4];
221 void (*function) (void);
222};
223
224static const struct op operators[] = {
225#if ENABLE_FEATURE_DC_LIBM
226 {"**", power},
227 {"exp", power},
228 {"pow", power},
229#endif
230 {"%", mod},
231 {"mod", mod},
232 {"and", and},
233 {"or", or},
234 {"not", not},
235 {"eor", eor},
236 {"xor", eor},
237 {"+", add},
238 {"add", add},
239 {"-", sub},
240 {"sub", sub},
241 {"*", mul},
242 {"mul", mul},
243 {"/", divide},
244 {"div", divide},
245 {"p", print_no_pop},
246 {"f", print_stack_no_pop},
247 {"o", set_output_base},
248};
249
250/* Feed the stack machine */
251static void stack_machine(const char *argument)
252{
253 char *end;
254 double number;
255 const struct op *o;
256
257 next:
258 number = strtod(argument, &end);
259 if (end != argument) {
260 argument = end;
261 push(number);
262 goto next;
263 }
264
265 /* We might have matched a digit, eventually advance the argument */
266 argument = skip_whitespace(argument);
267
268 if (*argument == '\0')
269 return;
270
271 o = operators;
272 do {
273 char *after_name = is_prefixed_with(argument, o->name);
274 if (after_name) {
275 argument = after_name;
276 o->function();
277 goto next;
278 }
279 o++;
280 } while (o != operators + ARRAY_SIZE(operators));
281
282 bb_error_msg_and_die("syntax error at '%s'", argument);
283}
284
285int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
286int dc_main(int argc UNUSED_PARAM, char **argv)
287{
288 INIT_G();
289
290 argv++;
291 if (!argv[0]) {
292 /* take stuff from stdin if no args are given */
293 char *line;
294 while ((line = xmalloc_fgetline(stdin)) != NULL) {
295 stack_machine(line);
296 free(line);
297 }
298 } else {
299 do {
300 stack_machine(*argv);
301 } while (*++argv);
302 }
303 return EXIT_SUCCESS;
304}
305
generated by cgit at 2024-05-15 05:39:23 (GMT)