release/src/router/busybox/miscutils/dc.c

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