Grobkonzept und CRC-Berechnungssoftware

Software/CRC_Test/.gitignore

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+build

Software/CRC_Test/crc.c

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+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+// Berechnen einer 8 Bit CRC-Pruefsumme
+uint8_t crc8(uint8_t* data, size_t size);
+
+// Berechnen einer 32 Bit CRC-Pruefsumme
+uint32_t crc32(uint8_t* inBytes, size_t size, uint32_t polynomial);
+
+// Check einer 32 Bit CRC-Pruefsumme
+int checkCrc32(uint8_t* data, size_t size, uint32_t crc, uint32_t polynomial);
+
+int main()
+{
+    char msg[] = "Hello World!\0\0\0\0";
+    uint32_t crc = crc32((uint8_t*) msg, strlen(msg)+4, 0x4C11DB7);
+    printf("CRC32 of '%s': 0x%08x\n\n", msg, crc);
+
+    int crcValid = checkCrc32((uint8_t*) msg, strlen(msg), crc, 0x4C11DB7);
+    // String einlesen und CRC32 ausgeben
+    // char input[1024];
+    // printf("String eingeben:\n");
+    // while (1)
+    // {
+    //     // Liest eine Zeile von stdin ein und speichert sie in 'eingabe'
+    //     if (fgets(input, sizeof(input), stdin) != NULL) {
+    //         // Entfernt das Newline-Zeichen, das fgets hinzufügt
+    //         size_t laenge = strlen(input);
+    //         if (laenge > 0 && input[laenge - 1] == '\n') {
+    //             input[laenge - 1] = '\0';
+    //         }
+    //     }
+
+    //     crc = crc32((uint8_t*) input, strlen(input));
+    //     printf("'%s' -> 0x%08x\n\n", input, crc);
+    // }
+
+    return 0;
+}
+
+uint8_t crc8(uint8_t* inBytes, size_t size)
+{
+    uint8_t crc = 0x0; // initial value
+    uint8_t polynomial = 0x7;
+
+    for (size_t i = 0; i < size; i++) {
+        for (int bit = 7; bit >= 0; bit--) {
+            // get next bit
+            uint8_t inBit = (inBytes[i] & (1<<bit)) ? 1 : 0;
+
+            // check if MSB is set
+            uint8_t MSB_high = crc & 0x80;
+
+            // input Bit reinschieben
+            crc = (uint8_t) (crc << 1);
+            crc ^= inBit;
+
+            if (MSB_high) {
+                crc ^= polynomial;
+            }
+            // for (int in = 0; in < 8; in++) {
+            //     printf("%d", !!((crc << in) & 0x80));
+            // }
+            // printf("\n");
+        }
+    }
+    return crc;
+}
+
+uint32_t crc32(uint8_t* inBytes, size_t size, uint32_t polynomial)
+{
+    uint32_t crc = 0x0; // initial value
+
+    for (size_t i = 0; i < size; i++) {
+        for (int bit = 7; bit >= 0; bit--) {
+            // get next bit
+            uint8_t inBit = (inBytes[i] & (1<<bit)) ? 1 : 0;
+
+            // check if MSB is set
+            uint32_t MSB_high = crc & 0x80000000;
+
+            // input Bit reinschieben
+            crc <<= 1;
+            crc ^= inBit;
+
+            if (MSB_high) {
+                crc ^= polynomial;
+            }
+            // for (int in = 0; in < 8; in++) {
+            //     printf("%d", !!((crc << in) & 0x80));
+            // }
+            // printf("\n");
+        }
+        // printf("0x%x\n", crc);
+    }
+    return crc;
+}
+
+int checkCrc32(uint8_t* data, size_t size, uint32_t crc, uint32_t polynomial)
+{
+    // Daten und CRC zusammenhaengend in den HEAP Speicher kopieren
+    uint8_t *dataCrc = malloc(size + 4);
+    memcpy_s(dataCrc, size+4, data, size);
+    memcpy_s(dataCrc+size, 4, &crc, 4);
+
+    if (crc32(dataCrc, size+4, polynomial) == 0) return 1;
+    else return 0;
+}