init
This commit is contained in:
commit
133ed9188a
131
args.h
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131
args.h
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/* args.h - argument handling
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Copyright (C) 2012 Connor Olding
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ARGS_H_
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#define ARGS_H_
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#include <stdio.h>
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#include <string.h>
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/* interface */
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extern char args_info[];
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extern char args_usage[];
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extern char args_help_suffix[];
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extern const int args_count;
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extern char* args_args[];
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extern void (*args_functions[])();
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void args_handle(int argc, char* argv[]);
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char* args_poll();
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void args_print_help();
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/* implemenation */
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static const int args_columns = 3;
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static char* args_program_name = NULL;
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static int args_argc = 0;
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static char** args_argv = NULL;
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static int args_current = 0;
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static int args_previous = 0;
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static void args_print_info()
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{
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printf(args_info);
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}
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static void args_print_usage()
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{
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printf(args_usage, args_program_name);
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}
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static void args_print_args()
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{
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int i;
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for (i = 0; i < args_count * args_columns; i += args_columns) {
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printf(" %s, %s %s\n",
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args_args[i], args_args[i + 1], args_args[i + 2]);
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}
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printf(args_help_suffix);
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}
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void args_print_help()
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{
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args_print_info();
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puts("");
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args_print_args();
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exit(0);
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}
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static int args_get_index(char* name)
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{
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int i;
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for (i = 0; i < args_count * args_columns; i++) {
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if (i % args_columns == args_columns - 1)
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continue; /* skip checking the description column */
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if (!strcmp(args_args[i], name)) {
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return i / args_columns;
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}
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}
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return -1;
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}
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char* args_poll()
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{
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if (args_current >= args_argc) {
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if (args_current - 1 == args_previous)
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fprintf(stderr, "%s requires an argument.\n",
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args_argv[args_previous]);
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else
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fprintf(stderr, "%s requires another argument.\n",
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args_argv[args_previous]);
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args_print_usage();
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exit(1);
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}
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args_current++;
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return args_argv[args_current - 1];
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}
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void args_handle(int argc, char** argv)
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{
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args_argc = argc;
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args_argv = argv;
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args_current = 0;
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args_program_name = args_poll();
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while (args_current < args_argc) {
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char* name;
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int index;
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args_previous = args_current;
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name = args_poll();
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index = args_get_index(name);
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if (index < 0) {
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fprintf(stderr, "Unknown option: %s\n", name);
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args_print_usage();
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exit(1);
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}
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args_functions[index]();
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}
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}
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#endif
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161
crc32.h
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161
crc32.h
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/* crc32.h - 32-bit cyclic redundancy check calcuations
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Copyright (C) 2012 Connor Olding
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef CRC32_H_
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#define CRC32_H_
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#include <stdlib.h>
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/* interface */
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typedef unsigned long uint32;
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void crc_cycle(uint32 *remainder, char c);
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uint32 crc_reflect(uint32 input);
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void crc_set_big_endian();
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void crc_set_little_endian();
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void crc_set_polynomial(uint32 p);
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/* implementation */
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static char crc_big_endian = 0;
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static const int crc_table_size = 0x100;
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static uint32* crc_be_table = NULL; /* big endian */
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static uint32* crc_le_table = NULL; /* little endian */
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static uint32 crc_polynomial = 0x04C11DB7;
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uint32 crc_reflect(uint32 input)
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{
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uint32 reflected = 0;
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unsigned int i;
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for (i = 0; i < sizeof(uint32) * 8; i++) {
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reflected <<= 1;
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reflected |= input & 1;
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input >>= 1;
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}
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return reflected;
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}
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static uint32* crc_alloc(size_t size)
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{
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uint32* p = (uint32*) malloc(size * sizeof(uint32));
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if (p == NULL)
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exit(1);
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return p;
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}
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static void crc_allocate_tables_once()
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{
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static char allocated = 0;
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if (crc_big_endian && !(allocated & 1)) {
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crc_be_table = crc_alloc(crc_table_size);
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allocated |= 1;
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} else if (!crc_big_endian && !(allocated & 2)) {
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crc_le_table = crc_alloc(crc_table_size);
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allocated |= 2;
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}
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}
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static void crc_fill_big_endian_table()
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{
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const uint32 least_significant_bit = 1 << 31;
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int c, i;
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crc_allocate_tables_once();
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for (c = 0; c < crc_table_size; c++) {
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crc_be_table[c] = c << 24;
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for (i = 0; i < 8; i++) {
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if (crc_be_table[c] & least_significant_bit) {
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crc_be_table[c] <<= 1;
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crc_be_table[c] ^= crc_polynomial;
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} else {
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crc_be_table[c] <<= 1;
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}
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}
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}
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}
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static void crc_fill_little_endian_table()
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{
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const uint32 least_significant_bit = 1;
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const uint32 reflected_polynomial = crc_reflect(crc_polynomial);
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int c, i;
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crc_allocate_tables_once();
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/* printf("p: %08X\n", (int)reflected_polynomial); */
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for (c = 0; c < crc_table_size; c++) {
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crc_le_table[c] = c;
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for (i = 0; i < 8; i++) {
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if (crc_le_table[c] & least_significant_bit) {
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crc_le_table[c] >>= 1;
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crc_le_table[c] ^= reflected_polynomial;
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} else {
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crc_le_table[c] >>= 1;
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}
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}
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}
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}
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static void crc_fill_tables_once()
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{
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static char filled = 0;
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if (crc_big_endian && !(filled & 1)) {
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crc_fill_big_endian_table();
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filled |= 1;
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} else if (!crc_big_endian && !(filled & 2)) {
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crc_fill_little_endian_table();
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filled |= 2;
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}
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}
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void crc_set_big_endian()
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{
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crc_big_endian = 1;
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}
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void crc_set_little_endian()
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{
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crc_big_endian = 0;
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}
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void crc_set_polynomial(uint32 p)
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{
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crc_polynomial = p;
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}
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void crc_cycle(uint32 *remainder, char c)
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{
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crc_fill_tables_once();
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if (crc_big_endian) {
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const uint32 newByte = crc_be_table[
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((*remainder) >> 24) ^ c];
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/* printf("%08X00 ^ %08X =\n",
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(int)(*remainder), (int)newByte); */
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*remainder = ((*remainder) << 8) ^ newByte;
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} else {
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const uint32 newByte = crc_le_table[
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((*remainder) ^ c) & 0xFF];
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/* printf(" %08X ^ %08X =\n",
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(int)((*remainder) >> 8), (int)newByte); */
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*remainder = ((*remainder) >> 8) ^ newByte;
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}
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}
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#endif
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151
main.c
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151
main.c
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@ -0,0 +1,151 @@
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/* crc32 - 32-bit cyclic redundancy check calculator
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Copyright (C) 2012 Connor Olding
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "crc32.h"
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#include "args.h"
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#ifdef _MSC_VER
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#define FREOPEN_BLANK ("")
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#else
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#define FREOPEN_BLANK (NULL)
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#endif
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static uint32 remainder = 0xFFFFFFFF;
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static FILE* input_stream = NULL;
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static char* input_name = "-";
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static char print_binary = 0;
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static char xor_output = 1;
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static char reflect_output = 0;
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char args_info[] = "crc32 - 32-bit cyclic redundancy check calculator\n";
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char args_usage[] = "Usage: %s [-i f] [-s n] [-p n] [-e] [-x] [-r] [-b]\n";
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char args_help_suffix[] = "\n\
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numbers (n) can be entered as hexadecimal or octal with prefixes\n";
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const int args_count = 8;
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char* args_args[] = {
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"-h","--help"," display this text",
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"-i","--input","f open file f for reading (default: stdin)",
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"-s","--start-at","n start cycle with n (default: 0xFFFFFFFF)",
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"-p","--polynomial","n use n for crc calculations (default: 0x04C11DB7)",
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"-e","--big-endian"," use big endian calculations (default: little)",
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"-b","--binary"," output as binary (default: hex with newline)",
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"-x","--xor"," xor the output by 0xFFFFFFFF",
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"-r","--reflect"," reverse the bits of the output",
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};
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void start_at()
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{
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remainder = strtoul(args_poll(), NULL, 0);
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}
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void set_input()
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{
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input_name = args_poll();
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}
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void set_polynomial()
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{
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const int p = strtoul(args_poll(), NULL, 0);
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crc_set_polynomial(p);
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}
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void set_big_endian()
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{
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crc_set_big_endian();
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}
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void set_binary()
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{
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print_binary = 1;
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}
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void set_xor()
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{
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xor_output = 0;
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}
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void set_reflect()
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{
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reflect_output = 1;
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}
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void (*args_functions[])() =
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{args_print_help, set_input, start_at, set_polynomial,
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set_big_endian, set_binary, set_xor, set_reflect};
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static void open_stream()
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{
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const char mode[] = "rb";
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if (!strcmp(input_name, "-")) {
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freopen(FREOPEN_BLANK, mode, stdin);
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input_stream = stdin;
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} else {
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input_stream = fopen(input_name, mode);
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}
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if (input_stream == NULL) {
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fprintf(stderr, "Could not open file for reading: %s\n",
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input_name);
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exit(1);
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}
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}
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static void close_stream()
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{
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fclose(input_stream);
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}
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static void cycle_input()
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{
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int c;
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open_stream();
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while ((c = getc(input_stream)) != EOF) {
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crc_cycle(&remainder, c);
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}
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close_stream();
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if (xor_output)
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remainder ^= 0xFFFFFFFF;
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if (reflect_output)
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remainder = crc_reflect(remainder);
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/* if remainder has unnecessary bits from
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left shifting, remove them
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remainder &= 0xFFFFFFFF;
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*/
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}
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static void print_crc()
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{
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if (print_binary)
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fwrite(&remainder, sizeof(remainder), 1, stdout);
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else
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printf("%08X\n", (int) remainder);
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}
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int main(int argc, char** argv)
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{
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crc_set_little_endian();
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args_handle(argc, argv);
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cycle_input();
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print_crc();
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return 0;
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}
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