switch-examples/nfc/source/main.c

// Include the most common headers from the C standard library
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>

// Include the main libnx system header, for Switch development
#include <switch.h>
#include "amiibo_char.h"

// See also libnx nfc.h.

#define PRINT_UPD(fmt, ...) ({   \
    printf(fmt, ## __VA_ARGS__); \
    consoleUpdate(NULL);         \
})

// Indefinitely wait for an event to be signaled
// Break when + is pressed, or if the application should quit (in this case, return value will be non-zero)
Result eventWaitLoop(Event *event) {
    Result rc = 0;
    while (appletMainLoop()) {
        rc = eventWait(event, 0);
        hidScanInput();
        if (R_SUCCEEDED(rc) || (hidKeysDown(CONTROLLER_P1_AUTO) & KEY_PLUS))
            break;
    }
    return rc;
}

// Main program entrypoint
int main(int argc, char* argv[])
{
    Result rc = 0;

    // This example uses a text console, as a simple way to output text to the screen.
    // If you want to write a software-rendered graphics application,
    //   take a look at the graphics/simplegfx example, which uses the libnx Framebuffer API instead.
    // If on the other hand you want to write an OpenGL based application,
    //   take a look at the graphics/opengl set of examples, which uses EGL instead.
    consoleInit(NULL);

    PRINT_UPD("NFC example program.\n");

    PRINT_UPD("Scan an amiibo tag to display its character.\n");
    PRINT_UPD("Press + to exit.\n\n");

    // Initialize the nfp:user and nfc:user services.
    rc = nfpuInitialize();

    // Check if NFC is enabled. If not, wait until it is.
    if (R_SUCCEEDED(rc)) {
        bool nfc_enabled = false;
        rc = nfpuIsNfcEnabled(&nfc_enabled);

        if (R_SUCCEEDED(rc) && !nfc_enabled) {
            // Get the availability change event. This is signaled when a change in NFC availability happens.
            Event availability_change_event = {0};
            rc = nfpuAttachAvailabilityChangeEvent(&availability_change_event);

            // Wait for a change in availability.
            if (R_SUCCEEDED(rc)) {
                PRINT_UPD("NFC is disabled. Please turn off plane mode via the quick settings to continue.\n");
                rc = eventWaitLoop(&availability_change_event);
            }

            eventClose(&availability_change_event);
        }
    }

    if (R_FAILED(rc))
        goto fail_0;

    // Get the handle of the first controller with NFC capabilities.
    HidControllerID controller = 0;
    if (R_SUCCEEDED(rc)) {
        u32 device_count;
        rc = nfpuListDevices(&device_count, &controller, 1);
    }

    if (R_FAILED(rc))
        goto fail_0;

    // Get the activation event. This is signaled when a tag is detected.
    Event activate_event = {0};
    if (R_FAILED(nfpuAttachActivateEvent(controller, &activate_event)))
        goto fail_1;

    // Get the deactivation event. This is signaled when a tag is removed.
    Event deactivate_event = {0};
    if (R_FAILED(nfpuAttachDeactivateEvent(controller, &deactivate_event)))
        goto fail_2;

    // Start the detection of tags.
    rc = nfpuStartDetection(controller);
    if (R_SUCCEEDED(rc))
        PRINT_UPD("Scanning for a tag...\n");

    // Wait until a tag is detected.
    if (R_SUCCEEDED(rc)) {
        rc = eventWaitLoop(&activate_event);
        if (R_SUCCEEDED(rc))
            PRINT_UPD("A tag was detected, please do not remove it from the NFC spot.\n");
    }

    // If a tag was successfully detected, load it into memory.
    if (R_SUCCEEDED(rc))
        rc = nfpuMount(controller, NfpuDeviceType_Amiibo, NfpuMountTarget_All);

    // Retrieve the model info data, which contains the amiibo id.
    if (R_SUCCEEDED(rc)) {
        NfpuModelInfo model_info = {0};
        rc = nfpuGetModelInfo(controller, &model_info);
        
        if (R_SUCCEEDED(rc))
            PRINT_UPD("Amiibo character: %s.\n", get_amiibo_char(model_info));
    }
    
    if (R_SUCCEEDED(rc)) {
        PRINT_UPD("You can now remove the tag.\n");
        eventWaitLoop(&deactivate_event);
    }

    // If an error happened during detection/reading, print it.
    if (R_FAILED(rc))
        PRINT_UPD("Error: 0x%x (%04d-%04d).\n", rc, (R_MODULE(rc) | 2000), (R_VALUE(rc) >> 9));
    
    // Unmount the tag.
    nfpuUnmount(controller);

    // Stop the detection of tags.
    nfpuStopDetection(controller);

    // Wait for the user to explicitely exit.
    PRINT_UPD("Press + to exit.\n");
    while (appletMainLoop()) {
        hidScanInput();
        if (hidKeysDown(CONTROLLER_P1_AUTO) & KEY_PLUS)
            break;
    }

    // Cleanup.
fail_2: 
    eventClose(&deactivate_event);
fail_1:
    eventClose(&activate_event);
fail_0:
    nfpuExit();
    // Deinitialize and clean up resources used by the console (important!)
    consoleExit(NULL);
    return 0;
}