add utils

app/src/main/cpp/utils.h

@@ -0,0 +1,84 @@
+//
+// Created by ACER on 2023/02/27.
+//
+
+#ifndef CCCC_UTILS_H
+#define CCCC_UTILS_H
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <random>
+#include <vector>
+#include <sstream>
+#include <iostream>
+
+#include <endian.h>
+#include <android/log.h>
+
+#define LOGTAG "CCCC_LOGGER"
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOGTAG, __VA_ARGS__)
+
+typedef std::vector<uint8_t> bytes;
+
+inline bytes randomBytes(size_t length) {
+    // We use static in order to instantiate the random engine
+    // and the distribution once only.
+    // It may provoke some thread-safety issues.
+    static std::uniform_int_distribution<uint8_t> distribution(
+            std::numeric_limits<uint8_t>::min(),
+            std::numeric_limits<uint8_t>::max());
+    static std::default_random_engine generator;
+
+    std::vector<uint8_t> data(length);
+    std::generate(data.begin(), data.end(), []() { return distribution(generator); });
+    return data;
+}
+
+inline void logBytes(char* msg, const bytes& data) {
+    unsigned char charmap[] = {
+            '0', '1', '2', '3',
+            '4', '5', '6', '7',
+            '8', '9', 'A', 'B',
+            'C', 'D', 'E', 'F'
+    };
+    std::string stream;
+    for (size_t i = 0; i < data.size(); i++) {
+        stream += charmap[(data[i] >> 4)];
+        stream += charmap[data[i] & 0x0f];
+    }
+    LOGI(msg, stream.c_str());
+}
+
+inline uint64_t bytes2num(bytes data) {
+    uint64_t num = 0;
+    num = std::accumulate(data.begin(), data.end(), num,
+                            [](uint64_t l, uint8_t r) {
+                                return (l << 8) | r;
+                            });
+    return num;
+}
+
+inline bytes num2bytes(uint64_t num) {
+    bytes r;
+    uint8_t *b = (uint8_t *) &num;
+    for (size_t i = 0; i < 8; i++) {
+#ifdef __ARMEB__
+        r.push_back(b[i]);
+#else
+        r.push_back(b[7 - i]);
+#endif
+    }
+    return r;
+}
+
+inline uint bytecount(uint64_t num) {
+    // find the least byte needed for num
+    uint count = 0;
+    while (num != 0) {
+        count++;
+        num >>= 8;
+    }
+    return count;
+}
+
+#endif //CCCC_UTILS_H