Flash Simulator Configuration

The simulator is configured using the mco_flashsim_params_t structure, defined in include/mcoflashsim.h:

    typedef struct {
        size_t                      page_size;       /* page size in bytes */
        mco_xflash_page_t           pages_per_block; /* number of pages in erase block */
        mco_xflash_block_t          n_blocks;        /* total number of blocks */
        timer_unit                  erase_delay;     /* time to perform block erase (microseconds) */
        timer_unit                  read_delay;      /* time to read a page (microseconds) */
        timer_unit                  prog_delay;      /* time to program a page (microseconds) */
        timer_unit                  copy_delay;      /* time to copy back a page (microseconds) */
        mco_bool                    realtime_delays; /* wait for specified delays */
        mco_bool                    file_based;      /* store flash content only in image file */
        mco_bool                    managed;         /* simulate MANAGED flash media (e.g. SD card) */
        unsigned int                random_seed;     /* seed for random number generator */
        unsigned int                bad_block_ratio; /* inject bad block error every bad_block_ratio operations */
        unsigned int                ecc_error_ratio; /* inject ECC error every ecc_error_ratio read operations */
        char const                 *image_filename;  /* Name of file to save/load the flash content */
    } mco_flashsim_params_t;

The pointer to this structure is passed into mco_flashsim_open().

1. The first three fields define the geometry of the emulated device.
2. erase_delay, read_delay, prog_delay, and copy_delay simulate the execution time of basic I/O operations on flash memory.
3. realtime_delays
   • If set to MCO_YES, the simulator enforces real-time execution delays using a simple busy loop. This ensures that applications take the same time to execute in the simulator as they would on actual hardware.
   • If set to MCO_NO, the simulator only accounts for elapsed I/O time without enforcing delays.
4. random_seed: The simulator is capable of generating random errors in erase/prog operations (see bad_block_ratio below). The generator seed can be defined via random_seed.
5. bad_block_ratio: When set to a value greater than 0, the simulator injects an MCO_E_DISK_BAD_BLOCK error during write-type operations - specifically prog (page program), erase (block erase), and copy (page copy). After every (bad_block_ratio - 1) successful write operations, the next such operation will fail with this error.
6. ecc_error_ratio: Controls the frequency of simulated ECC (error-correcting code) errors during read-type operations - specifically read and copy (since copy involves reading source data). After every (ecc_error_ratio - 1) successful read operations, the next read (or read phase of a copy) will return an MCO_E_DISK_CRC_MISMATCH error.
7. image_filename is specifies the file used to persist the flash contents.
8. managed indicates whether the simulator should emulate managed flash media (e.g., an SD card or eMMC). If set to MCO_YES, the simulator relaxes the erase-before-write requirement: pages can be programmed without first erasing their block. This mimics the behavior of managed flash devices that handle wear leveling and bad-block management internally. Note that image save/load functionality (via image_filename) remains active regardless of this setting - it is not disabled in managed mode.