1 files changed, 135 insertions, 0 deletions
diff --git a/liblfvm/vm_config.cc b/liblfvm/vm_config.cc
new file mode 100644
index 0000000..8acb797
--- /dev/null
+++ b/liblfvm/vm_config.cc
@@ -0,0 +1,135 @@
+/*
+ * This source code is released into the public domain.
+ */
+
+module;
+
+#include <algorithm>
+#include <coroutine>
+#include <expected>
+#include <format>
+#include <functional>
+#include <ranges>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+
+module liblfvm;
+
+import nihil;
+
+namespace lfvm {
+
+/*
+ * Split an option into name and value.
+ */
+[[nodiscard]] auto parse_option(std::string_view str)
+	-> std::expected<std::pair<std::string_view, std::string_view>,
+			 nihil::error>
+{
+	auto split = std::ranges::find(str, '=');
+	if (split == str.end())
+		return std::unexpected(nihil::error(
+				"missing '=' in option string"));
+
+	auto option = std::string_view(str.begin(), split);
+	if (option.empty())
+		return std::unexpected(nihil::error(
+				"invalid option name"));
+
+	auto value = std::string_view(std::next(split), str.end());
+	if (value.empty())
+		return std::unexpected(nihil::error(
+				"invalid option value"));
+
+	return std::make_pair(option, value);
+}
+
+/*
+ * Parse a boolean option (true/false).
+ */
+[[nodiscard]] auto parse_bool(std::string_view value)
+	-> std::expected<bool, nihil::error>
+{
+	using namespace std::literals;
+
+	static auto true_values = std::unordered_set{
+		"yes"sv, "true"sv, "enabled"sv, "on"sv
+	};
+
+	static auto false_values = std::unordered_set{
+		"no"sv, "false"sv, "disabled"sv, "off"sv
+	};
+
+	if (true_values.find(value) != true_values.end())
+		return true;
+
+	if (false_values.find(value) != false_values.end())
+		return false;
+
+	return std::unexpected(nihil::error("invalid value for boolean"));
+}
+
+auto set_vm_option(vm_config &vm, std::string_view option_string)
+	-> std::expected<void, nihil::error>
+{
+	using namespace std::literals;
+
+	// The table of options we know how to set.
+	static auto options = std::unordered_map<
+		std::string_view,
+		std::function<
+			std::expected<void, nihil::error>(
+				vm_config &, std::string_view)
+			>
+		> {
+
+std::make_pair("memory"sv,
+[](vm_config &vm, std::string_view str) -> std::expected<void, nihil::error> {
+	// Due to limitations in UCL, the memory size is limited to
+	// int64_t.  In practice, this is not an issue.
+	auto new_size = co_await nihil::parse_size<std::int64_t>(str);
+	co_await vm.memory_size(new_size);
+	co_return {};
+}),
+
+std::make_pair("ncpus"sv,
+[](vm_config &vm, std::string_view str) -> std::expected<void, nihil::error> {
+	auto ncpus = co_await nihil::parse_size<unsigned>(str);
+	co_await vm.ncpus(ncpus);
+	co_return {};
+}),
+
+std::make_pair("wire_memory"sv,
+[](vm_config &vm, std::string_view str) -> std::expected<void, nihil::error> {
+	auto b = co_await parse_bool(str);
+	vm.wire_memory(b);
+	co_return {};
+}),
+
+std::make_pair("include_memory_in_core"sv,
+[](vm_config &vm, std::string_view str) -> std::expected<void, nihil::error> {
+	auto b = co_await parse_bool(str);
+	vm.include_memory_in_core(b);
+	co_return {};
+}),
+
+	};
+
+	auto [name, value] = co_await parse_option(option_string);
+
+	auto option = options.find(name);
+	if (option == options.end())
+		co_return std::unexpected(nihil::error(
+				std::format("unknown option '{}'", name)));
+
+	co_await option->second(vm, value).transform_error(
+		[&](nihil::error cause) {
+			return nihil::error(
+				std::format("failed to set {}", name),
+				std::move(cause));
+		});
+	co_return {};
+}
+
+} // namespace lfvm