diff options
Diffstat (limited to 'miscutils/dc.c')
-rw-r--r-- | miscutils/dc.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/miscutils/dc.c b/miscutils/dc.c new file mode 100644 index 0000000..ff2bc3b --- /dev/null +++ b/miscutils/dc.c @@ -0,0 +1,256 @@ +/* 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 { \ + base = 10; \ +} 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()); +} + +#if ENABLE_FEATURE_DC_LIBM +static void power(void) +{ + double topower = pop(); + + push(pow(pop(), topower)); +} +#endif + +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) +{ + static const char bases[] ALIGN1 = { 2, 8, 10, 16, 0 }; + unsigned b = (unsigned)pop(); + + base = *strchrnul(bases, b); + if (base == 0) { + bb_error_msg("error, base %u is not supported", b); + base = 10; + } +} + +static void print_base(double print) +{ + unsigned x, i; + + if (base == 10) { + printf("%g\n", print); + return; + } + + x = (unsigned)print; + switch (base) { + case 16: + printf("%x\n", x); + break; + case 8: + printf("%o\n", x); + break; + default: /* base 2 */ + i = (unsigned)INT_MAX + 1; + do { + if (x & i) break; + i >>= 1; + } while (i > 1); + do { + bb_putchar('1' - !(x & i)); + i >>= 1; + } while (i); + bb_putchar('\n'); + } +} + +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}, +#if ENABLE_FEATURE_DC_LIBM + {"**", power}, + {"exp", power}, + {"pow", power}, +#endif + {"%", 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 UNUSED_PARAM, 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; +} |