Init

base.c

@@ -0,0 +1,88 @@
+//
+// Created by bruno on 4/29/25.
+//
+
+#include <string.h>
+#include <stdio.h>
+#include <stdint-gcc.h>
+#include "base.h"
+
+// Base64 decoding table
+const unsigned char dtable[256] = {
+        ['A'] = 0,  ['B'] = 1,  ['C'] = 2,  ['D'] = 3,
+        ['E'] = 4,  ['F'] = 5,  ['G'] = 6,  ['H'] = 7,
+        ['I'] = 8,  ['J'] = 9,  ['K'] = 10, ['L'] = 11,
+        ['M'] = 12, ['N'] = 13, ['O'] = 14, ['P'] = 15,
+        ['Q'] = 16, ['R'] = 17, ['S'] = 18, ['T'] = 19,
+        ['U'] = 20, ['V'] = 21, ['W'] = 22, ['X'] = 23,
+        ['Y'] = 24, ['Z'] = 25,
+        ['a'] = 26, ['b'] = 27, ['c'] = 28, ['d'] = 29,
+        ['e'] = 30, ['f'] = 31, ['g'] = 32, ['h'] = 33,
+        ['i'] = 34, ['j'] = 35, ['k'] = 36, ['l'] = 37,
+        ['m'] = 38, ['n'] = 39, ['o'] = 40, ['p'] = 41,
+        ['q'] = 42, ['r'] = 43, ['s'] = 44, ['t'] = 45,
+        ['u'] = 46, ['v'] = 47, ['w'] = 48, ['x'] = 49,
+        ['y'] = 50, ['z'] = 51,
+        ['0'] = 52, ['1'] = 53, ['2'] = 54, ['3'] = 55,
+        ['4'] = 56, ['5'] = 57, ['6'] = 58, ['7'] = 59,
+        ['8'] = 60, ['9'] = 61, ['+'] = 62, ['/'] = 63,
+};
+
+
+int base64_decode(const char *in, unsigned char *out, size_t *out_len) {
+    size_t len = strlen(in);
+    size_t i, j;
+    unsigned char a, b, c, d;
+
+    if (len % 4 != 0) return -1;
+
+    for (i = 0, j = 0; i < len; i += 4) {
+        a = dtable[(unsigned char)in[i]];
+        b = dtable[(unsigned char)in[i+1]];
+        c = dtable[(unsigned char)in[i+2]];
+        d = dtable[(unsigned char)in[i+3]];
+
+        out[j++] = (a << 2) | (b >> 4);
+        if (in[i+2] != '=') {
+            out[j++] = (b << 4) | (c >> 2);
+            if (in[i+3] != '=')
+                out[j++] = (c << 6) | d;
+        }
+    }
+    *out_len = j;
+    return 0;
+}
+
+void hex_dump(const unsigned char *data, size_t len) {
+    for (size_t i = 0; i < len; i++) {
+        printf("%02X ", data[i]);
+        if ((i + 1) % 16 == 0)
+            printf("\n");
+    }
+    printf("\n");
+}
+
+static uint32_t crc32_table[256];
+
+// Call this once before computing CRCs
+void init_crc32_table(void) {
+    uint32_t poly = 0xEDB88320;  // reversed polynomial of 0x04C11DB7
+    for (uint32_t i = 0; i < 256; i++) {
+        uint32_t crc = i;
+        for (uint8_t j = 0; j < 8; j++) {
+            if (crc & 1)
+                crc = (crc >> 1) ^ poly;
+            else
+                crc >>= 1;
+        }
+        crc32_table[i] = crc;
+    }
+}
+
+uint32_t crc32_le(uint32_t crc, const uint8_t *buf, size_t len) {
+    crc = ~crc;
+    while (len--) {
+        crc = crc32_table[(crc ^ *buf++) & 0xFF] ^ (crc >> 8);
+    }
+    return ~crc;
+}