Besta RTOS NAND dumper. Note that most boards I came across don't have proper support for the nand_* API so this likely wouldn't work as expected on boards other than BA110L, BA742 and KA745C.

nand.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>

#include <muteki/ui/event.h>
#include <muteki/ui/canvas.h>
#include <muteki/errno.h>
#include <muteki/ftl.h>

#include <mutekix/console.h>

#define dbgprintf mutekix_console_printf
#define dbgputs mutekix_console_puts

// NDSF
const unsigned int MAGIC = 0x4653444e;
#define CHECKPOINT_FILE "A:\\nand.sav"
#define DUMP_PART_FILE "A:\\nand.bin"

#define PART_SIZE_MIB 1024


int wait_for_key_press() {
    ui_event_t uievent = {0};
    while (true) {
        if ((TestPendEvent(&uievent) || TestKeyEvent(&uievent)) && GetEvent(&uievent) && uievent.event_type == UI_EVENT_TYPE_KEY) {
            return uievent.key_code0;
        }
    }
}

void print_nand_info() {
    nand_params_t nand_info = {0};
    nand_info.magic = 0x44;

    int result = nand_get_params(0, &nand_info);

    if (result < 0) {
        dbgputs("Failed to read NAND info.");
        return;
    }

    size_t nand_id_len_rational = (nand_info.nand_id_length > 8 || nand_info.nand_id_length <= 0) ? 8 : nand_info.nand_id_length;

    dbgprintf("NAND ID: ");
    for (size_t i = 0; i < nand_id_len_rational; i++) {
        dbgprintf("%02x", nand_info.nand_id[i]);
    }
    dbgputs("");

    dbgprintf("Name: %s\n", nand_info.name);
    dbgprintf("Size: %zd MiB\n", nand_info.size_mib);
    dbgprintf("Data page size: %zd\n", nand_info.data_page_size);
    dbgprintf("Spare page size: %zd\n", nand_info.spare_page_size);
    dbgprintf("Erase size: %zd\n", nand_info.erase_size);
    dbgprintf("unk_0x1c: %d, unk_0x40: %d\n", nand_info.unk_0x1c, nand_info.unk_0x40);

    dbgputs("");
}

size_t load_offset() {
    unsigned int magic;
    size_t offset;
    FILE *f = fopen(CHECKPOINT_FILE, "rb");
    if (f == NULL) {
        return 0;
    }
    
    fread(&magic, 1, sizeof(magic), f);
    if (magic != MAGIC) {
        dbgputs("Invalid checkpoint file. Starting over.");
        fclose(f);
        return 0;
    }

    fread(&offset, 1, sizeof(offset), f);
    fclose(f);
    return offset;
}

void save_offset(size_t offset) {
    FILE *f = fopen(CHECKPOINT_FILE, "wb");
    if (f == NULL) {
        dbgputs("Failed to save checkpoint file.");
        return;
    }

    fwrite(&MAGIC, 1, sizeof(MAGIC), f);
    fwrite(&offset, 1, sizeof(offset), f);

    fclose(f);
}

void dump_nand() {
    bool page_addressing = false;
    size_t mib_offset = load_offset();
    bool bad_read_in_chunk = false;
    bool abort = false;
    
    nand_params_t nand_info = {0};
    nand_info.magic = 0x44;

    int result = nand_get_params(0, &nand_info);

    if (result < 0) {
        dbgputs("Failed to read NAND info.");
        return;
    }
    
    if (nand_info.nand_id_length == 0) {
        dbgputs("Emulated NAND detected. Using page addressing mode.");
        page_addressing = true;
    }

    size_t pages_per_mib = 0x100000 / nand_info.data_page_size;
    size_t leftover_size_mib = nand_info.size_mib - mib_offset;
    size_t actual_size_mib = (leftover_size_mib < PART_SIZE_MIB) ? leftover_size_mib : PART_SIZE_MIB;

    size_t page_offset = mib_offset * pages_per_mib;
    if (!page_addressing) {
        page_offset *= nand_info.data_page_size;
    }

    void *buffer = malloc(nand_info.data_page_size);
    if (buffer == NULL) {
        dbgputs("Failed to allocate memory.");
        return;
    }
    FILE *f = fopen(DUMP_PART_FILE, "wb");
    if (f == NULL) {
        dbgputs("Failed to open file.");
        free(buffer);
        return;
    }

    dbgprintf("Dumping NAND region %d MiB - %d MiB", mib_offset, mib_offset + actual_size_mib);

    for (size_t rel_offset = 0; rel_offset < actual_size_mib * 0x100000; rel_offset += nand_info.data_page_size) {
        if (page_addressing) {
            int read_result = nand_read_page(0, page_offset, buffer, 1, 0);
            if (read_result < 0) {
                dbgputs("Unrecoverable read error. Aborting.");
                abort = true;
                break;
            }
            fwrite(buffer, 1, nand_info.data_page_size, f);
            page_offset++;
        } else {
            size_t sub_page_offset = page_offset;
            while (sub_page_offset < page_offset + nand_info.data_page_size) {
                // Try to read a page. Continue when there's an error.
                int read_result = nand_read_page(0, sub_page_offset, buffer, 1, 0);
                if (read_result < 0) {
                    bad_read_in_chunk = true;
                }
                if (read_result < 0 || sub_page_offset != page_offset) {
                    // There's some error. Read sub-page by sub-page until we got the entire page.
                    fwrite(buffer, 1, 512, f);
                    sub_page_offset += 512;
                } else {
                    // We got it on first try. Break out of the loop.
                    fwrite(buffer, 1, nand_info.data_page_size, f);
                    break;
                }
            }
            page_offset += nand_info.data_page_size;
        }
        if (rel_offset != 0 && rel_offset % 0x100000 == 0) {
            dbgprintf("%c", bad_read_in_chunk ? '!' : '.');
            bad_read_in_chunk = false;
            mib_offset++;
        }
    }
    if (!abort) {
        dbgprintf("%c", bad_read_in_chunk ? '!' : '.');
        mib_offset++;
        save_offset(mib_offset);
    }
    fclose(f);
    free(buffer);
    dbgputs("");
}

int main() {
    bool waiting_for_option = true;
    bool reprint_options = true;

    mutekix_console_init(NULL);

    dbgputs("Besta RTOS NAND Dumper");

    while (waiting_for_option) {
        if (reprint_options) {
            dbgputs("Select an option:");
            dbgputs("1: NAND Info");
            dbgputs("2: Continue from last checkpoint");
            dbgputs("3: Start over");
            dbgputs("Q: Quit\n");
        }
        switch (wait_for_key_press()) {
            case KEY_1:
                print_nand_info();
                reprint_options = true;
                break;
            case KEY_2:
                dump_nand();
                reprint_options = true;
                break;
            case KEY_3:
                unlink(CHECKPOINT_FILE);
                dump_nand();
                reprint_options = true;
                break;
            case KEY_Q: // fall-through
            case KEY_ESC:
                waiting_for_option = false;
                reprint_options = false;
                break;
            default:
                reprint_options = false;
                break;
        }
        ClearAllEvents();
    }
    mutekix_console_fini();
    return 0;
}