Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
#include <stdio.h> #include <stdint.h> #define CRC32_POLY 0xEDB88320 uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { crc = (crc >> 1) ^ (-((int)crc & 1) & CRC32_POLY); } } return ~crc; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\": %X\n", str, hash); return 0; }
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | #include <stdio.h> #include <stdint.h> #define CRC32_POLY 0xEDB88320 uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { crc = (crc >> 1) ^ (-((int)crc & 1) & CRC32_POLY); } } return ~crc; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\": %X\n", str, hash); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | #include <stdio.h> #include <stdint.h> #define CRC32_POLY 0xEDB88320 uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { crc = (crc >> 1) ^ (-((int)crc & 1) & CRC32_POLY); } } return ~crc; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\": %X\n", str, hash); return 0; } |
CRC32 hash of "correct horse battery staple": CB7E6E10
main.c: In function 'main':
main.c:22:32: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
22 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:4:1: note: include '<string.h>' or provide a declaration of 'strlen'
3 | #include <stdint.h>
+++ |+#include <string.h>
4 |
main.c:22:32: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
22 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:22:32: note: include '<string.h>' or provide a declaration of 'strlen'
Testing if the previous output contains the string cb7e6e10: True
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; static const uint32_t table[256] = { 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D }; for (size_t i = 0; i < len; i++) { crc = table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("%08X\n", hash); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; static const uint32_t table[256] = { 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D }; for (size_t i = 0; i < len; i++) { crc = table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("%08X\n", hash); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 | #include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { uint32_t crc = 0xFFFFFFFF; static const uint32_t table[256] = { 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D }; for (size_t i = 0; i < len; i++) { crc = table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("%08X\n", hash); return 0; } |
CB7E6E10
main.c: In function 'main':
main.c:51:32: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
51 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:4:1: note: include '<string.h>' or provide a declaration of 'strlen'
3 | #include <stdint.h>
+++ |+#include <string.h>
4 |
main.c:51:32: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
51 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:51:32: note: include '<string.h>' or provide a declaration of 'strlen'
Testing if the previous output contains the string cb7e6e10: True
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
#include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { const uint32_t crc_table[256] = { 0, 1996959894, 3993919788, 2567524794, 124634137, 1886057615, 3915621685, 2657392035, 249268274, 2044508324, 3772115230, 2547177864, 162941995, 2125561021, 3887607047, 2428444049, 498536548, 1789927666, 4089016648, 2227061214, 450548861, 1843258603, 4107580753, 2211677639, 325883990, 1684777152, 4251122042, 2321926636, 335633487, 1661365465, 4195302755, 2366115317, 997073096, 1281953886, 3579855332, 2724688242, 1006888145, 1258607687, 3524101629, 2768942443, 901097722, 1119000684, 3686517206, 2898065728, 853044451, 1172266101, 3705015759, 2882616665, 651767980, 1373503546, 3369554304, 3218104598, 565507253, 1454621731, 3485111705, 3099436303, 671266974, 1594198024, 3322730930, 2970347812, 795835527, 1483230225, 3244367275, 3060149565, 1994146192, 31158534, 2563907772, 4023717930, 1907459465, 112637215, 2680153253, 3904427059, 2013776290, 251722036, 2517215374, 3775830040, 2137656763, 141376813, 2439277719, 3865271297, 1802195444, 476864866, 2238001368, 4066508878, 1812370925, 453092731, 2181625025, 4111451223, 1706088902, 314042704, 2344532202, 4240017532, 1658658271, 366619977, 2362670323, 4224994405, 1303535960, 984961486, 2747007092, 3569037538, 1256170817, 1037604311, 2765210733, 3554079995, 1131014506, 879679996, 2909243462, 3663771856, 1141124467, 855842277, 2852801631, 3708648649, 1342533948, 654459306, 3188396048, 3373015174, 1466479909, 544179635, 3110523913, 3462522015, 1591671054, 702138776, 2966460450, 3352799412, 1504918807, 783551873, 3082640443, 3233442989, 3988292384, 2596254646, 62317068, 1957810842, 3939845945, 2647816111, 81470997, 1943803523, 3814918930, 2489596804, 225274430, 2053790376, 3826175755, 2466906013, 167816743, 2097651377, 4027552580, 2265490386, 503444072, 1762050814, 4150417245, 2154129355, 426522225, 1852507879, 4275313526, 2312317920, 282753626, 1742555852, 4189708143, 2394877945, 397917763, 1622183637, 3604390888, 2714866558, 953729732, 1340076626, 3518719985, 2797360999, 1068828381, 1219638859, 3624741850, 2936675148, 906185462, 1090812512, 3747672003, 2825379669, 829329135, 1181335161, 3412177804, 3160834842, 628085408, 1382605366, 3423369109, 3138078467, 570562233, 1426400815, 3317316542, 2998733608, 733239954, 1555261956, 3268935591, 3050360625, 752459403, 1541320221, 2607071920, 3965973030, 1969922972, 40735498, 2617837225, 3943577151, 1913087877, 83908371, 2512341634, 3803740692, 2075208622, 213261112, 2463272603, 3855990285, 2094854071, 198958881, 2262029012, 4057260610, 1759359992, 534414190, 2176718541, 4139329115, 1873836001, 414664567, 2282248934, 4279200368, 1711684554, 285281116, 2405801727, 4167216745, 1634467795, 376229701, 2685067896, 3608007406, 1308918612, 956543938, 2808555105, 3495958263, 1231636301, 1047427035, 2932959818, 3654703836, 1088359270, 936918000, 2847714899, 3736837829, 1202900863, 817233897, 3183342108, 3401237130, 1404277552, 615818150, 3134207493, 3453421203, 1423857449, 601450431, 3009837614, 3294710456, 1567103746, 711928724, 3020668471, 3272380065, 1510334235, 755167117 }; uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc = crc_table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\" is: %u\n", str, hash); return 0; }
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | #include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { const uint32_t crc_table[256] = { 0, 1996959894, 3993919788, 2567524794, 124634137, 1886057615, 3915621685, 2657392035, 249268274, 2044508324, 3772115230, 2547177864, 162941995, 2125561021, 3887607047, 2428444049, 498536548, 1789927666, 4089016648, 2227061214, 450548861, 1843258603, 4107580753, 2211677639, 325883990, 1684777152, 4251122042, 2321926636, 335633487, 1661365465, 4195302755, 2366115317, 997073096, 1281953886, 3579855332, 2724688242, 1006888145, 1258607687, 3524101629, 2768942443, 901097722, 1119000684, 3686517206, 2898065728, 853044451, 1172266101, 3705015759, 2882616665, 651767980, 1373503546, 3369554304, 3218104598, 565507253, 1454621731, 3485111705, 3099436303, 671266974, 1594198024, 3322730930, 2970347812, 795835527, 1483230225, 3244367275, 3060149565, 1994146192, 31158534, 2563907772, 4023717930, 1907459465, 112637215, 2680153253, 3904427059, 2013776290, 251722036, 2517215374, 3775830040, 2137656763, 141376813, 2439277719, 3865271297, 1802195444, 476864866, 2238001368, 4066508878, 1812370925, 453092731, 2181625025, 4111451223, 1706088902, 314042704, 2344532202, 4240017532, 1658658271, 366619977, 2362670323, 4224994405, 1303535960, 984961486, 2747007092, 3569037538, 1256170817, 1037604311, 2765210733, 3554079995, 1131014506, 879679996, 2909243462, 3663771856, 1141124467, 855842277, 2852801631, 3708648649, 1342533948, 654459306, 3188396048, 3373015174, 1466479909, 544179635, 3110523913, 3462522015, 1591671054, 702138776, 2966460450, 3352799412, 1504918807, 783551873, 3082640443, 3233442989, 3988292384, 2596254646, 62317068, 1957810842, 3939845945, 2647816111, 81470997, 1943803523, 3814918930, 2489596804, 225274430, 2053790376, 3826175755, 2466906013, 167816743, 2097651377, 4027552580, 2265490386, 503444072, 1762050814, 4150417245, 2154129355, 426522225, 1852507879, 4275313526, 2312317920, 282753626, 1742555852, 4189708143, 2394877945, 397917763, 1622183637, 3604390888, 2714866558, 953729732, 1340076626, 3518719985, 2797360999, 1068828381, 1219638859, 3624741850, 2936675148, 906185462, 1090812512, 3747672003, 2825379669, 829329135, 1181335161, 3412177804, 3160834842, 628085408, 1382605366, 3423369109, 3138078467, 570562233, 1426400815, 3317316542, 2998733608, 733239954, 1555261956, 3268935591, 3050360625, 752459403, 1541320221, 2607071920, 3965973030, 1969922972, 40735498, 2617837225, 3943577151, 1913087877, 83908371, 2512341634, 3803740692, 2075208622, 213261112, 2463272603, 3855990285, 2094854071, 198958881, 2262029012, 4057260610, 1759359992, 534414190, 2176718541, 4139329115, 1873836001, 414664567, 2282248934, 4279200368, 1711684554, 285281116, 2405801727, 4167216745, 1634467795, 376229701, 2685067896, 3608007406, 1308918612, 956543938, 2808555105, 3495958263, 1231636301, 1047427035, 2932959818, 3654703836, 1088359270, 936918000, 2847714899, 3736837829, 1202900863, 817233897, 3183342108, 3401237130, 1404277552, 615818150, 3134207493, 3453421203, 1423857449, 601450431, 3009837614, 3294710456, 1567103746, 711928724, 3020668471, 3272380065, 1510334235, 755167117 }; uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc = crc_table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\" is: %u\n", str, hash); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | #include <stdio.h> #include <stdint.h> uint32_t crc32(const char *data, size_t len) { const uint32_t crc_table[256] = { 0, 1996959894, 3993919788, 2567524794, 124634137, 1886057615, 3915621685, 2657392035, 249268274, 2044508324, 3772115230, 2547177864, 162941995, 2125561021, 3887607047, 2428444049, 498536548, 1789927666, 4089016648, 2227061214, 450548861, 1843258603, 4107580753, 2211677639, 325883990, 1684777152, 4251122042, 2321926636, 335633487, 1661365465, 4195302755, 2366115317, 997073096, 1281953886, 3579855332, 2724688242, 1006888145, 1258607687, 3524101629, 2768942443, 901097722, 1119000684, 3686517206, 2898065728, 853044451, 1172266101, 3705015759, 2882616665, 651767980, 1373503546, 3369554304, 3218104598, 565507253, 1454621731, 3485111705, 3099436303, 671266974, 1594198024, 3322730930, 2970347812, 795835527, 1483230225, 3244367275, 3060149565, 1994146192, 31158534, 2563907772, 4023717930, 1907459465, 112637215, 2680153253, 3904427059, 2013776290, 251722036, 2517215374, 3775830040, 2137656763, 141376813, 2439277719, 3865271297, 1802195444, 476864866, 2238001368, 4066508878, 1812370925, 453092731, 2181625025, 4111451223, 1706088902, 314042704, 2344532202, 4240017532, 1658658271, 366619977, 2362670323, 4224994405, 1303535960, 984961486, 2747007092, 3569037538, 1256170817, 1037604311, 2765210733, 3554079995, 1131014506, 879679996, 2909243462, 3663771856, 1141124467, 855842277, 2852801631, 3708648649, 1342533948, 654459306, 3188396048, 3373015174, 1466479909, 544179635, 3110523913, 3462522015, 1591671054, 702138776, 2966460450, 3352799412, 1504918807, 783551873, 3082640443, 3233442989, 3988292384, 2596254646, 62317068, 1957810842, 3939845945, 2647816111, 81470997, 1943803523, 3814918930, 2489596804, 225274430, 2053790376, 3826175755, 2466906013, 167816743, 2097651377, 4027552580, 2265490386, 503444072, 1762050814, 4150417245, 2154129355, 426522225, 1852507879, 4275313526, 2312317920, 282753626, 1742555852, 4189708143, 2394877945, 397917763, 1622183637, 3604390888, 2714866558, 953729732, 1340076626, 3518719985, 2797360999, 1068828381, 1219638859, 3624741850, 2936675148, 906185462, 1090812512, 3747672003, 2825379669, 829329135, 1181335161, 3412177804, 3160834842, 628085408, 1382605366, 3423369109, 3138078467, 570562233, 1426400815, 3317316542, 2998733608, 733239954, 1555261956, 3268935591, 3050360625, 752459403, 1541320221, 2607071920, 3965973030, 1969922972, 40735498, 2617837225, 3943577151, 1913087877, 83908371, 2512341634, 3803740692, 2075208622, 213261112, 2463272603, 3855990285, 2094854071, 198958881, 2262029012, 4057260610, 1759359992, 534414190, 2176718541, 4139329115, 1873836001, 414664567, 2282248934, 4279200368, 1711684554, 285281116, 2405801727, 4167216745, 1634467795, 376229701, 2685067896, 3608007406, 1308918612, 956543938, 2808555105, 3495958263, 1231636301, 1047427035, 2932959818, 3654703836, 1088359270, 936918000, 2847714899, 3736837829, 1202900863, 817233897, 3183342108, 3401237130, 1404277552, 615818150, 3134207493, 3453421203, 1423857449, 601450431, 3009837614, 3294710456, 1567103746, 711928724, 3020668471, 3272380065, 1510334235, 755167117 }; uint32_t crc = 0xFFFFFFFF; for (size_t i = 0; i < len; i++) { crc = crc_table[(crc ^ data[i]) & 0xFF] ^ (crc >> 8); } return crc ^ 0xFFFFFFFF; } int main() { const char *str = "correct horse battery staple"; uint32_t hash = crc32(str, strlen(str)); printf("CRC32 hash of \"%s\" is: %u\n", str, hash); return 0; } |
CRC32 hash of "correct horse battery staple" is: 3414060560
main.c: In function 'main':
main.c:50:32: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
50 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:4:1: note: include '<string.h>' or provide a declaration of 'strlen'
3 | #include <stdint.h>
+++ |+#include <string.h>
4 |
main.c:50:32: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
50 | uint32_t hash = crc32(str, strlen(str));
| ^~~~~~
main.c:50:32: note: include '<string.h>' or provide a declaration of 'strlen'
Testing if the previous output contains the string cb7e6e10: False
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #include <stdio.h> unsigned int crc32(const char *data, int len) { unsigned int crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ 0xEDB88320; } else { crc >>= 1; } } } return ~crc; } int main() { const char *data = "correct horse battery staple"; unsigned int hash = crc32(data, 28); printf("%u\n", hash); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #include <stdio.h> unsigned int crc32(const char *data, int len) { unsigned int crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ 0xEDB88320; } else { crc >>= 1; } } } return ~crc; } int main() { const char *data = "correct horse battery staple"; unsigned int hash = crc32(data, 28); printf("%u\n", hash); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #include <stdio.h> unsigned int crc32(const char *data, int len) { unsigned int crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc ^= data[i]; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ 0xEDB88320; } else { crc >>= 1; } } } return ~crc; } int main() { const char *data = "correct horse battery staple"; unsigned int hash = crc32(data, 28); printf("%u\n", hash); return 0; } |
3414060560
Testing if the previous output contains the string cb7e6e10: False
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
Write a c program that calculates the crc32 hash of the string "correct horse battery staple" and prints it to stdout. Dont call any builtin crc32 functions.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #include <stdio.h> #include <string.h> // CRC32 Polynomial #define POLYNOMIAL 0xEDB88320L // CRC32 Table unsigned long crc32_table[256]; // Initialize CRC32 table void init_crc32_table() { for (int i = 0; i < 256; i++) { unsigned long crc = i; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ POLYNOMIAL; } else { crc >>= 1; } } crc32_table[i] = crc; } } // Calculate CRC32 hash of a string unsigned long calculate_crc32(char *str, int len) { unsigned long crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc = (crc >> 8) ^ crc32_table[(crc ^ str[i]) & 0xFF]; } return crc ^ 0xFFFFFFFF; } int main() { char str[] = "correct horse battery staple"; int len = strlen(str); init_crc32_table(); unsigned long crc32 = calculate_crc32(str, len); printf("%08lX\n", crc32); return 0; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #include <stdio.h> #include <string.h> // CRC32 Polynomial #define POLYNOMIAL 0xEDB88320L // CRC32 Table unsigned long crc32_table[256]; // Initialize CRC32 table void init_crc32_table() { for (int i = 0; i < 256; i++) { unsigned long crc = i; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ POLYNOMIAL; } else { crc >>= 1; } } crc32_table[i] = crc; } } // Calculate CRC32 hash of a string unsigned long calculate_crc32(char *str, int len) { unsigned long crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc = (crc >> 8) ^ crc32_table[(crc ^ str[i]) & 0xFF]; } return crc ^ 0xFFFFFFFF; } int main() { char str[] = "correct horse battery staple"; int len = strlen(str); init_crc32_table(); unsigned long crc32 = calculate_crc32(str, len); printf("%08lX\n", crc32); return 0; } |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #include <stdio.h> #include <string.h> // CRC32 Polynomial #define POLYNOMIAL 0xEDB88320L // CRC32 Table unsigned long crc32_table[256]; // Initialize CRC32 table void init_crc32_table() { for (int i = 0; i < 256; i++) { unsigned long crc = i; for (int j = 0; j < 8; j++) { if (crc & 1) { crc = (crc >> 1) ^ POLYNOMIAL; } else { crc >>= 1; } } crc32_table[i] = crc; } } // Calculate CRC32 hash of a string unsigned long calculate_crc32(char *str, int len) { unsigned long crc = 0xFFFFFFFF; for (int i = 0; i < len; i++) { crc = (crc >> 8) ^ crc32_table[(crc ^ str[i]) & 0xFF]; } return crc ^ 0xFFFFFFFF; } int main() { char str[] = "correct horse battery staple"; int len = strlen(str); init_crc32_table(); unsigned long crc32 = calculate_crc32(str, len); printf("%08lX\n", crc32); return 0; } |
CB7E6E10
Testing if the previous output contains the string cb7e6e10: True