add hex conv

CMakeLists.txt

@@ -3,6 +3,9 @@ cmake_minimum_required(VERSION 3.9 FATAL_ERROR)
 project(solanaceae)
 
 add_library(solanaceae_util
+	./solanaceae/util/utils.hpp
+	./solanaceae/util/utils.cpp
+
 	./solanaceae/util/config_model.hpp
 	./solanaceae/util/config_model.inl
 

solanaceae/util/utils.cpp

@@ -0,0 +1,53 @@
+#include "./utils.hpp"
+
+#include <cassert>
+
+namespace detail {
+	constexpr uint8_t nib_from_hex(char c) {
+		assert((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f'));
+
+		if (c >= '0' && c <= '9') {
+			return static_cast<uint8_t>(c) - '0';
+		} else if (c >= 'a' && c <= 'f') {
+			return (static_cast<uint8_t>(c) - 'a') + 10u;
+		} else {
+			return 0u;
+		}
+	}
+
+	constexpr char nib_to_hex(uint8_t c) {
+		assert(c <= 0x0f);
+
+		if (c <= 0x09) {
+			return c + '0';
+		} else {
+			return (c - 10u) + 'a';
+		}
+	}
+} // detail
+
+std::vector<uint8_t> hex2bin(const std::string& str) {
+	return hex2bin(std::string_view{str});
+}
+
+std::vector<uint8_t> hex2bin(const std::string_view str) {
+	assert(str.size() % 2 == 0); // TODO: should this be a hard assert??
+	std::vector<uint8_t> bin{};
+	bin.resize(str.size()/2, 0);
+
+	for (size_t i = 0; i < bin.size(); i++) {
+		bin[i] = detail::nib_from_hex(str[i*2]) << 4 | detail::nib_from_hex(str[i*2+1]);
+	}
+
+	return bin;
+}
+
+std::string bin2hex(const std::vector<uint8_t>& data) {
+	std::string str;
+	for (size_t i = 0; i < data.size(); i++) {
+		str.push_back(detail::nib_to_hex(data[i] >> 4));
+		str.push_back(detail::nib_to_hex(data[i] & 0x0f));
+	}
+	return str;
+}
+

solanaceae/util/utils.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+[[nodiscard]] std::vector<uint8_t> hex2bin(const std::string& str);
+[[nodiscard]] std::vector<uint8_t> hex2bin(const std::string_view str);
+[[nodiscard]] std::string bin2hex(const std::vector<uint8_t>& bin);
+