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    Contents of /trunk/mkinitrd-magellan/busybox/miscutils/dc.c

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    Revision 532 - (show annotations) (download)
    Sat Sep 1 22:45:15 2007 UTC (16 years, 9 months ago) by niro
    File MIME type: text/plain
    File size: 3885 byte(s) 
    -import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
    4 */
    5
    6 #include "busybox.h"
    7 #include <ctype.h>
    8 #include <stdio.h>
    9 #include <stdlib.h>
    10 #include <string.h>
    11 #include <unistd.h>
    12 #include <math.h>
    13
    14 /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
    15
    16 static double stack[100];
    17 static unsigned int pointer;
    18 static unsigned char base;
    19
    20 static void push(double a)
    21 {
    22 if (pointer >= (sizeof(stack) / sizeof(*stack)))
    23 bb_error_msg_and_die("stack overflow");
    24 stack[pointer++] = a;
    25 }
    26
    27 static double pop(void)
    28 {
    29 if (pointer == 0)
    30 bb_error_msg_and_die("stack underflow");
    31 return stack[--pointer];
    32 }
    33
    34 static void add(void)
    35 {
    36 push(pop() + pop());
    37 }
    38
    39 static void sub(void)
    40 {
    41 double subtrahend = pop();
    42
    43 push(pop() - subtrahend);
    44 }
    45
    46 static void mul(void)
    47 {
    48 push(pop() * pop());
    49 }
    50
    51 static void power(void)
    52 {
    53 double topower = pop();
    54
    55 push(pow(pop(), topower));
    56 }
    57
    58 static void divide(void)
    59 {
    60 double divisor = pop();
    61
    62 push(pop() / divisor);
    63 }
    64
    65 static void mod(void)
    66 {
    67 unsigned int d = pop();
    68
    69 push((unsigned int) pop() % d);
    70 }
    71
    72 static void and(void)
    73 {
    74 push((unsigned int) pop() & (unsigned int) pop());
    75 }
    76
    77 static void or(void)
    78 {
    79 push((unsigned int) pop() | (unsigned int) pop());
    80 }
    81
    82 static void eor(void)
    83 {
    84 push((unsigned int) pop() ^ (unsigned int) pop());
    85 }
    86
    87 static void not(void)
    88 {
    89 push(~(unsigned int) pop());
    90 }
    91
    92 static void set_output_base(void)
    93 {
    94 base=(unsigned char)pop();
    95 if ((base != 10) && (base != 16)) {
    96 fprintf(stderr, "Error: base = %d is not supported.\n", base);
    97 base=10;
    98 }
    99 }
    100
    101 static void print_base(double print)
    102 {
    103 if (base == 16)
    104 printf("%x\n", (unsigned int)print);
    105 else
    106 printf("%g\n", print);
    107 }
    108
    109 static void print_stack_no_pop(void)
    110 {
    111 unsigned int i=pointer;
    112 while (i)
    113 print_base(stack[--i]);
    114 }
    115
    116 static void print_no_pop(void)
    117 {
    118 print_base(stack[pointer-1]);
    119 }
    120
    121 struct op {
    122 const char *name;
    123 void (*function) (void);
    124 };
    125
    126 static const struct op operators[] = {
    127 {"+", add},
    128 {"add", add},
    129 {"-", sub},
    130 {"sub", sub},
    131 {"*", mul},
    132 {"mul", mul},
    133 {"/", divide},
    134 {"div", divide},
    135 {"**", power},
    136 {"exp", power},
    137 {"pow", power},
    138 {"%", mod},
    139 {"mod", mod},
    140 {"and", and},
    141 {"or", or},
    142 {"not", not},
    143 {"eor", eor},
    144 {"xor", eor},
    145 {"p", print_no_pop},
    146 {"f", print_stack_no_pop},
    147 {"o", set_output_base},
    148 {0, 0}
    149 };
    150
    151 static void stack_machine(const char *argument)
    152 {
    153 char *endPointer = 0;
    154 double d;
    155 const struct op *o = operators;
    156
    157 if (argument == 0)
    158 return;
    159
    160 d = strtod(argument, &endPointer);
    161
    162 if (endPointer != argument) {
    163 push(d);
    164 return;
    165 }
    166
    167 while (o->name != 0) {
    168 if (strcmp(o->name, argument) == 0) {
    169 (*(o->function)) ();
    170 return;
    171 }
    172 o++;
    173 }
    174 bb_error_msg_and_die("%s: syntax error", argument);
    175 }
    176
    177 /* return pointer to next token in buffer and set *buffer to one char
    178 * past the end of the above mentioned token
    179 */
    180 static char *get_token(char **buffer)
    181 {
    182 char *start = NULL;
    183 char *current;
    184
    185 current = skip_whitespace(*buffer);
    186 if (*current != 0) {
    187 start = current;
    188 while (!isspace(*current) && *current != 0) { current++; }
    189 *buffer = current;
    190 }
    191 return start;
    192 }
    193
    194 /* In Perl one might say, scalar m|\s*(\S+)\s*|g */
    195 static int number_of_tokens(char *buffer)
    196 {
    197 int i = 0;
    198 char *b = buffer;
    199 while (get_token(&b)) { i++; }
    200 return i;
    201 }
    202
    203 int dc_main(int argc, char **argv)
    204 {
    205 /* take stuff from stdin if no args are given */
    206 if (argc <= 1) {
    207 int i, len;
    208 char *line = NULL;
    209 char *cursor = NULL;
    210 char *token = NULL;
    211 while ((line = xmalloc_getline(stdin))) {
    212 cursor = line;
    213 len = number_of_tokens(line);
    214 for (i = 0; i < len; i++) {
    215 token = get_token(&cursor);
    216 *cursor++ = 0;
    217 stack_machine(token);
    218 }
    219 free(line);
    220 }
    221 } else {
    222 if (*argv[1]=='-')
    223 bb_show_usage();
    224 while (argc >= 2) {
    225 stack_machine(argv[1]);
    226 argv++;
    227 argc--;
    228 }
    229 }
    230 return EXIT_SUCCESS;
    231 }