Tactility/TactilityKernel/source/module.cpp

#include <cstring>
#include <algorithm>
#include <new>
#include <tactility/concurrent/mutex.h>
#include <tactility/module.h>

#include "tactility/driver.h"

#include <vector>

constexpr auto* TAG = "module";

struct ModuleInternal {
    bool started = false;
    bool drivers_ready = false;
};

struct ModuleLedger {
    std::vector<Module*> modules;
    Mutex mutex {};

    ModuleLedger() { mutex_construct(&mutex); }
    ~ModuleLedger() { mutex_destruct(&mutex); }
};

static ModuleLedger ledger;

extern "C" {

error_t module_construct(Module* module) {
    if (module->internal != nullptr) {
        LOG_E(TAG, "Module %s was already constructed", module->name);
        return ERROR_INVALID_STATE;
    }
    module->internal = new (std::nothrow) ModuleInternal();
    if (module->internal == nullptr) return ERROR_OUT_OF_MEMORY;
    return ERROR_NONE;
}

error_t module_destruct(Module* module) {
    if (module->internal == nullptr) {
        LOG_E(TAG, "Module %s was already destructed", module->name);
        return ERROR_INVALID_STATE;
    }
    delete module->internal;
    module->internal = nullptr;
    return ERROR_NONE;
}

error_t module_add(Module* module) {
    mutex_lock(&ledger.mutex);
    bool exists = false;
    for (auto* ledger_module : ledger.modules) {
        if (ledger_module == module) {
            exists = true;
            break;
        }
    }
    if (!exists) {
        ledger.modules.push_back(module);
    }
    mutex_unlock(&ledger.mutex);
    return exists ? ERROR_INVALID_STATE : ERROR_NONE;
}

error_t module_remove(Module* module) {
    mutex_lock(&ledger.mutex);
    ledger.modules.erase(std::remove(ledger.modules.begin(), ledger.modules.end(), module), ledger.modules.end());
    mutex_unlock(&ledger.mutex);
    return ERROR_NONE;
}

error_t module_start(Module* module) {
    LOG_I(TAG, "start %s", module->name);

    auto* internal = module->internal;
    if (internal == nullptr) { return ERROR_INVALID_STATE; }
    if (internal->started) { return ERROR_NONE; }

    if (module->start != nullptr) {
        auto error = module->start();
        if (error != ERROR_NONE) {
            return error;
        }
    }

    if (module->drivers != nullptr && !internal->drivers_ready) {
        auto* driver_location = module->drivers;
        while (*driver_location != nullptr) {
            auto driver = *driver_location;
            check(driver_construct_add(driver) == ERROR_NONE);
            driver_location++;
        }
        internal->drivers_ready = true;
    }

    internal->started = true;
    return ERROR_NONE;
}

bool module_is_started(Module* module) {
    auto* internal = module->internal;
    return internal != nullptr && internal->started;
}

error_t module_stop(Module* module) {
    LOG_I(TAG, "stop %s", module->name);

    auto* internal = module->internal;
    if (internal == nullptr) { return ERROR_INVALID_STATE; }
    if (!internal->started) { return ERROR_NONE; }

    if (module->drivers != nullptr && internal->drivers_ready) {
        size_t count = 0;
        while (module->drivers[count] != nullptr) {
            count++;
        }
        for (size_t i = count; i-- > 0;) {
            check(driver_remove_destruct(module->drivers[i]) == ERROR_NONE);
        }
        internal->drivers_ready = false;
    }

    if (module->stop != nullptr) {
        auto error = module->stop();
        if (error != ERROR_NONE) {
            return error;
        }
    }

    internal->started = false;
    return ERROR_NONE;
}

error_t module_construct_add_start(Module* module) {
    error_t error = module_construct(module);
    if (error != ERROR_NONE) { return error; }
    error = module_add(module);
    if (error != ERROR_NONE) { return error; }
    return module_start(module);
}

error_t module_ensure_started(Module* module) {
    if (module->internal == nullptr) {
        error_t result = module_construct(module);
        if (result != ERROR_NONE) { return result; }
    }

    error_t add_result = module_add(module);
    if (add_result != ERROR_NONE && add_result != ERROR_INVALID_STATE) { return add_result; }

    if (!module->internal->started) {
        error_t result = module_start(module);
        if (result != ERROR_NONE) { return result; }
    }

    return ERROR_NONE;
}

error_t module_ensure_destructed(Module* module) {
    if (module->internal != nullptr) {
        error_t result;
        if (module->internal->started) {
            result = module_stop(module);
            if (result != ERROR_NONE) { return result; }
        }

        result = module_remove(module);
        if (result != ERROR_NONE) { return result; }

        result = module_destruct(module);
        if (result != ERROR_NONE) { return result; }
    }

    return ERROR_NONE;
}

bool module_resolve_symbol(Module* module, const char* symbol_name, uintptr_t* symbol_address) {
    if (!module_is_started(module)) return false;
    auto* symbol_ptr = module->symbols;
    if (symbol_ptr == nullptr) return false;
    while (symbol_ptr->name != nullptr) {
        if (strcmp(symbol_ptr->name, symbol_name) == 0) {
            *symbol_address = reinterpret_cast<uintptr_t>(symbol_ptr->symbol);
            return true;
        }
        symbol_ptr++;
    }
    return false;
}

bool module_resolve_symbol_global(const char* symbol_name, uintptr_t* symbol_address) {
    mutex_lock(&ledger.mutex);
    for (auto* module : ledger.modules) {
        if (!module_is_started(module))
            continue;
        if (module_resolve_symbol(module, symbol_name, symbol_address)) {
            mutex_unlock(&ledger.mutex);
            return true;
        }
    }
    mutex_unlock(&ledger.mutex);
    return false;
}

}