File: bitdump.c 1 /* 2 The MIT License (MIT) 3 4 Copyright © 2020-2025 pacman64 5 6 Permission is hereby granted, free of charge, to any person obtaining a copy of 7 this software and associated documentation files (the “Software”), to deal 8 in the Software without restriction, including without limitation the rights to 9 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 10 of the Software, and to permit persons to whom the Software is furnished to do 11 so, subject to the following conditions: 12 13 The above copyright notice and this permission notice shall be included in all 14 copies or substantial portions of the Software. 15 16 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 SOFTWARE. 23 */ 24 25 /* 26 You can build this command-line app by running 27 28 cc -Wall -s -O2 -o ./bitdump ./bitdump.c 29 */ 30 31 #include <fcntl.h> 32 #include <stdbool.h> 33 #include <stdio.h> 34 #include <string.h> 35 #include <sys/stat.h> 36 37 #ifdef _WIN32 38 #include <windows.h> 39 #endif 40 41 // info is the multi-line help message 42 const char* info = "" 43 "bitdump [options...] [filenames...]\n" 44 "\n" 45 "Show all bits for all input bytes, starting each output line with the\n" 46 "leading byte's offset.\n" 47 "\n" 48 "\n" 49 "Options\n" 50 "\n" 51 " -h, --h show this help message\n" 52 " -help, --help aliases for option -h\n" 53 ""; 54 55 // EMIT_CONST abstracts emitting string constants without their final null byte 56 #define EMIT_CONST(w, x) fwrite(x, sizeof(x) - 1, 1, w) 57 58 inline void write_bytes(FILE* w, const unsigned char* src, size_t len) { 59 fwrite(src, len, 1, w); 60 } 61 62 /* 63 tlp = '(f"{bin(v)[2:]:>08}" for v in range(256))' | lineup 8 | gsub '\t' | 64 tlp 'f" \"{l}\""' 65 */ 66 const unsigned char lookup[256 * 8] = "" 67 "0000000000000001000000100000001100000100000001010000011000000111" 68 "0000100000001001000010100000101100001100000011010000111000001111" 69 "0001000000010001000100100001001100010100000101010001011000010111" 70 "0001100000011001000110100001101100011100000111010001111000011111" 71 "0010000000100001001000100010001100100100001001010010011000100111" 72 "0010100000101001001010100010101100101100001011010010111000101111" 73 "0011000000110001001100100011001100110100001101010011011000110111" 74 "0011100000111001001110100011101100111100001111010011111000111111" 75 "0100000001000001010000100100001101000100010001010100011001000111" 76 "0100100001001001010010100100101101001100010011010100111001001111" 77 "0101000001010001010100100101001101010100010101010101011001010111" 78 "0101100001011001010110100101101101011100010111010101111001011111" 79 "0110000001100001011000100110001101100100011001010110011001100111" 80 "0110100001101001011010100110101101101100011011010110111001101111" 81 "0111000001110001011100100111001101110100011101010111011001110111" 82 "0111100001111001011110100111101101111100011111010111111001111111" 83 "1000000010000001100000101000001110000100100001011000011010000111" 84 "1000100010001001100010101000101110001100100011011000111010001111" 85 "1001000010010001100100101001001110010100100101011001011010010111" 86 "1001100010011001100110101001101110011100100111011001111010011111" 87 "1010000010100001101000101010001110100100101001011010011010100111" 88 "1010100010101001101010101010101110101100101011011010111010101111" 89 "1011000010110001101100101011001110110100101101011011011010110111" 90 "1011100010111001101110101011101110111100101111011011111010111111" 91 "1100000011000001110000101100001111000100110001011100011011000111" 92 "1100100011001001110010101100101111001100110011011100111011001111" 93 "1101000011010001110100101101001111010100110101011101011011010111" 94 "1101100011011001110110101101101111011100110111011101111011011111" 95 "1110000011100001111000101110001111100100111001011110011011100111" 96 "1110100011101001111010101110101111101100111011011110111011101111" 97 "1111000011110001111100101111001111110100111101011111011011110111" 98 "1111100011111001111110101111101111111100111111011111111011111111" 99 ""; 100 101 // write_bin is faster than calling fprintf(w, "%08b", b): this matters 102 // because it's called for every input byte 103 inline void write_bin(FILE* w, unsigned char b) { 104 const void* ptr = &lookup[8 * b]; 105 fwrite(ptr, 8, 1, w); 106 } 107 108 void write_decimal_uint(FILE* w, size_t n) { 109 if (n < 1) { 110 EMIT_CONST(w, "00000000"); 111 return; 112 } 113 114 size_t digits; 115 // 20 is the most digits unsigned 64-bit ints can ever need 116 unsigned char buf[24]; 117 for (digits = 0; n > 0; digits++, n /= 10) { 118 buf[sizeof(buf) - 1 - digits] = (n % 10) + '0'; 119 } 120 121 // left-pad the coming digits up to 8 chars 122 if (digits < 8) { 123 write_bytes(w, (unsigned char*)"00000000", 8 - digits); 124 } 125 126 // emit all digits 127 unsigned char* start = buf + sizeof(buf) - digits; 128 write_bytes(w, start, digits); 129 } 130 131 void write_hex_uint(FILE* w, size_t n) { 132 if (n < 1) { 133 EMIT_CONST(w, "00000000"); 134 return; 135 } 136 137 size_t digits; 138 // 20 is the most digits unsigned 64-bit ints can ever need 139 unsigned char buf[24]; 140 for (digits = 0; n > 0; digits += 2, n /= 256) { 141 unsigned char b = n % 256; 142 const char* hex_digits = "0123456789abcdef"; 143 buf[sizeof(buf) - 1 - digits - 1] = hex_digits[b >> 4]; 144 buf[sizeof(buf) - 1 - digits - 0] = hex_digits[b & 0x0f]; 145 } 146 147 // left-pad the coming digits up to 8 chars 148 if (digits < 8) { 149 write_bytes(w, (unsigned char*)"00000000", 8 - digits); 150 } 151 152 // emit all digits 153 unsigned char* start = buf + sizeof(buf) - digits; 154 write_bytes(w, start, digits); 155 } 156 157 void decimal_offset(FILE* w, size_t offset) { 158 write_decimal_uint(w, offset); 159 putc(' ', w); 160 } 161 162 void hexadecimal_offset(FILE* w, size_t offset) { 163 write_hex_uint(w, offset); 164 putc(' ', w); 165 } 166 167 void no_offset(FILE*, size_t) { 168 } 169 170 // handle_reader shows all bytes read from the source given as colored hex 171 // values, showing offsets and ASCII symbols on the sides of each output line 172 void handle_reader(FILE* w, FILE* src, void (*start_row)(FILE*, size_t)) { 173 const size_t bufcap = 32 * 1024; 174 unsigned char buf[bufcap]; 175 size_t offset = 0; 176 177 while (!feof(w)) { 178 const size_t len = fread(&buf, sizeof(buf[0]), sizeof(buf), src); 179 if (len < 1) { 180 // assume input is over when no bytes were read 181 if (offset > 0) { 182 putc('\n', w); 183 } 184 break; 185 } 186 187 for (size_t i = 0; i < len; i++, offset++) { 188 const size_t rem = offset % 8; 189 if (rem == 0) { 190 if (offset > 0) { 191 putc('\n', w); 192 } 193 start_row(w, offset); 194 } else { 195 putc(' ', w); 196 } 197 write_bin(w, buf[i]); 198 } 199 } 200 } 201 202 // handle_file handles data from the filename given; returns false only when 203 // the file can't be opened 204 bool handle_file(FILE* w, const char* path, void (*start_row)(FILE*, size_t)) { 205 FILE* f = fopen(path, "rb"); 206 if (f == NULL) { 207 // ensure currently-buffered/deferred output shows up right now: not 208 // doing so may scramble results in the common case where stdout and 209 // stderr are the same, thus confusing users 210 putc('\n', w); 211 212 fprintf(stderr, "\x1b[31mcan't open file named %s\x1b[0m\n", path); 213 return false; 214 } 215 216 handle_reader(w, f, start_row); 217 218 fclose(f); 219 return true; 220 } 221 222 // is_help_option simplifies control-flow for func run 223 bool is_help_option(char* s) { 224 return (s[0] == '-') && ( 225 strcmp(s, "-h") == 0 || strcmp(s, "-help") == 0 || 226 strcmp(s, "--h") == 0 || strcmp(s, "--help") == 0 227 ); 228 } 229 230 // run returns the number of errors 231 int run(int argc, char** argv, FILE* w) { 232 size_t files = 0; 233 size_t errors = 0; 234 const void (*start_row)() = decimal_offset; 235 236 // handle all filenames/options given 237 for (size_t i = 1; i < argc && !feof(w); i++) { 238 // a `-` filename stands for the standard input 239 if (argv[i][0] == '-' && argv[i][1] == 0) { 240 handle_reader(w, stdin, start_row); 241 continue; 242 } 243 244 if (is_help_option(argv[i])) { 245 // help option quits the app right away 246 fprintf(stderr, "%s", info); 247 return 0; 248 } 249 250 if (files > 0) { 251 // put an empty line between adjacent outputs 252 putc('\n', w); 253 } 254 255 if (!handle_file(w, argv[i], start_row)) { 256 errors++; 257 } 258 files++; 259 } 260 261 // no filenames means use stdin as the only input 262 if (files == 0) { 263 handle_reader(w, stdin, start_row); 264 } 265 266 return errors; 267 } 268 269 int main(int argc, char** argv) { 270 #ifdef _WIN32 271 setmode(fileno(stdin), O_BINARY); 272 // ensure output lines end in LF instead of CRLF on windows 273 setmode(fileno(stdout), O_BINARY); 274 setmode(fileno(stderr), O_BINARY); 275 #endif 276 277 return run(argc, argv, stdout) == 0 ? 0 : 1; 278 }